What is the recommended treatment for acute cystitis in a pregnant woman?

Treatment of Acute Cystitis in Pregnancy

Nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 7 days is the recommended first-line treatment for acute cystitis in pregnant women. 1, 2

Why Nitrofurantoin is Preferred

Pregnancy represents a complicated cystitis scenario requiring different management than simple cystitis in non-pregnant women. 2 Nitrofurantoin is the optimal choice because:

• It maintains excellent efficacy with clinical cure rates of 88-93% and bacterial cure rates of 81-92% 1
• Minimal resistance patterns make it reliable for empiric therapy 1
• Safety profile in pregnancy is well-established, particularly in the first and second trimesters 3
• Limited collateral damage to normal flora compared to broader-spectrum agents 1

Treatment Duration

Pregnant women require 7 days of treatment, not the shorter 5-day course used in non-pregnant women. 2, 4 This extended duration is necessary because:

• Pregnancy is classified as complicated cystitis requiring 7-14 days of therapy 2
• The 7-day regimen has demonstrated effectiveness in preventing recurrent UTIs and progression to pyelonephritis during pregnancy 3

Critical Agents to Avoid

Trimethoprim-sulfamethoxazole must NOT be used in the third trimester due to potential fetal complications, despite being a first-line option in non-pregnant women. 5 This is a European Urology guideline recommendation that should be strictly followed.

Fluoroquinolones should be avoided throughout all trimesters due to concerns about fetal cartilage development. 5

Alternative Option: Cephalexin

If nitrofurantoin cannot be used (e.g., due to allergy or intolerance), cephalexin 500 mg every 12 hours for 7-14 days is an acceptable alternative. 4

• The FDA label specifically indicates cephalexin for uncomplicated cystitis 4
• Cephalexin has demonstrated effectiveness for postcoital prophylaxis in pregnant women with recurrent UTIs (250 mg single dose), suggesting safety in pregnancy 3
• However, β-lactams generally have inferior efficacy compared to nitrofurantoin and more adverse effects 1

Common Pitfalls to Avoid

• Do not use 3-5 day short-course therapy as recommended for non-pregnant women; pregnancy requires minimum 7 days 2, 4
• Do not prescribe trimethoprim-sulfamethoxazole in the third trimester even if local resistance rates are favorable 5
• Do not use amoxicillin or ampicillin due to poor efficacy and high resistance rates worldwide 1
• Avoid fosfomycin as it has not been adequately studied in pregnancy and has inferior microbiological cure rates (78%) compared to nitrofurantoin (86%) 1

Monitoring

Symptoms should improve within 48-72 hours of appropriate therapy. 2 If symptoms persist or worsen:

• Obtain urine culture and susceptibility testing 2
• Consider retreatment with a 7-day regimen using an alternative agent 2
• Evaluate for progression to pyelonephritis (fever, flank pain) 2