Intestinal muscularis propria increases in thickness with corrected gestational age and is focally attenuated in patients with isolated intestinal perforations.

Purpose: Intestinal perforations are common in premature infants, leading to a diagnostic dilemma between necrotizing enterocolitis and isolated intestinal perforation (IIP). IIP is thought to result from a congenital or acquired absence of the muscularis propria. However, developmental events leading to IIP are not well understood. This study examines the relationship between corrected gestational age (CGA) and intestinal muscle development in controls and patients with IIP.

Methods: Specimens from stillbirths and infants undergoing intestinal surgery from 8 to 48weeks' CGA were collected from 2005 to 2012. Twelve patients with IIP were identified. Control specimens were collected during 25 fetal autopsies and 39 bowel resections. In each case, three sections of intestine were examined histologically for muscularis mucosa, circular and longitudinal muscle thickness. Comparisons of control and perforated specimens were performed via linear regression and ANOVA.

Results: Controls and adjacent normal segments in IIP showed a linear relationship between thickness of circular and longitudinal muscles with CGA. Circular and longitudinal muscles were thinner in perforated segments than in adjacent normals and CGA-matched controls (p<0.05).

Conclusion: Intestinal muscularis propria increases in thickness with CGA. Muscle thickness is focally attenuated in patients with isolated intestinal perforations, while the remaining intestine is normal, suggesting that primary repair is an appropriate treatment.