title: Natural history of fetal renal pyelectasis.
abstract: OBJECTIVE
  To follow the natural progression of fetal renal pyelectasis detected in the mid second trimester ultrasound in an unselected obstetric population.
  
  
  METHODS
  Single-centered, retrospective study that included all level II ultrasounds done from Jan 2008 to Dec 2009. The initial level II ultrasound was done in the mid second trimester. The renal pyelectasis detected on the antenatal ultrasound (AUS) was classified as mild (5-7 mm), moderate (7.1-9 mm), or severe (>9.1 mm). Postnatal outcomes were classified as "Resolved", "Improving", or "Worsened".
  
  
  RESULTS
  Ninety-eight cases of fetal renal pyelectasis were detected. Sixteen patients were excluded. Of the remaining 82 cases of fetal pyelectasis, 32 (39%) were mild, 21 (25.6%) moderate, and 29 (35.4%) severe. In 74 (90.2%) infants, pyelectasis resolved, remained stable, or improved in the postnatal ultrasound. In eight (9.8%) infants, pyelectasis worsened.
  
  
  CONCLUSIONS
  Totally, 90.2% of pyelectasis detected on AUS resolved spontaneously, remained stable or improved. The magnitude of fetal renal pyelectasis did not correlate with postnatal outcome. All fetal renal pyelectasis ≥ 5 mm detected on the mid second trimester ultrasound should be followed antenatally. Those fetuses with persistent pyelectasis should be evaluated after birth and followed until resolution of pyelectasis or until a diagnosis is obtained.
authors.affiliation: Department of Pediatrics, Mount Sinai Hospital, Chicago, IL, USA. srih@sinai.org
authors.forename: Hari B
authors.initials: HB
authors.lastname: Srinivasan
authors.forename: Nishant
authors.initials: N
authors.lastname: Srinivasan
authors.forename: Prajwal
authors.initials: P
authors.lastname: Dhungel
authors.forename: Ruth
authors.initials: R
authors.lastname: London
authors.forename: Charles
authors.initials: C
authors.lastname: Lampley
authors.forename: Gopal
authors.initials: G
authors.lastname: Srinivasan
mesh_terms: D002641:Chicago / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D049590:Postpartum Period; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D058536:Pyelectasis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal