Meconium plug syndrome usually occurs in infants who are otherwise healthy and has an incidence of 1 in 500 live births.
Meconium plug syndrome is generally regarded as a functional immaturity of the colon, resulting in failure to pass the first stool.
Etiology of Meconium Plug Syndrome
Meconium plug syndrome is more common among
Infants of mothers with diabetes
Infants of mothers treated with magnesium sulfate for eclampsia Preeclampsia and Eclampsia Preeclampsia is new-onset or worsening of existing hypertension with proteinuria after 20 weeks gestation. Eclampsia is unexplained generalized seizures in patients with preeclampsia. Diagnosis... read more , preeclampsia Preeclampsia and Eclampsia Preeclampsia is new-onset or worsening of existing hypertension with proteinuria after 20 weeks gestation. Eclampsia is unexplained generalized seizures in patients with preeclampsia. Diagnosis... read more , or preterm labor Preterm Labor Labor (contractions resulting in cervical change) that begins before 37 weeks gestation is considered preterm. Risk factors include prelabor rupture of membranes, uterine abnormalities, infection... read more
One study noted that 16% of cases of meconium plug syndrome were associated with magnesium tocolysis (1 Etiology references Meconium plug syndrome is colonic obstruction caused by thick meconium. Diagnosis is based on radiographic contrast enema and sometimes testing for Hirschsprung disease (because failure to pass... read more ). Hirschsprung disease is present in about 10 to 40% of infants with meconium plug syndrome (2 Etiology references Meconium plug syndrome is colonic obstruction caused by thick meconium. Diagnosis is based on radiographic contrast enema and sometimes testing for Hirschsprung disease (because failure to pass... read more ). Meconium plug syndrome is also associated with cystic fibrosis Cystic Fibrosis Cystic fibrosis is an inherited disease of the exocrine glands affecting primarily the gastrointestinal and respiratory systems. It leads to chronic lung disease, exocrine pancreatic insufficiency... read more 
.
Etiology references
1. Cuenca AG, Ali AS, Kays DW, Islam S: "Pulling the plug"--management of meconium plug syndrome in neonates. J Surg Res 175(2):e43-e46, 2012. doi: 10.1016/j.jss.2012.01.029
2. Buonpane C, Lautz TB, Hu YY: Should we look for Hirschsprung disease in all children with meconium plug syndrome? J Pediatr Surg 54(6):1164, 2019. doi: 10.1016/j.jpedsurg.2019.02.036
Symptoms and Signs of Meconium Plug Syndrome
Infants present in the first few days of life with failure to pass stools, abdominal distention, and vomiting. Thick, inspissated, rubbery meconium forms a cast of the colon, resulting in complete obstruction.
Diagnosis of Meconium Plug Syndrome
Radiographic contrast enema
Sometimes testing for Hirschsprung disease
Diagnosis of meconium plug syndrome is of exclusion and should be differentiated primarily from Hirschsprung disease Hirschsprung Disease Hirschsprung disease is a congenital anomaly consisting of a failure of neuronal colonization (and thus a failure of innervation) of the lower intestine, usually limited to the colon, resulting... read more 
, especially if symptoms of distal obstruction persist despite passing the meconium plug.
Plain abdominal x-rays are nonspecific and can show signs of low intestinal obstruction. Conversely, contrast enema shows the characteristic appearance of the outline of the inspissated meconium against the wall of the colon, providing a double-contrast impression (1 Diagnosis reference Meconium plug syndrome is colonic obstruction caused by thick meconium. Diagnosis is based on radiographic contrast enema and sometimes testing for Hirschsprung disease (because failure to pass... read more ). Unlike meconium ileus Diagnosis Meconium ileus is obstruction of the terminal ileum by abnormally tenacious meconium; it most often occurs in neonates with cystic fibrosis. Meconium ileus accounts for up to 33% of neonatal... read more , microcolon is not typically seen on x-ray with meconium plug syndrome because meconium plug syndrome is a distal process.
Patients with meconium plug syndrome should be tested for cystic fibrosis Diagnosis Cystic fibrosis is an inherited disease of the exocrine glands affecting primarily the gastrointestinal and respiratory systems. It leads to chronic lung disease, exocrine pancreatic insufficiency... read more .
Diagnosis reference
1. Manzoor A, Talat N, Adnan HM, et al: Contrast Enema: Solving Diagnostic Dilemmas in Neonates With Lower Intestinal Obstruction. Cureus 14(3):e23458, 2022. doi: 10.7759/cureus.23458
Treatment of Meconium Plug Syndrome
Radiographic contrast enema
The water-soluble contrast enema can be therapeutic by separating the plug from the intestinal wall and expelling it. Occasionally, repeated enemas are required.
Rarely, surgical decompression is required. Although most infants are healthy thereafter, diagnostic studies may be needed to rule out Hirschsprung disease or cystic fibrosis.
