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

Background: It is usually recommended that neonates with antenatally diagno sed hydronephrosis are put on prophylactic antibiotics and undergo the foll owing investigations ultrasound, MCU and a radio-isotope renogram. Objective: To question the need for such an extensive protocol in antenatal ly diagnosed hydronephrosis on the basis of an improved understanding of th is condition. Methods: 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 circumsta nces: bilateral hydronephrosis, dilated ureter(s) or presence of UTI. A ren ogram was avoided if the AP diameter of the renal pelvis was below 15 mm an d the calyces were not dilated. Results: 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 needled a pyeloplasty - their AP diameter exc eeded 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 unila teral hydronephrotic kidneys showed a paradoxical supranormal function, ran ging from 54-60%. The contralateral kidney was completely normal on the RNS . Conclusion: 1) The vast majority of antenatally diagnosed hydronephrosis ha ve a benign course, only 2/54 or 3.7% required a pyeloplasty. 2) Invasive i nvestigations like an MCU are not necessary in most cases. 3) Routine antib iotic prophylaxis is not required in all unilateral cases and in bilateral ones after VUR has been excluded.