Microscopic hematuria in pregnancy: relevance to pregnancy outcome

The significance of dipstick or microscopic hematuria in pregnancy is uncertain, with some studies suggesting this is associated with a greater risk for preeclampsia. We sought to determine the prevalence and clinical significance of microscopic hematuria during pregnancy.

This was a prospective case-control study in the antenatal Clinic of St George Hospital, Kogarah, Australia, a teaching hospital without tertiary referral antenatal care, with approximately 2,600 deliveries per year. One thousand pregnant women attending for routine antenatal care were invited to have a routine urinalysis performed and be referred to a nephrology clinic for further investigation if dipstick microscopic hematuria was detected on more than 1 occasion before 32 weeks' gestation. Main outcome measures were the prevalence of dipstick hematuria, prevalence of hematuria confirmed by urine microscopy, and the development of preeclampsia or gestational hypertension or delivery of a small-for-gestational-age baby.

One hundred seventy-eight of 902 women (20%) who entered the study had dipstick hematuria on at least 2 occasions in pregnancy; 66 of 126 women (53%) who had hematuria before 32 weeks attended the nephrology clinic, where microscopic hematuria was confirmed in 40 women (61%). Renal imaging results were normal in all except 1 woman, and all women had a serum creatinine level of 0.90 mg/dL or less (< or =80 micromol/L). The development of preeclampsia or gestational hypertension or delivery of a small-for-gestational-age baby were similar in women with and without dipstick hematuria. Microscopic hematuria persisted in half (15 women) of those who attended for follow-up after 3 months postpartum.

Dipstick hematuria is very common during pregnancy, but rarely signifies a disorder likely to impact on the pregnancy outcome. Postpartum follow-up is recommended to detect women who have persistent hematuria and presumed underlying mild glomerulonephritis.