The presence of leukocytes, also known as white blood cells, in urine during pregnancy warrants attention. While a small number can be normal, elevated levels often indicate an underlying process requiring medical evaluation. Understanding what triggers their appearance is important.
Understanding Leukocytes in Urine
Leukocytes are immune cells produced in the bone marrow, circulating to fight infections and foreign substances. Their detection in a urine sample signals an immune response within the urinary tract, bladder, or kidneys.
A small amount of leukocytes in urine, up to 5 per high power field (WBC/HPF), can be normal, even during pregnancy. Higher counts, suggesting pyuria, indicate inflammation or infection within the urinary system. Elevated leukocytes, especially alongside bacteria or nitrites, often signify a urinary tract infection.
Common Causes During Pregnancy
Pregnant individuals are more susceptible to urinary tract infections (UTIs). Hormonal changes and the growing uterus can relax urinary tract muscles and impede bladder emptying, creating an environment conducive to bacterial growth. UTI symptoms include a burning sensation during urination, frequent urges, cloudy or foul-smelling urine, and lower abdominal pain.
Asymptomatic bacteriuria (ASB), the presence of bacteria in urine without symptoms, is another common cause. Affecting 2% to 7% of pregnant individuals, untreated ASB can progress to kidney infections and increases the risk of preterm labor and low birth weight. Regular screening for ASB is a routine part of prenatal care.
Vaginal contamination can also lead to leukocyte detection in a urine sample, even without a urinary tract infection. Vaginal discharge or inflammation can introduce leukocytes during collection. To minimize this, healthcare providers advise a clean-catch midstream urine sample: the genital area is cleaned, and the initial urine stream is discarded before collection.
Less Common Causes and Considerations
A kidney infection, pyelonephritis, is a more serious cause of leukocytes in urine during pregnancy. It often develops if a lower UTI or asymptomatic bacteriuria goes untreated, allowing bacteria to ascend to the kidneys. Pyelonephritis presents with severe symptoms, including high fever, chills, nausea, vomiting, and lower back or side pain. This condition requires prompt medical attention due to potential complications for both the pregnant individual and the baby, such as preterm labor.
Other inflammatory conditions, not directly bacterial, can also result in leukocytes in the urine. These include kidney stones, which can cause irritation and blockages. While less common as primary causes, such conditions can trigger an immune response, leading to leukocytes.
Diagnosis and Treatment Approaches
When leukocytes are found in a pregnant individual’s urine, further diagnostic tests identify the underlying cause. An initial dipstick test screens for leukocyte esterase, indicating leukocytes, and nitrites, suggesting bacterial infection. If positive, a detailed urinalysis with microscopy counts leukocytes and looks for other elements.
A urine culture is often the most definitive test, identifying specific bacteria and their antibiotic sensitivity. This guides the healthcare provider in selecting effective and safe antibiotic treatment. Prompt medical consultation is important for diagnosis and treatment, as untreated infections can lead to complications for both the pregnant individual and the baby.
Treatment for urinary tract infections during pregnancy primarily involves antibiotics. The choice of antibiotic is carefully considered to ensure it is safe and effectively eliminates bacteria. Completing the full course of prescribed antibiotics is important, even if symptoms improve. After treatment, follow-up urine tests, often including another urine culture, confirm the infection has cleared.