Postpregnancy Genital Tract and Wound Infections

Nell Tharpe, CNM, CRNFA, MS

Disclosures

J Midwifery Womens Health. 2008;53(3):236-246. 

In This Article

Endometritis

Endometritis is described as a polymicrobial infection in which aerobic and anaerobic bacteria (Chlamydia trachomatis, mycoplasmas, and/or Ureaplasme urealyticum) are presumed to ascend into the uterus from the lower genital tract.[19] Infection may extend into the fallopian tubes and pelvic peritoneum, as well as into the incised edges of the uterine myometrium following surgical delivery.[5] Postpartum endometritis occurs much more commonly following cesarean birth, with a rate that ranges in the literature from 5% to 30% compared to a reported range of 0.2% to 0.9% for vaginal birth.[3,4,5,20]

Careful attention to hand washing and strict adherence to aseptic technique remain the foundations of infection prevention and control.[16] Critical evaluation of each woman's individual risk for infection coupled with diligent postpartum assessment for signs and symptoms of infection allows for improved detection of infection and offers an opportunity for prompt treatment.[7,12]

Prophylactic antibiotic administration during cesarean birth has been demonstrated to decrease the incidence and severity of postpartum endometritis by as much as 75%.[15] A Cochrane review of 81 randomized controlled trials found that the use of prophylactic antibiotics during cesarean birth resulted in a "major, clinically important, and statistically significant reduction"[15] in fever, endometritis, and wound infection following cesarean birth. In this review, the average incidence of endometritis in the groups of women who did not receive prophylactic antibiotics before surgery ranged from 7.03% for women undergoing an elective cesarean birth, to 30.14% for women undergoing nonelective cesarean birth, and 19.90% in those studies where the indication for cesarean birth was not defined or included both groups. The overall relative risk for all patients was 0.39 (95% confidence interval [CI], 0.31-0.43), and the authors noted remarkable consistency in the relative risk related to the effect of prophylactic antibiotic therapy regardless of elective or nonelective surgical status of the patient.[15]

A single intraoperative dose of a cephalosporin, such as cefazolin (Ancef; GlaxoSmithKline, Philadelphia, PA), cefotetan (Cefotan; AstraZeneca Pharmaceuticals, Washington, DC), or cefoxitin (Mefoxin; Merck & Co, Inc, New York), is commonly used as antibiotic prophylaxis for prevention of post-cesarean endometritis, with cefazolin identified as being the most cost-effective for routine use.[21,22,23] Antibiotic administration is typically delayed until after the umbilical cord is clamped to avoid utero-placental transfer of antibiotic to the fetus, which has the potential for masking of neonatal infection.[24] However, a recent randomized, double-blind, placebo-controlled trial by Sullivan et al.[25] determined that administration of cefazolin 15 to 50 minutes before skin incision resulted in decreased infectious morbidity (relative risk [RR], 0.4; 95% CI, 0.18-0.87) and endometritis (RR, 0.2; 95% CI, 0.15-0.94) compared to the control group receiving cefazolin at cord clamping, without increasing the rates of newborn sepsis work-ups or complications. Sullivan postulated that delaying antibiotic administration resulted in "bacterial contamination of the uterus and subcutaneous tissues well before adequate [antibiotic] tissue levels can be achieved."[25]

A 1999 Cochrane review of 51 randomized trials concluded that a single dose of either ampicillin or a first-generation cephalosporin administered at cesarean birth had similar efficacy in reducing the incidence of post-cesarean endometritis and wound infections. The review examined randomized trials that compared different antibiotic regimens in women undergoing cesarean birth. Both ampicillin and first-generation cephalosporins demonstrated comparable efficacy with an odds ratio (OR) of 1.27 (95% CI, 0.84-1.93).[22]

However, Andrews et al.[19] found that the presence of U urealyticum in the upper genital tract was associated with a three-fold increase in post-cesarean endometritis, and despite prophylactic antibiotic administration with cefotetan, an eight-fold increase in post-cesarean endometritis in women who had gone into spontaneous labor before surgical delivery. In this randomized clinical trial, one cohort of women received parenteral doxycycline (Vibramycin Hyclate Intravenous; Pfizer Inc, New York) plus a single oral dose of azithromycin (Zithromax; Pfizer Inc) 6 to 12 hours following surgery in addition to the standard dose of cefotetan following clamping of the umbilical cord. The other group of women was given the standard dose of cefotetan only. The group given the additional doxycycline had a one-third reduction in post-cesarean endometritis (16.9% vs 24.7%; P = .020), as well as an associated reduction in wound infections and shortened hospitalization for women diagnosed with endometritis.[19] While general recommendations for antibiotic prophylaxis for cesarean include use of a single drug,[26] these data suggest that a combined broad-spectrum antibiotic regimen be considered for women at significant risk for post-cesarean infection, defined by the authors as women "managed in tertiary care centers."[19] Preventive measures for women who give birth vaginally do not differ substantially from those directed at women who undergo surgical delivery or abortion with the exception of antibiotic prophylaxis for women who are carriers for group B streptococcus,[27] and limiting the number of vaginal exams performed in labor ( Table 2 ).

Postpartum endometritis usually presents between the second to seventh postpartum day and is clinically recognized by the presence of fever, uterine tenderness, abdominal pain, and either purulent lochia or a positive culture of endometrial fluid or tissue.[5,28,29] Endometritis is frequently a diagnosis of exclusion after thorough evaluation fails to identify physical or laboratory evidence of an alternate site of infection.[5,20] The clinician should perform a thorough examination, which commonly includes serial assessment of vital signs, palpation of the uterus for tenderness, and evaluation of the lochia for purulent appearance and/or foul odor. Initial diagnostic studies include a complete blood count and urine culture. Blood cultures are obtained in the presence of sustained temperature elevation. Bacteremia may be present in up to 20% of women.[20] Blood cultures are best obtained during the peak temperature elevations and chills that are associated with bacteremia.[5,29]

Treatment of postpartum endometritis is based on the timing and clinical severity of the illness and consists of administration of parenteral or oral antimicrobial agents, antipyretics, and supportive therapy. Broad-spectrum antibiotics that include coverage for beta-lactamase-producing anaerobes are the recommended first-line antibiotics.[20,29] Although combination therapy using clindamycin (Cleocin; Pfizer Inc) and an aminoglycoside such as gentamicin (Garamycin; Schering-Plough, Summit, NJ) represents the "gold standard" for the treatment of endometritis, empiric treatment with a cephalosporin is frequently used as first-line therapy. In a Cochrane review that included 19 studies comparing clindamycin and an aminoglycoside with other parenteral empiric treatments for endometriosis, French and Smaill[20] found that the other regimens were associated with more treatment failures (RR, 1.44; 95% CI, 1.15-1.80). Three trials in the review (n = 253) compared continued oral antibiotic therapy following parenteral therapy and found no differences in recurrence of endometritis, thus administration of oral antibiotics following parenteral therapy is not recommended.[20]

Moderate to severe endometrial infection occurs most frequently in the first 48 hours postpartum, usually following cesarean birth. Women typically experience fever (>38.3°C) and chills, with an associated elevation in pulse and white blood count.[29] Treatment consists of supportive inpatient care, parenteral antibiotic therapy, and possible uterine exploration. Preferred antibiotics include combination clindamycin-gentamicin therapy, cephalosporins, beta-lactam antimicrobials, or extended-spectrum penicillins.[20,29] Once adequate therapy is initiated, rapid improvement typically occurs, with many women discharged after being afebrile for 24 hours after vaginal delivery and 48 hours after cesarean birth. Failure of fever to resolve within 48 to 72 hours requires consultation with a physician colleague accompanied by careful reassessment for an atypical organism or extra-pelvic cause of infection.[19,29,30]

Many postpartum infections, including mild endometritis, become apparent following hospital discharge and are diagnosed and treated on an ambulatory basis.[12,23]

Mild endometritis is limited to the decidua and superficial myometrium, is associated with minimal fever (<38.3°C), and typically occurs between 2 days and 6 weeks after vaginal delivery.[29] Women who are diagnosed with mild endometritis on an ambulatory basis are frequently treated using oral antibiotics, such as clindamycin or ofloxacin, or doxycycline if chlamydial infection is suspected and the woman is not breastfeeding.[23] Alternately, the woman may be admitted for inpatient parenteral therapy. Sample antibiotic regimens are listed in Table 3 .

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