A rare variant of gallstone ileus

Clinical History

A 76-year-old man affected by Alzheimer's disease was admitted in ER for onset of vomiting and malaise.
Symptoms started manifesting two days before and progressively worsened.
His past medical history was significant for diabetes, hypertension and moderate renal failure.
A physical examination showed a distended abdomen with mild tenderness in the epigastric region.

Imaging Findings

The ultrasound examination was very difficult to perform for the patient's conditions but it showed air in the biliary ducts while the gallbladder was not visible; this evidence was misinterpreted with cholecystectomy outcome.
The abdominal radiogram showed gastric dilatation, aerobilia and a large calcification in the right hypochondrium.
To evaluate this detection and differentiate between an ectopic or orthotopic gallstone we performed an abdominal non-enhanced CT scan.
This showed that the gallstone was wedged in the duodenum, moreover a remarkable amount of fluid in the stomach greatly distending it, the presence of air in the gallbladder and bile ducts and a likely cholecysto-duodenal fistula.
Based on these findings, a diagnosis of Bouveret's syndrome was defined.
For further topographic information, a gastrografin meal was requested. This showed a complete gastric outlet obstruction, caused by ectopic gallstone.
Subsequently the patient underwent gastroscopy with the aim to remove the gallstone. Unfortunately it was not possible to remove the gallstone endoscopically and it was necessary to perform surgery.

Discussion

Bouveret’s syndrome (BS) is a very rare complication of cholelithiasis caused by the migration and wedging of gallstones in the duodenal bulb or pylorus through a bilio-enteric fistula resulting in a gastric outlet obstruction. Having the same pathophysiology, (BS) can be considered an unusual variant of gallstone ileus [1, 2, 3, 4].
Recurrent inflammation of the gallbladder caused by gallstones can cause erosion and necrosis of the gallbladder wall with the formation of biliodigestive fistula and the passage of gallstone in the gut.
This condition is occurring in less than 1% of patients with cholelithiasis; in most patients gallstones are small in size and are eliminated without causing any obstruction. Only 15% of patients develop an intestinal obstruction named gallstone ileus, commonly in the terminal ileum [2]. Even rarer is the obstruction at the stomach or duodenum level.
This condition was first described by Bouveret in 1896 [5] and occurs more frequently in women and in elderly people. It usually presents non-specific symptoms such as: abdominal pain, nausea, vomiting, some patients can present haematemesis, jaundice and alteration of hepatic enzymes.
BS is often overlooked and delayed due to its rarity and non-specificity of its clinical features. The diagnosis is frequently made with the help of imaging or endoscopy, and ultrasound is an excellent imaging modality to study the biliary tract, however, it is poorly effective at locating a collapsed gallbladder especially if it is filled with air; only in 60% of cases a fluid-filled stomach, aspects of chronic cholecystitis, pneumobilia and ectopic gallstone [2-6] can be seen.
Abdominal radiogram may demonstrate some signs, known as Rigler’s triad, (gastric dilatation, ectopic gallstone and pneumobilia) in 30-35% of cases [3, 4, 5].
Rigler’s triad is more clearly noticeable on CT that can also show the exact level of obstruction, the status of the gallbladder and sometimes the site of the entero-biliary fistula.
If gallstones are isoattenuating and not well visualized on CT, magnetic resonance cholangiopancreatography or contrast media meal may be useful [7-8]
Gastrografin series can visualize an intraluminal filling defect, absence or lesser degree of transit of the contrast medium and the bilio-enteric fistula.
The extensive comorbidity and advanced age of these patients require prompt removal of the gallstones.
Despite the low success rate reported in the literature, an endoscopic treatment, with or without lithotripsy, should be considered the first therapeutic choice in high-risk elderly patients. Reported methods include: retrieval of gallstones with Dormia basket, extracorporeal shockwave lithotripsy, electrohydraulic lithotripsy and laser lithotripsy.
If endoscopic treatment fails, the patient will need surgical operation [1-9].

Differential Diagnosis List

Final Diagnosis

Bouveret's syndrome

URL:	https://www.eurorad.org/case/13967
DOI:	10.1594/EURORAD/CASE.13967
ISSN:	1563-4086