Although aseptic surgical techniques have dramatically reduced the incidence of surgical site infections, these infections remain the most common surgical complication, affecting up to 5 percent of postoperative patients. Selective use of antibiotics is effective for infection prophylaxis, but this benefit must be weighed against the risk for selection of antibiotic-resistant bacteria. The American College of Obstetricians and Gynecologists (ACOG) reviewed the evidence for appropriate antibiotic prophylaxis in women undergoing gynecologic procedures.

Microorganisms from the patient's skin or vagina are the pathogenic source in most surgical site infections. These organisms are usually aerobic gram-positive cocci (e.g., staphylococci) but also may include fecal flora (e.g., anaerobic bacteria, gram-negative anaerobes) when incisions are made near the perineum or groin. Only a narrow window of antimicrobial effectiveness is available, requiring that antibiotics be administered shortly before or at the time of bacterial inoculation (i.e., when the incision is made, the vagina is entered, or the pedicles are clamped). A delay of only three hours can result in ineffective prophylaxis. Data indicate that for lengthy procedures, administering additional intraoperative doses of an antibiotic can maintain adequate levels throughout the surgery. An additional dose also may be appropriate in patients who have lost more than 1,500 mL of blood.

Laparotomies and laparoscopies do not breach surfaces colonized with vaginal bacteria, and infections after these procedures more often result from contamination with skin bacteria. Hysterosalpingography, sonohysterography, intrauterine device (IUD) insertion, endometrial biopsy, and dilation and curettage may introduce endocervical and upper vaginal bacteria into the endometrium and fallopian tubes. Physicians should consider the polymicrobial nature of these infections when choosing a treatment for endometritis or pelvic inflammatory disease.

Hysterectomy

Women undergoing abdominal or vaginal hysterectomy should receive a single dose of antibiotics. Most studies show no particular regimen to be superior to any other. Antibiotic prophylaxis is a reasonable option in women undergoing laparoscopically assisted hysterectomy, although no evidence is available to support this use. Bacterial vaginosis is a risk factor for surgical site infection after hysterectomy. Treatment of bacterial vaginosis with metronidazole (Flagyl) for at least four days, beginning just before surgery, significantly reduces vaginal cuff infection in patients with abnormal flora.

IUD Insertion and Endometrial Biopsy

Most of the risk of IUD-related infection occurs in the first few weeks to months after insertion, which suggests that contamination of the endometrial cavity during the procedure is the infecting mechanism. However, four randomized clinical trials found that pelvic inflammatory disease is uncommon after IUD insertion regardless of whether antibiotic prophylaxis is used. A Cochrane review found that administration of doxycycline (Vibramycin) or azithromycin (Zithromax) before IUD insertion confers little benefit. ACOG concludes that prophylactic antibiotic use provides no benefit in women with negative screening results for gonorrhea and chlamydia before IUD insertion.

No data are available on infectious complications of endometrial biopsy. However, the incidence of such complications is thought to be negligible, and ACOG recommends that this procedure be performed without the use of antibiotic prophylaxis.

Laparoscopy and Laparotomy

No data are available to recommend antibiotic prophylaxis in women undergoing abdominal surgery that does not involve vaginal or intestinal procedures. Antibiotic prophylaxis is not indicated for diagnostic laparoscopy.

Hysterosalpingography, Sonohysterography, and Hysteroscopy

Postoperative pelvic inflammatory disease is an uncommon but potentially serious complication in patients undergoing hysterosalpingography. Patients with dilated fallopian tubes at the time of the procedure are at greater risk than women with nondilated tubes. Antibiotic prophylaxis is not recommended for patients with no history of pelvic infection. If the procedure demonstrates dilated fallopian tubes, 100 mg of doxycycline may be given twice daily for five days. In women with a history of pelvic infection, doxycycline can be administered before the procedure and continued if dilated fallopian tubes are found.

No data are available on which to base recommendations for women undergoing sonohysterography, but reported rates of postprocedure infection are low. The risks of sonohysterography probably are similar to those of hysterosalpingography, and the same considerations should be taken into account.

Infectious complications after hysteroscopic surgery are uncommon (0.18 to 1.5 percent of patients). A prospective study evaluating the effectiveness of amoxicillin/clavulanate (Augmentin) in preventing bacteremia associated with the procedure found no significant difference in postoperative infection between treated patients and the placebo group. Therefore, ACOG does not recommend routine antibiotic prophylaxis in women undergoing this procedure.

Surgical Abortion

A meta-analysis of 11 placebo-controlled, blinded clinical trials found that women who were given periabortal antibiotics had a 42 percent overall decreased risk of infection. ACOG concludes that antibiotic prophylaxis is effective in women undergoing surgical abortion, regardless of risk. The optimal antibiotic and dosing regimens are unclear.

Preoperative Bowel Preparation

Appropriate prophylaxis for women undergoing surgery that may involve the bowel includes a mechanical bowel preparation without oral antibiotics and the use of a broad-spectrum parenteral antibiotic administered immediately before surgery.