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Bladder

The urinary bladder is a hollow, muscular organ located in the pelvic cavity that functions as a reservoir for urine produced by the kidneys.^[1] It receives urine through the paired ureters and stores it until voluntary expulsion via the urethra during the process of micturition.^[2] In healthy adults, the bladder typically holds 400 to 600 milliliters of urine, though the first sensation of fullness often occurs at around 150 to 250 milliliters.^[3] Structurally, the bladder consists of a detrusor muscle layer composed of smooth muscle that allows it to expand during filling and contract forcefully during emptying, surrounded by an inner mucosal lining called the urothelium that provides a barrier against urine reabsorption.^[2] The organ is divided into the dome (or apex), body, fundus, and neck, with the trigone region at the base marking the entry points of the ureters and the internal urethral orifice.^[1] Positioned posterior to the pubic symphysis and anterior to the vagina in females or rectum in males, the bladder's location shifts from intra-abdominal in children to pelvic in adults as it grows.^[1] The bladder's function is regulated by a complex neural system involving sympathetic nerves for storage (relaxing the detrusor and contracting the bladder neck) and parasympathetic nerves for voiding (contracting the detrusor and relaxing the urethra), coordinated by centers in the brainstem and higher cortical areas for voluntary control.^[2] This coordination typically develops between ages 2 and 4 years, enabling conscious regulation of urination.^[1] Beyond storage and excretion, the bladder contributes to maintaining urinary tract homeostasis by modulating urine composition through epithelial transport mechanisms.^[2]

Structure

Gross anatomy

The urinary bladder is a hollow, muscular organ located in the pelvic cavity, positioned posterior to the pubic symphysis and anterior to the rectum in males or the uterus and vagina in females.^[4]^[5] In males, it lies superior to the prostate gland and posterior to the seminal vesicles, while in females, its inferior surface rests on the pelvic floor near the pubic symphysis.^[6] This positioning reflects sexual dimorphism, with the male detrusor muscle thicker to accommodate the longer urethra and associated reproductive structures due to higher voiding pressures.^[7] The bladder's shape varies with its degree of distension: it assumes a tetrahedral form when empty, with a base, apex, and inferolateral surfaces, and becomes globular or oval when full.^[8] In adults, its typical capacity ranges from 400 to 600 mL, allowing for urine storage without significant discomfort, though overdistension beyond this volume risks ischemic damage to the detrusor muscle and potential irreversible impairment.^[9] Internally, the bladder features a smooth triangular region known as the trigone at its base, formed by the right and left ureteral orifices superiorly and the internal urethral orifice inferiorly.^[10] This trigone serves as a stable area for the entry and exit of urine, with the ureteral orifices positioned at the superolateral angles and the urethral orifice at the apex of the triangle.^[11] The bladder wall consists of four primary layers from inner to outer: the mucosa lined by transitional epithelium, the submucosa (or lamina propria) of connective tissue, the muscularis layer dominated by the detrusor muscle, and an outer adventitia or serosa depending on the region's peritoneal covering.^[12] The serosa covers the superior surface where the bladder is intraperitoneal when distended, while the adventitia envelops the remainder as an extraperitoneal structure.^[13]

Microanatomy

The urinary bladder's wall consists of four primary histological layers, each contributing to its function in urine storage and expulsion: the mucosa, submucosa (or lamina propria), muscularis, and adventitia/serosa.^[12] The innermost mucosa is lined by the urothelium, a specialized stratified transitional epithelium that varies in thickness from 5 to 7 layers when the bladder is relaxed to 2 to 3 layers when distended, enabling accommodation of urine volume without compromising barrier integrity.^[12] This epithelium comprises basal cells (a single layer of cuboidal cells with mitotic potential), intermediate cells (2 to 3 layers of polygonal or low columnar cells rich in glycogen), and apical umbrella cells (a superficial layer of large, often binucleated, dome-shaped cells that form the primary impermeable barrier).^[14]^[12] The urothelium's impermeability is maintained by several cellular adaptations, including tight junctions between umbrella cells that minimize paracellular flux of ions and solutes, and asymmetric unit membrane plaques composed of uroplakins (hexagonal protein complexes covering up to 90% of the apical surface) that provide a highly resistant lipid-protein barrier against urine penetration.^[12] Additionally, a superficial glycosaminoglycan (GAG) layer, primarily chondroitin sulfate, coats the umbrella cells, shielding the underlying tissue from the toxic components of urine such as urea and cations while facilitating selective permeability.^[15] Beneath the urothelium lies the lamina propria (functionally equivalent to the submucosa in the bladder), a loose connective tissue layer rich in extracellular matrix, elastic fibers, blood vessels, lymphatics, nerves, fibroblasts, immune cells, and occasional adipocytes, which supports mucosal folding and nutrient diffusion.^[12]^[14] The muscularis, or detrusor muscle, forms the thick intermediate layer responsible for bladder contraction, consisting of three interlacing smooth muscle bundles: an inner longitudinal layer, a middle circular layer, and an outer longitudinal layer, which are randomly oriented in the bladder body but more distinctly layered near the neck for coordinated peristalsis.^[12]^[14] This arrangement allows powerful, omnidirectional contraction during voiding. The outermost adventitia is a fibrous connective tissue layer containing blood vessels and nerves, while the superior surface (dome) is partially covered by a thin serosa, a visceral peritoneum extension that provides peritoneal continuity without a distinct mesothelial lining elsewhere.^[12] Specialized mucosal folds, known as rugae, arise from the lamina propria and urothelium, permitting expansion of the bladder wall during filling without stretching the tissue excessively.^[14]

Vascular supply

The arterial supply to the urinary bladder primarily arises from branches of the internal iliac artery, including the superior, middle, and inferior vesical arteries. The superior vesical artery, a remnant of the umbilical artery, supplies the superior and anterosuperior aspects of the bladder, while the middle vesical artery provides blood to the base and the inferior vesical artery to the inferolateral surfaces and lower portion. In females, the uterine artery contributes additional supply to the anterosuperior bladder wall via vaginal and vesical branches. Variations occur, such as the inferior vesical artery originating from the internal pudendal artery in some individuals, and supplementary contributions from the obturator and inferior gluteal arteries.^[1]^[16]^[17] Venous drainage occurs through the vesical venous plexus, a network surrounding the bladder that collects blood from its walls and empties primarily into the internal iliac veins on both sides. This plexus forms connections with adjacent pelvic veins, including potential portocaval anastomoses via links to superior rectal veins in cases of portal hypertension, allowing collateral flow between portal and systemic circulations. The internal iliac veins then converge into the common iliac veins, ultimately reaching the inferior vena cava.^[1]^[18] Lymphatic drainage of the bladder follows regional patterns based on anatomical zones. The superolateral surfaces drain to the external iliac lymph nodes, while the posterior and inferolateral aspects, including the trigone region, primarily drain to the internal iliac, sacral, and common iliac nodes. The fundus and neck may also involve the external and common iliac nodes, with bilateral drainage common regardless of tumor laterality in pathological contexts. These pathways originate from a subepithelial and muscular lymphatic plexus within the bladder wall.^[1]^[19]^[20] Developmentally, the bladder's superior vesical artery persists from the allantoic (umbilical) artery, which supplies the early cloaca-derived bladder; remnants of these vessels may remain in the urachus, the fibrous cord connecting the bladder apex to the umbilicus, potentially leading to patent urachal anomalies if not fully obliterated.^[21]^[22]

Innervation

The innervation of the bladder involves a coordinated network of autonomic and somatic nerves that regulate storage and voiding functions, with sensory afferents providing feedback on bladder distension. Parasympathetic fibers originate from the sacral spinal cord segments S2-S4, traveling via the pelvic splanchnic nerves (nervi erigentes) to synapse in the inferior hypogastric (pelvic) plexus and intramural ganglia, where they release acetylcholine to stimulate muscarinic receptors on detrusor smooth muscle cells, promoting contraction during micturition, while also facilitating relaxation of the internal urethral sphincter.^[1]^[23] Sympathetic innervation arises from the lower thoracic and upper lumbar spinal segments (T10-L2), with preganglionic fibers exiting via the lumbar splanchnic nerves to form the superior hypogastric plexus, which divides into the hypogastric nerves connecting to the inferior hypogastric plexus; these fibers release norepinephrine to inhibit detrusor contraction via β-adrenergic receptors and contract the internal urethral sphincter through α-adrenergic receptors, thereby facilitating urine storage by maintaining low intravesical pressure.^[1]^[23] Somatic control is mediated by the pudendal nerve, originating from S2-S4, which innervates the external urethral sphincter composed of striated muscle; this allows voluntary contraction via cholinergic transmission at nicotinic receptors to prevent leakage during storage, with relaxation enabling voiding.^[1]^[23] Sensory afferents consist primarily of myelinated Aδ-fibers, which detect bladder wall stretch and fullness to signal the urge to void, and unmyelinated C-fibers, which respond to noxious stimuli, pain, or excessive distension; these travel alongside efferent pathways in the pelvic (for the bladder dome and body) and hypogastric (for the base and trigone) nerves, synapsing in the lumbosacral spinal cord to convey visceral sensations to higher centers.^[1]^[23] Reflex arcs for bladder control are coordinated at the spinal level in the sacral cord (S2-S4), where afferent inputs trigger parasympathetic outflow for detrusor contraction and pudendal inhibition for sphincter relaxation during micturition, while supraspinal modulation occurs via the pontine micturition center in the brainstem, which integrates cortical inputs for voluntary initiation and cessation of voiding, ensuring coordinated autonomic and somatic responses.^[1]^[23]

Embryonic development

The urinary bladder originates from the cloaca, a common cavity for the digestive and urogenital systems in the early embryo. During the fourth week of gestation, the cloaca is divided by the descending urorectal septum into the anterior urogenital sinus and the posterior anorectal canal, with this process completing by week 7.^[24] The cranial portion of the urogenital sinus expands to form the bladder primordium, while the caudal part develops into the urethra.^[24] The vesicoureteral junction forms through the interaction of the ureteric buds, which arise from the mesonephric (Wolffian) ducts around week 5, and the urogenital sinus. Initially, the ureteric buds open into the mesonephric ducts, but by week 6, they separate and migrate cranially to open directly into the posterior bladder wall, establishing the oblique intramural course that prevents reflux.^[24] As the kidneys ascend between weeks 6 and 9, the ureters elongate, positioning their orifices at the superolateral aspects of the bladder trigone.^[24] The allantois, an extraembryonic structure connected to the urogenital sinus, is incorporated into the ventral bladder wall during early development. By the end of the first trimester, the intraembryonic portion of the allantois obliterates, forming the urachus, which persists as the median umbilical ligament in adults.^[24] The bladder trigone, the triangular area bounded by the ureteral orifices and urethral opening, develops from the absorbed common excretory ducts (derived from the mesonephric ducts) incorporated into the posterior bladder wall around weeks 6 to 7. This mesodermal origin contrasts with the endodermal derivation of the rest of the bladder, leading to distinct epithelial and immunological properties, such as differences in antigen expression and immune surveillance that may influence susceptibility to certain pathologies. However, recent molecular studies suggest the trigone epithelium may be primarily endodermal in origin, challenging the classic view and potentially affecting interpretations of its unique properties.^[24]^[25]^[26] Sexual differentiation of the bladder and urethra begins around weeks 9 to 12, influenced by gonadal hormones. In males, under androgen stimulation, the mesonephric ducts persist and contribute to the prostatic urethra, with the prostatic utricle forming as a small blind pouch from the caudal mesonephric duct remnants at the verumontanum. In females, the mesonephric ducts largely regress due to the absence of androgens, leaving Gartner's duct as a vestigial remnant that may run parallel to the vagina and occasionally cause cysts.^[24] Congenital anomalies of the bladder often arise from disruptions in these processes, such as incomplete septation of the cloaca leading to bladder exstrophy, where the bladder mucosa is exposed externally due to failed abdominal wall closure around weeks 4 to 6. Ectopic ureter results from abnormal separation of the ureteric bud from the mesonephric duct, causing the ureter to insert aberrantly into the urethra, vagina, or seminal vesicles.^[24]

Physiology

Urine storage

The bladder's ability to store urine relies on a low-pressure accommodation process that allows gradual filling without significant increases in intravesical pressure, primarily through detrusor muscle relaxation mediated by sympathetic innervation and β3-adrenergic receptor activation.^[27] This relaxation, combined with urothelial signaling involving ATP exocytosis, promotes bladder wall compliance and enables storage of up to 400-600 mL of urine in healthy adults.^[27] Continence during storage is maintained by the coordinated action of the internal and external urethral sphincters. The internal sphincter, composed of smooth muscle at the bladder-urethra junction, remains tonically contracted under sympathetic control to prevent urine leakage, while the external sphincter, made of striated muscle, provides voluntary somatic regulation via the pudendal nerve.^[28]^[29] The bladder mucosa serves as a protective barrier, with its apical glycosaminoglycan (GAG) layer acting as a waterproof coating that isolates urothelial cells from urinary solutes, thereby preventing reabsorption of urine components and reducing irritation to the underlying tissue.^[30] Damage to this GAG layer can compromise barrier function, leading to increased permeability.^[31] Sensory feedback during filling is provided by low-threshold Aδ mechanoreceptive afferents in the pelvic nerve, which respond to bladder distension with graded firing rates and transmit signals via the spinal cord to the brainstem, informing the brain of fill status and eliciting storage reflexes.^[32] These afferents activate at pressures below 25 mmHg, aligning with the initial sensations of bladder fullness reported at approximately 40% of capacity.^[32] Bladder capacity varies with age; in children, it increases progressively through maturation and toilet training, estimated as (age in years + 2) × 30 mL, reaching adult levels of approximately 400–500 mL.^[3] In the elderly, capacity typically decreases due to reduced compliance and detrusor instability, contributing to lower storage volumes.^[33]

Micturition process

The micturition process, also known as urination or voiding, involves a coordinated sequence of neural and muscular events that enable the bladder to empty efficiently while maintaining continence until appropriate. This reflex arc is initiated when the bladder reaches a threshold volume, typically between 200 and 400 mL in adults, at which point stretch receptors in the detrusor muscle detect distension and send afferent signals via pelvic nerves to the sacral spinal cord (S2-S4 segments). These sacral signals are then integrated by the pontine micturition center (PMC) in the brainstem, which serves as the primary switch for transitioning from urine storage to expulsion by activating parasympathetic outflow and inhibiting sympathetic and somatic pathways.^[34] Once initiated, detrusor contraction begins under parasympathetic mediation from the pelvic nerves, releasing acetylcholine onto M3 muscarinic receptors in the bladder smooth muscle. This contraction proceeds in two phases: an initial isometric phase where intravesical pressure rises without significant volume change due to closed sphincters, followed by an isotonic phase as urine flows out, generating peak detrusor pressures of approximately 20-40 cmH₂O in healthy adults to overcome urethral resistance.^[35]^[36] Concurrently, sphincter relaxation occurs sequentially: the internal urethral sphincter (smooth muscle) relaxes first via parasympathetic release of nitric oxide, followed by inhibition of the external urethral sphincter (skeletal muscle) through pudendal nerve withdrawal, ensuring coordinated outlet opening.^[34] Urethral dynamics during micturition include funneling of the bladder neck and proximal urethra, which widens the outflow path to facilitate urine expulsion, resulting in typical peak flow rates of 20-25 mL/s in males and slightly higher (25-30 mL/s) in females due to shorter urethral length.^[37] Volitional control overlays this reflex, allowing postponement of voiding through cortical override from the frontal micturition center in the prefrontal cortex, which tonically suppresses PMC activity until socially appropriate; this inhibitory mechanism matures by ages 3-4 years, enabling reliable daytime continence in children.^[34]

Clinical significance

Infections and inflammations

Bacterial cystitis, the most common form of bladder infection, is primarily caused by Escherichia coli, which accounts for the majority of cases in otherwise healthy individuals.^[38] Symptoms typically include dysuria (painful urination), urinary frequency, urgency, and suprapubic discomfort, often without fever unless the infection ascends to the kidneys.^[39] Risk factors include urinary catheterization, which facilitates bacterial ascension into the bladder, and sexual intercourse, which can introduce pathogens from the perineal flora.^[40]^[41] Interstitial cystitis, also known as bladder pain syndrome (IC/BPS), is a chronic non-infectious inflammatory condition characterized by persistent bladder pain, urinary frequency, and urgency lasting more than six months, without evidence of bacterial infection or other identifiable causes.^[42] It affects the bladder epithelium and underlying tissues, leading to inflammation that is not responsive to antibiotics. A subset of cases involves Hunner lesions, which are focal inflammatory areas visible on cystoscopy, often accompanied by epithelial denudation and bleeding upon distention.^[43] Mast cells play a key role in the pathophysiology, contributing to neurogenic inflammation and heightened pain signaling through mediator release in the bladder wall.^[44] Less common infectious causes include fungal and viral pathogens, particularly in vulnerable populations. Fungal cystitis, most often due to Candida species such as C. albicans, predominantly occurs in immunocompromised patients, such as those with diabetes, prolonged catheterization, or undergoing chemotherapy, leading to symptoms of dysuria and hematuria.^[45] Viral hemorrhagic cystitis is frequently caused by adenovirus types 11 and 21, especially in immunocompromised individuals like bone marrow transplant recipients, resulting in severe bladder bleeding, pain, and clot retention.^[46] Schistosomiasis of the bladder, caused by the parasitic trematode Schistosoma haematobium, is a major infectious cause in endemic regions. Eggs deposited by adult worms in the bladder venules provoke granulomatous inflammation, leading to fibrosis, calcification, and hematuria.^[47] Chronic infection increases the risk of squamous metaplasia in the urothelium, a precancerous change particularly prevalent in sub-Saharan Africa and the Middle East, where the parasite is transmitted via freshwater snails.^[48]^[49] Treatment for bacterial cystitis typically involves short-course antibiotics, with nitrofurantoin as a first-line option due to its efficacy against common uropathogens like E. coli and low resistance rates.^[50] For IC/BPS, pentosan polysulfate sodium is an approved oral therapy that aims to restore the glycosaminoglycan layer of the bladder epithelium, reducing inflammation and symptoms in select patients.^[51] Recent research as of 2025 highlights the bladder and gut microbiomes' roles in cystitis recurrence, with dysbiosis—such as reduced Lactobacillus diversity—promoting pathogen adhesion and biofilm formation, suggesting potential for probiotic interventions to prevent relapses.^[52]^[53]

Functional disorders

Functional disorders of the bladder encompass conditions that impair urine storage or emptying, primarily arising from neuromuscular dysfunction or mechanical obstruction, leading to symptoms such as incontinence or retention. These disorders disrupt the coordinated activity between the detrusor muscle and urethral sphincter, often resulting in involuntary leakage or incomplete voiding. Common manifestations include urinary incontinence and bladder retention, which can significantly affect quality of life and require targeted interventions to prevent complications like urinary tract infections or renal damage. Urinary incontinence refers to the involuntary loss of urine, with stress incontinence occurring due to sphincter weakness that allows leakage during activities increasing intra-abdominal pressure, such as coughing or sneezing. Urge incontinence stems from overactive detrusor contractions, causing sudden and intense urges to urinate that are difficult to suppress. Overflow incontinence arises from chronic urinary retention, where the bladder overfills and leaks small amounts due to inadequate emptying. These types may overlap in mixed presentations, but each highlights distinct failures in bladder control mechanisms. Bladder retention involves the inability to fully empty the bladder, classified as acute or chronic. Acute retention often occurs postoperatively or due to sudden obstructions, presenting as a painful inability to void despite a full bladder. Chronic retention develops gradually, commonly from benign prostatic hyperplasia (BPH) in males, which compresses the urethra, or neurogenic causes such as spinal cord injury or diabetic neuropathy affecting bladder innervation. In diabetes, autonomic neuropathy leads to detrusor underactivity and impaired sensation, promoting persistent residual urine volumes. Neurogenic bladder arises from neurological impairments that alter bladder reflex arcs, leading to uncoordinated detrusor and sphincter function. Conditions like spina bifida result in congenital disruptions of sacral nerve pathways, causing detrusor-sphincter dyssynergia (DSD), where the sphincter contracts simultaneously with the detrusor during voiding attempts, impeding emptying. Multiple sclerosis similarly affects central nervous system pathways, producing detrusor hyperreflexia or areflexia, with detrusor-sphincter dyssynergia (DSD) in approximately 35% of cases, exacerbating storage and voiding difficulties.^[54] Overactive bladder (OAB) syndrome is characterized by idiopathic detrusor hyperactivity, manifesting as urgency with or without incontinence, often accompanied by increased daytime frequency and nocturia. This condition affects approximately 16% of adults, with prevalence rising with age due to age-related changes in bladder innervation and muscle function. Unlike neurogenic forms, idiopathic OAB lacks identifiable neurological pathology but shares similar detrusor overactivity. Management of these functional disorders typically begins with conservative measures like pelvic floor exercises, followed by pharmacological and procedural options. Anticholinergics, such as oxybutynin, inhibit detrusor contractions to alleviate urge incontinence and OAB symptoms by blocking muscarinic receptors. For refractory cases, intradetrusor injections of botulinum toxin reduce overactivity by temporarily paralyzing the detrusor muscle, improving storage capacity. Intermittent self-catheterization is a key intervention for retention and neurogenic bladder, allowing manual emptying to prevent overdistension while minimizing infection risk.

Neoplasms

Bladder neoplasms encompass both benign and malignant tumors arising from the bladder's epithelial or mesenchymal tissues. Malignant neoplasms, particularly urothelial carcinoma, predominate and account for the majority of cases, while benign tumors are far less common and typically present with fewer systemic effects.^[55] Urothelial carcinoma represents approximately 90% of all bladder malignancies. Key risk factors include tobacco smoking, which contributes to 50-65% of cases through exposure to carcinogenic aromatic amines, and occupational exposure to aniline dyes or other industrial chemicals. Staging follows the TNM system, where T describes tumor invasion depth (e.g., Ta for non-invasive papillary, T1 for submucosal invasion, T2-T4 for muscle or beyond), N indicates regional lymph node involvement, and M denotes distant metastasis; this classification guides prognosis and therapy selection.^[56]^[57]^[58]^[59] Rarer malignant subtypes include squamous cell carcinoma (about 5% of cases), often linked to chronic irritation from schistosomiasis infection in endemic regions, and adenocarcinoma (1-2%), which may arise from urachal remnants or glandular metaplasia. These variants tend to present at more advanced stages with poorer outcomes compared to urothelial carcinoma. Paraneoplastic syndromes, such as neurological manifestations or hypercalcemia, can occasionally accompany advanced bladder malignancies, though they are infrequent.^[55]^[60] Bladder tumors spread primarily via lymphatic routes to pelvic and iliac lymph nodes, with hematogenous dissemination to the lungs, liver, or bones in advanced disease. Five-year relative survival rates are approximately 73% for localized disease but drop to 6% for distant metastatic cases, underscoring the importance of early detection.^[61]^[62] Treatment modalities vary by stage and histology. Transurethral resection of bladder tumor (TURBT) serves as initial management for non-muscle-invasive disease, often followed by intravesical therapy with Bacillus Calmette-Guérin (BCG) or mitomycin to reduce recurrence. For muscle-invasive or advanced cases, radical cystectomy with urinary diversion (e.g., orthotopic neobladder) remains standard, potentially combined with neoadjuvant chemotherapy. Recent advancements as of 2025 include PD-1/PD-L1 inhibitors like pembrolizumab, approved for advanced urothelial carcinoma, which have demonstrated improved overall survival in cisplatin-ineligible patients with advanced disease and improved disease-free survival as adjuvant therapy post-cystectomy in high-risk patients, though overall survival benefit was not significant.^[56]^[63]^[64] Additionally, in October 2025, the FDA granted priority review to enfortumab vedotin plus pembrolizumab for perioperative treatment of cisplatin-ineligible muscle-invasive bladder cancer, with a target action date of April 2026.^[65] Benign tumors, such as papillomas (transitional cell proliferations with low malignant potential) and leiomyomas (mesenchymal smooth muscle tumors), are typically managed conservatively or with local excision if symptomatic.

Transplantation

Bladder transplantation represents a emerging therapeutic option for severe urinary tract reconstruction, building on decades of preclinical research. Experimental animal models of bladder transplantation date back to the 1950s, with early studies in dogs exploring vascularized grafts and later advancements in rat models demonstrating partial graft survival rates of up to 52% at four weeks and evidence of nerve regeneration by six months.^[66] Prior human efforts were confined to partial grafts, such as the 2008 procedure by Kato et al., which involved transplanting a donor bladder patch alongside kidneys and ureters in a six-month-old girl, yielding satisfactory short-term function at three weeks post-surgery but limited long-term applicability.^[66] Indications for bladder transplantation primarily encompass end-stage bladder dysfunction arising from neurogenic causes, such as spinal cord injury or congenital anomalies affecting 6-24% of dialysis patients, or extensive resection due to bladder cancer, where conventional reconstructions like bowel diversions lead to high complication rates including infections, incontinence, and metabolic disturbances.^[67] These patients often face diminished quality of life from incomplete emptying or reliance on artificial devices, positioning transplantation as a potential restorative alternative.^[68] The surgical procedure entails orthotopic implantation following cystectomy, with vascular anastomosis of the donor bladder's superior and inferior vesical arteries and veins to the recipient's external iliac vessels to ensure perfusion, alongside ureteral reimplantation using techniques like the Lich-Gregoir method to maintain continuity with the urinary system.^[67] Nerve-sparing approaches are employed where feasible to preserve pelvic autonomic innervation, though full sensory and motor recovery remains challenging due to denervation during harvest.^[69] In combined kidney-bladder transplants, the kidney is anastomosed first, followed by bladder placement and ureteroneocystostomy to connect the new kidney directly to the graft.^[70] The world's first complete human bladder transplant was performed on May 4, 2025, at Ronald Reagan UCLA Medical Center in a collaborative trial between USC and UCLA, led by Dr. Inderbir Gill and Dr. Nima Nassiri, for a dialysis-dependent patient with irreparable bladder damage from prior cancer resection and bilateral nephrectomy.^[71]^[70] The eight-hour procedure successfully restored urine production and drainage, eliminating the need for dialysis and achieving initial clinical stability.^[70] Post-transplant outcomes necessitate lifelong immunosuppression to mitigate acute and chronic rejection risks, akin to those in cardiac allografts, with functional recovery evaluated through urodynamic studies showing improved capacity, compliance, and sensation in early follow-up, marking preliminary success in continence restoration.^[67]^[72]

Diagnostic methods

Diagnostic methods for assessing bladder structure, function, and pathology encompass a range of imaging, endoscopic, urodynamic, and laboratory techniques. These approaches enable clinicians to evaluate conditions such as infections, obstructions, tumors, and functional impairments by providing insights into bladder anatomy, urine dynamics, and cellular composition. Selection of methods depends on clinical suspicion, with noninvasive options often preceding more invasive procedures to minimize patient discomfort and risk. Imaging plays a central role in initial bladder evaluation. Ultrasound is widely used to measure post-void residual (PVR) urine volume, a key indicator of incomplete emptying, via portable bladder scanners or formal examination; volumes exceeding 100-200 mL may suggest retention.^[73] Computed tomography (CT) and magnetic resonance imaging (MRI) are employed to detect masses, tumors, and stones, offering detailed visualization of bladder wall thickness and surrounding structures; CT excels in identifying calculi, while MRI provides superior soft-tissue contrast for staging neoplasms.^[74] Cystography, including voiding cystourethrography (VCUG), assesses vesicoureteral reflux by imaging urine flow from the bladder to the ureters during filling and voiding, grading reflux severity from I to V.^[75] Endoscopy allows direct visualization of the bladder interior. Cystoscopy involves inserting a thin, lighted tube (cystoscope) through the urethra to inspect the mucosal surface for abnormalities like inflammation, stones, or tumors, and facilitates biopsy for histopathological analysis; it is the gold standard for confirming bladder cancer.^[76]^[77] Urodynamic studies quantify bladder function. Cystometry measures intravesical pressure during filling to assess compliance, calculated as the change in volume divided by the change in detrusor pressure; values below 20 mL/cmH₂O indicate poor compliance and risk of upper tract damage.^[78] Uroflowmetry noninvasively records urine flow rate and volume over time, with maximum flow rates typically 15-25 mL/s in healthy adults; reduced rates suggest obstruction or detrusor weakness.^[36] Laboratory tests provide supportive diagnostic data. Urinalysis detects infections through leukocyte esterase, nitrites, and bacteria, while urine cytology examines shed cells for malignancy, achieving 40-60% sensitivity for high-grade tumors.^[79] Biomarkers such as nuclear matrix protein 22 (NMP22) assay urine for elevated protein levels associated with bladder cancer, offering 50-90% sensitivity for noninvasive and invasive disease, respectively, as an adjunct to cytology.^[80] Advanced techniques enhance precision. Virtual cystoscopy uses CT or MRI datasets to generate three-dimensional bladder reconstructions, detecting lesions larger than 5 mm with accuracy comparable to conventional cystoscopy in some cases, reducing the need for invasive procedures.^[81] As of 2025, AI-assisted imaging integrates deep learning models to analyze ultrasound, CT, and cystoscopic images for early tumor detection, improving segmentation and classification accuracy by up to 90% in high-risk populations.^[82]

Comparative anatomy

Mammals

In mammals, the urinary bladder is a thin-walled, elastic, muscular sac that serves as a reservoir for urine, allowing for temporary storage before voiding. The ureters typically implant obliquely into the posterior bladder wall, forming a functional valve mechanism that prevents reflux of urine back into the upper urinary tract during filling. This basic structure is conserved across mammalian species, enabling accommodation of varying urine volumes while maintaining continence. The bladder's wall comprises the urothelium (a specialized impermeable lining), underlying lamina propria, a thick detrusor muscle layer for contraction, and an outer adventitia or serosa. ^[83] Anatomical and functional variations exist among mammals, often reflecting dietary, reproductive, or environmental adaptations. In rodents such as rats, the bladder is a single-chambered organ, but the proximal urinary tract can be influenced by reproductive structures; for instance, males produce urethral plugs from coagulated seminal proteins that may temporarily occlude the urethra near the bladder neck, aiding sperm competition but potentially complicating urination. These plugs form an eosinophilic mass that fills the proximal urethra and occasionally extends toward the bladder, highlighting species-specific integrations of urinary and reproductive systems. ^[84] In contrast, herbivores like horses exhibit bladders with greater relative capacity to handle high urine production from fibrous diets; the equine bladder typically holds 4–4.5 liters when full, supporting daily outputs of up to 15 liters in healthy adults. ^[85] ^[86] Female marsupials display urinary adaptations tied to their reproductive biology, where the bladder empties into a common urogenital sinus shared with the reproductive tract, facilitating efficient waste management during pouch rearing of altricial young. This configuration, seen in species like kangaroos and opossums, allows for concentrated urine production and minimal interference with pouch hygiene, as the young complete development externally attached to the mother. ^[87] Environmental pressures further drive specialization; in desert-dwelling mammals such as the kangaroo rat (Dipodomys spp.), the bladder stores extremely hyperosmotic urine (up to 6,000 mosmol/kg H₂O) produced by elongated renal papillae and efficient tubular reabsorption, minimizing evaporative water loss and enabling survival without free water intake. ^[88] Bladder pathologies in mammals share common risks like bacterial cystitis from ascending infections, but manifestations vary by species due to anatomical, microbial, and behavioral differences. Feline idiopathic cystitis (FIC), prevalent in domestic cats, exemplifies a stress-associated, non-infectious inflammation causing recurrent hematuria, dysuria, and urgency, often without identifiable pathogens and linked to neurogenic or mucosal barrier defects. ^[89] In equines, species-specific conditions include idiopathic hemorrhagic cystitis, characterized by bloody urine and mucosal friability, potentially triggered by environmental toxins or vascular fragility, with survival rates exceeding 90% under supportive care. ^[90] These variations underscore the need for tailored veterinary diagnostics, such as species-adjusted imaging and urinalysis, to address bladder disorders effectively. ^[91]

Other vertebrates

In reptiles, the urinary bladder typically functions as a simple sac for temporary urine storage and osmoregulation, reabsorbing water and electrolytes to maintain internal balance, particularly in species like lizards where it buffers dehydration in neonates.^[92] ^[93] This structure is present in many lizards and turtles, aiding buoyancy regulation in freshwater turtles such as Pseudemys scripta elegans by adjusting fluid volume.^[94] However, it is absent in snakes and crocodilians, where urine drains directly into the cloaca for storage and mixing with fecal matter, reflecting adaptations to terrestrial and semi-aquatic lifestyles.^[95] Amphibians possess a thin-walled vesicular urinary bladder derived embryonically from the allantois, which connects to the cloaca and serves primarily as a reservoir for hypotonic urine produced by the kidneys.^[96] In frogs and toads, such as Bufo cognatus, the bladder plays a critical osmoregulatory role by storing and reabsorbing water across its permeable epithelium, often holding volumes equivalent to 30% or more of body weight to sustain hydration during periods of aridity.^[97] ^[98] This reabsorption, facilitated by hormones like arginine vasotocin, allows amphibians to tolerate desiccation and supports their semi-terrestrial existence, with the bladder acting as an extrarenal organ for ion and fluid homeostasis.^[94] Most fish lack a distinct urinary bladder, as their excretory systems prioritize continuous urine flow through the ureters to the external environment for rapid osmoregulation in aquatic settings.^[94] Exceptions occur in certain species adapted to variable salinities, such as lungfish (Protopterus spp.), where a rudimentary bladder-like structure assists in retaining and modifying urine to counter osmotic challenges during freshwater habitation or aestivation.^[99] Similarly, coelacanths (Latimeria chalumnae) possess a urinary bladder that stores urine with specific osmotic properties, including high urea levels, to maintain balance in marine environments.^[100] These bladder analogs in lungfish and coelacanths highlight specialized roles in ionoregulation for transitional or deep-sea lifestyles. Birds do not have a true urinary bladder; instead, the cloaca functions as a multifunctional reservoir where urine from the ureters mixes with fecal material.^[101] The avian kidneys excrete nitrogenous waste primarily as semisolid uric acid, which concentrates in the cloaca to minimize water loss—urate salts precipitate as a white paste, conserving fluids essential for flight efficiency.^[102] ^[103] This cloacal storage allows for periodic voiding of combined wastes, with water reabsorption occurring via the rectal epithelium to further enhance desiccation resistance. Evolutionarily, the urinary bladder has arisen independently at least twice across vertebrates, serving diverse osmoregulatory needs before being lost in birds to reduce body mass for aerial locomotion and in most fish to facilitate constant aquatic adjustments.^[94] These losses underscore adaptations to specific habitats, with retention in amphibians and select reptiles preserving transitional functions.

Invertebrates

Invertebrates lack a true bladder homologous to that found in vertebrates, instead possessing diverse excretory structures adapted for osmoregulation, waste filtration, and fluid storage in varied environments. These analogous organs, such as nephridia or glandular systems, handle urine production and temporary storage without a centralized urinary bladder, reflecting the evolutionary divergence of non-chordate lineages.^[104] In crustaceans, particularly decapods like lobsters, the antennal glands—also known as green glands—serve as primary excretory organs for osmoregulation, filtering hemolymph to produce urine that is temporarily stored before release. These glands, located in the cephalothorax near the antennal bases, actively transport ions and water, enabling adaptation to both freshwater and marine salinities by reabsorbing salts or excreting excess ions as needed.^[105]^[106] In species such as the green crab (Carcinus maenas), the antennal glands regulate hemolymph osmolality through selective ion reabsorption, preventing dehydration in hypotonic environments. Insects employ Malpighian tubules as blind-ended excretory structures projecting from the hindgut junction, which secrete primary urine into the gut lumen for subsequent processing. These tubules facilitate ion and water transport, with the rectal bladder—a dilated portion of the hindgut—enabling efficient reabsorption of water and essential electrolytes, crucial for survival in arid habitats. For instance, in desert-adapted species like the desert locust (Schistocerca gregaria), this mechanism conserves up to 90% of filtered water, producing concentrated uric acid waste to minimize desiccation risk.^[107]^[108]^[109] Mollusks, including cephalopods such as octopuses, utilize renal sacs and pericardial coelom extensions for excretory functions, where glandular appendages filter coelomic fluid to eliminate ammonia and other nitrogenous wastes. In Octopus dofleini, the reduced pericardial cavity encloses branchial hearts and connects to renal sacs that directly release ammonia into the mantle cavity, bypassing extensive storage and integrating with respiratory processes.^[110]^[111] These structures in cephalopods support high metabolic demands, with renal appendages aiding in ion balance amid active predation lifestyles.^[112] Annelids demonstrate analogous urine storage through nephridia, paired tubular organs in each body segment that collect coelomic fluid for filtration and temporary holding before expulsion via nephridiopores. In earthworms like Lumbricus terrestris, these nephridia function as metanephridia, drawing in primary urine from the coelom for selective reabsorption, providing a decentralized system suited to terrestrial burrowing without a unified bladder.^[113]^[104] This evolutionary diversity underscores the absence of a conserved bladder homolog across invertebrate phyla, with adaptations driven by habitat-specific needs rather than shared ancestry. Recent research highlights gaps in understanding climate change effects, with limited 2025 studies exploring how saline shifts—driven by ocean acidification and altered precipitation—disrupt antennal gland osmoregulation in crustaceans, potentially impairing ionoregulatory enzyme activity like Na+/K+-ATPase in mud crabs (Scylla paramamosain).^[114]^[115] Further investigations are needed to quantify these impacts on broader invertebrate excretory resilience.^[116]

References

[1]
Anatomy, Abdomen and Pelvis: Bladder - StatPearls - NCBI Bookshelf
The bladder is a subperitoneal, hollow muscular organ that acts as a reservoir for urine. The bladder is located in the lesser pelvis when empty and extends ...
[2]
Physiology, Bladder - StatPearls - NCBI Bookshelf - NIH
Urine, created by the kidneys, is drained into the bladder by the bilateral ureters. The bladder then acts as the storage site for this waste product until ...Introduction · Development · Function · Mechanism
[3]
Physiology, Urination - StatPearls - NCBI Bookshelf
Sep 13, 2023 · Urination or micturition primarily functions in the excretion of metabolic products and toxic wastes. The urinary tract also serves as a storage ...
[4]
Bladder: Anatomy, Location, Function & Related Conditions
In males, it rests between the pubic bone in the front and the rectum in the back. In females, it rests in front of the vagina and uterus.
[5]
Urinary bladder & urethra: Anatomy, location, function - Kenhub
The urinary bladder is found inferior to the peritoneum, sitting on the pelvic floor. In females its inferior surface lays on the pubic symphysis and its ...
[6]
Anatomy of the urinary organs of the pelvis: Video, Causes, & Meaning
The urinary bladder sits posterior to the pubic bones and the pubic symphysis. In males, the bladder is anterior to the rectum and superior to the prostate ...
[7]
Sex differences in lower urinary tract biology and physiology - PMC
Oct 22, 2018 · Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed ...Missing: vesicles | Show results with:vesicles
[8]
Bladder Trigone - an overview | ScienceDirect Topics
The shape, position, size, and relationships of the bladder vary according to its degree of filling. When empty, the bladder is shaped like a tetrahedron ...
[9]
Post-operative urinary retention: Review of literature
Jan 15, 2019 · Stretching of bladder beyond its maximum capacity of 400-600 mL has potential to cause ischemic damage and irreversible insult to the ...
[10]
Urinary bladder: Anatomy, function and clinical notes - Kenhub
Dec 6, 2023 · Internally, the base of the urinary bladder bears a smooth, triangular region called the trigone. The openings of the ureters (ureteric orifices) ...
[11]
Urinary bladder | Radiology Reference Article | Radiopaedia.org
Oct 22, 2025 · The superolateral angles are formed by the ureteric orifices and the inferior angle is formed by the internal urethral orifice.
[12]
Histology, Bladder - StatPearls - NCBI Bookshelf - NIH
Feb 25, 2023 · Muscularis propria, also known as the detrusor muscle, consists of three sublayers: inner longitudinal, middle circular, and outer longitudinal.
[13]
Gross anatomy of the bladder. - Medscape Reference
Nov 11, 2024 · The anatomy of the bladder forms an extraperitoneal muscular urine reservoir that lies behind the pubic symphysis in the pelvis.
[14]
Histology - Bladder & urothelial tract - Pathology Outlines
Aug 31, 2023 · Histology · 4 layers (from inside out): urothelium, lamina propria, muscularis propria, serosa / adventitia · Urothelium: 3 layers of cells.
[15]
Increased bladder permeability in interstitial cystitis/painful bladder ...
Oct 27, 2015 · The umbrella cells are coated with a dense layer of GAG, mostly if not exclusively, chondroitin sulfate. They also have tight junctions here ...Anatomical Structure · The Gag Layer · Bladder-Bowel...
[16]
Middle vesical artery | anatomy - Britannica
The middle vesical artery supplies the base of the bladder. The inferior vesical artery supplies the inferolateral surfaces of the bladder.
[17]
Anatomy, Abdomen and Pelvis: Bladder Detrusor Muscle - NCBI - NIH
The walls of the bladder are mainly formed by detrusor muscle, which allows the bladder to contract to excrete urine or relax to hold urine.
[18]
Venous Drainage of the Abdomen - TeachMeAnatomy
A porto-systemic anastomosis is a connection between the veins of the portal venous system, and the veins of the systemic venous system. The major sites of ...
[19]
The Urinary Bladder - Structure - Function - TeachMeAnatomy
The bladder is an organ of the urinary system, situated anteriorly in the pelvic cavity. It collects and acts a temporary store for urine.
[20]
Lymphadenectomy in Management of Invasive Bladder Cancer - NIH
The bladder lymphatic drainage has well-defined origin from lymphatic plexus within its wall, in the submucosa and extending into the muscles. Lymphatic ...
[21]
The link between vascular dysfunction, bladder ischemia, and aging ...
Studies of experimental models have shown that pelvic arterial insufficiency and outlet obstruction may result in significant bladder ischemia. These ischemic ...
[22]
Development of the Urinary System - Kidney - TeachMeAnatomy
The urinary bladder is initially drained by the allantois. However, this is obliterated during fetal development and becomes a fibrous cord – the urachus. A ...Development Of The Kidneys · Mesonephros · Metanephros
[23]
Urachus - Pathology Outlines
Jul 24, 2025 · The urachus, originated from remnants of allantois, is a fibrous cord connecting the umbilicus to the anterosuperior aspect of the bladder ...
[24]
Neurophysiology of Lower Urinary Tract Function and Dysfunction
The lower urinary tract is innervated by 3 sets of peripheral nerves involving the parasympathetic, sympathetic, and somatic nervous systems.
[25]
Embryology, Kidney, Bladder, and Ureter - StatPearls - NCBI - NIH
Aug 8, 2023 · The urinary tract starts with the nephrogenic cord, forming three kidneys. The bladder develops from the urogenital sinus, and the ureteric bud ...
[26]
Proteomics as a Complementary Technique to Characterize Bladder ...
... antigen), with affectations in the PIK3/AKT/mTOR signaling pathway. These ... bladder trigone. Eur. Urol. 2009;56:346–353. doi: 10.1016/j.eururo ...
[27]
Neurogenic bladder pathophysiology, assessment and ...
Mar 3, 2025 · The primary function of the bladder is to store and empty urine, and the frequency of voiding in individuals with a bladder capacity of 400–600 ...
[28]
Urothelial ATP exocytosis: regulation of bladder compliance in the ...
Jul 14, 2016 · We conclude that urothelial, VNUT-dependent ATP exocytosis is involved in urine storage mechanisms that promote the relaxation of the bladder ...Results · Figure 4. Cystometry In... · Discussion
[29]
Autonomic Regulation of the Bladder - Neuroscience - NCBI Bookshelf
Autonomic control of bladder function. The sympathetic innervation of the bladder originates in the lower thoracic and upper lumbar spinal cord segments (T10-L2) ...
[30]
Clinical and Functional Anatomy of the Urethral Sphincter - PMC - NIH
The urethral sphincter can be used to control micturition. Voiding urine begins with voluntary relaxation of the external sphincter muscle of the bladder.
[31]
Glycosaminoglycan Replacement Therapy with Intravesical ...
Nov 2, 2023 · The GAG layer is a thin, waterproof polysaccharide coating that plays an isolating role. It separates sensitive urothelial cells from urinary ...
[32]
how much do we know about their role in the bladder? - PubMed
Jun 25, 2016 · Damage to the GAG layer disrupts its protective barrier function giving rise to increased permeability into the deep layers of the urothelium ...
[33]
Afferent Nerve Regulation of Bladder Function in Health and Disease
These thresholds are consistent with the conditions in which humans report the first sensation of bladder filling.
[34]
A healthy bladder: a consensus statement - PMC - NIH
Normal functional bladder capacity in adults ranges from approximately 300 to 400 ml (58,59). Although the International Continence Society defines urinary ...
[35]
The Aging Bladder - PMC - NIH
It has been demonstrated that, as women age, flow rate, voided volume, and bladder capacity decrease and postvoid residual urine volume increases. In contrast, ...
[36]
The neural control of micturition - PMC - PubMed Central - NIH
Here we review the neural control of micturition and how disruption of this control leads to abnormal storage and release of urine.Missing: internal | Show results with:internal
[37]
Bladder Outflow Obstruction Versus Detrusor Underactivity
May 6, 2021 · Bladder emptying involves a constant interaction between detrusor contraction (isometric and isotonic) and outflow resistance (active and ...
[38]
Urodynamic Testing and Interpretation - StatPearls - NCBI Bookshelf
A good quality pressure reading should have these fluctuations mirrored between in the vesical and abdominal traces, causing a net detrusor pressure of close to ...Procedures · Potential Diagnosis · Normal and Critical Findings · Interfering Factors
[39]
Uroflowmetry – Knowledge and References - Taylor & Francis
Uroflowmetry provides information on the flow of urine from the urethra: Normal peak flow rates: 20–25 ml/s (male) and 20–30 ml/s (female)Shape of the curve ...
[40]
Cystitis - StatPearls - NCBI Bookshelf
Acute cystitis is typically caused by a bacterial infection of the urinary bladder. Complicated cystitis, on the other hand, is associated with risk factors ...
[41]
Uncomplicated Urinary Tract Infections - StatPearls - NCBI Bookshelf
Feb 21, 2025 · Typical UTI symptoms include urinary frequency, urgency, suprapubic discomfort, and dysuria. While UTIs are very common in women, they are ...
[42]
UTI: Epidemiology, Infection Mechanisms & Treatment Options
Risk factors for developing a CAUTI include prolonged catheterization, female gender, older age and diabetes. UTIs are caused by both Gram-negative and Gram- ...
[43]
Recurrent UTIs in Women: Etiology & Risk Factors
The impact on sexual intimacy is particularly significant as UTI can cause pain or discomfort during sexual intercourse, leading to avoidance of sexual activity ...<|separator|>
[44]
Interstitial Cystitis/Bladder Pain Syndrome - StatPearls - NCBI - NIH
The condition is characterized by chronic inflammation and lower urinary tract symptoms, not due to infection or any other clearly identifiable cause.[1][2] As ...
[45]
Interstitial cystitis/bladder pain syndrome: The evolving landscape ...
Apr 4, 2020 · The Hunner lesion subtype is a distinct inflammatory disease with proven bladder etiology characterized by epithelial denudation and enhanced ...Missing: Hunner's | Show results with:Hunner's<|separator|>
[46]
Mast cell activation syndrome in pain syndromes bladder pain ...
Overall, there is agreement that mast cells play an intricate role in pain syndromes and in particular in BPS/IC. Mast cells participate early in disease ...Missing: involvement | Show results with:involvement
[47]
Hemorrhagic cystitis: A challenge to the urologist - PMC - NIH
[5] Fungal organisms associated with hemorrhagic cystitis include Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus and Torulopsis glabrata.
[48]
Comprehensive Review of Urinary Tract Infections in Renal ...
Feb 8, 2024 · Adenovirus: Adenovirus infections have the potential to lead to hemorrhagic cystitis, a viral UTI characterized by hematuria (blood in the urine) ...
[49]
Schistosomiasis and Cancer of the Bladder - NCBI - NIH
Within East Africa, a coastal strain of S. haematobium is more virulent than that at Lake Victoria, where infested bladders do not show severe changes. When ...
[50]
Schistosomiasis and urinary bladder cancer in North Western ...
May 24, 2013 · Schistosoma haematobium, which is the agent for urinary schistosomiasis, is commonly found in Sub-Saharan Africa and the Middle East.
[51]
Predisposition to urinary tract epithelial metaplasia in Schistosoma ...
haematobium-endemic Msambweni area of Coast Province, Kenya. Among 705 evaluable cytology specimens, prevalence of inflammation (39%), hyperkeratosis (30%), ...
[52]
Definitions of Urinary Tract Infection in Current Research - NIH
... interstitial cystitis), or ... Retrospective evaluation of nitrofurantoin and pivmecillinam for the treatment of lower urinary tract infections in men.Results · Uti Definition And... · Discussion
[53]
Therapeutic strategies for uncomplicated cystitis in women - PMC
Apr 29, 2024 · Pentosan polysulfate sodium (PPS) is an oral medication approved by the U.S. Food and Drug Administration for the treatment of painful bladder ...
[54]
Recurrent Cystitis in Women—A Real-World Analysis of Bacteria ...
Sep 16, 2024 · The microbiomes of the intestines and the urinary bladder can also influence the risk of developing recurrent cystitis and are simultaneously ...
[55]
Long-Term Antibiotics for Disturbed Bladder Microbiome Disorders
May 6, 2025 · Emerging evidence suggests that the bladder microbiome, which is unique to each individual, plays a pivotal role in maintaining bladder health.
[56]
Bladder Cancer - StatPearls - NCBI Bookshelf
The most critical factor in the pathological assessment of urothelial carcinoma is identifying the extent of invasion to set proper staging, followed by the ...
[57]
Bladder Cancer Treatment (PDQ®) - NCI
May 2, 2025 · Bladder cancer treatment options depend on if it is nonmuscle or muscle invasive and may include surgery, BCG, chemotherapy, and targeted ...
[58]
Epidemiology of Bladder Cancer - PMC - PubMed Central - NIH
Mar 13, 2020 · The strongest risk factor for bladder cancer is tobacco smoking, which accounts for 50–65% of all cases. Occupational or environmental toxins ...
[59]
Risk Factors Associated with Urothelial Bladder Cancer - PMC
Jul 22, 2024 · Smoking tobacco was comprehended to be the major risk factor for UBC. Smoke from tobacco products contains polycyclic aromatic hydrocarbons (PAHs) and aromatic ...
[60]
Bladder Cancer Stages - NCI
May 16, 2025 · Bladder cancer is usually staged using the TNM staging system. Your cancer may be described by this staging system in your pathology report.
[61]
Adenocarcinoma of the urinary bladder - PMC - PubMed Central - NIH
Adenocarcinoma is an uncommon malignancy in the urinary bladder which may arise primarily in the bladder as well as secondarily from a number of other organs.
[62]
Transitional Cell Carcinoma of the Bladder Manifestating as ... - NIH
Bladder cancer usually spreads via the lymphatic and hematogenous routes, the most common sites of metastases of urinary bladder cancers being the regional ...
[63]
Bladder Cancer — Cancer Stat Facts - SEER
Rate of New Cases and Deaths per 100,000: The rate of new cases of bladder cancer was 18.0 per 100,000 men and women per year. · Lifetime Risk of Developing ...
[64]
Immunotherapeutic strategies for invasive bladder cancer - NIH
Apr 30, 2025 · Currently approved PD-1 inhibitors for the treatment of bladder cancer include pembrolizumab and nivolumab. Pembrolizumab exerts its ...
[65]
URINARY TRACT TUMORS - Comparative Oncology - NCBI - NIH
13.2. Papilloma has an incidence of approximately 17% in cattle and 14% in dogs of all urinary bladder and tract tumors. The tumor usually occurs in adult and ...
[66]
A Review of Transplantation Practice of the Urologic Organs - NIH
In the field of urology, transplantation of the penis, testicle, urethra, vas deferens, and bladder has been described in animal models and human patients, but ...
[67]
BLADDER TRANSPLANTATION: THE NEW FRONTIER IN ... - NIH
Jun 17, 2024 · Combined kidney and bladder transplantation has the potential to emerge as the next frontier in abdominal organ transplants.
[68]
WCET 2024: Bladder Transplantation: Preclinical Work ... - UroToday
Aug 12, 2024 · Patients often experience incontinence, incomplete emptying, and other dysfunctions, leading to a diminished quality of life. With artificial ...Missing: indications | Show results with:indications
[69]
Kidney and Bladder Transplantation: Advances, Barriers ... - MDPI
The success of a bladder transplant depends on the precise restoration of blood supply, functional nerve integration, and the prevention of complications such ...Missing: sparing | Show results with:sparing
[70]
USC, UCLA complete first-in-human bladder transplant
May 18, 2025 · First the kidney, then the bladder, were transplanted. The new kidney was then connected to the new bladder. The entire procedure took ...
[71]
First human bladder transplant performed at UCLA - Urology
May 18, 2025 · A UCLA surgical team has performed the first -in-human bladder transplant. The surgery was successfully completed at Ronald Reagan UCLA ...Missing: history | Show results with:history
[72]
First-Ever Human Bladder Transplant Marks Medical Milestone - EMJ
May 22, 2025 · The eight-hour procedure involved transplanting the kidney first, followed by the bladder, with the new organs then connected. The kidney began ...Missing: history | Show results with:history
[73]
Bladder Post Void Residual Volume - StatPearls - NCBI Bookshelf
The PVR may be determined through urinary catheterization, a portable dedicated bladder scanner, or a formal ultrasound examination. When used in conjunction ...Introduction · Procedures · Potential Diagnosis · Normal and Critical Findings
[74]
Imaging of the urinary tract: the role of CT and MRI - PMC - NIH
Computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly valuable tools for assessing the urinary tract in adults and children.
[75]
Vesicoureteral Reflux - StatPearls - NCBI Bookshelf
Vesicoureteral reflux (VUR) is characterized by the abnormal backward flow of urine from the urinary bladder into the upper urinary tract during voiding.Introduction · Anatomy and Physiology · Preparation · Technique or Treatment
[76]
Cystoscopy - Mayo Clinic
Oct 25, 2025 · This imaging exam uses a hollow tube with a lens to show the inside of the bladder and find the cause of bladder symptoms.
[77]
Bladder Cancer Diagnosis - NCI
Mar 1, 2024 · A biopsy is usually done during a cystoscopy procedure. Biopsy is a procedure in which a sample of cells or tissue is removed from the bladder ...Cystoscopy · Biopsy · Urine Tumor Marker Test<|separator|>
[78]
Non-invasive assessment of urinary bladder compliance using ... - NIH
Bladder compliance is calculated by dividing the volume change by the change in detrusor pressure. Normal bladder compliance is defined as a value of >40 mL ...
[79]
Tests for Bladder Cancer - American Cancer Society
Mar 12, 2024 · NMP22 BladderChek: This test looks for the NMP22 protein in the urine. People who have bladder cancer often have higher levels of this protein.
[80]
The value of the NMP22 test for superficial bladder cancer diagnosis ...
NMP22 test can be used as an adjunctive tool for the detection of bladder cancer, but its diagnostic performance is limited in surveillance.
[81]
Bladder Tumor Detection at Virtual Cystoscopy | Radiology
CONCLUSION: CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate ...
[82]
https://pubmed.ncbi.nlm.nih.gov/39738572/
[83]
Review of Animal Models to Study Urinary Bladder Function - PMC
Comparison of the advantages and disadvantages of studying urinary bladder diseases in animal models. The animals are listed in order of laboratory priority.Missing: mammals | Show results with:mammals
[84]
Urethral plug--a new secondary male sex characteristic in rat and ...
The urethral plug is an eosinophilic mass filling the proximal urethra in male rats and other rodents. Its absence may indicate health issues.Missing: multi- chambered scientific paper
[85]
The urinary system - Veterian Key
Jul 8, 2016 · The normal equine bladder can accommodate 4–4.5L of urine. Horses usually urinate four to six times daily and, depending on size, will ...
[86]
Urinary production in the healthy horse and in horses deprived of ...
Total daily 24-hour urinary output was obtained from 11 healthy horses fed alfalfa hay with free access to salt during periods of high environmental ...Missing: herbivores mammals
[87]
[PDF] The Female Urogenital System of the lYIarsupialia with special ...
It is proposed to discuss the general disposition of the female urogenital organs in the Marsupialia and in particular to examine the variations to be.
[88]
Architecture of kangaroo rat inner medulla - PubMed Central - NIH
We hypothesize that the inner medulla of the kangaroo rat Dipodomys merriami, a desert rodent that concentrates its urine to more than 6,000 mosmol/kgH2O water, ...
[89]
Prevalence, Risk Factors, Pathophysiology, Potential Biomarkers ...
Jun 21, 2022 · This review aims to provide readers with a comprehensive understanding of feline idiopathic cystitis by summarizing and updating studies ...
[90]
Equine idiopathic hemorrhagic cystitis: Clinical features and ...
Mar 31, 2018 · 3.2.1 Comparison of the two groups ... Horses with hemorrhagic cystitis were significantly more likely to survive than were horses with bladder ...Missing: mammals | Show results with:mammals
[91]
Disease Overview of the Urinary Tract in Exotic Companion ...
The most common problems affecting the ferret urinary system described in the literature are Aleutian disease of the kidney, renal tumors, renal cysts, ...
[92]
Role of the Urinary Bladder in Osmotic Regulation of Neonatal Lizards
In neonatal lizards, the urinary bladder appears to be useful, as it is in amphibians, as an extrarenal osmoregulatory organ that can buffer body water ...
[93]
Anatomy and Physiology of the Reptile Renal System - PubMed
Reptile kidneys maintain a constant extracellular environment within the body. They excrete waste products, maintain normal concentrations of salt and water.
[94]
The vertebrate urinary bladder: osmoregulatory and other uses - PMC
The bladder may serve more biological uses than simple storage. The importance of bladder functions can be inferred from its presence among vertebrates, ...
[95]
[PDF] Effect of Furosemide Administration on Plasma Analytes and Urine ...
Certain species of reptiles, such as snakes and crocodilians, lack a urinary bladder, so urine flows directly to the cloaca and is often admixed with feces ( ...
[96]
Urinary System Development
The urinary system develops from the intermediate mesoderm, forming the urogenital ridge, three kidneys, and the bladder/urethra from the urogenital sinus.
[97]
The Adaptive Value of Bladder Water in the Toad, Bufo cognatus
The animal having a standard weight. (S.W.) of 41 gm. had bladder filled with a volume of water equal to 31 per cent of gross body weight while the 64 gm.Missing: capacity percentage
[98]
Physiological control of water exchange in anurans - PMC - NIH
Feb 10, 2022 · Many frogs are able to absorb water rapidly through a highly vascularized area of ventral skin called the “seat patch”, which is associated with ...
[99]
Osmoregulation during Long-Term Fasting in Lungfish and Elephant ...
Feb 23, 2016 · Vertebrates control the osmolality of their extra- and intra-cellular compartments despite large variations in salt and water intake.Missing: urinary bladder
[100]
OSMOTIC CONSTITUENTS OF THE COELACANTH LATIMERIA ...
Pickford Composition of bladder urine of the coelacanth, Latimeria chalumnae, Journal of Experimental Zoology 196, no.33 (May 2005): 371–380. https://doi ...
[101]
Animal Specific Training: Birds - UW-Milwaukee
Urinary System. The ureters of birds collect waste products from the kidneys and continue to the cloaca and do not empty into the urinary bladder as in mammals.
[102]
Biology 2e, Biological Diversity, Vertebrates, Birds | OpenEd CUNY
The cloaca allows water to be reabsorbed from waste back into the bloodstream. Thus, uric acid is not eliminated as a liquid but is concentrated into urate ...
[103]
12.1 Digestive Systems – Animal Physiology
Birds do not have separate openings to excrete urine and feces. Instead, uric acid from the kidneys is secreted into the large intestine and combined with waste ...
[104]
MicroRNAs in Tissue Regeneration: Lessons from Animal Models
Oct 15, 2025 · Indeed, only a few vertebrate species, such as fish and amphibians, exhibit tissue-specific regenerative capabilities, including appendage, ...
[105]
Excretion - Nephridia, Malpighian Tubules, Coelomocytes | Britannica
Annelids are segmented animals that typically contain a pair of nephridia on each segment. Each nephridium has the form of a very fine tubule, often of ...
[106]
Functional anatomy and ion regulatory mechanisms of the antennal ...
May 2, 2014 · In crustaceans, the antennal glands are known to be important in osmoregulation, and they play a functional role analogous to that of the ...
[107]
Anatomical and molecular insights into the antennal gland of the ...
Jun 15, 2024 · Crustaceans have an excretory organ called the antennal gland (AnG), also known as the maxillary gland or green gland. This gland is located at ...
[108]
Multiple Functions of Malpighian Tubules in Insects: A Review - PMC
They play a key role in the production of primary urine and osmoregulation, selectively reabsorbing water, ions, and solutes.
[109]
41.9: Excretion Systems - Malpighian Tubules of Insects
Nov 22, 2024 · Water and electrolytes are reabsorbed when these organisms are faced with low-water environments and uric acid is precipitated and excreted ...
[110]
Review: Malpighian Tubule, an Essential Organ for Insects
The final phase of excretion occurs in the rectum, with ions and water is reabsorbed at this location. Thus, the large intestine which is the final composition ...
[111]
Excretion in the Cephalopod, Octopus Dofleini
In comparison with other molluscs the pericardial cavity of cephalopods is much reduced and in octopods encloses only the branchial heart appendage. The ...Missing: mollusk | Show results with:mollusk
[112]
Functional Histology: The Tissues of Common Coleoid Cephalopods
Mar 8, 2019 · The renal and pericardial appendages are gland-like structures protruding in the renal and pericardial coelomic sacs, respectively. In octopus ...
[113]
[PDF] Cephalopods of the World. An Annotated and Illustrated Catalogue ...
... Octopus vulgaris Cuvier, 1797 ... renal appendages, enclosed within membranes to form the renal sacs. These spongy tissues release ammonia directly ...Missing: mollusk | Show results with:mollusk
[114]
Evolutionary morphology of podocytes and primary urine-producing ...
The primary urine is temporally stored in the coelomic cavity, and then enters the metanephridium through its proximal opening, metanephridial funnel, or ...
[115]
Analysis based on osmoregulatory enzymes and LC-MS technology ...
In this study, we measured the changes in the activity of key osmoregulatory enzymes (Na+/K+-ATPase, NKCC, CA and V-ATPase) in the antennal gland of the mud ...Missing: climate shifts
[116]
Transcriptional response of salinity stress in red claw crab Uca arcuata
Mar 18, 2025 · Changes in seawater salinity directly affect the osmotic pressure regulation mechanism of aquatic animals. Once an osmotic pressure imbalance ...
[117]
Aquatic Organisms in Response to Salinity Stress: Ecological ... - MDPI
Climate change is altering salinity dynamics in marine ecosystems, primarily through increased evaporation, shifting precipitation patterns, and polar ice melt, ...