Screening for asymptomatic bacteriuria in pregnancy. A decision and cost analysis.

Screening women for asymptomatic bacteriuria on the first prenatal visit is a standard of obstetric care. Treating women with positive results decreases the risk of pyelonephritis and possible prematurity. This study uses decision and cost analysis to compare the utility of screening for asymptomatic bacteriuria with not screening. Data are based on published reports and average charges for services. Costs are based on 1988 charges, projected for the expected results of outpatient screening, possible suppressive therapy, and risks of pyelonephritis. Screening is based on the combined sensitivities and specificities of the MacConkey and CLED (cysteine-lactose-electrolyte-deficient agar) panels of the dip-slide culture. Under the baseline assumptions, the risk of pyelonephritis is estimated to be 2 cases per 100 screened women vs 3.5 cases per 100 unscreened women. The anticipated cost of screening 100 women is $9,939, compared with $12,824 for not screening 100 women. Screening is cost saving unless the cost of screening is above $26, the length of hospitalization for pyelonephritis is fewer than 2.2 days, the risk of asymptomatic bacteriuria falls below 2%, the risk of pyelonephritis with asymptomatic bacteriuria falls below 13%, or the efficacy of treatment in preventing pyelonephritis falls below 38%.