Infectious disease UPDATE Patrick Duff, MD Dr. Duff is Professor of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville. The author reports no financial relationships relevant to this article. Recent news and expert perspective on therapy for cesarean incision wounds, vaginal cleansing, managing skin abscesses, C difficile infection in obstetric patients, and risks of maternal Zika virus infection n this Update I highlight 5 interesting inves- third investigation examines the role of sys- tigations on infectious diseases. The first temic antibiotics, combined with surgical Iaddresses the value of applying prophylac- drainage, for patients who have subcutane- tically a negative-pressure wound dressing to ous abscesses ranging in size up to 5 cm. The prevent surgical site infection (SSI) in obese fourth study presents new information about women having cesarean delivery (CD). The the major risk factors for Clostridium difficile second report assesses the effectiveness of infections in obstetric patients. The final study a preoperative vaginal wash in reducing the presents valuable sobering new data about the frequency of postcesarean endometritis. The risks of congenital Zika virus infection. IN THIS ARTICLE Pre-CD vaginal Negative-pressure wound cleansing therapy after CD shows some page 33 C difficile benefit in preventing SSI infection in Yu L, Kronen RJ, Simon LE, Stoll CR, Colditz GA, Tuuli Six studies were ran- pregnancy MG. Prophylactic negative-pressure wound therapy af- domized controlled page 36 ter cesarean is associated with reduced risk of surgical trials (RCTs), 2 were retro- site infection: a systematic review and meta-analysis. spective cohort studies, and 1 Congenital Am J Obstet Gynecol. 2018;218(2):200–210.e1. was a prospective cohort study. Five studies risks of were considered high quality; 4 were of low Zika by u and colleagues sought to determine quality. trimester if the prophylactic use of negative- page 37 Y pressure devices, compared with Details of the study standard wound dressing, was effective in Several types of negative-pressure devices reducing the frequency of SSI after CD. were used, but the 2 most common were the The authors searched multiple databases Prevena incision management system (KCI, and initially identified 161 randomized con- San Antonio, Texas) and PICO negative- trolled trials and cohort studies for further pressure wound therapy (Smith & Nephew, assessment. After applying rigorous exclu- St. Petersburg, Florida). The majority of sion criteria, they ultimately selected 9 stud- patients in all groups were at high risk for ILLUSTRATION: USED WITH PERMISSION. COURTESY OF KCI, AN ACELITY COMPANY USED WITH PERMISSION. COURTESY ILLUSTRATION: ies for systematic review and meta-analysis. wound complications because of obesity. CONTINUED ON PAGE 32 mdedge.com/obgmanagement Vol. 30 No. 7 | July 2018 | OBG Management 31 UPDATE infectious disease CONTINUED FROM PAGE 31 accounted for by the difference in the rate of SSI. How negative-pressure devices aid wound healing Yu and colleagues explained that negative- pressure devices exert their beneficial effects in various ways, including: • shrinking the wound • inducing cellular stretch • removing extracellular fluids Passive wound closure (left) compared with negative-pressure wound therapy • creating a favorable environment for with the Prevena incision management system (right). healing • promoting angiogenesis and neurogenesis. The primary outcome of interest was Multiple studies in nonobstetric patients the frequency of SSI. Secondary outcomes have shown that prophylactic use of negative- included dehiscence, seroma, endometritis, pressure devices is beneficial in reducing the a composite measure for all wound compli- rate of SSI.1 Yu and colleagues’ systematic cations, and hospital readmission. review and meta-analysis confirms those The absolute risk of SSI in the interven- findings in a high-risk population of women tion group was 5% (95% confidence interval having CD. [CI], 2.0%–7.0%) compared with 11% (95% CI, 7.0%–16.0%) in the standard dressing group. Study limitations The pooled risk ratio was 0.45 (95% CI, 0.31– Before routinely adopting the use of negative- 0.66). The absolute risk reduction was 6% pressure devices for all women having CD, (95% CI, -10.0% to -3.0%), and the number however, obstetricians should consider the needed to treat was 17. following caveats: There were no significant differences in • The investigations included in the study the rate of any of the secondary outcomes by Yu and colleagues did not consistently other than the composite of all wound distinguish between scheduled versus complications. This difference was largely unscheduled CDs. • The reports did not systematically consider WHAT THIS EVIDENCE MEANS FOR PRACTICE other major risk factors for wound compli- cations besides obesity, and they did not Results of the systematic review and meta-analysis by Yu and col- control for these confounders in the statis- leagues suggest that prophylactic negative-pressure wound therapy tical analyses. in high-risk mostly obese women after CD reduces SSI and overall • The studies included in the meta-analysis wound complications. The study’s limitations, however, must be kept did not provide full descriptions of other in mind, and more data are needed. It would be most helpful if a measures that might influence the rate of large, well-designed RCT was conducted and included 2 groups with SSIs, such as timing and selection of pro- comparable multiple major risk factors for wound complications, and in which all women received the following important interventions2–4: phylactic antibiotics, selection of suture • removal of hair in the surgical site with a clipper, not a razor material, preoperative skin preparation, • cleansing of the skin with a chlorhexidine rather than an iodophor and closure techniques for the deep subcu- solution taneous tissue and skin. • closure of the deep subcutaneous tissue if the total subcutaneous • None of the included studies systemati- layer exceeds 2 cm in depth cally considered the cost-effectiveness of • closure of the skin with suture rather than staples the negative-pressure devices. This is an • administration of antibiotic prophylaxis, ideally with a combination important consideration given that the of cefazolin plus azithromycin, prior to the surgical incision. acquisition cost of these devices ranges from $200 to $500. OF KCI, AN ACELITY COMPANY USED WITH PERMISSION. COURTESY ILLUSTRATION: 32 OBG Management | July 2018 | Vol. 30 No. 7 mdedge.com/obgmanagement Vaginal cleansing before CD lowers risk of postop endometritis Caissutti C, Saccone G, Zullo F, et al. Vaginal cleansing placebo or with no treat- before cesarean delivery: a systematic review and meta- ment, women in the treat- analysis. Obstet Gynecol. 2017;130(3):527–538. ment group had a significantly lower rate of endometritis (4.5% aissutti and colleagues aimed to compared with 8.8%; relative risk [RR], 0.52; determine if cleansing the vagina 95% CI, 0.37–0.72). When only women in C with an antiseptic solution prior to labor were considered, the frequency of surgery reduced the frequency of postcesar- endometritis was 8.1% in the intervention ean endometritis. They included 16 RCTs group compared with 13.8% in the control (4,837 patients) in their systematic review group (RR, 0.52; 95% CI, 0.28–0.97). In the and meta-analysis. The primary outcome was women who were not in labor, the difference the frequency of postoperative endometritis. in the incidence of endometritis was not sta- tistically significant (3.5% vs 6.6%; RR, 0.62; Details of the study 95% CI, 0.34–1.15). The studies were conducted in several coun- In the subgroup analysis of women with tries and included patients of various socio- ruptured membranes at the time of surgery, economic classes. Six trials included only the incidence of endometritis was 4.3% in FAST patients having a scheduled CD; 9 included the treatment group compared with 20.1% TRACK both scheduled and unscheduled cesar- in the control group (RR, 0.23; 95% CI, 0.10– eans; and 1 included only unscheduled 0.52). In women with intact membranes at Women treated cesareans. In 11 studies, povidone-iodine the time of surgery, the incidence of endo- with vaginal was the antiseptic solution used. Two tri- metritis was not significantly reduced in the cleansing before als used chlorhexidine diacetate 0.2%, and treatment group. cesarean had a 1 used chlorhexidine diacetate 0.4%. One Interestingly, in the subgroup analysis significantly lower trial used metronidazole 0.5% gel, and of the 10 trials that used povidone-iodine, rate of endometritis another used the antiseptic cetrimide, which the reduction in the frequency of postcesar- compared with is a mixture of different quaternary ammo- ean endometritis was statistically significant those who received nium salts, including cetrimonium bromide. (2.8% vs 6.3%; RR, 0.42; 95% CI, 0.25–0.71). placebo or no In all trials, patients received prophylac- However, this same protective effect was treatment—4.5% tic antibiotics. The antibiotics were adminis- not observed in the women treated with vs 8.8% (RR, 0.52; tered prior to the surgical incision in 6 trials; chlorhexidine. In the 1 trial that directly com- 95% CI, 0.37–0.72) they were given after the umbilical cord was pared povidone-iodine with chlorhexidine, clamped in 6 trials. In 2 trials, the antibiotics there was no statistically significant differ- were given at varying times, and in the final ence in outcome. 2 trials, the timing of antibiotic administration was not reported. Of note, no trials described Simple intervention, solid benefit the method of placenta removal, a factor of Endometritis is the most common complica- considerable significance in influencing the tion following CD. The infection is polymi- rate of postoperative endometritis.5,6 crobial, with mixed aerobic and anaerobic Endometritis frequency reduced with organisms. The principal risk factors for post- vaginal cleansing; benefit greater in cesarean endometritis are low socioeco- certain groups.