title: Should prenatal hydronephrosis that resolves before birth be followed postnatally? Analysis and comparison to persistent prenatal hydronephrosis.
abstract: BACKGROUND
  Prenatal ultrasonography has greatly enhanced detection of congenital genitourinary abnormalities. However, although persistent prenatal hydronephrosis (PPH) is typically imaged and followed postnatally, it remains unclear if prenatal hydronephrosis that resolves in utero (RPH) should be similarly managed. We determined postnatal abnormalities associated with RPH and compared these to those associated with PPH.
  
  
  METHODS
  We performed a retrospective review of all consecutive patients evaluated for prenatal hydronephrosis over 24 months. Patients were followed prenatally with serial ultrasounds and postnatally with ultrasonography and a voiding cystourethrogram.
  
  
  RESULTS
  Of the consecutive 165 patients enrolled in the study, 72 had RPH. The average prenatal anterior-posterior renal pelvis length was significantly longer in patients with PPH (5.5 mm) than in those with RPH (4.9 mm) (p = 0.01). Recurrent postnatal hydronephrosis occurred in 44% of patients with RPH, with eventual resolution in 34% of those affected. In comparison, 29% of PPH cases resolved postnatally. Mean time to resolution was statistically shorter for PPH (116 days) than for RPH (175 days) (p = 0.01). Seven PPH patients required surgery, while no RPH patients needed intervention (difference was statistically significant).
  
  
  CONCLUSIONS
  A significant number of RPH children had postnatal hydronephrosis. Despite a slower resolution time, no children with RPH required intervention. Although RPH may recur postnatally, the significantly lower chance of intervention being required suggests that these children may not require postnatal imaging.
authors.affiliation: Department of Urology, Naval Medical Center San Diego, 34800 Bob Wilson Drive, San Diego, CA, 92134, USA, patrick.scarborough@med.navy.mil.
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Scarborough
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ferrara
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Storm
mesh_terms: D019468:Disease Management; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D006869:Hydronephrosis / Q000151:congenital / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D007223:Infant; D007231:Infant, Newborn; D007682:Kidney Pelvis / Q000473:pathology; D008297:Male; D009929:Organ Size; D011247:Pregnancy; D011379:Prognosis; D011859:Radiography; D012008:Recurrence; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods / Q000706:statistics & numerical data; D014481:United States; D014718:Vesico-Ureteral Reflux / Q000000981:diagnostic imaging
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