title: Rate and predictors of spontaneous resolution of prenatally diagnosed primary nonrefluxing megaureter.
abstract: OBJECTIVE
  We assessed clinical and ultrasound predictors of the spontaneous resolution of prenatally diagnosed, primary nonrefluxing megaureter.
  
  
  METHODS
  Primary nonrefluxing megaureter was prenatally diagnosed in 54 neonates from 1993 to 1998, including 15 in whom it was bilateral (69 megaureters). Median followup period from birth to the last radiology examination was 25.8 months (range 2.3 to 72).
  
  
  RESULTS
  Of the patients 10 underwent surgical repair for severe hydroureteronephrosis, including decreasing renal function on diuretic renography in 1, and an episode of bilateral obstruction and acute renal failure in 1. Hydroureteronephrosis resolved in 39 cases (72%) and persisted in 5 at 30 to 72 months of followup. Laterality, gender and retrovesical ureteral diameter had no significant effect on the resolution rate (p >0.05). Mean initial ureteral diameter in patients with resolution was less than in those without resolution and in those who underwent surgery (0.8 versus 1.15 and 1.32 cm., respectively). Presenting hydronephrosis grade was a significant predictor of the resolution rate (p = 0.03). Grades 1 to 3 hydronephrosis resolved at a median age of 12.9, 23.9 and 34.6 months, respectively (range 4.1 to 66). In patients in whom grades 4 and 5 hydronephrosis resolved the median age at resolution was 48.5 months.
  
  
  CONCLUSIONS
  Most cases of prenatally diagnosed, primary nonrefluxing megaureter resolve spontaneously. Grades 1 to 3 hydronephrosis tend to resolve between ages 12 and 36 months. For these grades followup intervals may be progressively elongated after a pattern of improving hydronephrosis has been established. In children with grade 4 or 5 hydronephrosis, or a retrovesical ureteral diameter of greater than 1 cm. the condition may resolve slowly and require surgery.
authors.affiliation: Department of Urology, Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Dawn L
authors.initials: DL
authors.lastname: McLellan
authors.forename: Alan B
authors.initials: AB
authors.lastname: Retik
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Bauer
authors.forename: David A
authors.initials: DA
authors.lastname: Diamond
authors.forename: Anthony
authors.initials: A
authors.lastname: Atala
authors.forename: James
authors.initials: J
authors.lastname: Mandell
authors.forename: Robert L
authors.initials: RL
authors.lastname: Lebowitz
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Borer
authors.forename: Craig A
authors.initials: CA
authors.lastname: Peters
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000151:congenital* / Q000175:diagnosis; D006965:Hyperplasia / Q000175:diagnosis; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D012075:Remission, Spontaneous; D016216:Ultrasonography, Prenatal; D014513:Ureter / Q000002:abnormalities*; D014567:Urography