Sir.—In his recent article in the Journal (129:1145-1150, 1975), Raffensperger stated that for establishing the diagnosis of Hirschsprung disease in the neonatal period, the clinical presentation and a barium enema showing clear transition between dilated and narrow bowel is sufficient, and that rectal biopsy is not routinely indicated. Recent reports of identical roentgenographic findings with normal rectal histology and spontaneous clinical improvement1 suggest that a histologic diagnosis be established in every neonate suspected of having Hirschsprung disease prior to surgery. Suspicion of the small left colon syndrome should be particularly great for infants of diabetic mothers.2