Answer of July 2010

Clinical History:

A 52-year-old man presented with abdominal distension for several days. Physical examination revealed diffuse abdominal tenderness. Contrast CT of the abdomen and pelvis was performed.

Diagnosis:

Bezoar obstruction with Meckel diverticulum.

Discussion:

CT showed small bowel dilatation down to distal ileum, where an intra-luminal lesion is seen at the transition point.  Small bowel faeces sign and "string of pearls" appearance were present, suggestive of mechanical small bowel obstruction.   A blind-ended tubular structure was seen adjacent to the aforementioned lesion.  Findings were compatible with small bowel obstruction due to bezoar formation adjacent to a Meckel diverticulum, which was confirmed upon laparotomy.

Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract. It is a true diverticulum formed by incomplete obliteration of the ileal end of the vitelline duct. It arises from the anti-mesenteric border of the distal ileum, usually within 50-60cm of ileocaecal valve. 50% contain heterotopic gastric +/- pancreatic, colonic or duodenal mucosa. 90% of the cases with bleeding contain gastric mucosa. On Tc-99m pertechnetate scan, it is seen as tracer accumulation in RLQ in synchrony with gastric activity. On angiography, the presence of vitelline artery is pathognomonic.

Complications of Meckel diverculum include:

Haemorrhage due to acid from ectopic gastric mucosa
Intestinal obstruction - intussusception,  volvulus, peritoneal bands, hernias, or bezoars
Diverticulitis
Littre¡¦s hernia
Malignant transformation (rare)
Rule of 2's:

2% of population
Male : female ~ 2 : 1
Within 2 feet of ileocaecal valve
2 inches long (on average)
Symptomatic usually before age 2
2 main complications in adults: intestinal obstruction (40%) and diverticulitis (20%)
A bezoar is a persistent concretion of foreign matter composed of accumulated ingested material in intestines, and is a cause of intestinal obstruction.  Predisposing factors include previous gastric surgery, inadequate chewing, poor dentition, dentures, delayed gastrointestinal transit.

Bezoar formation in a Meckel diverticulum is a relatively uncommon complication.  Postulated mechanisms include anatomical distortion, impaired motility, stasis of gut matters within the diverticulum, and lodging of bezoar in the diverticulum in a Y-shaped "pantaloon" fashion.