Teaching Case

Patient A: 19-year-old male patient with 3 days of right iliac fossa pain, diarrhoea and mildly raised inflammatory markers.

Patient B: 65-year-old male patient with vomiting, constipation and intermittent abdominal pain for 2 days. He had abdominal distension, a tender umbilical region and raised urea and CRP.

Patient A: Contrast-enhanced CT abdomen and pelvis revealed short segment thickening of the terminal ileum and caecum which showed mild wall thickening and surrounding mesenteric lymphadenopathy, suggestive of inflammatory bowel disease. The appendix was normal. As an incidental finding, there was a blind-ended tubular structure arising from the anti-mesenteric border of the distal ileum. It measured approximately 3 cm in length and displayed no associated inflammatory change, with clear fat planes surrounding it. Features were in keeping with an uncomplicated Meckel’s diverticulum.

Patient B: Contrast-enhanced CT abdomen and pelvis showed multiple fluid-filled dilated loops of small bowel and intra-abdominal free fluid in keeping with high grade small bowel obstruction. The transition point was at the distal ileum where there was a thick-walled blind-ending tubular structure with associated inflammatory fat stranding. Intra-operative findings confirmed the presence of an inflamed Meckel’s diverticulum at the transition point.

Meckel’s diverticulum is an ileal outpouching typically located on the anti-mesenteric border of the ileum, 30-90 cm from the ileo-caecal valve and measuring 0.5-15 cm in length [1]. It is usually located in the right lower quadrant but can be found in the periumbilical region. It is the most common congenital anomaly of the gastrointestinal tract, with a 2-3% prevalence [2]. 62% of Meckel’s diverticulae contain ectopic gastric mucosa and the prevalence of ectopic gastric mucosa reduces with age. Uncomplicated Meckel’s diverticulae are asymptomatic and only pose a risk to the patient if a complication occurs. They are most often discovered as an incidental finding on CT imaging or can present as a complication of the diverticulum. A common complication is gastrointestinal haemorrhage, which is the most frequent complication in children [3]. The gold standard for investigation in children is the Meckel’s scan, a scintigraphy scan which relies on the ectopic gastric mucosa taking up Tc99m pertechnetate. Conventional barium studies such as small bowel follow through may still have a role in diagnosis where cross-sectional imaging is inconclusive [3]. However, barium studies are being superseded by MR enterography and CT enterography. Both of these modalities are accurate in the detection of small bowel diseases and offer superior assessment of the small bowel wall compared to plain CT, owing to distension of the small bowel loops with intra-luminal contrast. In a study comparing both modalities, MR enterography had superior sensitivity to CT enterography for detection of Meckel’s diverticulum causing occult gastrointestinal bleeding [4]. MR enterography added diagnostic value through its better soft-tissue contrast and its ability to perform functional imaging [4]. In acute haemorrhage, CT angiography may reveal a vascular blush at the site of the diverticulum. Small bowel obstruction is the second most common complication and occurs via several methods including diverticulitis, as in this case. It is uncommon for the diverticulum to be visualised at the site of obstruction on CT and it is often diagnosed intra-operatively, however, CT remains extremely useful in the investigation of small bowel obstruction [3]. The lifetime risk of developing complications is reported to be between 4-40% [5]. The risk falls with increasing age and is as low as 0% in the elderly population [6]. Surgical excision is controversial in asymptomatic cases and usually indicated in complicated cases. Meckel's diverticulum should be considered as a cause of small bowel obstruction. Documentation of an incidental finding of Meckel's diverticulum is important in case future complications occur.