Are patients with antenatally diagnosed hydronephrosis being over-investigated and overtreated?

It is usually recommended that neonates with antenatally diagnosed hydronephrosis are put on prophylactic antibiotics and undergo the following investigations--ultrasound, MCU and a radio-isotope renogram.

To question the need for such an extensive protocol in antenatally diagnosed hydronephrosis on the basis of an improved understanding of this condition.

Over a 3-year-period, persistent postnatal hydronephrosis was seen in 42 neonates; in 12 it was bilateral. Antibiotic prophylaxis was stopped in the unilateral cases. An MCU was done mainly in the following circumstances: bilateral hydronephrosis, dilated ureter(s) or presence of UTI. A renogram was avoided if the AP diameter of the renal pelvis was below 15 mm and the calyces were not dilated.

1) The AP diameter of the pelvis was recorded in 40 renal units as follows--< 15 mm--22, 15-20 mm--10, 20-40 mm--6, > 40 mm--2. Both the patients in the latter group needed a pyeloplasty--their AP diameter exceeded 8 cms and an RNS showed depressed function. 2) In those patients who did not receive antibiotics or had a MCU, none has had a UTI. 3) Four unilateral hydronephrotic kidneys showed a paradoxical supranormal function, ranging from 54-60%. The contralateral kidney was completely normal on the RNS.

1) The vast majority of antenatally diagnosed hydronephrosis have a benign course, only 2/54 or 3.7% required a pyeloplasty. 2) Invasive investigations like an MCU are not necessary in most cases. 3) Routine antibiotic prophylaxis is not required in all unilateral cases and in bilateral ones after VUR has been excluded.