What is the recommended treatment for a pregnant woman with possible pyelonephritis?

Treatment of Pyelonephritis in Pregnancy

Pregnant women with pyelonephritis should be treated with intravenous ceftriaxone 1-2 grams once daily as first-line therapy, with hospitalization strongly recommended for initial management. 1

Initial Management and Hospitalization

• Hospitalization is the standard of care for most pregnant women with pyelonephritis, particularly those beyond early pregnancy, as this is considered a complicated urinary tract infection with significant maternal and fetal risks. 2, 1, 3
• Obtain urine culture and blood cultures before initiating antibiotics to guide subsequent therapy adjustments. 1
• Intravenous hydration should be initiated alongside antibiotic therapy. 4, 5

First-Line Antibiotic Regimens

Ceftriaxone is the preferred agent:

• Administer ceftriaxone 1-2 grams IV once daily as empiric treatment due to its proven efficacy and excellent safety profile in pregnancy. 1
• Alternative: Cefepime 1-2 grams IV every 12 hours is an acceptable second-line option. 1
• Second and third-generation cephalosporins are recommended based on their safety profile and efficacy against common uropathogens. 6

Critical Antibiotics to Avoid

Fluoroquinolones (ciprofloxacin, levofloxacin) are absolutely contraindicated in pregnancy due to potential fetal cartilage and skeletal toxicity. 2, 1

Additional contraindications:

• Avoid trimethoprim-sulfamethoxazole, particularly in the first trimester (neural tube defect risk) and near term (kernicterus risk). 1
• Ampicillin should not be used due to high resistance rates to E. coli, the most common pathogen. 6

Duration of Therapy

• Continue IV antibiotics until the patient is afebrile for 48 hours. 7
• Total treatment duration should be 10-14 days (parenteral plus oral therapy). 8, 4
• After clinical improvement with IV therapy, patients may transition to oral cephalexin to complete the treatment course. 7, 5

Diagnostic Imaging Considerations

Ultrasound or MRI should be used (not CT) to evaluate for complications in pregnant patients to avoid radiation exposure to the fetus. 2, 1

Imaging is indicated when:

• Fever persists beyond 72 hours of appropriate antibiotic therapy 1
• History of urolithiasis or renal function disturbances 2
• Clinical deterioration occurs 2
• Evaluation for renal abscess or obstruction is needed 1

Outpatient Management (Selected Cases Only)

Outpatient treatment may be considered only for carefully selected low-risk patients in the first or early second trimester (before 24 weeks):

• Administer ceftriaxone 1-2 grams IM for initial doses, followed by oral cephalexin 500 mg every 6 hours for 10 days total. 7
• This approach showed equivalent outcomes to inpatient therapy in one randomized trial, but most patients should still be hospitalized. 7
• Outpatient management is not appropriate for patients with bacteremia, severe symptoms, or inability to tolerate oral intake. 7, 5

Monitoring and Follow-Up

• Perform urine culture 5-14 days after completion of therapy to document clearance. 7
• Patients who have had pyelonephritis remain at substantially increased risk for recurrence and require close monitoring throughout pregnancy. 3
• If fever persists beyond 48-72 hours, obtain imaging to evaluate for complications such as renal abscess or obstruction. 1

Prevention of Recurrence

Screen for and treat asymptomatic bacteriuria at the initial prenatal visit, as this reduces pyelonephritis risk from 20-35% to 1-4%. 2, 1

For asymptomatic bacteriuria in pregnancy:

• Treat with 4-7 days of antimicrobial therapy (not single-dose regimens). 2
• Options include nitrofurantoin, fosfomycin trometamol, or first-generation cephalosporins. 2, 6

Common Pitfalls to Avoid

• Do not use fluoroquinolones despite their excellent efficacy in non-pregnant patients—fetal risks outweigh benefits. 2, 1
• Do not discharge patients prematurely—ensure 48 hours afebrile before transitioning to oral therapy or discharge. 7
• Do not fail to obtain cultures—empiric therapy must be adjusted based on susceptibility results, as resistance patterns vary. 1, 6
• Do not use CT imaging as first-line—ultrasound or MRI protect the fetus from radiation. 2, 1