Maternal Hydration Status Affects Renal Pelvic-Calyceal Diameter in Pregnancy

ABSTRACT

Our objective was to evaluate the effect of maternal hydration status on the maternal renal collecting system during the third trimester of pregnancy. Thirty-five patients with uncomplicated singleton pregnancies were studied between 28 and 40 weeks of gestation. Ultrasound of the maternal kidneys was performed at baseline and after oral hydration with 1 L of water. Renal pelvic dilation was defined as a mean pelvic-calyceal diameter of > 10 mm. Results were analyzed with the Student paired t test and the McNemar test for comparing correlated proportions; p < 0.05 was considered significant. Prior to hydration, 19 patients (54%) had renal pelvic dilation: 7 on the right side, 2 on the left side, and 10 bilateral. Sixty minutes after hydration, 33 patients (94%) had renal pelvic dilation: 7 on the right side, 1 on the left side, and 25 bilateral. Renal pelvic dilation peaked 60 to 90 minutes after oral hydration. We concluded that hydration status substantially affects maternal renal imaging studies during the third trimester of pregnancy.

KEYWORDS

Pregnancy - maternal hydronephrosis - renal ultrasound - renal pelvic dilation

REFERENCES

• 1 Anderson I H, Jones G R, Standen J R. Ultrasonographic assessment of hydronephrosis of pregnancy.  J Can Assoc Radiol. 1983;  34 29-31
• 2 Cietak K A, Newton J R. Serial qualitative maternal nephrosonography in pregnancy.  Br J Radiol. 1985;  58 399-404
• 3 Fried A M. Hydronephrosis of pregnancy: ultrasonographic study and classification of asymptomatic women.  Am J Obstet Gynecol. 1979;  135 1066-1070
• 4 Fried A M, Woodring J H, Thompson D J. Hydronephrosis of pregnancy: a prospective sequential study of the course of dilatation.  J Ultrasound Med. 1983;  2 255-259
• 5 Murao F. Ultrasonic evaluation of hydronephrosis during pregnancy and puerperium.  Gynecol Obstet Invest. 1993;  35 94-98
• 6 Muller-Suur R, Tyden M. Evaluation of hydronephrosis in pregnancy using ultrasound and renography.  Scand J Urol Nephrol. 1985;  19 267-273
• 7 Peake S L, Roxburgh H B, Langlois S L. Ultrasonographic assessment of hydronephrosis of pregnancy.  Radiology. 1983;  146 167-170
• 8 Rasmussen P E, Nielsen F R. Hydronephrosis during pregnancy: a literature survey.  Eur J Obstet Gynecol Reprod Biol. 1988;  27 249-259
• 9 Watson W J, Brost B C. Maternal hydronephrosis in pregnancy: poor association with symptoms of flank pain.  Am J Perinatol. 2006;  23 463-466
• 10 Woo J S, Wan C W, Ma H K. Pregnancy hydronephrosis-a longitudinal ultrasonic evaluation.  Aust N Z J Obstet Gynaecol. 1984;  24 9-13