Renal pelvic diameters in human fetuses: anatomical reference for diagnosis of fetal hydronephrosis

To evaluate renal pelvis diameters in human fetuses, to establish normative patterns of their growth and size during the second gestational trimester.

We studied 140 kidneys (70 fetuses; 38 male, 32 female) ranging in age from 12-25 weeks' postconception. The renal pelvis was dissected and the transverse and longitudinal diameters were measured. The renal length, width, and thickness were assessed. To compare the quantitative data in both sexes, Student's t-test was used (P <.05).

The mean transverse diameter in male fetuses was 3.61 mm in the right side and 3.58 mm in the left. In female fetuses, it was 3.51 mm in the right side and 3.43 mm in the left. There was no statistical significant difference between the sides either in males (P <.81) or in females (P <.33). There was no significant difference in the mean transverse diameter between male and female fetuses (P <.9). The mean longitudinal diameter in male fetuses was 4.28 mm in the right side and 4.31 mm in the left. In female fetuses, it was 4.17 mm in the right side and 4.33 mm in the left. There was no significant statistical difference between the sides in either males (P <.82) or females (P <.33). There was no significant difference in the mean longitudinal diameter between male and female fetuses (P <.9).

Transverse and longitudinal diameters are useful as parameters for assessment of the renal pelvis in human fetuses.