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McBurney's point

McBurney's point is an anatomical landmark located in the right lower quadrant of the abdomen, specifically at the junction of the outer one-third and inner two-thirds of a line drawn from the right anterior superior iliac spine to the umbilicus (or approximately one-third of the distance from the anterior superior iliac spine to the umbilicus).^[1]^[2] Named after American surgeon Charles McBurney, who first described it in 1889 as the site of maximal tenderness in cases of acute appendicitis, the point serves as a critical reference during physical examinations for abdominal pain.^[3] Tenderness elicited at McBurney's point, referred to as McBurney's sign, is a classic indicator of appendiceal inflammation, often accompanied by localized guarding and rebound tenderness in the right lower quadrant.^[2] This finding helps clinicians differentiate appendicitis from other causes of abdominal pain, though it is not pathognomonic and must be evaluated alongside symptoms like periumbilical pain migration, nausea, and fever, as well as diagnostic tests such as ultrasound or CT imaging.^[1] Historically, McBurney's work emphasized early surgical intervention based on this sign, contributing to advancements in appendicitis management that reduced mortality from the condition.^[4] In contemporary practice, McBurney's point remains a foundational element of the abdominal exam, particularly in resource-limited settings where imaging may not be immediately available, underscoring its enduring clinical utility despite evolving diagnostic technologies.^[5]

Definition and Anatomy

Anatomical Location

McBurney's point is a landmark on the surface of the lower right abdomen, precisely located at one-third the distance from the right anterior superior iliac spine (ASIS) to the umbilicus.^[6] This positioning places it within the right iliac fossa, corresponding to the anatomical region where the base of the vermiform appendix typically attaches to the cecum.^[7] To identify McBurney's point clinically, begin by palpating the right ASIS, which is the bony prominence at the anterior end of the iliac crest. Draw an imaginary straight line from the right ASIS to the umbilicus, a distance of approximately 10-15 cm in adults depending on body habitus. Measure one-third of this line's length starting from the right ASIS and moving medially toward the umbilicus to locate the point. Equivalently, starting from the umbilicus, measure two-thirds of the distance laterally toward the right ASIS.^[8] In terms of surface anatomy, McBurney's point overlies the base of the appendix near the junction of the cecum and vermiform appendix, situated superficial to the ileocecal valve in the right lower quadrant.^[7]^[8] Anatomical diagrams commonly illustrate this by marking the point along the line between the ASIS and umbilicus, relative to the pelvic brim and abdominal quadrants, with the underlying digestive structures such as the cecum and appendix base shown in cross-section for reference.^[6]

Relation to the Appendix

McBurney's point overlies the base of the vermiform appendix in the right lower quadrant of the abdomen, typically adjacent to the cecum and the terminal ileum near the ileocecal valve.^[8] This superficial landmark corresponds to the convergence of the taeniae coli at the tip of the cecum, where the appendix arises as a blind-ending tubular structure.^[6] The position of the appendix exhibits considerable anatomical variability, which can impact the reliability of McBurney's point as a consistent landmark. The retrocecal position—where the appendix lies posterior to the cecum—is the most common, occurring in approximately 65-70% of cases based on cadaveric and imaging studies.^[9] Other positions include pelvic (20-30%), subcecal (5-10%), pre-ileal, post-ileal, and paracecal (each less than 5%).^[9] For instance, one radiographic study of 275 patients found that only 35% of appendix bases lay within 5 cm of McBurney's point, with 15% more than 10 cm distant, highlighting the point's limitations in atypical configurations.^[10] Similarly, multidetector CT analysis in 100 patients revealed the appendix at the exact level of McBurney's point in just 4%, within 3 cm in 36%, and more than 5 cm away in 36%, often positioned cranially (51%) or caudally (43%) to the point.^[11] Embryologically, the appendix develops from the midgut as a cecal diverticulum around the 6th week of gestation, becoming distinct by the 8th week, with the cecum and appendix undergoing a 270-degree counterclockwise rotation around the superior mesenteric artery axis during weeks 6-10.^[8] This rotation, followed by descent into the right iliac fossa between weeks 14-15, establishes the typical position adjacent to McBurney's point; incomplete rotation or fixation can result in malpositioned appendices.^[12] Rare congenital anomalies, such as situs inversus totalis, reverse the midgut orientation, placing the appendix and corresponding tenderness point in the left lower quadrant.^[12] In imaging modalities like ultrasound and computed tomography (CT), McBurney's point serves as a key reference for scanning the right iliac fossa to identify and visualize the appendix.^[11] For example, three-dimensional MDCT reconstructions use the point to measure appendix location relative to the anterior superior iliac spine and umbilicus, aiding in precise localization even in variant positions, with mean radial distances from the point averaging 42 mm.^[11] This approach enhances diagnostic accuracy by guiding focused imaging of the region overlying the appendix base.^[13]

Clinical Significance

McBurney's sign refers to the deep tenderness or pain elicited upon palpation at McBurney's point, serving as an indicator of localized peritonitis resulting from inflammation of the appendix.^[2] This physical finding is particularly associated with acute appendicitis, where the inflamed appendix causes irritation to the overlying parietal peritoneum.^[14] The pathophysiological mechanism involves the progression of appendiceal inflammation, which initially produces visceral pain but evolves to somatic pain as the process irritates the parietal peritoneum at McBurney's point, often manifesting as rebound tenderness upon release of pressure.^[2] This irritation stems from reflex activation of the 11th and 12th thoracic nerve endings due to the inflammatory infiltrate.^[14] Additionally, continuous firm pressure at the point may elicit Aaron's sign, characterized by referred pain to the epigastric region, further suggesting appendiceal involvement.^[15] In its diagnostic role, a positive McBurney's sign strongly suggests acute appendicitis, highlighting the need for prompt intervention to mitigate the risk of appendiceal rupture and peritonitis.^[2] Historically, it guided the site for incision in open appendectomy procedures, localizing the pathology to the right lower quadrant.^[16] Despite its utility, McBurney's sign has limitations, with sensitivity ranging from 50% to 94%, largely attributable to variations in appendix position such as retrocecal or pelvic malpositions that alter pain localization.^[17] It is not pathognomonic, necessitating correlation with clinical symptoms like anorexia and fever, as well as laboratory findings such as leukocytosis, to enhance diagnostic confidence.^[2] Differential considerations include conditions like mesenteric adenitis, which can produce similar right lower quadrant tenderness but typically follows a viral illness.^[18] To elicit the sign, the patient should be positioned supine with relaxed abdominal muscles, followed by gentle deep palpation at McBurney's point using fingertip pressure, while avoiding superficial guarding to accurately assess rebound tenderness.^[2] In modern practice, McBurney's sign is integrated with imaging modalities, such as ultrasound preferred for pediatric patients due to its non-invasive nature (sensitivity 70-90%), and computed tomography as the gold standard with over 95% accuracy for confirming appendicitis.^[19] Reliance on the sign has declined since the 2000s, influenced by the rise of laparoscopic appendectomy and non-operative management strategies using antibiotics for uncomplicated cases, which achieve success rates around 70-95% and reduce surgical interventions.^[20]

Other Medical Applications

McBurney's point serves as a reliable anatomical landmark in various surgical and interventional procedures beyond diagnostic palpation, particularly for accessing the right lower quadrant while minimizing risks to surrounding structures. In laparoscopic appendectomy, it guides the placement of trocars to facilitate minimally invasive access to the peritoneal cavity. For instance, a hybrid technique involves an oblique 12-mm incision directly at McBurney's point for inserting an 11-mm optical trocar with a 0° telescope, allowing initial visualization and dissection while reducing the need for additional ports.^[21] Another key application is in peritoneal dialysis catheter placement, where the point provides a low-site entry in the right iliac fossa to optimize catheter positioning and function. A novel insertion method from McBurney's point, often assisted by laparoscopy, uses local anesthesia and ultrasound guidance to tunnel the catheter through the abdominal wall, directing its tip toward the pelvis to prevent migration and occlusion. This approach has demonstrated safety, reduced patient discomfort, and lower rates of early dysfunction compared to traditional paramedian sites, with success rates exceeding 90% in initial studies.^[22]^[23] The landmark's utility extends to rare procedural contexts, such as exploratory laparotomy for right lower quadrant pathology, where incisions centered on McBurney's point enable targeted exposure without extensive dissection.^[24] As a procedural landmark, McBurney's point offers advantages in avoiding major vascular structures, notably the inferior epigastric artery, which lies medial to the site, thereby lowering the risk of hemorrhage during muscle-splitting incisions. Its position also ensures consistent peritoneal access through layered tissues—skin, subcutaneous fat, external oblique aponeurosis, internal and transversus abdominis muscles, transversalis fascia, and peritoneum—while preserving the rectus abdominis and reducing long-term incisional hernia incidence to under 1%.^[25]^[26]^[27] Despite these benefits, procedures at McBurney's point carry risks including bowel perforation, vascular injury, and postoperative infection, with surgical site infections occurring in approximately 5-10% of cases. Updated 2025 guidelines from surgical societies emphasize preoperative imaging, such as ultrasound or CT, to identify anatomical variants like appendix malposition or adhesions, ensuring safer incision planning.^[28]^[29]

Historical Development

Discovery by Charles McBurney

Charles Heber McBurney (1845–1913) was an American surgeon renowned for his advancements in abdominal surgery. Born on February 17, 1845, in Roxbury, Massachusetts, he earned his undergraduate degrees from Harvard University in 1866 and his medical degree from Columbia University's College of Physicians and Surgeons in 1870. McBurney rose to prominence as a professor of surgery at Columbia starting in 1889, where he emphasized meticulous clinical observation and innovative operative techniques, establishing himself as a pioneer in the field of abdominal procedures.^[30] McBurney's initial description of the point that bears his name emerged from his surgical practice amid the evolving understanding of appendiceal pathology. In a seminal 1889 paper titled "Experience with Early Operative Interference in Cases of Disease of the Vermiform Appendix," published in the New York Medical Journal, he identified a specific site of maximal tenderness on the right lower abdomen as a key diagnostic indicator for appendicitis, based on his observations from numerous clinical cases. This point, located approximately 1.5 to 2 inches from the right anterior superior iliac spine along a line to the umbilicus, allowed for more precise localization of appendiceal inflammation during physical examination.^[31]^[32] The discovery occurred during a pivotal period in the late 19th century when appendicitis was beginning to be recognized as a distinct clinical entity, distinct from earlier vague diagnoses such as "perityphlitis," which referred to inflammation around the cecum without pinpointing the appendix's role. Prior to this shift, conditions involving the right iliac fossa were often treated conservatively with rest and medications, leading to high complication rates; Reginald Fitz's 1886 paper had first proposed appendicitis as a specific diagnosis linked to perforation and peritonitis, setting the stage for McBurney's practical contributions. McBurney's work built on this foundation by integrating anatomical knowledge with bedside findings to guide surgical decision-making.^[33] McBurney's broader contributions included his strong advocacy for early appendectomy as the preferred treatment, which dramatically improved outcomes by intervening before perforation and abscess formation. In an era when untreated or delayed cases carried mortality rates approaching 50%, his approach to prompt surgical removal reduced overall mortality to under 10% in appropriately selected patients, transforming appendicitis from a frequently fatal condition into a manageable one and establishing the point as a cornerstone of his diagnostic protocol.^[33]^[31]

Evolution of the Concept

Following Charles McBurney's initial description in 1889, the concept of the point of maximal tenderness in acute appendicitis was initially imprecise, defined as located between 1.5 and 2 inches from the anterior superior iliac spine (ASIS) along a straight line to the umbilicus.^[31] This measurement reflected clinical observation rather than a fixed anatomical proportion, leading to variability in application among early practitioners. By the early 1900s, collaborators and subsequent medical literature refined the definition to the more standardized "one-third rule," positioning it at the junction of the outer and middle thirds of the line from the ASIS to the umbilicus, enhancing reproducibility in surgical and diagnostic contexts.^[30] In the 20th century, the concept evolved through integration into probabilistic diagnostic tools and empirical studies highlighting its limitations. The 1986 Alvarado score formalized McBurney's sign—tenderness at the point—as a key component (2 points out of 10) for estimating appendicitis likelihood, combining it with symptoms, leukocytosis, and rebound tenderness to improve diagnostic accuracy beyond isolated physical findings.^[34] Concurrently, studies from the 1930s to 1950s, including anatomical dissections and clinical series, quantified the variability in appendiceal position, revealing that the base of the appendix aligns with the point in only about 30-40% of cases due to anatomical diversity, prompting a shift toward cautious interpretation and reduced over-reliance on the sign alone.^[35] The advent of imaging technologies in the 2000s further transformed the concept's role, diminishing the primacy of physical examination. Ultrasound and computed tomography (CT) scans achieved sensitivities of 86-98% and specificities of 81-98% for appendicitis, often supplanting McBurney's sign in resource-rich settings by directly visualizing appendiceal inflammation, perforation, or abscesses.^[36] By 2025, advancements in artificial intelligence (AI)-assisted scoring systems have begun incorporating the sign alongside biomarkers such as C-reactive protein (CRP) levels and vital signs, with machine learning models demonstrating AUROCs up to 92.3% in predicting appendicitis severity when physical exam findings like tenderness are weighted with laboratory data.^[37] The term "McBurney's point" gained official eponymous status in medical nomenclature after McBurney's death in 1913, reflecting its rapid adoption in textbooks and surgical practice.^[38] While broader debates in medicine have questioned eponyms for lacking descriptive precision, McBurney's point has been retained for its historical significance and mnemonic value in teaching.^[39] Its legacy persists in medical curricula worldwide, particularly in resource-limited settings where imaging access is restricted, serving as a foundational bedside diagnostic tool for prompt appendicitis identification.^[40]

References

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Nov 9, 2022 · Tenderness on palpation in the RLQ over the McBurney point is the most important sign in these patients. A careful physical examination, not ...<|control11|><|separator|>
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The Appendix - Retrocecal - Arterial supply - Appendicitis - TeachMeAnatomy
### Summary of McBurney's Point Location and Anatomical Significance
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The Foundational Model of Anatomy (FMA) ontology is both a theory of anatomy ... A number of anatomical points and anchored fiat lines, such as McBurney's point.
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Only 35% of appendix bases were found to lie within 5 cm of McBurney's point, and 15% were more than 10 cm distant.
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The purpose of this study was to show the relation between McBurney's point and the appendix in patients undergoing 3D MDCT and to investigate the effect of ...Abstract · Introduction · Discussion
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Nov 30, 2020 · This novel method of PD catheter insertion from the McBurney point was safe, caused less discomfort, and was effective in preventing catheter dysfunction.
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The overall sensitivity of this method is of 89% and its specificity is of 92%. It is not reliable in diagnosing appendicitis in women, with only a 75% ...
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