A 90-year-old woman with an unknown personal history was admitted to the emergency department with a 5-day history of abdominal pain and distension, nausea and vomiting. Physical examination revealed diffuse abdominal distension and pain, with normoactive bowel sounds.
An erect abdominal radiograph was performed and revealed central dilated small bowel loops with air fluid levels, indicative of small intestinal obstruction and no signs of pneumobilia or ectopic stones. The patient underwent an abdominal and pelvic CT that showed two gallstones in the distal choledochal duct, with intra and extra-hepatic bile ducts dilatation, and a large gallstone (3.5cm) in the lumen of the distal ileum, associated with a marked dilatation of proximal small bowel loops and gastric distension. CT also showed a collapsed gallbladder with air within the lumen, wall thickening and densification of the surrounding fat and a cholecystoduodenal fistula.
Gallstone ileus is an infrequent cause of mechanical bowel obstruction and occurs when a gallstone impacts in the ileum, usually in the ileocecal valve, most frequently moving through a biliary enteric fistula . The fistula could be formed between any parts of the extrahepatic biliary system and gastrointestinal tract, but the most common site is between the gallbladder and the duodenum [1, 3, 4]. It is a serious complication of cholelithiasis and affects primarily eldery patients, mostly females . Symptoms of gallstone obstruction are vague and include partial or complete small-bowel obstruction, complaining of abdominal distension, nausea, and vomiting. The nonspecific clinical presentation tends to delay diagnosis and treatment. Therefore, proper imaging plays an important role in establishing an accurate and timely diagnosis. The classic radiologic sign of gallstone ileus is the Rigler triad: small bowel obstruction, pneumobilia, and ectopic gallstones [2, 4].
Plain abdominal radiography can be valuable in the initial appreciation, however, only in a few cases is this triad of findings present because most gallstones are radiolucent and the presence of air in the biliary tree is not sufficient enough to be detected . In most cases there is only evidence of small bowel obstruction. As a result, CT scanning is increasingly used when small-bowel obstruction is suspected and allows a correct diagnosis of gallstone ileus and aid in deciding the best treatment . Common findings include small-bowel obstruction with transition point, ectopic intraluminal calculi, gas-fluid levels in gallbladder fossa, free abdominal fluid, cholecystoduodenal fistula, pneumobilia, and thickened duodenum [1, 5]. Size, location and morphology of the gallstone, as well as additional impacted stones are important parameters to consider . The obstructing stone is classically greater than 2.5cm in diameter and care must be taken in finding the gallstone, as only a small number are calcified and density may be very similar to bowel content . Free fluid, free gas, portal venous gas or mural gas are signs of more advanced disease and poorer prognosis. This condition has a high mortality rate largely because most patients are eldery with associated co-morbidities. The decision to intervene surgically depends on the patient’s clinical condition and the procedure of choice is controversial, but the enterolithotomy without cholecystectomy and fistula repair is an option in older patients - this was done on that patient but with cholecystectomy and she had recovered unexpectedly well [2, 3]. Any delay in diagnosis and treatment may lead to serious complications such as ischemic lesions, ulcerations of the bowel, abscess formation, and peritonitis.
Differential Diagnosis List
Other causes of small bowel obstruction
Lower abdominal/pelvic calcification