Leukocytes, or white blood cells, are a vital part of the body’s immune system, defending against foreign invaders like bacteria and viruses. Finding them in urine during pregnancy is common. This article explores what their presence might mean for expectant mothers.
Understanding Leukocytes in Urine During Pregnancy
Leukocytes are immune cells produced in the bone marrow, and their primary function involves identifying and neutralizing threats to the body’s health. They migrate to areas of infection or inflammation to initiate a protective response. While urine is typically sterile, a small number of leukocytes can sometimes be detected even in healthy individuals. A normal range of leukocytes in urine is generally considered to be 0-5 white blood cells per high-power field (WBC/HPF) when viewed under a microscope.
During pregnancy, physiological changes affect the urinary system. Hormonal shifts, such as increased progesterone, relax smooth muscles in the urinary tract, potentially slowing urine flow and causing incomplete bladder emptying. The growing uterus also pressures the bladder and ureters, which are the tubes connecting the kidneys to the bladder. These changes create an environment more conducive to bacterial growth, often leading to leukocytes in urine.
Common Causes of Elevated Leukocytes
Elevated leukocytes in urine during pregnancy often indicate an underlying condition that requires attention. The most frequent cause is a urinary tract infection (UTI), which occurs when bacteria multiply within the urinary system. Escherichia coli (E. coli) is the most common bacterium responsible for 80% to 90% of UTIs in pregnant individuals. The presence of these bacteria triggers an immune response, leading to an increase in leukocytes in the urine.
Another cause is asymptomatic bacteriuria (ASB), where bacteria are present in the urine without noticeable symptoms. ASB affects approximately 2% to 7% of pregnant women. Although symptom-free, untreated ASB can advance to more severe infections like cystitis (bladder infection) or pyelonephritis (kidney infection).
Less common causes for elevated leukocytes include other infections or inflammatory conditions. Kidney infections, often a progression from untreated UTIs, can lead to an increase in leukocytes, sometimes accompanied by symptoms like fever, chills, and flank pain. Vaginal infections, such as yeast infections or bacterial vaginosis, can also result in leukocytes appearing in a urine sample due to contamination during collection. Additionally, conditions like kidney stones or other obstructions in the urinary tract can cause inflammation and lead to an increase in leukocytes.
Potential Implications and Management
If underlying conditions, particularly UTIs or asymptomatic bacteriuria, are left unaddressed during pregnancy, there can be serious implications for both the mother and the developing baby. Untreated UTIs can progress to pyelonephritis, which can lead to maternal complications such as sepsis (a life-threatening systemic infection) or preeclampsia. For the baby, untreated infections increase the risk of preterm birth and low birth weight.
When elevated leukocytes are detected, a healthcare provider orders further tests to identify the specific cause. A urinalysis checks for white blood cells, red blood cells, and bacteria. A urine culture identifies the type of bacteria present and determines which antibiotics will be most effective. A positive urine culture in pregnancy is defined as a bacterial colony count of 100,000 colony-forming units per milliliter (CFU/mL) or higher of a single organism.
Management primarily involves antibiotic therapy when a bacterial infection is confirmed. Healthcare providers will prescribe antibiotics considered safe during pregnancy, such as nitrofurantoin, cephalexin, or amoxicillin-clavulanate. It is important to complete the entire course of medication as prescribed, even if symptoms improve, to ensure the infection is fully eradicated and prevent recurrence. The specific treatment choice and duration depend on the identified cause and the severity of the infection.
Prevention and Monitoring
Preventing urinary tract infections during pregnancy involves several steps to promote urinary tract health:
Drink plenty of water to flush bacteria from the urinary system.
Maintain proper hygiene, wiping front to back after using the toilet.
Urinate before and immediately after sexual intercourse.
Avoid holding urine for extended periods.
Ensure complete bladder emptying.
Routine prenatal care plays an important role in early detection and management of conditions like UTIs. Healthcare providers include regular urine screenings as part of prenatal appointments, often at the first visit and periodically thereafter. These screenings help identify elevated leukocyte levels or asymptomatic bacteriuria even before symptoms appear. If an infection is diagnosed and treated, follow-up urine tests may be necessary to confirm the successful clearance of the infection.