Small Bowel Diverticula

Epidemiology

Duodenal diverticula are the most common type of small bowel diverticula and are found in up to 23% of autopsies and in as many as 27% of patients undergoing upper endoscopy procedures. Duodenal diverticula are intraluminal or extraluminal, with the former being congenital and quite rare. Extraluminal duodenal diverticula are much more common, second in incidence only to large bowel diverticula. Unlike intraluminal diverticula that develop in utero, the extraluminal type usually develop in the fifth decade of life or later.

Pathogenesis

An intraluminal duodenal diverticulum begins to form in utero as a duodenal web, most often in the second portion of the duodenum. This web becomes stretched over time by peristaltic flow creating a saclike shape within the lumen of the duodenum that becomes a false diverticulum. If the apex of the diverticulum does not have an opening and remains closed, neonatal duodenal obstruction will occur.

An extraluminal diverticulum, like those most commonly seen in the colon, is acquired. It is most often located within 2 cm of the ampulla of Vater. It is a false diverticulum that contains only the mucosa and submucosa that herniated between the muscle at sites of weakness in the bowel wall. These areas of weakness are usually where the blood supply to the bowel creates small structural defects, allowing the mucosa and submucosa to herniate outward.

Clinical Presentation

Although duodenal diverticula are relatively common, only 12% of patients will develop symptoms. The most commonly reported symptoms are postprandial epigastric pain, bloating, nausea, vomiting, and gastrointestinal bleeding. Because most of these symptoms can be caused by other more common gastrointestinal problems, the diagnosis is often delayed or missed.

Like diverticular disease of the colon, duodenal diverticula can lead to complications that include perforation, bleeding, infection, and obstruction. The incidence of obstruction from an intraluminal diverticulum is much more common given its anatomic location within the lumen of the duodenum. There have even been case reports of duodenal diverticula causing obstruction of the ampulla of Vater that resulted in biliary obstruction and pancreatitis. For the far more common extraluminal type, perforation and bleeding are more often seen.

Diagnosis

Duodenal diverticula can be diagnosed under direct visualization with esophagogastroduodenoscopy (EGD) or endoscopic retrograde cholangiopancreatography (ERCP), which can also be used for therapeutic treatment. Radiographic means of diagnosis are less invasive and are considered more appropriate initial methods of evaluation. Fluoroscopy can reliably identify duodenal diverticula with an upper GI study and small bowel follow-through. The classic “wind-sock” sign describes the saclike projection of an intraluminal duodenal diverticulum outlined by oral contrast within the duodenum. Extraluminal duodenal diverticula can be similar in appearance to those seen in the colon as an outpouching. Computed tomography (CT) with oral and intravenous (IV) contrast along with magnetic resonance cholangiopancreatography can also be helpful diagnostic modalities.

Management

Less than 1% of patients with duodenal diverticula require invasive endoscopic or surgical interventions. Among those who require surgery, the morbidity and mortality can be quite high. Endoscopy is an appropriate means of controlling hemorrhage and ERCP is often effective in relieving biliary and pancreatic obstruction with sphincterotomy and stent placement, although there is a risk of perforation if a sphincterotomy is performed and the diverticulum is in close proximity to the ampulla of Vater.

Perforation, if not contained, must be managed surgically. The morbidity and mortality are higher for diverticula in close proximity to the ampulla. During surgical exploration, a Kocher maneuver is performed to allow thorough evaluation of the duodenum ( Fig. 77.1 ). Diverticulectomy may be feasible if there is adequate distance from the ampulla. If the diverticulum is close, the ampulla should be cannulated to avoid injury. Once the diverticulum is resected, the duodenum should be closed in two layers transversely to avoid stricture and can be buttressed with an omental or jejunal patch.

Biliary and enteric diversions have been described if the diverticulum is very close to or involves the ampulla. Even more invasive means such as pancreaticoduodenectomy have been reported with a relatively low risk of complications, but there is not adequate data at this time to justify its use in all cases. In the setting of perforation where diverticulectomy cannot be safely performed or if the patient is not a surgical candidate, wide drainage and antibiotics can sometimes serve as definitive management.