Surgery
Surgery is a medical specialty that employs operative manual and instrumental techniques on patients to investigate or treat pathological conditions, including diseases, injuries, and deformities, with the goals of restoring function, alleviating suffering, or prolonging life.[1][2] Ancient evidence of surgical practices appears in the Edwin Smith Papyrus, an Egyptian text dating to approximately 1600 BCE that documents procedures for managing wounds, fractures, and tumors using empirical observations rather than supernatural explanations.[3] Major advancements transformed surgery from rapid, painful interventions limited by patient tolerance into a precise science, beginning with the first public demonstration of ether anesthesia in 1846, which enabled prolonged operations, followed by Joseph Lister's introduction of antiseptic methods in the 1860s that reduced mortality from postoperative sepsis through carbolic acid sprays and sterile protocols.[4][5] Twentieth-century achievements include the first successful human kidney transplant between identical twins in 1954, establishing solid organ transplantation as a viable therapy for end-stage organ failure, and the widespread adoption of laparoscopic techniques in the 1980s, which minimized incision sizes, reduced recovery times, and lowered complication risks compared to open procedures.[6][7] Contemporary surgery spans over a dozen recognized subspecialties, such as cardiothoracic and neurosurgery, incorporating robotic systems for enhanced precision and ongoing debates over intervention efficacy, including concerns about overtreatment and persistent rates of surgical-site infections affecting up to 5% of cases despite protocols.[8][9]Definitions and Classifications
Definition and Scope
Surgery constitutes a branch of medicine focused on the diagnosis and treatment of injuries, diseases, deformities, and other disorders through operative manual and instrumental techniques that physically alter bodily structures or functions.[10] These procedures typically involve incision, excision, abrasion, or manipulation of tissues to repair damage, remove pathological material, or investigate underlying conditions.[11] As defined by the American Medical Association, surgery entails structurally altering the human body via tissue incision or destruction, distinguishing it as an integral component of medical practice rather than a mere technical intervention.[12] The scope of surgery encompasses both therapeutic and diagnostic applications, ranging from emergency interventions for trauma—such as controlling hemorrhage or stabilizing fractures—to elective procedures aimed at improving quality of life, like organ transplantation or reconstructive repairs.[13] It integrates foundational principles of anatomy, physiology, pathology, and immunology to address congenital anomalies, acquired diseases, and functional impairments, often requiring multidisciplinary collaboration with anesthesiology, radiology, and pathology.[14] Modern advancements have expanded this scope to include minimally invasive methods, such as laparoscopy and robotics, which reduce tissue trauma compared to traditional open techniques, while maintaining the core objective of causal restoration through direct physical correction.[15] Surgical practice demands rigorous preoperative assessment to mitigate risks like infection or anesthesia complications, with outcomes empirically tied to procedural precision and patient-specific factors such as age and comorbidities.[16] While surgery excels in scenarios where non-operative treatments fail—evidenced by its role in over 300 million annual global procedures resolving acute threats like appendicitis or cancer resection—it is not universally applicable, yielding inferior results for conditions better managed pharmacologically or conservatively due to inherent risks of operative morbidity.[13][10]Types of Surgery
Surgical procedures are classified according to several criteria, including urgency, purpose, technique or degree of invasiveness, extent, and the anatomical region or medical specialty involved. These classifications aid in planning, resource allocation, and risk assessment, reflecting the diverse applications of surgery in treating disease, injury, or congenital anomalies.[17][18] By urgency, surgeries divide into elective, urgent, and emergency categories. Elective procedures are scheduled in advance for non-life-threatening conditions, allowing time for preoperative optimization, such as cataract removal or joint replacement.[18] Urgent surgeries address conditions requiring intervention within hours to days to prevent deterioration, like certain bowel obstructions. Emergency surgeries demand immediate action, often within minutes, to preserve life or limb, exemplified by trauma laparotomy or ruptured aneurysm repair.[19][20] By purpose, surgeries encompass diagnostic (e.g., biopsy to confirm pathology), curative (aimed at removing or destroying diseased tissue, such as tumor resection), palliative (to alleviate symptoms without curing, like debulking in advanced cancer), restorative or reconstructive (to repair function or appearance post-trauma or congenital defect), and cosmetic (elective enhancement of appearance).[21] ![Cardiac surgery operating room][float-right] By technique and invasiveness, open surgery remains foundational, involving a large incision for direct access, as in traditional appendectomy, typically closed with stitches or staples.[22] Minimally invasive approaches, including laparoscopy (using small incisions and a camera for abdominal procedures), endoscopy (via natural orifices, e.g., colonoscopy with polypectomy), arthroscopy (joint-specific), and robotic-assisted surgery (enhancing precision with articulated instruments), reduce recovery time and complications compared to open methods, though they require specialized equipment and training.[23] Microsurgery employs magnified visualization for delicate structures like vessels or nerves.[22] By extent, procedures classify as minor (outpatient, low risk, e.g., hernia repair under local anesthesia) or major (inpatient, higher complexity and physiological stress, e.g., organ transplantation requiring general anesthesia and extended monitoring).[24][25] By specialty or body system, surgery subdivides into recognized fields, with the American College of Surgeons identifying 14 primary ones: cardiothoracic (heart and chest, e.g., coronary artery bypass), colon and rectal (digestive tract lower end), general (abdomen, skin, soft tissue), gynecology and obstetrics (female reproductive), neurological (brain and spine), oral and maxillofacial (face and jaw), orthopedic (musculoskeletal), otolaryngology (ear, nose, throat), pediatric, plastic (reconstructive or aesthetic), thoracic (non-cardiac chest), urology (urinary and male reproductive), and vascular (blood vessels).[8] Subspecialties further refine these, such as hand surgery or surgical oncology.[26]Terminology and Nomenclature
The term surgery derives from the Ancient Greek cheirourgia (χειρουργία), composed of cheir (χείρ, "hand") and ergon (ἔργον, "work"), denoting manual operative treatment.[27][28] This etymology reflects the discipline's emphasis on hands-on intervention, as articulated by Roman physician Celsus in the 1st century CE, who described chirurgia as the branch of medicine involving manual work to address bodily defects or injuries.[29] The word entered Middle English around 1300 via Old French surgerie and Late Latin chirurgia, evolving to encompass both the act and the specialty.[30] Surgical nomenclature predominantly employs Greco-Latin roots, prefixes, and suffixes to systematically describe procedures, enabling precise communication across languages and disciplines. Common suffixes include -ectomy (excision or removal, e.g., appendectomy for appendix removal), -otomy or -stomy (incision or creation of an opening, e.g., tracheostomy), -plasty (reconstructive repair, e.g., rhinoplasty), -rrhaphy (suturing, e.g., herniorrhaphy), and -lysis (loosening or breakdown, e.g., tenolysis for tendon release).[31] Prefixes often specify anatomical location or approach, such as abdomino- for abdominal procedures or laparo- for minimally invasive abdominal access (e.g., laparotomy).[31] This root-based system facilitates derivation of terms like cholecystectomy (gallbladder removal, from chole- "bile," cyst- "bladder," and -ectomy) or hysterectomy (uterus removal), promoting universality despite regional variations in pronunciation or minor adaptations.[32] Procedures are further classified by urgency and invasiveness in clinical nomenclature. Elective surgery denotes planned, non-urgent interventions (e.g., joint replacement), urgent surgery addresses conditions requiring prompt action within hours to days (e.g., acute cholecystitis repair), and emergency surgery demands immediate operation to avert death or severe harm (e.g., ruptured aneurysm repair).[33] Invasiveness distinguishes open surgery (large incisions exposing organs) from minimally invasive techniques like laparoscopy (small ports with endoscopic visualization) or endoscopy (internal scoping without incision).[34] Major surgery typically involves general anesthesia, significant physiological trespass (e.g., organ resection), and higher risk, contrasting with minor surgery under local anesthesia for superficial issues (e.g., cyst excision), though boundaries remain context-dependent without universal thresholds.[35] Standardized coding systems enhance nomenclature for epidemiological and billing purposes. The NOMESCO Classification of Surgical Procedures (NCSP), developed by Nordic countries in 1996, codes operations by anatomical site, procedure type, and specificity (e.g., KJA00 for simple appendectomy).[36] Internationally, the International Classification of Health Interventions (ICHI) under WHO frameworks aims to harmonize terms, integrating with SNOMED CT for clinical interoperability, though adoption varies and free-text descriptions persist in records.[37] These systems prioritize anatomical precision and procedural intent over eponyms (e.g., Billroth procedure for gastrectomy variants), reducing ambiguity in global data exchange.[38]Surgical Procedures and Techniques
Preoperative Evaluation and Preparation
Preoperative evaluation begins with a comprehensive medical history and physical examination to identify comorbidities, previous surgical experiences, and factors influencing anesthetic risk, such as cardiovascular disease, respiratory conditions, or medication use.[39] This assessment determines the need for targeted diagnostic tests, avoiding routine screening like universal electrocardiography or chest radiography, which evidence shows do not improve outcomes in low-risk patients but may in those with specific indications, such as age over 50 or known cardiac history.[40] Laboratory investigations, including complete blood count, electrolytes, and coagulation studies, are guided by clinical suspicion rather than protocol, as indiscriminate testing increases costs without reducing perioperative morbidity.[41] Risk stratification employs standardized tools to quantify perioperative complications. The American Society of Anesthesiologists (ASA) Physical Status classification, introduced in 1941 and refined over decades, assigns categories from PS I (a normal healthy patient) to PS VI (a declared brain-dead patient whose organs are being harvested), facilitating communication of pre-anesthesia comorbidities and correlating with mortality rates—e.g., PS III patients (severe systemic disease) face approximately 1-3% risk of death in elective procedures.[42] [43] Cardiac-specific indices, such as the Revised Cardiac Risk Index, predict major adverse cardiac events by scoring factors like ischemic heart disease, heart failure, insulin-dependent diabetes, and high-risk surgery type, with scores of 0 indicating <1% risk and ≥3 indicating >9% risk.[44] Broader calculators, like the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) tool, integrate patient age, functional status, and procedure-specific data to estimate outcomes such as pneumonia or renal failure, though their predictive accuracy varies by surgical context and requires validation against empirical data.[45] Optimization of identified risks aims to mitigate complications through interventions like smoking cessation (reducing pulmonary issues by up to 50% if quit >8 weeks preoperatively), anemia correction via iron supplementation or transfusion thresholds tailored to hemoglobin levels below 10 g/dL in select cases, and glycemic control targeting HbA1c <8% in diabetics.[46] However, rigorous evidence questions the net benefit of aggressive preoperative medical consultations; a 2023 analysis of over 590,000 noncardiac surgeries found such consultations associated with no reduction in 30-day mortality or readmissions and, in some subgroups, increased harm due to delays or unnecessary interventions.[47] Causal mechanisms favor procedure-specific, evidence-based adjustments over blanket optimization, as systemic biases in academic guidelines may overemphasize consultation without accounting for opportunity costs like surgical postponement. Informed consent is obtained after full disclosure of the procedure's nature, anticipated benefits, material risks (e.g., infection rates of 1-5% for clean procedures), alternatives including nonoperative management, and potential complications, ensuring the competent patient voluntarily agrees without coercion.[48] Legal requirements, as per U.S. standards, mandate documentation of this process, with capacity assessed via understanding and reasoning ability rather than mere signature.[49] Final preparation includes nil per os status for solids after midnight and clear liquids up to 2 hours pre-induction to minimize aspiration risk, adjustment of chronic medications (e.g., continuing beta-blockers but holding anticoagulants per guidelines), and site-specific prophylaxis like antibiotics administered within 60 minutes of incision for procedures with infection risks exceeding 2%.[50] These steps, grounded in randomized trials, reduce nausea and bacterial contamination without evidence of harm from modest liberalization of fasting protocols in adults.[51]Intraoperative Procedures
The intraoperative phase begins when the patient enters the operating room and ends upon transfer to the postanesthesia care unit, encompassing anesthesia administration, surgical intervention, and immediate recovery from anesthesia.[52] This phase involves a multidisciplinary team including the surgeon, anesthesiologist, surgical assistants, and nurses, who maintain a sterile environment to minimize infection risk through practices such as skin decontamination with antiseptics and use of physical barriers.[53] Patient positioning is optimized for surgical access while preventing complications like nerve injury or pressure ulcers, followed by final skin preparation and draping.[54] Anesthesia induction occurs upon positioning, typically involving general, regional, or local methods tailored to the procedure, with maintenance ensuring unconsciousness or analgesia throughout.[55] Continuous monitoring includes electrocardiography, pulse oximetry for oxygen saturation, noninvasive blood pressure every five minutes, end-tidal capnography, and temperature assessment, as mandated by standards to detect physiological derangements promptly.[56] Advanced neuromonitoring, such as somatosensory evoked potentials or electromyography, may be employed in procedures risking neural damage to guide real-time adjustments.[57] The core surgical steps commence with incision to access the operative site, followed by dissection, tissue manipulation, and the specific intervention such as resection, repair, or reconstruction.[55] Hemostasis is achieved through mechanical methods like ligation or clipping, thermal energy devices such as electrocautery, or topical agents including gelatin sponges and thrombin-based products when conventional techniques prove insufficient.[58] [59] Closure involves layered suturing or stapling of tissues, ensuring approximation without undue tension to promote healing, often under imaging guidance in complex cases.[60] Intraoperative complications, including hemorrhage or adverse anesthetic events, are managed with protocols emphasizing rapid intervention, such as fluid resuscitation or pharmacological reversal, to stabilize the patient before closure.[61] Minimally invasive techniques, like laparoscopy, integrate specialized instruments and insufflation to reduce tissue trauma, though open approaches remain standard for certain anatomies.[62] Efficiency is enhanced by process mapping to streamline steps, reducing operative time without compromising safety.[63]Postoperative Management
Postoperative management encompasses the continuum of care from the immediate recovery phase following surgical closure through hospital discharge and outpatient surveillance, with the primary objectives of stabilizing the patient, mitigating complications, and facilitating recovery. This phase typically begins in a post-anesthesia care unit (PACU) where patients are monitored for vital signs, oxygenation, and emergence from anesthesia, with criteria for transfer to a ward including stable hemodynamics, adequate pain control, and return of protective airway reflexes. Evidence-based protocols, such as Enhanced Recovery After Surgery (ERAS), integrate multimodal interventions to attenuate surgical stress response, evidenced by reduced complication rates (from 20-30% in traditional care to 10-15% with ERAS implementation) and shortened hospital lengths of stay by 1-3 days across major procedures like colorectal resections.[64][65][66] Pain management relies on multimodal analgesia to minimize opioid use, incorporating regional blocks, non-steroidal anti-inflammatory drugs, and acetaminophen, which has demonstrated superior efficacy in reducing postoperative opioid consumption by up to 50% compared to opioid monotherapy while lowering nausea and sedation risks. Respiratory complications, such as atelectasis or pneumonia, affect 5-10% of patients post-major abdominal surgery; prevention involves incentive spirometry, early coughing exercises, and mobilization within 24 hours to enhance lung expansion and reduce ventilator-associated risks. Thromboprophylaxis with low-molecular-weight heparin or pneumatic compression devices is standard for moderate- to high-risk patients, halving deep vein thrombosis incidence (from 2-3% to under 1%) without significantly increasing bleeding events in randomized trials.[67][68][69] Wound care protocols emphasize aseptic techniques, with dressings changed within 48 hours and monitored for signs of surgical site infection (SSI), which occurs in 2-5% of clean procedures and up to 20% in contaminated cases; prophylactic antibiotics, administered within 60 minutes prior to incision, with re-dosing for prolonged procedures or significant blood loss, and discontinued within 24 hours for most surgeries, reduce SSI rates by 50% per meta-analyses. Fluid and nutritional management shifts from restrictive perioperative strategies to goal-directed therapy, avoiding overload that contributes to pulmonary edema in 10-15% of cases, while early oral intake (within 24 hours) in ERAS pathways accelerates gastrointestinal recovery without increasing anastomotic leak risks. Common complications, including urinary retention (5-10% post-spinal anesthesia) and delirium (up to 50% in elderly patients), necessitate vigilant surveillance and targeted interventions like intermittent catheterization or non-pharmacologic orientation protocols.[70][71][72] Discharge planning incorporates standardized criteria, such as tolerance of oral intake, independent ambulation, and pain control on oral agents, with follow-up to detect delayed issues like wound dehiscence (1-3% incidence). Overall, postoperative complication rates range from 7-15% in major surgeries, with prompt recognition and protocol-driven management improving survival; for instance, early intervention in sepsis halves mortality from 40% to 20%. Adoption of ERAS in emergency general surgery further extends benefits, reducing readmissions by 20-30% through standardized care bundles.[69][73][74]Surgical Environments and Teams
Surgical procedures are conducted in specialized environments optimized for sterility, precise instrumentation, and patient safety, primarily hospital operating rooms (ORs) and ambulatory surgery centers (ASCs). Hospital ORs accommodate complex, high-acuity interventions requiring intensive monitoring and support services, featuring modular designs with integrated imaging, advanced lighting, and ventilation systems providing 12 to 30 air changes per hour to maintain laminar airflow and reduce airborne contaminants.[75] ASCs, numbering over 5,000 in the U.S. as of 2024, focus on same-day elective procedures like cataracts or arthroscopies, offering lower costs—often 40-60% less than hospitals—and potentially reduced infection risks due to specialized focus and lower patient acuity.[76] These facilities emphasize efficient throughput, with ASCs handling millions of procedures annually while adhering to Medicare standards for physician ownership and accreditation.[77] Sterility in surgical environments is maintained through rigorous standards, including positive-pressure ventilation, HEPA filtration, and one-way traffic flows from contaminated to clean zones to prevent cross-contamination.[78] Operating rooms incorporate sterile cores for instrument processing, with protocols mandating surgical gowns, gloves, drapes, and aseptic techniques once the field is established; violations, such as unsterile instrument handling, elevate surgical site infection risks, which affect 2-5% of procedures globally.[79] Environmental controls also mitigate particulates via directional airflow, sweeping contaminants away from the sterile field, as validated by ASHRAE guidelines for OR ventilation.[80] The surgical team comprises multidisciplinary professionals with defined roles to ensure coordinated care. The surgeon directs the procedure, performing incisions, resections, and reconstructions, often assisted by residents or physician assistants for complex cases.[81] An anesthesiologist or certified registered nurse anesthetist (CRNA) administers anesthesia, monitors vital signs, and manages airway and hemodynamic stability throughout the operation.[82] Circulating nurses oversee non-sterile tasks, including documentation, supply procurement, and patient advocacy, while scrub technicians or nurses maintain the sterile field, passing instruments and counting sponges to prevent retained items.[83] Team coordination is enhanced by protocols like the WHO Surgical Safety Checklist, implemented since 2008, which includes sign-in (patient identity, consent, allergies), time-out (site marking, procedure confirmation), and sign-out (instrument counts, recovery plans) phases.[84] Multicenter trials demonstrate its use reduces major complications by 36% and mortality by 47% in diverse settings, underscoring the value of standardized communication in averting errors like wrong-site surgery.[85] In ASCs, teams may be leaner, excluding residents, but maintain equivalent core roles to uphold safety amid rising procedure volumes.[86]Epidemiology and Clinical Outcomes
Global Incidence and Prevalence
Approximately 313 million major surgical procedures are performed worldwide each year, encompassing a range from essential interventions like caesarean sections and trauma repairs to elective operations.60160-X/fulltext) This figure, derived from modeling national health data and validated against hospital records, highlights stark disparities: only 6% of these procedures occur in the lowest-income countries, which house over one-third of the global population.60160-X/fulltext) High-income countries perform upwards of 10,000 procedures per 100,000 population annually, while low- and middle-income countries (LMICs) average below 1,000, far short of the Lancet Commission's benchmark of 5,000 procedures per 100,000 to meet population needs.[87]60160-X/fulltext) The unmet need for surgery has grown to at least 160 million procedures annually as of 2025, driven by population growth, aging demographics, and persistent infrastructure gaps in LMICs, where conditions like trauma, obstetric complications, and cancer require surgical intervention but lack capacity.00985-7/fulltext) Globally, over 5 billion people—roughly 63% of the population—lack access to safe, timely surgical care, with surgical volume in the poorest quintile of countries accounting for just 3.5% of total procedures.[88] Data collection has improved, with 123 countries (56.9% of nations) reporting surgical volumes by 2023, up from prior years, though underreporting in fragile states likely underestimates true deficits.[89] Prevalence of surgical need correlates with disease burden, with non-communicable diseases (e.g., cardiovascular conditions requiring bypasses) dominating in wealthier regions and infectious or injury-related cases prevalent in LMICs; for instance, cataract surgeries constitute a high volume in low-resource settings due to treatable blindness.60160-X/fulltext) These patterns reflect causal factors like workforce shortages (e.g., fewer than 20 surgeons per 100,000 in many LMICs) and geographic barriers, rather than demand differences alone.[90] Ongoing monitoring via World Bank and WHO-aligned indicators underscores that scaling to equitable rates would require trillions in investment, prioritizing essential over cosmetic procedures, which reached 35 million globally in 2023 but represent a minor fraction of total need.[91]00985-7/fulltext)Mortality, Morbidity, and Complication Rates
Perioperative mortality rates for major surgery worldwide range from 0.5% to 5%, with an estimated 4.2 million deaths occurring within 30 days of surgery annually, many deemed preventable through improved safety measures.[92][93] In high-resource settings, such as industrialized countries, crude in-hospital mortality after major procedures averages around 1-2%, though implementation of standardized checklists has reduced rates from 1.5% to 0.8% in diverse hospital cohorts.[92][85] Emergency surgeries exhibit substantially higher mortality, with pooled estimates of 3-4.5% compared to 0.7% for elective procedures, reflecting delays in care and patient acuity.[94][95] Postoperative morbidity, encompassing non-fatal adverse events, affects up to 25% of inpatients undergoing major operations globally, with complication incidence often underestimated without comprehensive post-discharge tracking.[92] Using the Clavien-Dindo classification, minor complications (grades I-II) comprise 20-25% of cases, while major ones (grades III-V) occur in 5-15%, including organ injuries linked to 9-fold increased mortality odds and extended hospital stays by over 11 days.[96][97] In low- and middle-income countries, morbidity rates for essential procedures exceed 20%, driven by resource limitations and higher infection burdens.[98] Rates vary markedly by procedure type, as shown in the following selected examples from meta-analyses:| Procedure Type | Perioperative Mortality Rate | Major Complication Rate |
|---|---|---|
| Appendectomy | <0.1% | 5-10% |
| Cholecystectomy | <0.1% | 5-10% |
| Caesarean Delivery | <0.1% | 10-15% |
| Intracranial Surgery | 20-27% | 30-40% |
| Typhoid Intestinal Perforation | 20-27% | >40% |
Factors Influencing Outcomes
Patient characteristics significantly affect surgical outcomes, with advanced age associated with higher postoperative complication rates and mortality; for instance, older adults face elevated risks due to reduced physiological reserve and comorbidities.[103] Pre-existing conditions such as obesity (BMI ≥40), diabetes, cardiovascular disease, and smoking independently increase complication risks by up to 40% and prolong recovery, as smoking impairs wound healing and oxygenation.[104] [105] Poor nutritional status, assessed via tools like serum albumin levels, correlates with higher infection rates and extended hospital stays, while factors like mental health status and health literacy influence adherence to postoperative care and overall recovery.[105] [106] Surgeon-specific variables play a critical role, as higher procedural volume and experience reduce complication rates and mortality across specialties; meta-analyses show high-volume surgeons achieve up to 30-50% lower adverse event rates compared to low-volume peers in procedures like cancer resections and cardiac surgery.[107] [108] Subspecialty fellowship training and career length further enhance outcomes by refining technical proficiency, though surgeon age exhibits mixed effects—older surgeons (over 60) may incur slightly higher mortality risks (odds ratio 1.2-1.5) due to potential cognitive or dexterity declines, offset in some cases by accumulated expertise.[107] [109] Surgeon feedback mechanisms, such as performance audits, have demonstrated improvements in outcomes by targeting individual variability.[110] Institutional factors, particularly hospital procedural volume, consistently predict lower operative mortality; high-volume centers report 20-50% reduced death rates for complex surgeries like esophageal resections or coronary artery bypass grafting, attributable to specialized teams, protocols, and resource availability.[111] [108] Operating room organization, including team coordination and equipment standardization, influences efficiency and safety, with systematic reviews linking optimized workflows to shorter operative times and fewer errors.[112] System-related elements like elective versus emergency admission also matter, as planned procedures yield better results due to thorough preoperative optimization.[113]| Factor Category | Key Examples | Impact on Outcomes |
|---|---|---|
| Patient-Related | Age >65, comorbidities (e.g., obesity, smoking), nutrition | Increased complications (up to 40% higher), longer stays[104] [105] |
| Surgeon-Related | High volume (>50 cases/year), experience >10 years | Reduced mortality (20-50% lower), fewer errors[107] [114] |
| Hospital-Related | High volume (>100 cases/year), specialized teams | Lower operative mortality (OR 0.32-0.64)[111] [108] |