Antibiotic Prophylaxis in Gynaecological Surgery
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Direct answer
Antibiotic prophylaxis in gynaecological surgery is a short, usually single-dose course, most often cefazolin, given around the time of incision to prevent surgical site and pelvic infection. It is indicated for hysterectomy and caesarean section, where infection risk is substantial. Clean procedures that do not enter the genital tract or bowel generally need none.
What you must remember
- Drug of choice: Cefazolin is the usual first-line agent for hysterectomy and caesarean section, with alternatives chosen by allergy history and local antibiogram.
- Standard dose: Cefazolin 2 g IV for most adults, with 3 g for higher body weight, as per local protocol.
- Timing: The dose is given within 60 minutes before incision so that effective tissue levels are present during the operation.
- Caesarean timing: Current guidance (ACOG, WHO) is to give cefazolin before skin incision, which lowers maternal infection without increasing neonatal harm; older practice of waiting for cord clamping is no longer preferred.
- Redosing: Repeat the dose if the operation runs beyond the redosing interval or blood loss is large, per protocol.
- Allergy: For penicillin or cephalosporin allergy, a clindamycin-based regimen is used as an alternative, per local protocol.
- Surgical abortion: Routine prophylaxis is debated, and some protocols use a single dose of doxycycline; guidance on routine use differs.
- Stewardship: Prophylaxis is a single pre-incision dose, and extended postoperative courses are not needed in clean cases.
A timing and selection pathway for prophylaxis
Prophylaxis is a sequence of decisions, and each step narrows the drug, dose and timing. The aim is to cover the likely organisms at the moment of incision without prolonging exposure.
- Confirm the indication: Prophylaxis is justified when surgery enters the vagina, uterus or bowel, or when infection risk is high.
- Check allergy: Review penicillin and cephalosporin history before choosing the agent.
- Choose the agent: Cefazolin is first-line, with clindamycin-based alternatives for allergy and metronidazole added for some bowel or vaginal procedures.
- Time the dose: Give the antibiotic within 60 minutes before incision, including for caesarean section.
- Adjust for weight: Use 2 g for most adults and 3 g for higher body weight, per protocol.
- Redose when needed: Repeat the dose if the operation exceeds the redosing interval or there is major blood loss.
- Stop after surgery: A single dose is preferred, and postoperative courses are reserved for established infection.
Where the exam tries to catch you
Most antibiotic questions in gynaecology test timing and the indication rather than the drug name.
- Trap: Giving a multi-day postoperative course after every hysterectomy. Correct: A single pre-incision dose is standard, and extended courses add resistance without benefit in clean cases.
- Trap: Believing diagnostic laparoscopy needs cover because the abdomen is entered. Correct: Clean diagnostic laparoscopy without bowel or genital tract entry needs no routine prophylaxis.
- Trap: Giving the dose at the end of the operation. Correct: The dose must be given before incision, so that the antibiotic is active during the operation.
Frequently asked questions
Which antibiotic is used for prophylaxis in hysterectomy?
Cefazolin is the usual single-dose agent for abdominal and vaginal hysterectomy, given IV within 60 minutes before incision. Metronidazole may be added for procedures that enter the bowel or carry a risk of bacterial vaginosis, per local protocol. Women with a penicillin or cephalosporin allergy receive a clindamycin-based alternative.
What is the cefazolin dose for caesarean prophylaxis?
The standard cefazolin dose for caesarean section is 2 g IV for most adults, with 3 g used for higher body weight per protocol. It is given before skin incision, since this lowers maternal infection without increasing neonatal harm. Some guidance adds azithromycin for women in labour, and the choice follows local protocol.
Is antibiotic prophylaxis needed for surgical abortion?
Routine prophylaxis is not required for every surgical abortion, and guidance on its use differs between protocols. Some protocols give a single dose of doxycycline to reduce infection risk in higher-risk women. Treatment of an established infection is a separate decision from prophylaxis.
Which gynaecological procedures need no antibiotic prophylaxis?
Clean procedures that do not enter the vagina, uterus or bowel usually need no antibiotic prophylaxis. Examples include diagnostic laparoscopy without bowel entry, office hysteroscopy and endometrial biopsy. Routine cover is therefore reserved for procedures with a genuine infection risk.
Why is prolonged postoperative antibiotic use avoided after gynaecological surgery?
Extended antibiotic courses after clean gynaecological surgery do not reduce infection and they increase resistance, adverse effects and cost. Prophylaxis is therefore a single pre-incision dose unless an infection is already established. This is a standard antimicrobial stewardship principle tested in exams.