How do gallstones cause intestinal obstruction (ileus)?

From the Guidelines

Gallstone ileus occurs when a gallstone causes intestinal obstruction through a process called biliary-enteric fistula formation, where a gallstone erodes through the gallbladder wall into the adjacent small intestine, usually the duodenum, as described in the guidelines for the treatment of gallstones by the American College of Physicians 1. This process can lead to a mechanical obstruction, preventing the normal passage of intestinal contents, and causing symptoms such as abdominal pain, nausea, vomiting, and abdominal distension. The condition is more common in elderly patients with a history of gallstone disease and accounts for about 1-4% of all cases of small bowel obstruction. Some key points to consider in the diagnosis and treatment of gallstone ileus include:

• The importance of differentiating symptoms to determine the appropriate course of treatment, as symptomatic gallstones require different management than asymptomatic gallstones 1.
• The use of imaging studies, such as abdominal X-rays, to diagnose gallstone ileus, which may show air in the biliary tree (pneumobilia), intestinal obstruction, and an ectopic gallstone 1.
• The potential for gallbladder cancer, which accounts for approximately one third to one half of gallstone-related deaths in the United States, and the consideration of cholecystectomy to prevent future biliary pain, a biliary complication, gallbladder cancer, or death 1. Treatment typically involves surgery to remove the obstructing gallstone, though the management of the biliary-enteric fistula remains controversial and may be addressed during the same operation or in a later procedure depending on the patient's condition 1.

From the Research

Gallstone Ileus Mechanism

• Gallstone ileus (GSI) occurs when a gallstone passes from the biliary tract into the gastrointestinal tract via an abnormal pathway, known as a bilio-enteric fistula 2, 3, 4, 5, 6.
• This fistula is formed due to chronic inflammatory processes, which cause the gallbladder to adhere to and erode into the intestines 2, 4.
• The gallstone can then migrate through the fistula and become lodged in a narrowed segment of the bowel, causing a mechanical obstruction 3, 4, 5, 6.

Clinical Presentation

• GSI typically presents as small bowel obstruction, with symptoms such as abdominal pain, distension, and vomiting 2, 3, 4, 5, 6.
• In some cases, the gallstone can cause large bowel obstruction, as seen in the case of a 59-year-old woman with a large gallstone lodged in the sigmoid colon 3.
• Imaging studies, such as CT scans, are diagnostic in confirming small bowel obstruction and identifying the presence of a gallstone outside the gallbladder 2, 3, 4, 5, 6.

Management and Treatment

• The mainstay of treatment for GSI is surgical removal of the gallstone to relieve the intestinal obstruction 2, 3, 4, 5, 6.
• Simple enterolithotomy is a safe and effective procedure for removing the gallstone, and can be performed via an enterotomy proximal to the obstruction 4, 6.
• In some cases, more definitive surgical interventions, such as fistula repair, may be necessary to prevent recurrent symptoms or gallstone ileus 2, 4.