Main histological findings by disease group
| Finding | Total, n (%) | Idiopathic megarectum, n (%) | Post-ARM megarectum, n (%) |
| Fibrosis | 30/35 (85.7) | 19/24 (79.1) | 11/11 (100) |
| Elastosis | 19/35 (54.3) | 14/24 (58.3) | 5/11 (45.4) |
| Neuronal abnormalities | 6/35 (17.1) | 2/24 (8.3) | 4/11 (36.4), including all 3 plexus duplications |
| Muscular abnormalities | Abnormal muscle layers: 14/35 (40) | 9/24 (37.5) | 5/11 (45.4), including all 3 circular muscle duplications |
| Muscle hypertrophy: 27/35 (77.1) | 16/24 (66.7) | 10/11 (90.9) | |
| Decreased interstitial cells of Cajal | 6/27 (22.2) | 5/20 (25) | 1/7 (14.2) |
| Polyglucosan bodies | 15/32 (46.8) | 11/22 (50) | 4/10 (40) |
ARM, anorectal malformation.