Renal pelvicalyceal dilation in antepartum pyelonephritis: ultrasonographic findings.

The purpose of the present study was to determine whether pregnant women with pyelonephritis have differences of pelvicalyceal systems, compared with normal pregnant control subjects, that might predispose to upper urinary tract infection. Ultrasonographic examination of both kidneys in coronal and axial planes of 24 women with clinical pyelonephritis and positive urine cultures was compared with results in control subjects matched for gestational age, parity, and race. Women with right or bilateral pyelonephritis had increased dilation of the right calyceal system, compared with controls (1.7 cm vs 0.8 cm, p less than 0.001). Renal pelvis volume was increased as well (29.3 vs 5.5 cm3, p less than 0.001). Renal pelvicalyceal dilation in antepartum pyelonephritis was significantly increased compared with normal physiologic dilation of pregnancy. Follow-up nephrosonography in a small number of women (N = 10) after treatment of pyelonephritis did not reveal a consistent decrease in renal dilation, suggesting that dilation of the renal pelvis may antedate pyelonephritis. Further study of this phenomenon is warranted.