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Urinary Tract Infection in Pregnancy

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(See also Urinary Tract Infections (UTI).)

UTI is common during pregnancy, apparently because of urinary stasis, which results from hormonal ureteral dilation, hormonal ureteral hypoperistalsis, and pressure of the expanding uterus against the ureters. Asymptomatic bacteriuria occurs in about 15% of pregnancies and sometimes progresses to symptomatic cystitis or pyelonephritis. Frank UTI is not always preceded by asymptomatic bacteriuria. Asymptomatic bacteriuria, UTI, and pyelonephritis increase risk of preterm labor and premature rupture of the membranes.

Urinalysis and culture are routinely done at initial evaluation to check for asymptomatic bacteriuria. Diagnosis and treatment of symptomatic UTI is not changed by pregnancy, except drugs that may harm the fetus are avoided (see Table 2: High-Risk Pregnancy: Drugs With Adverse Effects During PregnancyTables). Asymptomatic bacteriuria may lead to pyelonephritis and should be treated with antibiotics similar to an acute UTI.

Antibacterial drug selection is based on individual and local susceptibility and resistance patterns, but good initial empiric choices include the following:

After treatment, proof-of-cure cultures are required. Women who have pyelonephritis or have had > 1 UTI may require suppressive therapy, usually with trimethoprim/sulfamethoxazole Some Trade Names
BACTRIM
SEPTRA
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(prior to 34 wk) or nitrofurantoin Some Trade Names
FURADANTIN
MACROBID
MACRODANTIN
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, for the rest of the pregnancy. In women who have bacteriuria with or without UTI or pyelonephritis, urine should be cultured monthly.

Last full review/revision December 2008 by Sean C. Blackwell, MD

Content last modified December 2008

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