Neonatal small left colon syndrome is a cause of functional colon obstruction in newborn infants. Small left colon sydrome is subset of meconium plug syndrome in which an enema demonstrates an apparent transition zone between the dilated and the normal-to-decreased caliber distal colon at the splenic flexure. There is a high association of maternal diabetes.

Patient #1: Failure to pass meconium

Small left colon syndrome must be differentiated from other diseases that cause a failure to pass meconium or abdominal distension in infants, including meconium plug syndrome, and congenital hypothyroidism.

Disease	Prominent clinical features	Radiological findings
Meconium plug syndrome	Transient intestinal obstruction for 1-2 days after birth. Obstruction is functional due to dilated colon and delayed passage of feces. Usually seen in premature infants.[1]
Small left colon syndrome	Reduced caliber of the colon starting from splenic flexure and going down, causing intestinal obstruction. Characterized by a sudden change of the colon diameter. Usually associated with gestational diabetes.[2]
Distal small intestine/colon atresia	Failure to pass meconium due to failure of intestine recanalization. Proximal lesions have an earlier onset of symptoms than distal lesions. Colonic atresia may affect normal children or may be associated with other abnormalities as Hirschsprung’s disease or gastroschisis.[3]
Meconium ileus	Intestinal obstruction due to inspissation of meconium in the distal ileum. Most cases of meconium ileus are secondary to cystic fibrosis. Typically presents with failure to pass meconium and abdominal distension with or without vomiting. Meconium ileus may first present with complications, including perforation and volvulus.[4]
Congenital hypothyroidism	Most infants are born asymptomatic.[5] Symptoms, if present, may include, but not limited to: Macroglossia Hoarse cry Umbilical hernia Puffy facies Increased head circumference Hypothermia