Antibiotic Prophylaxis for Postpartum Uterine Examination
For postpartum uterine examination in the setting of potential PPH, administer a single dose of ampicillin 2 g IV plus metronidazole 500 mg IV immediately before or during the procedure. 1
Primary Recommendation
- Ampicillin 2 g IV plus metronidazole 500 mg IV as a one-time dose is the recommended prophylactic regimen for uterine exploration or instrumentation in the postpartum period. 1 This combination provides coverage against the polymicrobial flora that can be introduced into the uterus during manual examination, including aerobic and anaerobic organisms.
Alternative Regimen for Penicillin Allergy
For patients with non-severe penicillin allergy, substitute cefazolin 1 g IV for ampicillin, maintaining metronidazole 500 mg IV. 1 This applies to patients without history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin exposure. 2
For patients with severe penicillin allergy (history of anaphylaxis, angioedema, respiratory distress, or urticaria), use clindamycin 900 mg IV plus an aminoglycoside (such as gentamicin 5 mg/kg IV) as alternatives. 2 Clindamycin provides anaerobic coverage similar to metronidazole while avoiding beta-lactam antibiotics entirely.
Special Circumstance: Prior GBS Prophylaxis
If the patient has already received intrapartum antibiotic prophylaxis for Group B Streptococcus (GBS) with ampicillin or penicillin, administer only metronidazole 500 mg IV as a single dose. 1 The prior GBS prophylaxis provides adequate gram-positive coverage, but anaerobic coverage must be added for uterine manipulation.
GBS prophylaxis regimens include penicillin G 5 million units IV initially then 2.5 million units IV every 4 hours, or ampicillin 2 g IV initially then 1 g IV every 4 hours. 3 If the patient received these within the preceding hours, only metronidazole is needed.
Timing and Administration
Administer antibiotics immediately before or during the uterine examination, not after completion. 1 Prophylactic antibiotics are most effective when tissue levels are established before bacterial contamination occurs.
This is a single-dose prophylactic regimen; do not continue antibiotics beyond the initial dose unless clinical signs of infection develop. 1
Rationale for This Regimen
Manual uterine examination introduces vaginal and cervical flora into the normally sterile uterine cavity, significantly increasing endometritis risk. 4, 1 The combination of ampicillin and metronidazole provides broad-spectrum coverage against the polymicrobial organisms most commonly implicated in postpartum endometritis.
Ampicillin covers gram-positive cocci (including Streptococcus and Enterococcus) and some gram-negative organisms, while metronidazole provides essential anaerobic coverage (including Bacteroides species). 1 Single-dose cephalosporin prophylaxis alone has been associated with increased Enterococcus faecalis colonization, which can lead to treatment failure. 5
Additional Considerations for PPH Management
During active PPH management requiring uterine examination, administer oxytocin 5-10 IU slowly IV or IM as first-line uterotonic therapy. 4, 6 This addresses uterine atony, the most common cause of PPH.
If bleeding persists after oxytocin, administer tranexamic acid 1 g IV within 3 hours of delivery, with a second dose available 0.5-23.5 hours later if bleeding continues. 7 Tranexamic acid reduces maternal death from hemorrhage when used in postpartum hemorrhage treatment.
Maintain fibrinogen levels ≥2 g/L during active hemorrhage and target hemoglobin >8 g/dL with transfusion as needed. 7, 4
Critical Pitfalls to Avoid
Do not delay antibiotic administration until after the examination is complete—this converts prophylaxis to treatment and reduces efficacy. 1
Do not omit metronidazole from the regimen, even if the patient received GBS prophylaxis, unless that prophylaxis was specifically ampicillin or penicillin-based. 1 Cefazolin used for GBS prophylaxis does not provide adequate anaerobic coverage.
Do not use cefazolin alone without metronidazole for uterine examination prophylaxis, as this increases risk of anaerobic infection and Enterococcus colonization. 5, 1
Do not continue prophylactic antibiotics beyond a single dose unless clinical endometritis develops (fever, uterine tenderness, foul-smelling lochia). 1 Prolonged prophylaxis promotes resistance without additional benefit.