340 Obstetrics and Gynecology Board Review •••
❍ Preoperative prophylactic antibiotics are recommended for what commonly performed gynecologic
surgeries?
Hysterectomy, urogynecology procedures, hysterosalpingogram, or chromotubation, induced abortion or dilation,
and evacuation. Antibiotics are generally not necessary in the case of operative hysteroscopy but may be considered
for patients with a prior history of pelvic inflammatory disease (PID).
❍ Preoperative prophylactic antibiotics are not necessary for which gynecology procedures?
Laparoscopy (diagnostic, operative, or tubal sterilization), laparotomy, intrauterine device (IUD) insertion, or
endometrial biopsy.
❍ At what time, should preoperative antibiotics be administered?
Antibiotics should be administered either shortly before or at the time of bacterial inoculation. It is therefore
recommended they be given at the time of induction of anesthesia or within 1 hour of incision.
❍ When should surgical prophylactic antibiotics be redosed?
Additional intraoperative antibiotics should be given at one to two times the half-life of the drug (3 hours for
cefazolin) or when there is increased blood loss (>1500 cc). In addition, the initial dose should be increased in
morbidly obese patients (BMI >35 or weight >100 kg).
❍ True or False: Antibiotics are necessary to prevent endocarditis in high-risk patients undergoing
genitourinary procedures.
False. The American Heart Association no longer recommends antibiotics solely for this purpose.
❍ How common are allergic reactions to penicillin?
Allergic reactions occur in 0.7% to 4% of courses of treatment with penicillin. Anaphylactic reactions occur in
only 0.2% and fatality in 0.0001%. Five to twenty percent of patients will report a history of reactions to b-lactam
antibiotics.
❍ What is the most commonly used preoperative antibiotic in patients without allergies?
Cefazolin is used most often due to its reasonably long half-life (1.8 hours) and low cost.
❍ True or False: Preoperative mechanical bowel preparation reduces the incidence of anastomotic leak and
wound infection in patients undergoing large bowel resection.
False. Historically this was believed to be true; however, randomized trials have shown the opposite.
❍ Is preoperative mechanical bowl preparation beneficial prior to advanced laparoscopic gynecologic
procedures?
Although one prospective study showed no difference, there is controversy as to whether its use improves visibility
of the surgical field.
❍ What is the incidence of deep vein thrombosis (DVT) in patients undergoing major gynecologic surgery?
In the absence of thromboprophylaxis, DVT may occur in 15% to 40% of patients. Use of appropriate prophylaxis
may reduce this rate by 68% to 76%.