Teaching Case

A 71-year-old female patient presented to the emergency department with sudden onset of upper quadrant abdominal pain, distension, and vomiting. The patient’s past medical history includes a previous episode of acute cholecystitis and pancreatitis. The present laboratory tests showed a mild increase in white blood cell count; abdominal radiography was requested to investigate the cause of the symptoms.

A PA erect abdominal radiograph revealed dilated small bowel loops containing air-fluid levels due to obstruction (Figure 1). A calcified structure about 2–3 cm with concentric layers forming an "onion" appearance was observed in the right iliac fossa, suggestive of a calculus. Additionally, a subtle linear radiolucency was noted at the level of the common bile duct and hepatic duct, consistent with pneumobilia (Figure 1), completing the Rigler triad of gallstone ileus.

The emergency surgeon requested a CT scan, which showed a fistula between the gallbladder and duodenum, causing the pneumobilia. The gallbladder presented abnormally thick walls and contained gas. An obstructing biliary stone was identified in the distal ileum, causing distension of the more proximal small bowel, which was fluid-filled with some air-fluid levels (Figures 2–5). A review of a previous CT, performed 4 years earlier for acute cholecystitis and pancreatitis, demonstrated a stone with the same appearance located in the gallbladder (Figure 6). Gallstone ileus was confirmed.

Gallstone ileus is defined as a mechanical obstruction caused by a biliary stone impacted in the GI tract [1].

Chronic cholecystitis can result in adhesions between the gallbladder and an enteric tract, most commonly the duodenum [2]; the chronic inflammation and presence of stones can lead to an erosion and formation of a bilio-enteric fistula, enabling the passage of stones from the gallbladder to the GI­ tract.

Gallstone ileus is a rare cause of GI obstruction, with an incidence of 3–3.5 patients per 100,000 hospital admissions [3].

It is a rare complication in 0.3% to 0.5% of patients with cholelithiasis.

This condition predominantly affects the elderly population, with a higher incidence in women than men, with a ratio of 3.5 to 4.5:1 [1]. Gallstone ileus accounts for 1% to 4% of cases of non-strangulating mechanical small intestinal obstruction [4].

The distal ileum and ileocecal valve are the most frequently impacted sites for stones, accounting for 60% to 75% of cases [5].

The mortality is estimated to be 12–27% [4].

Clinical presentation can be misleading, as physical examination alone does not provide distinguishing features from other causes of obstruction. However, a history of previous cholecystitis can raise suspicion of gallstone ileus in the diagnostic process.

Imaging is essential to confirm the diagnosis [6].

Abdominal x-rays alone can diagnose gallstone ileus when the Rigler triad is visible [7], which consists of:

• signs of (partial or complete) small bowel obstruction;
• an ectopic calcified gallstone, typically located in the right iliac fossa;
• pneumobilia.

Ultrasonography may be helpful conjoined with x-rays because, other than pneumobilia and signs of obstruction, it can detect even non-calcified stones.

CT has a much higher sensitivity, and it is useful to depict the bilio-enteric fistula and to better assess the exact location and number of stones for pre-operative planning [6,8].

Surgical treatment is always indicated to remove the stone, which consists in enterolithotomy. There is still debate in the literature regarding whether cholecystectomy and fistula repair should be performed in the same procedure [3].

Take home message

Gallstone ileus is a rare complication of cholelithiasis, predominantly affecting the elderly population. It can lead to small bowel obstruction and has a high mortality rate. Imaging, such as abdominal x-rays and CT scans, is crucial for diagnosis. Surgical treatment, including enterolithotomy, is necessary to remove the obstructing stone.

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