title: The progressive development of pyloric stenosis: a role for repeat ultrasound.
abstract: BACKGROUND
  Patients presenting in the first 3 months of life with nonbilious emesis are commonly studied by ultrasound. A negative study effectively rules out pyloric stenosis. However, the development of pyloric stenosis is a progressive and dynamic process. The rate of hypertrophy to the point of meeting diagnostic criteria is unknown and there is no data published in the literature regarding the role of repeat ultrasound in patients with persistent symptoms. During a prospective, randomized trial we identified 3 patients with negative ultrasounds who subsequently were diagnosed and treated for pyloric stenosis. We present this series as an illuminating depiction of the development of muscle hypertrophy in patients with pyloric stenosis.
  
  
  METHODS
  Patients with pyloric stenosis and repeat ultrasound were identified from our prospective, randomized trial. All patients had sonographic pyloric measurements obtained at our institution. Data included patient age upon presentation, ultrasound-defined pyloric parameters, operation, and outcome.
  
  
  RESULTS
  Three patients were identified with a negative ultrasound with a pyloric thickness ranging from 0.8 mm to 2.5 mm. Subsequent thickness on repeat ultrasound ranged from 3.5 to 6.2 mm. The rate of hypertrophy ranged from 0.17 mm/day to 0.5 mm/day.
  
  
  CONCLUSIONS
  A negative pyloric sonogram may be due to the fact that the patient is in the very initial stages of development of pyloric stenosis. Caregivers should counsel parents to return if symptoms persist and there should be a low threshold for repeat ultrasound in these patients.
authors.affiliation: Department of Surgery, Center for Prospective Trials, Children's Mercy Hospital, Kansas City, MO, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Keckler
authors.forename: D J
authors.initials: DJ
authors.lastname: Ostlie
authors.forename: G W
authors.initials: GW
authors.lastname: Holcomb Iii
authors.forename: S D
authors.initials: SD
authors.lastname: St Peter
mesh_terms: D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D046248:Pyloric Stenosis, Hypertrophic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014463:Ultrasonography