A Rolling Stone Without a Home: Bouveret Syndrome on PoCUS

This case report demonstrates the utility of point-of-care ultrasound (POCUS) to identify complicated gallbladder disease. In this case, the patient presented with abdominal pain and a known history of cholelithiasis. POCUS demonstrated signs of small bowel obstruction and subsequently guided the decision to pursue radiology-performed imaging.  Subsequently, the rare complication of Bouveret syndrome was identified. This case demonstrates the utility of POCUS to guide further imaging decisions.

Consent from the patient was obtained directly. Ottawa Hospital Research Institute REB review deferred for the case report was deferred due to direct patient consent.

Introduction, Bouveret Syndrome

Bouveret syndrome is a rare condition where a gastric outlet obstruction is caused by an impacted gallstone that reaches the small bowel through a biloenteric fistula.(1) The fistula forms due to chronic inflammation where the biliary system adheres to the bowels thus causing gallbladder wall ischemia and subsequent perforation allowing gallstone passage into the stomach or proximal duodenum.(1,2)

Gallstone ileus is an uncommon condition, comprising only 1-4% of cases of intestinal obstruction. Furthermore, Bouveret syndrome is a rare form of proximal gallstone ileus, representing between 1-3% of cases.(1,2) It is named after Leon Bouveret, a French physician who published two case reports in 1896.(3) The condition is most prevalent in elderly women, with a median age at presentation of 74 years.(1) Diagnosis is usually confirmed with computed tomography (CT), which is 93% sensitive, 100% specific and 99% accurate.(1) If CT is not available, abdominal x-rays can be used but these are only diagnostic in 21% of cases.(1)

This case demonstrates how point-of-care ultrasound (POCUS) can be helpful in guiding the choice of radiology-performed imaging in the emergency department (ED) and to expedite definitive care.

Figure 1: A large gallstone noted in the right upper quadrant (arrow) with posterior shadowing. The Sonographic Murphy sign was negative.

Clip 1: A sweep of the right upper quadrant. A stone with posterior shadowing noted again.

Figure 2:Still images of a dilated loop of small bowel shown with and without the outer walls highlighted in yellow.

Case Presentation

An 80-year-old female presented to the ED with abdominal pain and 3 episodes of vomiting. The patient’s past medical history was significant for an extensive right leg deep venous thrombosis (DVT) for which she was on apixaban. During routine monitoring of her liver enzymes while on apixaban, she was found to have elevated ALT and ALP for which an outpatient ultrasound (US) of her abdomen was ordered. This US was performed 11 days prior to her presentation to the ED.

Her outpatient imaging identified a 5cm nonmobile gallstone, as well as thickening of the gallbladder wall, pericholecystic fluid, and findings were noted to be in keeping with acute cholecystitis. These findings were discussed with a general surgeon who had previously met the patient for cholelithiasis. It was thought that she would not be a surgical candidate given her comorbidities and that the patient was noted to be asymptomatic without any abdominal pain, nausea or fevers.

In the ED, the patient described having a one-day history of epigastric pain, obstipation, vomiting and increasing abdominal distention. Her abdominal exam was remarkable for distention and significant tenderness to the epigastrium. Her vital signs were within normal limits.

Clip 2: POCUS clip showing a distended fluid filled stomach.

Clip 3: Proximal duodenum demonstrating dilation >2.5cm and to and fro movement of bowel contents.

PoCUS demonstrated a large gallstone with a negative sonographic murphy sign and the absence of a clearly identifiable gallbladder wall. (Figure 1, Clip 1).  PoCUS over the epigastrium demonstrated a distended fluid-filled stomach, and tracking to the duodenum there was noted to be to and fro movement of small bowel contents, dilated bowel loops greater than 2.5cm indicating small bowel obstruction (Figure 2, Clips 2 and 3).  A CT of the abdomen with contrast was then performed to further delineate the cause of the patient’s symptoms. The CT demonstrated a large gallstone that was impacted in the gallbladder neck, resulting in acute on chronic cholecystitis. The stone eroded into the duodenal lumen and produced duodenal obstruction (Figure 3).  

Broad-spectrum parenteral antibiotics were then initiated and general surgery was consulted to assess the patient. The patient ultimately underwent a laparotomy, pyloroplasty, and graham patch as well as duodenostomy, primary duodenal repair and patch. The patient was discharged for rehab due to deconditioning following recovery from her surgery.

Figure 3: A large gallstone (blue dot) can be visualized as well as distention of the stomach (yellow rectangle) consistent with Bouveret syndrome.

Discussion

Abdominal US and CT of the abdomen and pelvis are the two main imaging modalities that are used to help diagnose the etiology of abdominal pain in patients who present to the ED. Although both CT and US are readily available at many academic and large community hospitals, access can be limited in rural centers. Patients often need to be transferred to another centre for radiology performed imaging which is both time and resource-consuming. As such, it is helpful to have as much supportive information as possible when making the decision to transfer. Even in urban centers, access can be difficult due to bed block, and PoCUS can be a tool to better risk stratify our patients and imaging decisions. 

PoCUS is useful for the evaluation of the patient with right upper quadrant pain to look for acute cholecystitis(4) and can also be very helpful for diagnosing small bowel obstruction (SBO) with a sensitivity of 83% and specificity of 93%(5). It can especially be useful in centres where access to radiology US or CT is limited as it can be done quickly at bedside.  

In this case of Bouveret syndrome, PoCUS was used to guide radiology imaging choice and expedite the patient’s time to diagnosis. Upon initial review of the patient’s history with the recent abdominal ultrasound demonstrating acute cholecystitis as well as epigastric pain and tenderness on examination, we had a high suspicion of cholecystitis as the cause of the patient’s symptoms. The preferred choice for imaging for biliary pathology is typically ultrasound but in cases of complicated gallstone disease such as perforation or gangrenous disease, CT imaging is the first line(6).  With the PoCUS showing likely small bowel obstruction there was a high suspicion of complicated gallbladder disease and it was felt CT would in fact be the best imaging modality. In an environment where CT is not readily available, this would allow the physician to make a more confident decision regarding transfer for further imaging. The use of PoCUS in the assessment of our patient allowed us to proceed directly to CT imaging of the abdomen and efficiently establish the diagnosis and disposition for our patient.  

Concussion

In cases where the best imaging modality is unclear upon obtaining an initial history and physical examination, POCUS can be a helpful adjunct to guide radiology imaging selection.  In this case of a patient with known gallstone disease, the finding of small bowel obstruction on POCUS led to expedited definitive management.