Megacolon, as well as megarectum, is a descriptive term. It denotes dilatation of the colon that is not caused by mechanical obstruction.[1, 2] Although the definition of megacolon has varied in the literature, most researchers use the measurement of greater than 12 cm for the cecum as the standard. Because the diameter of the large intestine varies, the following definitions would also be considered: greater than 6.5 cm in the rectosigmoid region and greater than 8 cm for the ascending colon.
Megacolon can be divided into the following 3 categories:
Acute megacolon ( pseudo-obstruction)
Chronic megacolon, which includes congenital, acquired, and idiopathic causes