Gynecologic procedures carry a high risk of infection. Procedures that breach the endocervix may seed the endometrium and fallopian tubes with microorganisms from the upper vagina and endocervix. This can lead to the development of endometritis or pelvic inflammatory disease. In addition to regional infections, transient bacteremia during procedures can lead to bacterial endocarditis in susceptible patients who have existing cardiac lesions. Although excellent aseptic technique can dramatically reduce the incidence of procedurerelated infections, antimicrobial prophylaxis is recommended for several procedures.
Successful antimicrobial prophylaxis depends on the characteristics of the infecting organisms and their interaction with the selected antibiotic regimen. Systemic antibiotics are believed to augment natural defense mechanisms but rely on a narrow window of time to combat infection at the time of inoculation. Timing and method of delivery are as critical as choice of antibiotic for successful prophylaxis. For many procedures, antibiotic prophylaxis is given during the induction of anesthesia. During long surgeries, additional doses of antibiotics are given at intervals of one or two times the half-life of the antibiotic to maintain adequate levels throughout the procedure. Additional or increased doses may be used in patients at increased risk and when blood loss is substantial.
For most procedures, cephalosporins are the agents of choice because of their broad and appropriate spectrum of activity, in addition to the low incidence of allergy and adverse effects. Cefazolin (in a dosage of 1 g) is the most widely used antibiotic for “clean” procedures, because it combines long half-life (1.8 hours) with efficacy and reasonable cost. Table 1 shows recommended prophylactic regimens for common gynecologic procedures.
|Vaginal/abdominal hysterectomy*||Cefazolin||1 or 2 g IV single dose|
|Cefoxitin||2 g IV single dose|
|Cefotetan||1 or 2 g IV single dose|
|Metronidazole||500 mg IV single dose|
|Hysterosalpingogram||Doxycycline†||100 mg orally twice daily for 5 days|
|Induced abortion/D&C||Doxycycline||100 mg orally 1 hour before procedure and 200 mg orally after procedure|
|Metronidazole||500 mg orally twice daily for 5 days|
Various adverse reactions, ranging from minor skin rash to anaphylaxis, are possible with the use of prophylactic antibiotics. Diarrhea is common and may occur in up to 29 percent of patients, depending on the agent used and patient characteristics. Nearly 15 percent of hospitalized patients receiving betalactam antibiotics develop diarrhea, as do 10 to 25 percent of those receiving clindamycin. Anaphylaxis is rare and is reported to occur in 0.2 percent of patients on courses of penicillin treatment. A final serious concern is the potential to induce bacterial resistance to common antibiotics if prophylaxis is overused. As shown in Table 1, good clinical evidence supports antibiotic prophylaxis for certain procedures such as hysterectomy and induced abortion, and for other procedures when special circumstances (such as finding dilated fallopian tubes during hysterosalpingography) occur. Prophylaxis is not recommended for use in several common procedures such as laparoscopy, laparotomy, endometrial biopsy and insertion of intrauterine contraceptive devices.
|High-risk patients||Ampicillin plus gentamicin*||Ampicillin, 2 g IM or IV, plus gentamicin, 1.5 mg per kg (not to exceed 120 mg) within 30 minutes of starting the procedure; six hours later, ampicillin, 1 g IM/IV, or amoxicillin, 1 g orally|
|High-risk patients allergicto ampicillin/amoxicillin||Vancomycin plus gentamicin*||Vancomycin, 1 g IV over one to two hours, plus gentamicin, 1.5 mg per kg IV/IM (not to exceed 120 mg); complete injection/infusion within 30 minutes of starting the procedure|
|Moderate-risk patients||Amoxicillin or ampicillin||Amoxicillin, 2 g orally one hour before procedure, or ampicillin, 2 g IM/IV within 30 minutes of starting the procedure|
|Moderate-risk patients allergic to ampicillin/amoxicillin||Vancomycin*||Vancomycin, 1 g IV over one to two hours; complete infusion within 30 minutes of starting the procedure|
Patients with cardiac abnormalities are at risk of bacterial endocarditis following several gynecologic procedures. Patients with prosthetic cardiac valves or congenital heart disease are at highest risk, but patients with cardiomyopathy and acquired valvular disease are also at risk. The recommended regimens for patients undergoing genitourinary or gastrointestinal surgeries are constructed to accommodate the likely pathogens as well as the anticipated timing of bacteremia development (Table 2).
When appropriately used, prophylactic antibiotics are cost-effective in reducing the morbidity associated with gynecologic procedures. Older studies estimated savings of more than $100 per hysterectomy and a total savings of more than $500,000 in the United States for induced abortions.