In this case, the cause of the small-bowel obstruction was clinically obscure. The partial relief of symptoms following medical management indicated an incomplete bowel obstruction. The enteroclysis supported the diagnosis of a giant ileal diverticulum, which was later confirmed at laparotomy.
Giant ileal diverticulum is traditionally a disease found in middle-aged and older persons; it remains a rare cause of subacute intestinal obstruction in young individuals. A preoperative, contrast-enhanced computed tomography (CT) scan is useful in making the diagnosis because it provides direct visualization of the diverticulum and detection of any resultant complications.
A diverticulum is an out-pouching from the wall of the gastrointestinal tract, and it can occur from the stomach to the rectosigmoid colon. There are 2 varieties of diverticula: In the congenital variety, all layers of the bowel are present on the wall of the diverticulum (eg, Meckel diverticulum); in the acquired
variety, the wall on the diverticulum consists of mucosa and submucosa only and lacks a muscular layer. The majority of small bowel diverticula are thought to be of the latter variety. These diverticula are usually situated on the mesenteric border of the intestine in mesenteric fat. Acquired jejunoileal diverticulosis was first described by Sommering in 1794 and later in 1807 by Sir Astley Cooper. The true prevalence rate of this rare disease is not known. Autopsy studies report a prevalence rate less than 5% for the jejunoileal variety and 6%-22% for duodenal lesions. Diverticula are usually multiple and tend to be larger and higher in number in the proximal jejunum, whereas distal to the proximal jejunum they tend to be smaller and found in lesser numbers. Simultaneous involvement of both the jejunum and ileum is rare. Males are affected slightly more than females, and the disease is most often seen in adults in the fifth to seventh decades of life.
Current hypotheses regarding the etiology of jejunoileal diverticula focus on the abnormalities of smooth muscle and the myenteric plexus. Careful microscopic evaluation of resected specimens indicates 3 types of abnormality in the bowel wall: fibrosis and decreased number of normal muscle cells consistent with progressive systemic sclerosis; visceral myopathy as evidenced by the presence of fibrosis and degenerated smooth muscle cells; and neuronal and axonal degeneration indicative of a visceral neuropathy. Any of these abnormalities alone or in combination could lead to disordered and nonpropulsive smooth muscle contractions, resulting in increased intraluminal pressure and herniation of mucosa and submucosa through the weak mesenteric margin, which is penetrated by blood vessels. These pulsion diverticula (diverticula formed by pressure from within) usually have a narrow mouth with a thin or absent muscle layer. When the muscularis becomes weak or abnormal, the muscle wall of the diverticulum is thinned and fibrosed and the diverticulum are wide-mouthed.
Diverticula are silent in the majority of cases (60%-70%) and are incidentally found following a radiologic study or during laparotomy for another disease. Nonspecific chronic abdominal complaints, including crampy pain, postprandial bloating, flatulence and diarrhea, malabsorption, and vitamin B12 deficiency occur as a result of bacterial proliferation inside the diverticulum. Acute complications (8%-30%) are dangerous and often result in urgent or emergent laparotomy.