Background: The pathogenesis of colonic atresia (CA) has not been discussed in detail, although the theory of a prenatal vascular insult, hypothesized from patients with small bowel atresia, has been accepted in the past. This review questions this etiology by reviewing all patients with CA treated in two institutions.

Methods: A retrospective analysis was done of the medical notes of 30 patients with CA treated in two tertiary centers of neonatal surgery in Glasgow, UK, and in Wroclaw, Poland, over a 30-year period with special emphasis on the intraoperative findings and morphology of the atretic bowel.

Results: Thirteen patients had CA in association with an abdominal wall defect. Eleven patients had gastroschisis. A single fibrous cord atresia was noted in 2 patients and it was located in the ascending colon and transverse colon, respectively. Four patients had type IIIa atresia affecting the ascending colon in 3 and transverse colon in one. In 5 patients an extensive defect of the intestine with two atresias of the small and large bowel was noted. In 3 of them, a separate conglomerate of the prolapsed intestine was found to be necrotic or presenting as a cystic structure. Two of these patients had an unusually narrow abdominal wall defect of less than 1 cm. Isolated CA was noted in 17 patients. A type IIIa atresia affecting the right colon was found in 14 of them. In 2 patients the ascending colonic atresia was accompanied by an extensive defect of the transverse colon. A single sigmoid colon atresia and two fibrous cord atresias of the sigmoid and transverse colon were noted in single patients respectively.

Conclusions: Most cases of CA in babies with gastroschisis seem to result from bowel compression within the narrowing abdominal defect. A "two-point constriction" may lead to a wide spectrum of bowel pathologies and the morphology may depend on the viability of the intestinal segment between the atretic jejunum or ileum and the colon. Isolated CA presents with a wider spectrum in terms of anatomical types and location of the bowel pathology, but it seems that type II and IIIa atresias of the right colon may share a similar pathogenesis of temporary constriction within a closing umbilical ring.