Table 1.

UTD A and P classification [4]

UTD A Classification system for antenatal presentation of UTD
Risk category	Criteria
UTD A Normal	A Normal urinary tract is described as the one with no urinary tract abnormalities and anteroposterior renal pelvic diameter (APRPD) measuring less than 4 mm between 16 and 27 weeks’ gestation and less than 7 mm pelvic dilation at 28 or more weeks of gestation.
UTD A1(low risk)	A normal urinary tract with 4 to less than 7 mm pelvic dilation at 16–27 weeks’ gestation or 7 to less than 10 mm at 28 or more weeks of gestation with or without central calyceal dilation.
UTD A2–3 (increased risk)	Includes foetuses with APRPD of 7 mm or more between 16 and 27 weeks’ gestation or 10 mm or greater at 28 weeks of gestation, peripheral calyceal dilation, ureteral dilation, renal parenchymal, or bladder abnormalities.

UTD P Classification system for postnatal presentation of UTD
Risk category	Criteria
UTD P Normal	A normal urinary tract is described as the one with no urinary tract abnormalities and APRPD less than 10 mm.
UTD P1 (low risk)	Describes a normal urinary tract with APRPD 10 to less than 15 mm or central calyceal dilation.
UTD P2 (intermediate risk)	Describes APRPD 15 mm or more or peripheral calyceal dilation.
UTD P3 (high risk)	Describes additional ureteral dilation, abnormal renal echogenicity, or cysts or bladder abnormalities regardless of APRPD measurement.