Appendico-Ileal Knotting (Appendiceal Tourniquet Syndrome): A Systematic Review and Clinicopathological Classification.

Appendico-ileal knotting (AIK), also known as appendiceal tourniquet syndrome, is an exceptionally rare and frequently overlooked cause of small bowel obstruction in which the appendix encircles the ileum, creating a closed-loop obstruction that rapidly progresses to ischemia and bowel gangrene. Despite advancements in cross-sectional imaging, AIK remains a formidable diagnostic enigma. Its clinical masquerade as common small bowel obstruction, coupled with the absence of pathognomonic radiographic markers, results in a persistently low preoperative diagnostic rate that necessitates a high index of clinical suspicion to avoid catastrophic intestinal ischemia. Delayed recognition often results in advanced bowel compromise and increased operative morbidity. This systematic review consolidates more than a century of published surgical experience to provide the most comprehensive clinicopathological synthesis of AIK to date. Thirty-two surgically confirmed cases were analyzed with respect to demography, clinical presentation, radiological features, operative management, and outcomes. The condition predominantly affected adults with a marked male preponderance, although recent reports demonstrate increasing recognition in younger patients and females without prior abdominal surgery. Clinically, patients most often presented with features of acute or subacute distal small bowel obstruction, while classical signs of appendicitis were inconsistently observed, contributing to diagnostic delay. A consistent intraoperative finding across cases was the high incidence of bowel ischemia and gangrene at exploration, underscoring the aggressive nature of this pathology. While conventional radiography remained nonspecific, cross-sectional imaging demonstrated improved diagnostic yield when characteristic closed-loop obstruction patterns were identified. Surgical management was definitive, ranging from simple appendectomy with untwisting in selected viable cases to en bloc bowel resection with anastomosis or stoma formation depending upon the status of the affected segment of bowel. Despite advances in imaging and minimally invasive techniques, AIK continues to be associated with substantial morbidity and non-negligible mortality. Based on cumulative clinical, radiological, and operative insight, this review proposes a practical clinicopathological framework distinguishing inflammatory and mechanical subtypes of AIK. This distinction provides valuable insight into disease pathogenesis, explains variations in presentation, and has direct implications for surgical decision-making. The primary merit and novelty of this systematic review lie in its transition of AIK from an anecdotal surgical anomaly into a structured, classifiable clinical entity, rather than viewing AIK as a mere intraoperative surprise. Heightened awareness, early imaging, and prompt surgical intervention are essential to improving outcomes in this rare but life-threatening condition.