Treatment of Pyelonephritis in the 3rd Trimester of Pregnancy
Pregnant women with pyelonephritis in the third trimester should be hospitalized and initially treated with intravenous antimicrobials, as outpatient management is often not suitable for this population. 1
Initial Assessment and Diagnosis
- Obtain urinalysis and urine culture with antimicrobial susceptibility testing before starting antibiotics
- Evaluate for fever (>38°C), chills, flank pain, nausea, vomiting, and costovertebral angle tenderness
- Consider renal ultrasound to rule out urinary tract obstruction or stone disease
- Use ultrasound or MRI rather than CT to avoid radiation exposure to the fetus 2
Recommended Treatment Algorithm
Step 1: Initial Intravenous Therapy
Choose one of the following IV regimens:
- Ceftriaxone 1-2g IV once daily (preferred option) 2, 3
- Cefazolin 2g IV every 8 hours 3, 4
- Cefotaxime 2g IV every 8 hours 2
- Ampicillin plus gentamicin (if local resistance patterns permit) 4
Step 2: Duration of IV Therapy
- Continue IV antibiotics until patient is afebrile for at least 48 hours 3, 1
- Most patients require 2-4 days of IV therapy before clinical improvement
Step 3: Transition to Oral Therapy
After clinical improvement (afebrile for 48 hours), transition to oral antibiotics:
- Oral cephalexin 500mg four times daily to complete a total 10-14 day course 5, 3, 4
- Adjust oral therapy based on culture and sensitivity results
Special Considerations
Hospitalization vs. Outpatient Management
While outpatient management with intramuscular ceftriaxone has been studied in early pregnancy, research shows that approximately 30% of women in the third trimester failed outpatient management protocols and required hospitalization 1. Therefore, inpatient management is strongly recommended for third-trimester patients.
Monitoring During Treatment
- Daily vital signs and assessment of symptoms
- Monitor fetal heart rate and uterine activity
- Follow-up urine culture 5-14 days after completing therapy
- Continue surveillance for recurrent infection until delivery
Potential Complications
- Preterm labor (increased risk with pyelonephritis)
- Recurrent infection (occurs in approximately 6-8% of cases) 4
- Sepsis (blood cultures positive in approximately 8% of cases) 4
Common Pitfalls to Avoid
Avoiding fluoroquinolones: While effective for non-pregnant patients with pyelonephritis 2, fluoroquinolones should be avoided in pregnancy due to potential fetal risks.
Inadequate duration of therapy: Complete the full 10-14 day course of antibiotics even if symptoms resolve quickly to prevent recurrence.
Failure to obtain follow-up cultures: Post-treatment cultures are essential to confirm clearance of infection.
Premature discharge: Ensure the patient is truly afebrile for 48 hours before transitioning to oral therapy or considering discharge.
Neglecting to adjust antibiotics based on culture results: Always review culture results and adjust therapy accordingly.
Pyelonephritis in pregnancy requires prompt and effective treatment to prevent complications for both mother and fetus. The evidence strongly supports inpatient management with IV antibiotics initially, followed by oral therapy to complete a 10-14 day course.