Contrast enema in a neonate with meconium plug syndrome shows a small caliber of the descending colon and sigmoid colon. The ascending colon and transverse colon have a normal to slightly large caliber. Filling defects representing meconium are also present in the transverse colon. Meconium plug syndrome is also known as small left colon or functional immaturity of the colon is a functional disorder. It occurs more commonly in premature infants, infants of diabetic mothers, and infants of mothers treated with magnesium sulfate. Meconium plug syndrome is treated with contrast enema.