Characteristic features of MMIHS are a microcolon
with dilated, hypoperistaltic small bowel loops and a large bladder that can
be associated with a dilatation of the upper urinary tract. In most cases,
the myenteric and submucosal plexus are normal. The abdominal wall might be
hypotonic and thin walled, as in prune belly syndrome. One family with MMIHS
occurrence in the daughter and isolated prune belly syndrome in the son has
been described. One child who died shortly after birth showed cleft palate,
severe micrognathia, and a truncus arteriosus communis overriding both
ventricles. Another child had multiple cardiac rhabdomyomata at autopsy.
Also, one case of MMIHS in trisomy 18 has been reported, but the colon in
this child showed aganglionosis. Even with surgery, mortality is high, but
some success with intestinal transplantation has been reported.