What is the recommended treatment for pyuria in pregnancy?

Treatment of Pyuria in Pregnancy

Pregnant women with pyuria should be treated with a 4-7 day course of antimicrobial therapy based on culture and sensitivity results, with preferred options being nitrofurantoin or beta-lactam antibiotics such as ampicillin or cephalexin. 1, 2

Diagnosis and Screening

Pyuria (presence of white blood cells in urine) alone is not a reliable indicator for treatment decisions in pregnancy. The Infectious Diseases Society of America (IDSA) guidelines note that neutrophil-driven inflammatory responses including pyuria do not reliably discriminate between asymptomatic bacteriuria (ASB) and symptomatic UTI 1.

• All pregnant women should be screened for bacteriuria with urine culture at least once in early pregnancy (optimally at 12-16 weeks gestation) 2
• Urine culture is the gold standard for diagnosis, as dipstick testing for pyuria has low sensitivity (approximately 50%) 2
• Pyuria without bacteriuria does not require treatment
• Pyuria with bacteriuria requires treatment even if asymptomatic

Treatment Algorithm

1. Confirm bacteriuria with urine culture

   • Treat only if ≥105 CFU/mL of a single uropathogen is present
   • Pyuria alone without bacteriuria does not warrant treatment

2. Select appropriate antimicrobial therapy:

   • First-line options (4-7 day course):

     • Nitrofurantoin 100mg BID (avoid in G6PD deficiency and near term)
     • Cephalexin 500mg QID
     • Ampicillin 500mg QID (if susceptible)

   • Avoid:

     • Fluoroquinolones (contraindicated in pregnancy)
     • Tetracyclines (contraindicated in pregnancy)
     • Trimethoprim-sulfamethoxazole in first and third trimesters 2

3. Follow-up after treatment:

   • Obtain follow-up urine culture 1-2 weeks after completing therapy
   • If bacteriuria persists, retreat with a different antibiotic based on susceptibility

Rationale for Treatment

Treatment of bacteriuria (with or without pyuria) in pregnancy is essential because:

• Untreated asymptomatic bacteriuria increases risk of pyelonephritis 20-30 fold 2
• Treatment reduces pyelonephritis risk from 20-35% to 1-4% 2
• Treatment decreases risk of low birth weight infants and preterm delivery 2

The 2019 IDSA guidelines recommend a 4-7 day course of antimicrobial therapy rather than single-dose regimens, as seven days of therapy was more effective than a single dose in preventing adverse outcomes like lower birth weight 1.

Special Considerations

• For recurrent UTIs during pregnancy, postcoital prophylaxis with cephalexin (250 mg) or nitrofurantoin (50 mg) has been shown to be highly effective 3
• If Group B Streptococcus is isolated, treatment during pregnancy is required, and intrapartum prophylaxis should be administered 4
• E. coli is the most common pathogen in pregnancy-associated UTIs 4, 5
• Ampicillin resistance is common in E. coli, making it less reliable as empiric therapy 4, 5

Common Pitfalls to Avoid

• Treating pyuria without bacteriuria
• Using inadequate treatment duration (single-dose therapy is less effective)
• Selecting inappropriate antibiotics (avoid fluoroquinolones, tetracyclines)
• Failing to obtain follow-up cultures after treatment
• Not considering antibiotic resistance patterns when selecting therapy 2

By following these evidence-based recommendations, the risks of pyelonephritis and adverse pregnancy outcomes can be significantly reduced.