Beyond Rigler's Triad: Gallstone Ileus in the Absence of a Bilioenteric Fistula.

Gallstone ileus is an uncommon cause of mechanical intestinal obstruction, classically associated with bilioenteric fistula formation that enables gallstone migration into the gastrointestinal tract. Its incidence increases among elderly patients and is associated with significant morbidity due to delayed diagnosis. Obstruction typically occurs at the terminal ileum, and diagnosis traditionally relies on Rigler's triad: intestinal obstruction, pneumobilia, and an ectopic gallstone. Gallstone ileus without a bilioenteric fistula is an exceptionally rare presentation that challenges conventional diagnostic paradigms. The absence of pneumobilia or identifiable fistulous communication may obscure clinical suspicion and delay treatment. Proposed mechanisms include transpapillary migration through the ampulla of Vater, transient biliary dilation, spontaneously closed microfistulas, or intraluminal stone enlargement within areas of intestinal stasis. This case highlights the importance of considering non-fistulous gallstone ileus, even when classical radiologic findings are incomplete. Computed tomography remains the diagnostic modality of choice, allowing accurate identification of ectopic gallstones and obstruction sites. Surgical management with enterolithotomy alone is generally safe and effective, particularly in elderly patients, as additional biliary surgery is usually unnecessary in the absence of a fistula. Recognition of this rare variant is essential to ensure timely diagnosis and appropriate surgical management in patients with small bowel obstruction and a history of gallstone disease.