[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 from diagnosis. 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 of vesical obstruction have been observed. Of these 231 were referred on the basis of a prenatal diagnosis. Hydronephrosis of grade III or more was recorded in 73/231 with a pelvic diameter > or = 15 mm at ultrasonography (US) and a normal counter lateral kidney. Surgical treatment was planned in 39 cases on the basis of a separate function < 40%, either deterioration during follow-up or occurrence of clinical symptoms. Thirty four cases were treated conservatively and four were lost at follow. Of the remaining 30 cases, 14 had a pelvic diameter lager than 20 mm. They were all 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, of 14 with a pelvic diameter > 20 mm a recurrent severe hydronephrosis was found respectively at 39,56 and 68 months. In two of them, isotopic scan documented a reduced separate function. The third case reported recurrent symptoms. A pyeloplasty was performed in all the 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 mm) among a group of patients treated conservatively. Long time after spontaneous reduction recurrent hydronephrosis was documented in all of them by a new US, associated with deterioration of separate function and symptoms. Long term follow-up is recommendable in major cases of prenatally detected hydronephrosis cases, even after reduction, to warrant from recurrence and renal damage.
Calisti
A
A
U.O. di Chirurgia Pediatrica, Azienda Ospedaliera S. Camillo Forlanini, Roma. a.calisti@tiscali.it
Vallasciani
S
S
Perrotta
M L
ML
Miele
V
V
D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D011247:Pregnancy; D012008:Recurrence; D012075:Remission, Spontaneous; D012307:Risk Factors; D013997:Time Factors; D016216:Ultrasonography, Prenatal