[Natural history of prenatally diagnosed hydronephrosis: possible recurrence of dilatation after spontaneous reduction, in cases with pelvic diameter larger than 20 mms, recommends long term follow-up].
BACKGROUND
Long term follow-up of a prenatally diagnosed hydronephrosis usually extends no longer than the first two years of life. During this period spontaneous reduction occurs in most of the dilatations, not sustained by obstruction or reflux. Late recurrence of hydronephrosis is considered to be unusual. The aim of the present work has been to verify the risk of recurrent hydronephrosis long time after reduction and to identify factors associated to recurrence.


METHODS
In a seven years period (1992-99) 276 patients with hydronephrosis unrelated to reflux, duplex kidney, megaureter or vesical obstruction have been observed. Among them, 231 were referred after prenatal diagnosis. Hydronephrosis of grade III or more was recorded in 73/231 with a pelvic diameter > or = 15 mms at ultrasonography (US) and a normal counter-lateral kidney. Surgical treatment was elected in 39 cases on the basis of a separate function < 40%, deterioration during follow-up, or occurrence of clinical symptoms. Thirthy four cases were treated conservatively and four were lost at follow. Among the remaining 30 cases, 14 had a pelvic diameter lager than 20 mms. They were followed for a mean of 16.6 months (range 7-26) and spontaneous significant reduction of pelvic dilatation was recorded in all of them.


RESULTS
Patients were recalled after a mean of 32.1 months from the last US. In 3 cases among 14 with a pelvic diameter larger than 20 mms a recurrent severe hydronephrosis was found respectively at 39, 56, and 68 months. In two of them, isotopic scans documented a reduced separate function. The third case reported recurrent symtpoms. A pyeloplasty was performed in all cases.


CONCLUSIONS
Spontaneous reduction in most of the prenatally detected cases of neonatal hydronephrosis within the first two months of life make follow-up beyond this term controversial, whenever complete disappearance of pelvic dilatation has been documented. The Authors report three cases with severe hydronephrosis (pelvic diameter > 20 mms) among a group of patients treated conservatively. Long time after spontaneous reduction, recurrent hydronephrosis was documented in all by US, associated to deterioration of separate function and symptoms. Long term follow-up is recommendable in severe cases of prenatally detected hydronephrosis cases, even after reduction, to warrant from recurrence and renal damage.
Calisti
A
A
Azienda Ospedaliera S. Camillo Forlanini, Roma. a.calisti@tiscali.it
Vallasciani
S
S
Perrotta
M L
ML
Miele
V
V
D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000175:diagnosis* / Q000209:etiology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012008:Recurrence; D012075:Remission, Spontaneous; D012307:Risk Factors; D013997:Time Factors