What is the management of pyelonephritis in the 3rd trimester of pregnancy?

Management of Pyelonephritis in the 3rd Trimester of Pregnancy

Pregnant women with pyelonephritis in the third trimester require hospitalization and initial treatment with intravenous antimicrobials such as ceftriaxone, followed by oral therapy based on culture results. 1

Initial Assessment and Management

• Hospitalization: All pregnant women with pyelonephritis in the third trimester require inpatient management due to increased risks of maternal and fetal complications 1
• Diagnostic workup:
  • Urinalysis for white blood cells, red blood cells, and nitrites
  • Urine culture with antimicrobial susceptibility testing (essential for all cases)
  • Blood cultures to rule out bacteremia (present in approximately 14% of cases) 2
  • Ultrasound evaluation to rule out urinary tract obstruction or renal stones 3

Antimicrobial Therapy

Initial Intravenous Treatment

• First-line options:

  • Ceftriaxone 1-2 g IV once daily (preferred option) 1
  • Extended-spectrum cephalosporin (e.g., cefepime 1-2 g twice daily)
  • Piperacillin/tazobactam 3.375 g IV every 6 hours

• Avoid fluoroquinolones and aminoglycosides during pregnancy when possible due to potential fetal risks 3, 4

Transition to Oral Therapy

• Switch to oral antibiotics after clinical improvement (typically within 48-72 hours) and when afebrile for 24-48 hours
• Oral options (based on susceptibility results):
  • Oral cephalosporins (e.g., cephalexin 500 mg four times daily)
  • Amoxicillin-clavulanate 875/125 mg twice daily
  • Trimethoprim-sulfamethoxazole (only in third trimester) 160/800 mg twice daily 3

Duration of Therapy

• Total treatment duration: 10-14 days 3, 1
• Intravenous therapy should continue until clinically improved (typically 48-72 hours)

Monitoring and Follow-up

• During hospitalization:

  • Monitor vital signs, urine output, and fetal well-being
  • Obtain follow-up urine culture before discharge to confirm clearance of infection 5
  • Evaluate for signs of preterm labor, as pyelonephritis increases this risk 4

• After discharge:

  • Consider suppressive antibiotic therapy for remainder of pregnancy (e.g., nitrofurantoin 100 mg daily) to prevent recurrence 5
  • Obtain follow-up urine culture 1-2 weeks after completing therapy 1
  • Monthly urine cultures until delivery 6

Special Considerations

• Bacteremia: Present in approximately 14% of pregnant women with pyelonephritis; requires longer course of IV antibiotics 2
• Fluid management: Initial hydration with IV fluids (1 L normal saline over 4 hours) to ensure adequate urine output 2
• Antipyretics: Acetaminophen for fever control to prevent fetal complications
• Preterm labor: Monitor closely as pyelonephritis increases risk of preterm delivery 4

Common Pitfalls and Caveats

• Antibiotic resistance: E. coli resistance to ampicillin is high; avoid empiric use 4
• Inadequate follow-up: Failure to obtain post-treatment cultures increases risk of recurrence 5
• Insufficient duration: Shorter courses of antibiotics may lead to treatment failure
• Delayed transition to oral therapy: Unnecessarily prolonged IV therapy increases hospitalization costs and risks
• Failure to provide suppressive therapy: Up to 38% of women may have positive cultures after discharge without suppressive therapy 5

By following this structured approach to managing pyelonephritis in the third trimester of pregnancy, clinicians can optimize maternal and fetal outcomes while minimizing complications.