title: Prevalence of Hirschsprung's disease in premature infants: a systematic review.
abstract: OBJECTIVE
  Intestinal dysmotility in preterm infants has often been attributed to immature enteric nervous system. It is frequently reported that Hirschsprung's disease (HD) is rare in premature infants. The exact prevalence of HD in premature infants is not well documented. The classical signs of HD may often not be identified due to the complexity of symptoms of prematurity itself. This systematic review was designed to determine the prevalence and presentation of HD in premature infants.
  
  
  METHODS
  A systematic review of the literature using the keywords "Hirschsprung's disease", "aganglionosis", "congenital megacolon", "premature" and "preterm" was performed. Resulting publications were reviewed for epidemiology and morbidity. Only infants born <37 weeks of gestation or described as preterm birth by the authors were included. Reference lists were screened for additional relevant studies.
  
  
  RESULTS
  Twenty-six publications from 1964 to 2013 reported data on premature infants with HD. Out of a total number of 4,147 infants, prematurity was recorded in 257 cases, giving a prevalence rate of 6 % of preterm infants diagnosed with HD. During 1964-1999, reported prevalence of HD in premature infants ranged from 1.7 to 9.2 % (overall prevalence 5 %) and during 2000-2013 prevalence ranged from 4 to 19.4 % (overall prevalence 14 %). The prevalence of total colonic aganglionosis in premature infants was 13 % (15 out of 118 infants). Mean gestational age of preterm infants was 34.5 (± 0.7) weeks and mean age at diagnosis ranged from 18.3 days to 3.9 months. Abdominal distension was observed in 80 % of preterm infants, delayed passage of meconium in 57 and 37 % of premature infants presented with bile-stained vomiting.
  
  
  CONCLUSIONS
  In recent years, higher prevalence of HD has been reported in premature infants compared to previous years. Hirschsprung's disease should be considered in preterm infants presenting with features of intestinal obstruction.
authors.affiliation: National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Duess
authors.forename: Alejandro D
authors.initials: AD
authors.lastname: Hofmann
authors.forename: Prem
authors.initials: P
authors.lastname: Puri
mesh_terms: D014943:Global Health; D006627:Hirschsprung Disease / Q000453:epidemiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D015995:Prevalence