Leukocytes, also known as white blood cells, are key immune cells that fight infections and inflammation. When detected in urine, their presence often indicates an underlying condition requiring investigation, especially during pregnancy.
Understanding Leukocytes in Urine During Pregnancy
While a small number of leukocytes in urine can be normal during pregnancy, elevated levels warrant attention. Typically, healthy individuals, including pregnant ones, should have very few leukocytes in their urine, usually ranging from 0 to 5 white blood cells per high-powered field (WBC/HPF). Physiological changes during pregnancy alter the urinary tract, increasing susceptibility to conditions that raise leukocyte presence. These include increased pressure from the growing uterus on the bladder and ureters, restricting urine flow, and hormonal shifts. The immune system also experiences some suppression, contributing to a heightened infection risk.
Common Causes of Leukocytes in Urine During Pregnancy
Infections are the most frequent cause of increased leukocytes in urine during pregnancy. The body produces more white blood cells to combat these infections, which then appear in urine. Identifying the cause is crucial for appropriate management.
Urinary Tract Infections (UTIs) are the most common reason for elevated leukocytes in urine during pregnancy. UTIs occur when bacteria infect any part of the urinary system, including the kidneys, ureters, bladder, or urethra. Symptoms include a burning sensation during urination, frequent and urgent urination, cloudy or foul-smelling urine, and lower abdominal or back pain. Pregnant individuals are more prone to UTIs due to changes in urinary tract anatomy and hormonal influences.
Asymptomatic Bacteriuria (ASB) is another cause, where bacteria are present in significant amounts without noticeable symptoms. It affects approximately 2% to 10% of pregnant women. Despite the lack of symptoms, ASB is a concern because it can progress to serious infections like kidney infections, and is associated with increased risk of preterm labor and low birth weight. Routine screening for ASB is a standard part of prenatal care, often performed in the first trimester.
Kidney infections, or pyelonephritis, are a more severe form of urinary tract infection that also cause elevated leukocytes in urine. These infections typically present with pronounced symptoms, including high fever, chills, nausea, vomiting, and flank pain. Pyelonephritis can lead to serious complications for both the pregnant individual and the fetus, such as preterm labor or sepsis.
Sometimes, the presence of leukocytes in a urine sample can be due to contamination from vaginal discharge or external genital inflammation, rather than an infection within the urinary tract itself. Less common causes of leukocytes in urine include kidney stones, which can cause blockages and inflammation, and certain sexually transmitted infections or vaginitis. In some cases, leukocytes may be present without bacteria, a condition called sterile pyuria, which can be linked to viral infections or other inflammatory conditions.
Diagnosis and Management
When leukocytes are detected in urine during pregnancy, medical evaluation is necessary to determine the cause and guide treatment. Pregnant individuals should contact their healthcare provider if they notice symptoms of a urinary tract infection or if routine urine tests show leukocytes. Prompt attention prevents potential complications.
Diagnosis typically begins with a urinalysis, testing a urine sample for white blood cells, red blood cells, nitrites, and other infection indicators. A clean-catch midstream urine sample is crucial to minimize contamination and ensure accurate results. If urinalysis suggests an infection, a urine culture is usually performed to identify the specific bacteria and determine effective antibiotics.
Management of elevated leukocytes depends on the identified cause. If a bacterial infection (UTI, ASB, or pyelonephritis) is confirmed, antibiotic therapy is the primary treatment. Healthcare providers prescribe antibiotics safe for pregnancy, such as amoxicillin, cephalexin, or nitrofurantoin, avoiding those with fetal risks. Completing the entire antibiotic course as prescribed is essential, even if symptoms improve, to fully eradicate the infection and prevent recurrence. A follow-up urine culture may be recommended to confirm infection clearance.