Meckel’s scan
Meckel’s diverticulum is the most common congenital abnormality of the small intestine; it is caused by an incomplete obliteration of the vitelline duct.
It is usually of no consequence. However, it can be complicated by GI bleeding (usually rectal bleeding), intestinal obstruction, and acute inflammation of the diverticulum. Obstruction is most frequently caused by an omphalomesenteric band.
Discuss the indication for Meckel’s scan?
It is done when GI bleeding is suspected to be due to a Meckel’s diverticulum. Sometimes the lining of the Meckel’s diverticulum contains ‘gastric mucosa’ instead of the normal intestinal lining and this can lead to bleeding by acid induced damage of the adjacent mucosa. When bleeding occurs within a Meckel’s diverticulum, gastric mucosa is nearly always present. A Meckel’s scan is used to look for the presence of gastric mucosa in the intestine.
What is a Meckel’s scan?
- Meckel’s scan is a technetium-99m pertechnetate scintiscan. The technetium-99m pertechnetate is injected in a vein and is taken up by gastric mucosa and hence concentrate in areas where gastric mucosa is present.
- After intravenous injection of the isotope, the gamma camera is used to scan the abdomen. This procedure usually lasts approximately 30 minutes. Gastric mucosa secretes the radioactive isotope; thus, if the diverticulum contains this ectopic tissue, it is recognized as a hot spot.
- Administration of ranitidine enhances the accuracy of the scan. Ranitidine enhances the uptake and blocks the secretion of technetium-99m pertechnetate from ectopic gastric mucosa.
What are the disadvantages of Meckel’s scan?
- Meckel’s scan is specific for gastric mucosa (i.e. in the stomach or ectopic) and not specifically diagnostic of Meckel’s diverticulum, false positive results occur whenever ectopic gastric mucosa is present.
- False negative results can occur when gastric mucosa is very slight or absent in the diverticulum
- Low sensitivity and specificity in adults
