Associations, follow up data, and postnatal outcome of antenatally diagnosed Urinary Tract Dilatation - Five-year single tertiary center experience from South India.

Background: Urinary tract dilatations (UTD) are frequently diagnosed during Mid-Trimester Anomaly Scan (MTAS), at which time, given their variable progression and heterogeneous classification systems, offering suitable counsel to the couple is challenging.

Objective: Based on postnatal data, we aimed to guide parental counseling, and further evaluation of UTD diagnosed at MTAS. Specifically, the utility of multi-disciplinary UTD classification system was tested.

Methods: A retrospective observational study of all UTDs included from five years (2015-2020) MTAS register. The multi-disciplinary UTD classification system was used for antenatal/postnatal UTD categorization. Follow-up data were obtained from case records until the current age of children (2-6 years).

Results: Out of 527 fetal abnormalities, 103 had UTD at MTAS. Based on the third-trimester ultrasound, 49 were low-risk UTD A1, and 44 were increased-risk UTD A2-3 (including the nineteen UTD A1 at MTAS worsened to A2-3 by third-trimester). On postnatal follow-up of UTD A1 and A2-3, respectively, neonatal UTD P2/P3 was seen in 2% and 40.9%; complete spontaneous resolution was seen in 79.5% and 43.18%; none and 22.7% underwent surgical intervention; persistent P2/P3 UTD were seen on follow-up in 2% and 4.5% (excluding those who needed surgery); impaired renal function was seen in none and 36.3%, and recurrent UTI in 8.1% and 34.09%. The subgroup with progressive UTD (from A1 to A2-3 by third-trimester ultrasound) formed 43% of the final UTD A2-3 category. Among these 19 cases, surgical intervention was performed in eight (42%); impaired renal function was seen in 7 cases (36.8%), and recurrent UTI was seen in eight (42%).

Discussion: Given the diverse classification systems for UTD, ours is the second Indian data proving the prognostic utility of multi-disciplinary UTD classification system, specifically at third trimester scan, based on postnatal outcome. In contrast to published guidelines, our data suggests follow-up for renal pelvis anteroposterior diameter (APD) of 4-7 mm at MTAS, as some may worsen. Similar progression has been noted in other Indian studies, but the classification systems are different. Contrary to the published literature, we could not suggest a renal APD cut-off as a single criterion to predict surgical intervention. Significant limitations are retrospective observational design and multiple sonographers.

Conclusion: Our data helps guide parental counseling and further evaluation for UTD diagnosed at MTAS. The multi-disciplinary Consensus UTD Classification system, was helpful in prognostication.