Clinical Pearls & Morning Reports
Meckel’s diverticulum needs to be included in the differential diagnosis for any child being evaluated for hematochezia. If a technetium-99m pertechnetate scan is negative and other causes of bleeding have been ruled out, laparoscopy should be considered to assess for Meckel’s diverticulum. A Case Record of the Massachusetts General Hospital elaborates.
Q: What is a Meckel’s diverticulum?
A: Meckel’s diverticulum is the most common congenital malformation of the gastrointestinal tract, and if the diverticulum contains ectopic or heterotopic mucosa, it can cause gastrointestinal bleeding. It is located on the antimesenteric surface of the mid-ileum, and represents persistence of a proximal part of the vitelline duct (omphalomesenteric duct). In contrast to the mucosal herniation through the bowel wall that is present in diverticular disease, it contains all three layers of bowel wall.
Figure 2. (10.1056/NEJMcpc1616020/F2) Intraoperative Photograph.
Q: What causes the bleeding associated with a Meckel’s diverticulum?
A: The primary cause of bleeding is the presence of acid-producing ectopic gastric mucosa in the diverticulum, which leads to the development of an ulcer in adjacent normal mucosa. The ulcer can be present in the diverticulum itself but is usually located at the junction of the diverticulum and the ileum.
A: Technetium-99m pertechnetate normally accumulates in any gastric mucosa, including ectopic gastric mucosa; therefore, this radiotracer is useful in the evaluation of a suspected Meckel’s diverticulum. Technetium-99m pertechnetate is excreted by the urinary system, and activity is normally seen in the bladder and kidneys. Bowel or urinary activity is suggested by movement of focal radiotracer activity over time, whereas the focal accumulation in a Meckel’s diverticulum should remain fixed in position. A lateral view of the abdomen can be helpful in distinguishing urinary activity in the ureters, which are located in a posterior position. A false positive scan can result from inflammation, intussusception, bowel obstruction, or vascular lesions. A false negative scan can result from the presence of too little or no gastric mucosa in a Meckel’s diverticulum; approximately 20% of Meckel’s diverticula do not contain gastric mucosa.
A: A variety of operations can be performed to treat a Meckel’s diverticulum that causes gastrointestinal bleeding. These include simple diverticulectomy, wedge resection of the diverticulum and the small cuff of adjacent ileum at its base, and segmental small-bowel resection. Although removing both the ectopic mucosa and the ulcer would seem to be the best approach, removing the ectopic mucosa alone may be sufficient, since the ulcer would probably then heal. However, it is essential to remove all ectopic gastric mucosa, which cannot be reliably detected from the outside. Therefore, a reasonable approach is to perform a simple diverticulectomy for a diverticulum with a narrow base but to perform a wedge or segmental resection for a diverticulum with a broad base, since ectopic tissue may be left behind if the diverticular base is not fully excised.