A duodenal diverticulum is a pouch-like protrusion that forms in the wall of the duodenum, the first section of the small intestine. These diverticula are relatively common, often discovered incidentally during imaging for other conditions, with autopsy studies finding them in up to 22% of people. While the vast majority remain harmless and cause no symptoms, a small percentage can lead to various gastrointestinal problems and, rarely, serious complications that require medical intervention. The presence of a diverticulum is often a benign finding, but its specific location and size determine the potential for it to become a clinical concern.
Defining the Anatomy and Location
Duodenal diverticula (DD) are most frequently found in the second and third portions of the duodenum, which is divided into four segments. They are classified into two main types based on their structure and origin: extraluminal and intraluminal.
The common extraluminal type is an acquired or “false” diverticulum, consisting only of the inner layers (mucosa and submucosa) that have pushed outward through the muscle layer. These acquired pouches account for the majority of cases and protrude away from the intestinal canal.
Intraluminal diverticula are rare and considered “true” diverticula because they contain all layers of the duodenal wall. This congenital type results from incomplete recanalization during embryonic development and appears as a windsock-like pouch projecting into the intestinal lumen.
Up to 75% of extraluminal diverticula are located in the second portion of the duodenum, specifically in the periampullary area, within a radius of 2 to 3 centimeters of the ampulla of Vater. This location is significant because the ampulla is where the common bile duct and pancreatic duct join the duodenum, making these diverticula a direct risk factor for biliopancreatic complications.
Causes and Formation
Most duodenal diverticula are acquired and form through a process called pulsion, or pushing. This development is driven by increased pressure within the duodenal lumen, forcing the inner lining to herniate through weak points in the muscular wall. These weak areas often occur where blood vessels naturally penetrate the muscular layer to supply the inner intestinal lining.
The risk of developing these acquired diverticula increases significantly with age, suggesting that a gradual weakening of the intestinal muscle contributes to their formation. While the exact mechanism is not fully defined, conditions that increase internal duodenal pressure, such as chronic motility disorders or long-term straining, are believed to be contributing factors.
Clinical Presentation: Symptoms and Complications
For the vast majority of individuals, a duodenal diverticulum is an entirely asymptomatic finding discovered incidentally during diagnostic procedures. However, about 5% of patients will experience symptoms, which arise when the pouch becomes inflamed, obstructed, or bleeds.
Symptoms typically result from complications related to the diverticulum’s anatomy, often involving the stagnation of food and digestive juices within the sac. One common complication is diverticulitis, where trapped contents cause inflammation, leading to symptoms like abdominal pain, nausea, and vomiting. The pain is frequently localized to the upper right quadrant of the abdomen.
Complications can extend to the biliary and pancreatic systems, particularly with periampullary diverticula (sometimes known as Lemmel’s syndrome). Stagnation and pressure on the ampulla of Vater can obstruct the flow of bile and pancreatic fluid, leading to jaundice or pancreatitis. Furthermore, the diverticulum can contribute to the formation of bile duct stones, causing recurrent episodes of cholangitis or obstruction.
Although uncommon, a diverticulum can ulcerate and cause gastrointestinal bleeding, which may be chronic and subtle or, less frequently, severe. The most serious complication is perforation, where the diverticulum wall ruptures, often into the retroperitoneal space. Perforation causes severe abdominal pain, carries high mortality rates (up to 34%), and requires immediate attention.
Detection and Management Approaches
Because duodenal diverticula are often asymptomatic, they are usually detected incidentally during imaging studies. Common diagnostic tools include computed tomography (CT) scans, which show the out-pouching and may reveal signs like fat stranding or free air if a perforation has occurred. Upper gastrointestinal barium studies are also effective, showing the diverticulum as an extraluminal collection of contrast material.
Endoscopic procedures, such as esophagogastroduodenoscopy (EGD), allow direct visualization of the diverticulum’s opening, which is particularly useful for identifying periampullary diverticula. If a duodenal diverticulum is found but is not causing symptoms, the standard approach is conservative, often referred to as “watchful waiting.” Treatment is only initiated when complications arise and the diverticulum is conclusively identified as the source of the patient’s symptoms.
For symptomatic cases, the management approach depends entirely on the nature of the complication. Simple diverticulitis may be managed conservatively with bowel rest, intravenous fluids, and antibiotics. For complications involving the bile duct, endoscopic intervention may be used to clear stones or alleviate obstruction.
Surgical intervention, which may involve diverticulectomy (removal of the pouch) or more complex procedures, is reserved for severe complications like uncontrolled bleeding, obstruction that cannot be managed endoscopically, or perforation. Surgical treatment of a perforated diverticulum is complex due to the duodenum’s location and high risk of complications like duodenal leaks, but it is often necessary for unstable patients or those who fail conservative measures.