What is Rigler's triad and how is it treated?

Rigler's Triad: Diagnosis and Treatment

Rigler's triad is a set of three radiological findings pathognomonic for gallstone ileus, consisting of intestinal obstruction, pneumobilia (air in the biliary tract), and an ectopic gallstone in the bowel. Surgical intervention through enterolithotomy is the definitive treatment to prevent further complications and reduce mortality. 1

Diagnostic Features of Rigler's Triad

Rigler's triad consists of three key radiological findings:

• Small bowel obstruction - characterized by dilated bowel loops and air-fluid levels 1, 2
• Pneumobilia - presence of air in the biliary tract 1, 3
• Ectopic gallstone - visualization of an aberrant gallstone within the bowel lumen 1, 2

These findings are considered pathognomonic for gallstone ileus, though the complete triad is not always observed in all cases 2. Contrast-enhanced CT scan is the most effective imaging modality for identifying all components of the triad 3.

Clinical Presentation

Patients with gallstone ileus typically present with:

• Abdominal pain and distension 2
• Nausea and vomiting, often bilious 1
• Constipation or obstipation 2
• Early satiety and bloating 3
• Altered general condition, especially in elderly patients 1

It's important to note that symptoms may be intermittent and non-specific, which can delay diagnosis 3.

Pathophysiology

Gallstone ileus occurs as a complication of cholelithiasis when:

• A large gallstone erodes through the gallbladder wall into adjacent gastrointestinal structures, creating a biliodigestive fistula 1, 3
• The gallstone migrates through the gastrointestinal tract and becomes impacted, most commonly in the terminal ileum due to its narrow lumen 1, 2
• The obstruction leads to proximal bowel dilation and the clinical manifestations of intestinal obstruction 2

Treatment Approach

The definitive treatment for gallstone ileus is surgical intervention:

• Enterolithotomy - surgical removal of the obstructing gallstone through an incision in the bowel is the primary treatment approach 1, 3
• Laparoscopic techniques may be employed when feasible, though open laparotomy is often necessary for larger stones 3
• Simple enterolithotomy without addressing the biliary-enteric fistula is often sufficient in emergency situations to reduce operative time and complications 1

Special Considerations

• Gallstone ileus predominantly affects elderly patients with multiple comorbidities, increasing surgical risk 1
• Chronic gallstone ileus can occur, with stones remaining in the bowel for extended periods before causing acute obstruction 2
• Early diagnosis and prompt surgical intervention are crucial to reduce morbidity and mortality 3
• In rare cases, a variant called Bouveret's syndrome can occur when the stone impacts in the duodenum or stomach, causing gastric outlet obstruction 4

Potential Complications

• Delayed diagnosis can lead to increased morbidity and mortality 3
• Bowel perforation may occur at the site of stone impaction 1
• Recurrent gallstone ileus can develop if additional stones migrate through the persistent biliary-enteric fistula 4

Careful radiological assessment is essential for prompt diagnosis, with CT scan being the gold standard imaging modality to identify all components of Rigler's triad 1, 3.