Gallstone ileus

Gallstone ileus is a mechanical bowel obstruction caused by impaction of a gallstone in the ileum after being passed through a biliary-enteric fistula representing a complication of biliary–enteric fistulas.

• The diagnosis is often delayed since symptoms may be intermittent and investigations fail to identify the cause of the obstruction.
• In 1890, Courvoisier reported a 44% mortality after surgery in a series of 131 patients.
  
• Over the past century the mortality rate has declined to 5 to 24%.

Incidence

• Gallstone ileus is an unusual complication of cholelithiasis, occurring in less than 0.5 percent of patients.
• It is responsible for approximately 1 to 4 percent of all cases of mechanical obstruction and, in patients over age 65.
  
• About 0.4 to 1.5% of patients with cholelithiasis develop gallstone ileus.
  
• Virtually all cases of gallstone ileus are associated with a cholecystenteric fistula and significant surrounding inflammation.
  
• It accounts for 1 to 3% of all cases of nonstrangulated small bowel obstruction.
  
• In patients over the age of 65, gallstone ileus accounts for 25% of nonstrangulated bowel obstruction.

Gallstone ileus is a geriatric emergency; most studies report an average age between 65 and 78 years.

• However, the youngest patient in the literature was 13 years of age.
  
• Concomitant geriatric diseases are present in as many as 80 to 90% of cases.
  
• Reisner reported, in a review of 1001 cases, a ratio of female to male of 3.5 : 1.

PATHOGENESIS

• A minimal stone size of 2.0 to 2.5 cm in diameter is required to cause intestinal obstruction.
  
• Multiple stones are found in up to 40% of cases and are often the cause of early recurrence.

The following sequence is responsible for most cases of fistula formation.

• Pericholecystic inflammation after cholecystitis leads to the development of adhesions between the biliary and enteric systems.
  
• Pressure necrosis by the gallstone against the biliary wall then causes erosion and fistula formation.
• Sixty percent are cholecystoduodenal fistulas, but cholecystocolonic and cholecystogastric fistulas can also result in gallstone ileus.
• In addition, two cases of gallstone ileus have occurred after endoscopic sphincterotomy.
  
• In this setting, the stone is presumed to have passed into the small bowel through the sphincterotomy and to have been large enough to cause obstruction.
  
• Gallstone ileus is also a rare complication of Crohn's disease.

Once a stone enters the gastrointestinal tract, it may be vomited, passed spontaneously (80%), or become impacted.

• Gallstones increase in diameter as they pass down the bowel due to sedimentation of bowel contents.
• The ileocecal valve, as the narrowest part of the bowel, is the most frequent site of stone impaction.
• Duodenal obstruction by gallstones is also known as gastric outlet obstruction or Bouveret’s syndrome.
• In these cases, early vomiting is a common sign.
• Colonic gallstone ileus is usually found in association with an underlying pathological narrowing of the colon, such as postdiverticulitis stenosis or carcinoma.
  
• It may exceptionally be found without colonic abnormality in cases of cholecystocolonic fistula and very large stones.

Clinical features

• The classic clinical presentation of gallstone ileus is episodic subacute obstruction in an elderly female.
• The clinical presentation of gallstone ileus is rarely specific, and as many as half of the patients have no history of biliary symptoms.
  
• The symptoms do not differ from bowel obstruction of any other etiologies.
  
• The patient is usually acutely ill and dehydrated and typically complains about vomiting, abdominal pain, and distention with bowel sound of obstructive quality.
  
• The mean duration of these symptoms before admission was reported to be 4 days.
  
• Signs of local peritonitis in the right upper quadrant may indicate acute cholecystitis.
• Jaundice may be present in up to 25% of the patients.

Bouveret's syndrome is the term used to describe gastric outlet obstruction secondary to an impacted gallstone in the duodenum or pylorus.

• The presenting symptoms of this rare entity are epigastric pain, nausea, and vomiting.

Many affected patients have serious concomitant medical illnesses, including coronary disease, pulmonary disease, and diabetes mellitus.

Diagnostic imaging

The diagnosis is made before the operation in less than half of the patients.

• Delay in surgical treatment may lead to serious complications, such as electrolyte imbalance, ischemic lesions, ulcerations of the small bowel, abscess formation, and occasionally free perforation and peritonitis.

Plain abdominal films

Plain abdominal films are widely used as a screening in patients with acute abdomen.
Rigler described four radiologic signs of gallstone ileus on plain abdominal film:
(1) air in the biliary tree (pneumobilia),
(2) bowel obstruction,
(3) visualized stone, and
(4) migration of a previously observed stone.

• The presence of two of the first three signs has been considered pathognomonic of gallstone ileus.
• However, these characteristic signs are rarely completely present.
• Plain X-ray examination is diagnostic in only 35% of the cases.

Pneumobilia is the most important radiographic sign of Rigler’s tetrade.

• However, it is observed in only 30 to 50% of cases with fistulas.
  
• Concomitant occlusion of the cystic duct prevents the development of pneumobilia.
  
• The latter is not pathognomonic of biliary–enteric fistula because it is also seen in the presence of insufficient sphincter of Oddi following sphincteroplasty or endoscopic sphincterotomy.
  
• Emphysematous cholecystitis may also cause pneumobilia.

Balthazar reported a small series of patients with gallstone ileus in which air in the gallbladder was visible on plain films in most cases.

• In contrast, air in the duodenal bulb or biliary radicles is more rarely detected.
  
• The combination of air in the gallbladder and air in the duodenum (double air bubble in the right upper quadrant) was observed in 7 out of 11 patients and is also known as Balthazar’s sign.
• A significantly higher diagnostic accuracy (80 to 90%) may be achieved using contrast examinations.
  
• The demonstration of a diverticulum-like structure or a fistulous tract adjacent to the first duodenal segment associated with an intestinal obstruction on the delayed films suggests the correct diagnosis.

Ultrasonography

Ultrasonography may be more sensitive than plain films in patients with gallstone ileus due to the small volume of intestinal air associated with ileus of higher obstruction.
The most characteristic ultrasonographic findings include:
(1) location of a gallstone in a fluid filled intestine, (
2) a severely diseased gallbladder, and
(3) pneumobilia.

• some cases, ultrasonography may provide definitive diagnosis of gallstone ileus, and obviate the need for any further tests.
  
• However, the diagnostic sensitivity for the definitive diagnosis can be increased by combining ultrasound with plain films.

Computed tomography

• Computed tomography (CT) is increasingly used as a screening modality in patients with an acute abdomen.
  
• CT is often used in the elderly population, in whom signs and symptoms of abdominal pathologies are particularly vague and unspecific.
  
• Rigler’s criteria for gallstone ileus are also frequent findings in the CT scan.
  
• In a recently published series of 165 patients with small bowel obstruction, the sensitivity and specificity of abdominal CT scan in diagnosing gallstone ileus was 93 and 100%, respectively.
  
• A direct comparison of plain film, ultrasound, and CT in gallstone ileus demonstrated that the CT scan was superior to the other two imaging methods in terms of a much higher accuracy.

Treatment

Long-standing controversies surround the treatment of patients with gallstone ileus, and several therapeutic approaches have been proposed.

• Most authors agree that the immediate relief of the intestinal obstruction remains the cornerstone of management.

Two main surgical strategies have been proposed:

first, enterotomy with removal of the impacted stone and fistula repair including cholecystectomy in a one-stage operation;

second, a two-stage operation with surgical removal of the obstructing stone from the gut without biliary surgery.

• Biliary surgery and closure of the fistula are then eventually performed in a second operation.

Most investigators favor enterolithotomy alone in the initial surgical treatment of gallstone ileus due to the lower operative mortality.

• Some have pointed out that a number of fistulas spontaneously close once the stone has passed, particularly when the cystic duct is patent, and when there are no residual stones left in the gallbladder.
• In addition, cholecystectomy is often technically difficult because of the underlying chronic cholecystitis with concomitant adhesions.

However, complications arising from the untreated fistula in the two-stage procedure may contribute to a higher morbidity.

• For example, untreated fistulas may lead to recurrent gallstone ileus.
  
• A large review of 1001 cases has reported a similar mortality of the one-stage operation compared with the two-stage approach, or enterolithotonry alone.
  
• Therefore, the one-stage operation has recently become more popular, and is recommended whenever local and general conditions permit.

It is important to search for additional stones in the bowel, which often lead to recurrence of gallstone ileus.

• Manual propulsion of the smallest stones to the enterotomy of the larger stones may be used successfully, but caution is recommended because of the risk of injury of the intestinal mucosa.
  
• Attempts to crush impacted stones manually without enterolithotomy should be avoided for the same reason.
  
• Multiple enterotomies are safer than aggressive attempts at extracting all stones through one incision.

Laparoscopic treatment of gallstone ileus has been described but is often difficult as extensive adhesions occur in the area of the gallbladder.

• A two-stage operation is therefore usually advised.
  
• Laparoscopy may be useful to establish the diagnosis and offers a minimally invasive treatment of the ileus.
  
• This approach may possibly reduce mortality and morbidity in elderly and high-risk patients.
  
• Laparoscopy also reduces the risk of wound infection, which still represents the most common postoperative complication following treatment of gallstone ileus.

Alternative nonsurgical modalities have been proposed, including

• endoscopic removal of the gallstone,
  
• endoscopic sphincterotomy in cases of concurrent choledocholithiasis, and
  
• extracorporeal shockwave lithotripsy.
  • However, abdominal gas containing bowel loops may prevent visualization of the obstruction by ultrasonography, thereby precluding extracorporeal lithotripsy
• These methods may avoid emergency laparotomy, but they should be considered only in high-risk patients.
  
• In addition, they do not definitively manage the biliary disease.

Morbidity and mortality

• The morbidity and mortality are mostly determined by the presence of comorbid diseases of the patient and the duration of the ileus.
  
• In large series, the overall mortality varied between 5 and 24%.
  
• These figures are 5 to 10 times higher than in patients with intestinal obstructions from other causes.
  
• The most important factors influencing the risk of mortality include
  • advanced age,
    
  • comorbidities,
    
  • delayed consultation,
    
  • misdiagnosis,
    
  • delayed surgery, and
    
  • postoperative complications.
• The most common postoperative complications include
  • wound infection (27%),
  • pulmonary infection (26%), and
  • peritonitis (15%).

Severe postoperative bleeding has also been described, generally arising from the erosion of a blood vessel during the passage of the gallstones.