ACR Codes: 7.1
Meckel's diverticula occur in 1-3% of the general population; however, 80% of symptomatic diverticula present before the age of 10 years. They are congenital, true diverticula that contain all layers of the bowel wall. Ectopic gastric mucosa is found in the majority of Meckel's diverticula that have bled, this being the most frequent clinical presentation in adults. Before the introduction of enteroclysis it was unusual to identify a Meckel's diverticulum by barium radiology. Even with enteroclysis a thorough compression study of the distal 5 feet of ileum is required for their demonstration, both in the single contrast phase and during distention with methylcellulose. A Meckel's isotope scan which is a very useful diagnostic procedure in children, is less reliable in adults and, if negative, may have to be supplemented by a small bowel enema.
FURTHER CASE EXAMPLES: An alternative pattern at the origin of a Meckel's diverticulum is shown on Film .2; the saccular diverticulum arises by a narrow neck (arrow), as always from the antimesenteric border of the distal ileum.
An increased incidence of Meckel's diverticula has been suggested in patients with Crohn's disease. This is not a true increase, however; separation of distal ileal loops by the inflammatory process in Crohn's disease allows an easier identification of the diverticulum. Film .3 demonstrates a Meckel's diverticulum (arrows) in a patient with Crohn's disease of the distal ileum (broad arrows) by a small bowel meal, a method that will only rarely identify this lesion in otherwise normal small bowel.
A superior mesenteric arteriogram is included, mainly to draw attention to the vascular anatomy of this congenital structure. Film .4 demonstrates the arterial phase and outlines the vitelline artery (dots) in its straight course across normal branches to the small bowel; the wall of the diverticulum opacifies slightly; there is more intensive uptake of dye by the ectopic gastric mucosa (arrows). Film .5 represents the venous phase and outlines the vitelline vein (dots).
Film .6 is an isotope scan using 99m technetium pertechnetate which accumulates in the ectopic gastric mucosa that is very likely to be present in a Meckel's diverticulum if a patient has bled. The diverticulum shows activity (arrow) before the urinary bladder and continues to be seen above and separate from the bladder (lower arrow). Surgery confirmed the Meckel's diverticulum in this child.