What Causes Elevated Epithelial Cells in a Pregnant Woman’s Urinalysis?

During routine prenatal care, urinalysis is a standard screening tool used to assess maternal health and detect potential complications. One common finding that may prompt further evaluation is an elevated count of epithelial cells in the urine—often reported as “increased epithelial cells” or “many epithelial cells” on the urinalysis report.

Epithelial cells are normal components of urine in small numbers, originating from the lining of the urinary tract—including the renal tubules, ureters, bladder, and urethra—as well as the external genitalia. In pregnancy, mild elevations can occur due to physiological changes such as increased urinary stasis, hormonal influences on urothelial turnover, and greater shedding from the vaginal mucosa during specimen collection.

However, persistently high or markedly elevated epithelial cell counts—particularly when accompanied by other abnormal findings like leukocytes, nitrites, bacteria, or symptoms such as dysuria, suprapubic discomfort, or fever—may signal an underlying urinary tract infection (UTI), including asymptomatic bacteriuria, cystitis, or, less commonly, pyelonephritis. Pregnancy increases susceptibility to UTIs due to progesterone-mediated ureteral smooth muscle relaxation and mechanical compression of the ureters by the enlarging uterus, both contributing to urinary stasis and bacterial colonization.

Other potential contributors include contamination from vaginal secretions (especially if midstream clean-catch technique was not followed), vaginitis (e.g., candidiasis or trichomoniasis), or, rarely, more serious conditions such as renal tubular injury or transitional cell abnormalities. It is important to interpret epithelial cell counts in clinical context: isolated mild elevation without symptoms or other urinalysis abnormalities typically does not require intervention but should be rechecked at the next visit.

Clinicians generally do not diagnose or treat based solely on epithelial cell count. Instead, they correlate findings with symptoms, microscopy (e.g., presence of white blood cells or bacteria), urine culture results, and clinical judgment. When indicated, targeted antimicrobial therapy is initiated per current guidelines for UTIs in pregnancy to prevent adverse outcomes such as preterm birth or low birth weight.