Gallstone Ileus

Etiology

Gallstone ileus was first described in 1654 by Dr Erasmus Bartholin and is thought to be caused by the impaction of a gallstone in the gastrointestinal tract after passing through a biliary-enteric fistula. Gallstone ileus is more common in women (the ratio is 3.5 women to 1 man) and older patients, particularly those older than 60. Other factors contributing to gallstone ileus are a long history of cholelithiasis, repeated episodes of acute cholecystitis, and stones greater than 2 cm. According to the literature, approximately 40% to 50% of patients eventually diagnosed with gallstone ileus have a history of recent biliary colic bouts, jaundice, or acute cholecystitis.[4][5]

Epidemiology

Gallstone ileus occurs in 0.3% to 0.5% of all patients with gallstones and is one of the rarest causes of gallstone ileus, occurring in less than 0.1% of all mechanical obstruction cases and 1% to 4% of non-strangulating mechanical small bowel obstructions. Despite 350 years of medical advances, mortality remains high, ranging from 12% to 27%, partially because of non-specific symptoms, unremarkable biochemical investigations, high misdiagnosis rate, and delayed discovery.

Pathophysiology

The etiology of gallstone ileus results from adhesions forming between an inflamed gallbladder and an adjacent gastrointestinal (GI) tract, followed by gallstones causing pressure necrosis or inflammation between the 2 tissues. The inflammation or necrosis results in erosion and the formation of a cholecyst-enteric fistula. This direct access allows gallstones to move from the gallbladder to the GI tract. Fistulas can form within any part of the GI tract, with approximately 60% occurring in the duodenum due to the proximity. Less commonly, a gallstone may enter the duodenum through the common bile duct, a dilated papilla of Vater, or after an endoscopic sphincterotomy. A fistula between the gallbladder can also occur with the stomach, transverse colon, and distal small bowel. The pathology may be part of the natural course of Mirizzi syndrome.

Spillage of gallstones during laparoscopic cholecystectomy may also result in an intraabdominal abscess that can ulcerate the intestinal wall and lead to an entryway into the bowel lumen. The site of fistula formation, gallstone size, and bowel lumen size determine the impaction location. Gallstones most commonly impact the terminal ileum and ileocecal valve due to their narrow lumen and potentially less active peristalsis. Most gallstones smaller than 2 cm may pass spontaneously, while those larger are more likely to become impacted. The presence of diverticula, strictures, or neoplasms can also serve as impaction sites.[6][7] When gallstone impaction occurs, pressure is generated on the bowel walls, with proximal distension. Eventually, necrosis and even perforation can occur.

History and Physical

Unfortunately, the diagnosis is often delayed since symptoms may be nonspecific or intermittent, or investigations may fail to identify the cause of the obstruction due to the “tumbling phenomenon” as the stone tumbles through the variable portions of the GI tract. Patients typically present 4 to 8 days after symptoms start. The signs and symptoms are usually non-specific, including crampy, intermittent abdominal pain, variable abdominal distention, nausea, vomiting, and constipation intermittently as the stone travels through the GI tract. The degree of obstruction varies based on the location of the gallstone, and occasionally, the gallstone passes through the rectum without notice. The physical examination may be non-specific, but a clinician may appreciate abdominal distension, tenderness, high-pitched bowel sounds, and obstructive jaundice. Importantly, the intensity of the pain often does not correlate with the underlying anatomic alteration.

Evaluation

The diagnosis is usually made 3 to 8 days after symptoms, and a correct preoperative diagnosis is reported in 30% to 70% of cases. As a result, a high index of suspicion is necessary. Laboratory studies are usually non-specific, as only one-third of patients present with jaundice or alteration of hepatic enzymes. Ultrasound can be used to demonstrate fistulas, pneumobilia, impacted gallstones, and residual cholelithiasis or choledocholithiasis, but difficulties in locating stones and distortion by bowel gas make ultrasound suboptimal. Plain abdominal radiographs can also be used for diagnosis, with Rigler triad being present in some cases with partial or complete intestinal obstruction, pneumobilia or contrast in the biliary tree, and an ectopic gallstone. The gallstone can change position on serial films; the sensitivity ranges from 40% to 70%.

Computed tomography (CT) scanning is a better entity and has a sensitivity of 93%. Balthazar et al described a fifth sign: 2 air-fluid levels in the right upper quadrant on an abdominal radiograph corresponding to the duodenum and the lateral to the gallbladder, yet this sign is only present in approximately 24% of patients at the time of admission. Therefore, a CT scan should be performed if a clinician has a clinical suspicion but the patient has negative x-ray findings. Findings consistent with gallstone ileus include gallbladder wall thickening, pneumobilia, intestinal obstruction, and obstructing gallstones. Pneumobilia is a non-specific finding in approximately 30% to 60% of patients. A hepatobiliary iminodiacetic acid scan, magnetic resonance cholangiopancreatography, and esophagogastroduodenoscopy may be performed if there is still a question after CT scanning. However, gallstone ileus is more typically diagnosed intra-operatively when a patient is undergoing laparotomy for small bowel obstruction of unknown origin.[5][8][9]

Treatment / Management

Although the treatment and management of gallstone ileus are still under controversy, the main therapeutic goal is the extraction of the offending stone after resuscitation. Gallstone ileus involves 3 key elements: cholelithiasis, biliary-enteric fistula, and intestinal obstruction. Cholelithiasis and fistula are typically addressed by stone removal and fistula closure. Stone removal typically addresses intestinal obstruction. The current surgical options are 1) simple entero-lithotomy, 2) entero-lithotomy, cholecystectomy, and fistula closure (one-stage procedure), and 3) entero-lithotomy with cholecystectomy performed later (two-stage procedure). Most conclude that entero-lithotomy alone is the best option for most patients.

Some have advocated that a 1-stage procedure (cholecystectomy and fistula repair) should be considered in low-risk patients in good general condition and adequately stabilized preoperatively; 2-stage surgery is usually an option for those with persistent symptoms despite entero-lithotomy surgery. Whether interval biliary surgery should be performed simultaneously as the obstruction relief (1-stage procedure), performed later, remains unanswered.[3][10][11] Endoscopic management can be done, but it depends on the location of the stone. Anecdotal reports indicate that it is difficult and can be associated with bleeding. Plus, if the bowel enterotomy is large, closure can be difficult. Before surgery, patients need aggressive hydration and electrolyte replacement. Admission to the intensive care unit for patients with numerous comorbidities is recommended.(B3)

Differential Diagnosis

The differential diagnoses for gallstone ileus include the following:

• Acute pancreatitis
• Bile duct stones
• Cholecystitis
• Bile duct malignancy
• Peptic ulcer disease

Prognosis

Gallstone ileus is not a benign disorder; most patients also have several comorbid features. High morbidity and mortality rates have been reported for patients with gallstone ileus. An urgent repair is often associated with postoperative complications. The longer the operating time, the higher the risk of postoperative complications. The 1-stage procedure has higher morbidity, but the two-stage procedure means that the patient has to undergo general anesthesia again.

Complications

Complications may include bowel obstruction, infection, and pancreatitis. Other common complications include acute renal failure, wound dehiscence, biliary fistula, sepsis, urinary tract infections, anastomotic leaks, intra-abdominal abscess, and death.