Antenatal Hydronephrosis
Antenatal diagnosis of hydronephrosis based on AP diameter of renal pelvis
| Second Trimester | Third Trimester |
Mild | 4 mm | 7mm |
Moderate | 7 mm | 10 mm |
Severe | 10 mm | 15 mm |
Postnatal investigations for unilateral hydronephrosis or bilateral hydronephrosis in girls
1.USG on D3 to 4 after birth
2.If AP diameter > 10 mm start uroprophylaxis and do MCU after 6 weeks
3.If MCU shows no VUR , DTPA or EC scan at 2 months
Postnatal investigations for bilateral hydronephrosis in a boy
1.USG within 24 hours
2.MCU to check for PUV after the USG
3.If PUV , urine routine, RFT, catheterization and refer to pediatric surgeon
Indications for uroprophylaxis
Post natal USG showing AP dimeter of renal pelvis > 10 mm
Children with proved VUR
Drugs for uroprophylaxis in neonates
Amoxycillin 10 mg /kg as a single dose at night OR
Cephelexin 10 mg/kg as a single dose at night
Hydronephrosis is one of the commonest abnormalities detected on antenatal ultrasound with a prevalence of 1-2 per 1000 live births
The diagnosis of antenatal hydronephrosis is based on the degree of dilatation of the AP diameter of the renal pelvis. The limits of normalcy vary with the gestational age.
Posterior urethral valves, pelviureteric obstruction and vesicoureteral reflux are the three important underlying causes. Rarer causes include Ureterovesical junction obstruction, megaureter, ureterocele, ectopic ureter and urethral atresia. The majority of cases are transient, non obstructing, non refluxing hydronephrosis that resolve spontaneously over the first year of life.
Poor kidney function may be reflected as oligohydramnios, hyperechoic kidneys and renal cysts
Postnatal USG should be done to confirm the diagnosis after day 3 of life.
If APD <10mm and the baby shows no ureteral or bladder abnormalities and is voiding well the USG may be repeated at periodic intervals. Child can be monitored by USG alone, for resolution or progression of findings. (3 months, 6 months, then 6-12 monthly until resolution)
Infants with AP diameter > 10mm need to be initiated on uroprophylaxis. They should undergo MCU .This can be done afte 6 weeks of age.
Infants with AP diameter > 10 mmm who have no VUR on MCU should undergo a DTPA or EC scan with diuretic renogram to look for PUJ obstruction
In male children with bilateral hydronephrosis it is imperative to rule out posterior urethral valves.
Clinical examination for a palpable firm bladder and the voiding pattern needs to be assessed. USG should be done early to confirm antenatal findings and an MCU should be done to look for posterior urethral valves
In a girl child, the USG may be done after 3 days and MCU can be deferred and done after one month of age
All infants with pelvis AP diameter > 10mm should be started on uroprophylaxis.
1.All PUV who have abnormal RFT prior to valve fulguration
2 All PUV postoperatively
3.VUR s grade 3,4 and 5
4.Children with recurrent UTI
5.Prior to antireflux surgery