Prophylactic Antibiotic Regimen for Cesarean Section
The correct answer is C - No antibiotics needed, because the question asks about preventing endometriosis (a chronic gynecologic condition involving ectopic endometrial tissue), not endometritis (postoperative infection). However, if the question intended to ask about preventing endometritis after cesarean section, then none of the listed options represent the recommended first-line regimen. 1
Critical Clarification: Endometriosis vs. Endometritis
Endometriosis is a chronic condition where endometrial-like tissue grows outside the uterus, causing pain and infertility. It is not prevented by antibiotics and is not a complication of cesarean section that antibiotics address. 1
Endometritis is a postoperative infection of the uterine lining that occurs in 5-85% of cesarean deliveries without prophylaxis, and is prevented by appropriate antibiotic prophylaxis. 2, 3
If the Question Intended Endometritis Prevention
For preventing post-cesarean endometritis, the standard recommendation is cefazolin 2g IV given 30-60 minutes before skin incision, which is not listed among your options. 1, 4
Why the Listed Options Are Incorrect:
Option A (Gentamicin + Ceftriaxone): This combination is not a first-line prophylactic regimen according to major obstetric guidelines. It may be reserved for treatment of established infections or for patients with severe penicillin/cephalosporin allergies, but it is not standard prophylaxis. 1
Option B (Metronidazole alone): Metronidazole monotherapy is not recommended as first-line prophylaxis. While metronidazole may be added to ceftriaxone for broader coverage in suspected chorioamnionitis, it is not used alone for routine prophylaxis. 1, 5
Option D (Amoxicillin only): Amoxicillin alone is not recommended as the primary prophylactic agent. First-generation cephalosporins such as cefazolin are preferred due to superior efficacy and pharmacokinetics. 1, 6
The Evidence-Based Standard
Cefazolin 2g IV is the first-line prophylactic antibiotic for all women undergoing cesarean delivery, administered 30-60 minutes before skin incision (not after cord clamping). 1, 4
For women in labor or with ruptured membranes, adding azithromycin to cefazolin provides superior protection against postoperative endometritis compared to cefazolin alone. 1
For patients with severe penicillin/cephalosporin allergy, clindamycin 900 mg IV plus gentamicin 5 mg/kg may be used as combination therapy. 1
Common Pitfall
The most critical error would be confusing endometriosis (a chronic disease unrelated to surgical prophylaxis) with endometritis (a postoperative infection). Antibiotics do not prevent endometriosis. 1