Bouveret syndrome: a rare cause of gastric outlet obstruction

Background

Gallstone ileus is a rare complication of cholelithiasis (0.3%–4%). Rarely the offending gallstone obstructs the pylorus or duodenum (1%–3%).1 This form of proximal gallstone ileus is termed Bouveret syndrome. As the prevalence of cholelithiasis increases with age, it follows that Bouveret syndrome typically occurs in those over 65 years of age.2 Management is initially supportive, with need for urgent gastric decompression. Increasingly endoscopic techniques for stone removal have been discussed, though the mainstay of treatment continues to be open surgical lithotomy.

Making a diagnosis of Bouveret syndrome can be challenging. It often presents non-specifically, though predominant symptoms are nausea and vomiting with abdominal pain.3 Diagnostic investigation can be misleading, with abdominal ultrasound or CT only diagnostic in about 60% of cases. Likewise endoscopy is only able to identify the obstructing stone in 69% of cases.3 A high degree of suspicion must therefore be maintained to ensure early diagnosis and prompt management.

Case presentation

A 73-year-old man, with known gallstones and a previously perforated gallbladder was referred to the acute surgical team after attending the emergency department with abdominal pain and vomiting. He complained of being unable to tolerate food or drink for the past 2 days, vomiting with all oral intake. His abdominal pain was worst on the right side. He reported a normal bowel habit and denied any urinary symptoms.

He has a medical history of gallstones, requiring two previous surgical admissions. The first, 13 months prior to this presentation, for a gallstone obstructing the common bile duct, managed endoscopically (endoscopic retrograde cholangiopancreatography). The second, for a perforated gallbladder treated with antibiotics and percutaneous gallbladder drainage 1 month later. He also has type 2 diabetes mellitus, hypercholesterolaemia and hypertension.

On examination he was alert, afebrile and had normal observations. On inspection from the end of the bed, there was an obvious bulge in the left upper quadrant of the abdomen. His abdomen was soft but distended, with tenderness across the upper abdomen. There was an audible succussion splash.

Investigations

A venous blood gas was performed which identified a hypochloraemic metabolic alkalosis (pH : 7.455, base excess : 15.7 mmol/L, HCO₃ ⁻ : 34.5 mmol/L, Cl⁻ : 87 mmol/L) with a raised lactate (3.6 mmol/L). His other electrolytes were within normal limits, including potassium of 3.8 mmol/L. Further blood testing revealed mildly raised inflammatory markers (white cell count 13.4×10⁹/L, neutrophils 9.8×10⁹/L, C reactive protein 9 mg/L), with an otherwise normal full blood count. He had an acute kidney injury (stage 1), with a raised creatinine compared with his known baseline (Cr 10⁶ µmol/L, baseline 50–60 µmol/L). He had mildly raised calcium and phosphate levels (Ca²⁺ 2.68 mmol/L, PO₄ ²⁻ 1.72 mmol/L). Liver function tests, serum amylase and clotting studies were normal. A urine dipstick was unremarkable.

A CT scan was performed urgently which reported a large gallbladder calculus had eroded into the first part of the duodenum causing gastric outlet obstruction (see figure 1). It also revealed gas in the gallbladder suggestive of fistulous communication. This confirmed a diagnosis of Bouveret syndrome.

Figure 1

Coronal CT image, showing a dilated stomach with an obstructing gallstone in the duodenum.

Differential diagnosis

Prior to the CT scan having been performed, the history, examination findings and biochemical picture pointed towards a diagnosis of gastric outlet obstruction. There are many known causes of gastric outlet obstruction, both benign and malignant. If benign pathology, the most common cause is gastric or duodenal ulceration, though other causes include pancreatitis, granulomatous diseases, trichobezoar, gastric volvulus and in infants, pyloric stenosis. A particularly rare cause is mechanical obstruction by gallstones, termed Bouveret syndrome. Malignant causes to consider include adenocarcinoma of the stomach, pancreas or duodenum, gastrointestinal (GI) stromal tumours or metastases.

Treatment

The patient was initially managed by the placement of a wide-bore nasogastric tube for gastric decompression, from which 900 mL was immediately aspirated. The patient was instructed to remain nil by mouth and given intravenous fluids, peripheral parenteral nutrition and a variable rate insulin sliding scale. He had daily blood testing, and any deranged electrolytes were corrected accordingly. He was referred to the specialist upper GI surgical team and had surgery 1 week after initial presentation. Surgery was performed using an open approach, through a right-sided subcostal incision. Intraoperative findings were of a densely adhered omentum and duodenum to the gallbladder and liver bed. A large stone was palpable in the first part of the duodenum. A longitudinal gastrotomy was performed on a healthy area of stomach, 3 cm proximal to the pylorus. The 3 cm×3 cm obstructing gallstone was gently manoeuvred proximally and extracted using desjardins forceps (see figure 2). The gastrotomy was closed using absorbable sutures. An oesophagogastroduodenscopy was then performed intraoperatively, demonstrating a cholecysto-duodenal fistula (see figure 3). The endoscope passed easily through to the second part of the duodenum, so there was no need to perform a gastro-jejunostomy and operative management of the fistula tract was not warranted. A surgical drain was left in the right upper quadrant and the patient was admitted to the high dependency unit.

Figure 2

Photographs showing: (A) longitudinal gastrotomy incision. (B) Obstructing gallstone in situ in the duodenum. (C) The 3 cm×3 cm gallstone, following surgical removal.

Figure 3

Labelled endoscopic photograph showing the duodenal opening of the cholecysto-duodenal fistula.

The patient continued on total parenteral nutrition and gradual oral intake over the following 2 days. He was given a high dose of omeprazole (40 mg two times per day).

Outcome and follow-up

Following slow progression of diet with input from specialist upper GI dietician, the patient was discharged home on post-op day 14. He re-presented to the emergency department 1 day after discharge with right-sided abdominal pain and vomiting secondary to constipation, and was discharged the following day. Eight months on, the patient has had no further readmissions and no complications.