Thematic Area:

Urinary Tract Dilatation

The following guidance document has been adopted based on standardized reviews and is followed in all ERKNet centers:


Multidisciplinary Consensus on the Classification of Prenatal and Postnatal Urinary Tract Dilation

J Pediatr Urol 2014; 10:982-98


Core Recommendations:
  1. The anterior-posterior renal pelvic diameter (APRPD) is the preferred measure to characterize the severity of urinary tract (UT) dilatation. The likelihood of resolution of a urinary tract dilation is related to the APRPD at initial diagnosis.
  2. The term “UT dilatation” should be used consistently.  The use of non-specific terms (e.g. hydronephrosis, pyelectasis, pelviectasis, uronephrosis, UT fullness or prominence, and pelvic fullness) should be avoided.
  3. Prenatal risk stratification:  Low risk (UTD A1): APRPD 4 to <7 mm at <28 weeks, 7 to <10 mm at >28 weeks, ± central calyceal dilation, renal parenchyma of normal thickness and appearance, ureter not visible, normal bladder, no oligohydramnios Increased risk (UTD A2-3):  APRPD >7 mm at <28 weeks, >10 mm at >28 weeks, or any one of the following: dilation of peripheral calyces, abnormal parenchymal thickness or appearance, visibly dilated ureter, abnormal bladder, oligohydramnios
  4. Postnatal risk stratification: Low risk (UTD P1):  APRPD 10 to <15 mm (examined >48 h after birth) ± central calyceal dilation (with APRPD <10mm), renal parenchyma of normal thickness and appearance, ureter not visible, normal bladder.Intermediate risk (UTD P2):  APRPD >15 mm + central or peripheral calyceal dilation (with APRPD<15 mm), ± dilated ureter. Normal renal parenchymal thickness and appearance High risk (UTD P3): UT sonographhic findings as in UTD P2, with renal parenchymal thinning, increased echogenicity and/or decreased corticomedullary differentiation (even if APRPD <15 mm), or abnormal bladder (wall thickening, ureterocele, posterior urethral dilatation).


Comments by Evaluators:
  • Consensus document with recommendations based on literature evidence.
  • Recommendations were made by a panel of specialists, without external review.
  • There are future research directions that will help to improve the evidence for recommendations.