Maternal hydronephrosis in pregnancy: Poor correlation with clinical symptoms


      The objective of this study was to investigate the incidence, timing, and severity of maternal hydronephrosis during pregnancy, and to correlate these findings with maternal symptoms of flank pain.

      Study design

      Eighty one subjects were prospectively studied longitudinally during pregnancy. We included consecutive patients with a singleton pregnancy. Gravidas with chronic medical illness, recurrent UTI or pyelonephritis, or history of renal stones were excluded. Real time ultrasound of the maternal kidneys was done serially, in the first, second and third trimesters, as well as postpartum. Each subject was questioned about presence and severity of flank pain prior to the ultrasound. Scans were perfomed by a registered diagnostic medical sonographer, and all images were reviewed by one of the authors. All patients had 4 ultrasound studies performed.


      Seventeen of 81 patients (21%) were observed to have some degree of hydronephrosis, 14 on the right side and 3 bilateral. No cases of hydronephrosis were observed during the first trimester. Four of 81 had hydronephrosis initially noted during the second trimester; most cases were observed only during the third trimester. Nine patients reported significant flank pain; three of these had hydronephrosis. There was no observed correlation between flank pain and the development of hydronephrosis. Chi square = .282, P = .60; RR = 1.88 (0.54-6.15). There was no correlation between maternal symptoms and severity of hydronephrosis. Two patients developed severe hydronephrosis, with a mean renal pelvis diameter >7 cm, and both had no flank pain. At post partum sonography, all cases of hydronephrosis had resolved.


      Hydronephrosis is common during pregnancy, and it has a poor correlation with maternal symptoms. This may have implications for ureteral stent placement during pregnancy.
      Tabled 1Correlation of hydronephrosis with flank pain: Clinical results
      Hydronephrosis +Hydronephrosis −
      Flank pain36
      No flank pain1458