Curriculum · Gynecology / Women's Health / Infertility / Perinatal Care / Birth Spacing
Urinary tract infection in pregnancy
What it is
Bacteria in the urine of a pregnant woman are treated even when she has no symptoms. Asymptomatic bacteriuria in pregnancy is diagnosed from two consecutive voided urine specimens showing isolation of the same bacterial strain in quantitative counts of 10^5 colony-forming units (CFU)/mL or more. It is not one number: it occurs in 2-10% of pregnant women in one reading and affects up to 7% of pregnant women in another. Whether symptomatic or asymptomatic, it is important to treat it and so prevent progression to pyelonephritis, and that progression is made easier in pregnancy because the calyces and ureters dilate. Outside pregnancy the same result is read differently: in women age 70 and older the incidence of asymptomatic bacteriuria is 16%-18%, reaching 43% in chronically incontinent and disabled older adults, and there it does not require antibiotic therapy, since general malaise without urinary symptoms is unlikely to represent a urinary tract infection or to improve with antibiotics.
Causes and risk
The factors that predispose to cystitis, pyelonephritis, urethritis and asymptomatic bacteriuria are sexual activity, pregnancy itself, barrier contraceptives such as the diaphragm, prior urinary tract instrumentation, urinary catheterization whether in-dwelling or intermittent, congenital or acquired anatomic anomalies, and bladder dysfunction. The organisms are E. coli, which is the most common, then Klebsiella and Proteus.