title: Hypertrophic pyloric stenosis in premature infants: evaluation of sonographic criteria and short-term outcomes.
abstract: OBJECTIVE
  To examine the sonographic measurements of pyloric muscle and pyloric thickness in premature infants with hypertrophic pyloric stenosis (HPS) and to correlate these measurements with patients variables. We aimed also to evaluate the clinical features and short-term outcome of HPS in premature compared to term infants.
  
  
  METHODS
  The medical notes and the pyloric ultrasounds of all premature infants (<37 weeks) admitted to the Neonatal Surgical Unit with HPS over a 20-year period (1990-2010) were retrospectively reviewed. Sonographic measurements of the pyloric length, muscle thickness and the pyloric ratio (muscle thickness divided by pyloric diameter) were correlated to weight at presentation, duration of symptoms and corrected gestational age. Multiple regression and correlation analysis was carried out.
  
  
  RESULTS
  Seventy-five preterm infants were identified (51M:24F). Median gestational age was 34 weeks. Median weight at presentation was 2.74 kg. Forty-two had an ultrasound (US) before surgery, 37 measurements were analysed. Pyloric length, muscle thickness and pyloric ratio were not affected by weight at presentation (p = 0.67, p = 0.122, p = 0.849), corrected gestational age (CGA) (p = 0.921, p = 0.678, p = 0.076), or duration of symptoms (p = 0.827, p = 0.268, p = 0.281). Mean length of stay was 6 days and overall complication rate was 27 %, both higher than reported in term infants (p < 0.001).
  
  
  CONCLUSIONS
  Premature infants with HPS have a higher female preponderance than expected. Ultrasound measurements in premature infants with HPS are not affected by weight, corrected gestational age or duration of symptoms. In addition, they have a longer hospital stay and increased complication rate compared to term infants.
authors.affiliation: Department of Paediatric Surgery, Royal Hospital for Sick Children, Glasgow, G3 8SJ, Scotland, UK. salvatore.cascio@ggc.scot.nhs.uk
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cascio
authors.forename: Mairi
authors.initials: M
authors.lastname: Steven
authors.forename: Hannah
authors.initials: H
authors.lastname: Livingstone
authors.forename: David
authors.initials: D
authors.lastname: Young
authors.forename: Robert
authors.initials: R
authors.lastname: Carachi
mesh_terms: D000367:Age Factors; D001835:Body Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology; D046248:Pyloric Stenosis, Hypertrophic / Q000000981:diagnostic imaging* / Q000601:surgery*; D011708:Pylorus / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D012606:Scotland / Q000453:epidemiology; D012737:Sex Factors; D016896:Treatment Outcome; D014463:Ultrasonography