LAUSR

Aims: This study aims to determine the etiology of antenatal hydronephrosis (ANH) and predict need for surgical intervention based on antenatal renal pelvis anteroposterior diameter (APD). Materials and Methods: Combined prospective and retrospective study (2012–2018) of ANH cases with postnatal follow-up. Surgical intervention was correlated with the degree of hydronephrosis (HDN) and pelvis APD measured at the 2nd trimester, 3rd trimester, and postnatal 6-week follow-up. Results: One hundred and sixty-five patients were studied with a total of 219 ANH units. Transient HDN was seen in 116 units. Surgical intervention included pyeloplasty (n = 76), sub ureteric dextranomer injection (n = 8) and nephrectomy (n = 1). Chances of requiring surgery based on the degree of HDN in 2nd and 3rd trimester respectively were mild: 11.32% and 9.52%, moderate: 34.21% and 37.03% and severe: 85.71% and 86.27%. The mean increase in APD between the 2nd and 3rd trimester (n = 50) was lesser in conservatively managed (3.548 ± 4.219 mm) than surgically managed (8.261 ± 5.857 mm) patients (P = 0.002). In another subset (n = 37), the mean increase in APD between the 2nd trimester and postnatal period was less in conservatively managed (1.432 ± 0.612 mm) (P = 0.088) than surgically managed patients (12.91 ± 3.247 mm) (P = 0.004). The area under the receiver operating characteristic (ROC) curve showed that an APD of 8.2 mm in the 2nd trimester and 12.85 mm in the 3rd trimester correlated with the requirement of postnatal surgery. Conclusion: Apart from the degree of HDN, significant changes in APD between 2nd and 3rd trimester and cut off value suggested by the ROC curve will help during antenatal counseling with regard to requirement of postnatal surgery.