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.