Perforated jejunal diverticle presenting as acute abdomen

Introduction
Jejunal diverticulosis is a relatively rare condition, reported to occur in approximately 1% of autopsied patients. These patients remain asymptomatic in the majority of cases. However. jejunal diverticula may be responsible for unclear chronic abdominal symptoms or acute complications, including hemorrhage, intestinal obstruction, inflammation and perforation. Although acute complications are extremely rare, the mortality of perforation rises to 21-40% (Peters 1999; Chendrasekhar 1995). We report a case of perforated jejunal diverticulitis presenting as an acute abdomn in a 66-year old male.

Case report
A 66-year-old man presented at the emergency wards complaining about generalized abdominal pain of acute onset, which was followed by nausea, vomiting and flatulence. The medical history of the patient was completely free, except from the presence of duodenal ulcer, treated conservatively 40 years ago.
Physical examination revealed a distended and tender abdomen with guarding and rebound tenderness in the peri-umbilical region and the right upper quadrant, while bowel sounds were absent. The white blood cell count was elevated to 12,000/mm3, whereas urinalysis and biochemical tests were within the normal limits. Plain abdominal X-rays revealed no abnormalities, while urgent ultrasonography of the abdomen did not lead to any specific diagnosis, due to the air-filled bowel loops. A contrast-enhanced CT scan of the abdomen and pelvis showed dilatation of the small intestine on its upper half without and evidence of marked wall thickening or formation of intra-peritoneal abscess.
The patient was submitted to exploratory laparotomy though a midline incision, which revealed the presence of multiple divertiules covering almost the whole length of the jejunum (Fig. 1). The detailed inspection of the jejunum revealed the presence of a perforated diverticulum, which was covered with the adjacent loops and omentum (Fig. 2). The involved segment was resected and an end-to-end anastomosis was performed. Extensive peritoneal lavage and intraperitoneal placement of drains were subsequently done. The postoperative course of the patient was long due to development of postoperative respiratory insuffiency but no surgical complication occurred. The patient was discharged after 30 days of hospitalization.

Discussion
Jejunal diverticulosis was originally described by Somerling in 1794 and later by Sir Astley Cooper in 1807 (Williams 1981). Acquired diverticula of the small bowel have a reported incidence in the medical literature that varies from 0.06 to 2.3%. These diverticula are usually located along the mesenteric side predominantly involving the proximal jejunum, becoming smaller and less numerous as the ileum is approached distally (Williams 1981).
The diverticula formed by herniation of mucosa and submucosa through the muscular layer of the bowel wall (pseudodiverticula), are thought to be acquired pulsion lesions and are usually multiple. They arise on the mesenteric border of the bowel where the arteries pierce the intestinal wall, contrary to the true congenital Meckel’s diverticulum.
Their size usually varies from a few millimetres to more than 10 cm and they are present in greatest number in the jejunal part of the small bowel, where they also tend to be larger. This predominance of diverticula in the jejunum is attributed to the greater diameter of the penetrating jejunal arteries.
Acquired diverticula of the jejunum occur in patients of any age, mainly adults (normally after the age of 40 years old) and it has been described a 2:1 predilection for males.
The aetiology of small-bowel diverticula is unclear, but they probably occur because of motor dysfunction of the smooth muscle or dysfunction of the myenteric plexus in the small bowel. It is strongly speculated that an underlying abnormality in peristalsis with resultant intestinal dyskinesia and segmentally high intraluminal pressures plays an important role in their pathogenesis. Subsequent perforation might be precipitated by a blunt trauma to the abdominal wall, necrotizing inflammatory reaction, or a foreign body impaction in a diverticulum (Yagmur 2004).
Because the presentation and physical findings of perforated jejunal diverticula can be highly variable, a history of pre-existing jejunal diverticula should arouse suspicion for jejunal diverticula perforation, as the aetiology of acute abdominal pain in the elderly. Neither the symptoms nor the physical findings present any characteristic pattern that would suggest the diagnosis, as all of these features are common to several other acute abdominal diseases. Perforation of diverticula can cause generalized or localized intra-abdominal inflammatory disease, depending to the extent on the site of the perforation (Koger 1996). The symptomatology varies widely; jejunal diverticulum perforation is difficult to diagnose clinically because it is uncommon, has no specific symptoms, and often simulates various intra-abdominal inflammatory conditions, such as perforated ulcer, acute appendicitis, acute cholecystitis, colonic diverticulitis and other more familiar abdominal diseases. The perforation is usually walled off by the adjacent small bowel mesentery and only localized peritonitis may occur (Lempinen 2004; Cunningham 2005).
On the other hand, plain films of the abdomen and sonographic findings are non-specific in most cases of jejunal diverticulum perforation. This is the reason that, in approximately 90% of cases, laparotomy is carried out without correct preoperative diagnosis (Peters 1999). Computed tomography sometimes may be helpful in localizing the inflammatory process to the jejunum. The keys to the preoperative diagnosis of jejunal diverticulitis are the identification of an inflammatory mass containing gas, wall thickening in the involved segment or oedema of the surrounding tissues including fat. Furthermore, areas of low attenuation within the mass and rim enhancement after intravenous contrast administration may also be seen. Although an adjacent jejunal diverticulum can not be clearly visualized, diagnosis of jejunal diverticulitis is taken into differential diagnostic consideration via computed tomography. In the present case, however, the results of the preoperative CT scan, done before emergency surgery, were considered normal. No diverticula of the jejunum were seen in the CT scan (Sakurai 2005; Brady 1994).
As discussed above, jejunal diverticulum perforation is difficult to diagnose before surgery and is usually detected during laparotomy for acute abdominal pain. For the treatment of this condition, timely surgical intervention and resection of the involved jejunum are the keys to a successful outcome (Roses 1976).
In conclusion, it is essential not to underestimate this unusual entity among the differential diagnoses of acute abdomen. It is very important in early diagnosing patients with jejunal diverticula perforation and in differentiating surgical from nonsurgical conditions, thereby allowing the choice for conservative treatment when possible.

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