Should I be screened for bacteria in my urine?

What the USPSTF recommends

The 2019 statement is consistent with the 2008 recommendation; the grade for pregnancy moved from A to B because older studies used outdated antibiotic treatments and newer evidence shows a lower risk of kidney infection than earlier studies found (USPSTF 2019). It applies to adults 18 and older and to pregnant people of any age without signs or symptoms of a urinary tract infection. It does not apply to people with chronic medical or urinary tract conditions such as end-stage renal disease, indwelling urinary catheters, urinary stents or spinal cord injuries, transplant recipients, or people who are hospitalized or live in an institution such as a nursing home (USPSTF 2019).

How screening works in pregnancy

Screening is a midstream, clean-catch urine culture at the first prenatal visit or at 12 to 16 weeks of pregnancy, whichever comes first. It is generally done once; there is little evidence on the best timing or how often to repeat it (USPSTF 2019). A positive result usually leads to antibiotic treatment chosen for safety in pregnancy, with follow-up (USPSTF 2019).

Why it matters

Asymptomatic bacteriuria is found in an estimated 2% to 10% of pregnant women, in 1% to 6% of premenopausal women and in up to 22% of women older than 90; it is rare in men (USPSTF 2019). Changes during pregnancy raise the risk of a kidney infection (pyelonephritis), one of the most common nonobstetric reasons pregnant women are admitted to hospital. Pyelonephritis is linked to complications such as sepsis, low birth weight and preterm birth (USPSTF 2019). Outside pregnancy, bacteria in the urine without symptoms has not been shown to increase the risk of poor health outcomes (USPSTF 2019).

Common questions

Why not screen adults who are not pregnant?

The USPSTF found adequate evidence that treating bacteria found by screening in nonpregnant adults has no benefit, while antibiotics carry harms of their own. It concluded with moderate certainty that screening has no net benefit (USPSTF 2019).

What does a positive culture mean?

In pregnancy, a culture from a midstream, clean-catch sample with more than 100,000 colony-forming units per milliliter of a single germ counts as positive, and more than 10,000 per milliliter of group B streptococcus is commonly used as the threshold for treatment (USPSTF 2019). Your clinician will explain your result.

Also see the gestational diabetes screening check, the bacterial vaginosis in pregnancy check, the syphilis screening check and all screening tests by age.