Role of fetal renal pelvic dilatation - as a predictor of neonatal urological outcome

Abstract

Background: Mild pelvic dilatation is relatively frequent in the normal fetus but once it is detected, adequate follow-up is required. An abnormal finding, can affect parental attitude towards the pregnancy and their unborn baby. Therefore, it is necessary to have specific ultrasound criteria that differentiate transient dilatation from pathological abnormality to offer an accurate counseling to the parents. To evaluate the need for postnatal treatment- surveillance and or surgery in relation to grade of renal pelvic dilatation found on third trimester ultrasound and to identify a cut-off value of APD which discriminates transient pelvic dilatation from pathological abnormality. Methods: A Hospital based prospective study was conducted at Fernandez hospital, Fetal Medicine Unit (FMU), Hyderabad by reviewing the hospital records from January 2010 to January 2015 among 310 Antenatal cases with isolated fetal renal pelvic diameter (APD) > 7 mm in third trimester on ultrasound were included and post natal follow up was done for 1 year duration. Results: Post natal follow up identified that out of 162 mildly dilated renal pelvic units (APD 7-9 mm) 98 cases (60.4%) resolved and none required surgery. Out of 117 moderate hydronephrosis (APD 9-15 mm) 22 cases resolved (18.8%), 11 cases (9%) required surgery and out of 18 cases with severe hydronephrosis (APD of > 15mm) none of them resolved and 6 cases needed surgery. The cases which required surgery had either moderate or severe hydronephrosis with mean renal pelvic diameter of 11.3 mm. Similarly on the basis of receiver operating characteristic curves, the renal threshold that best predicted surgery in postnatal period was anteroposterior diameter of > 11 mm in third trimester, yielding sensitivity - 74.07%, specificity -93.97%, positive likelihood ratio - 12.27, not clinically significant. Conclusions: The need for postnatal treatment increased with the grade of antenatal RPD. Neonates with antenatal mild dilatation (renal pelvis diameter 11 mm required surgery.