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Professor, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora
Dr. Hobbins reports no financial relationships relevant to this field of study.
SYNOPSIS: A collection of articles and letters to the editors suggests that postpartum ultrasound evaluation of uterine wall thickness is of little value in predicting uterine wall complications in subsequent pregnancies, that two-layer closure of the uterus during cesarean delivery probably is better than single-layer closure, and that staple closure of the skin in patients with three or more previous cesarean deliveries is associated with more wound complications than suture closure.
SOURCE: Di Spiezio SA, et al. Risk of cesarean scar defect following single- vs double-layer uterine closure: A systematic review and meta-analysis of randomized clinical trials. Ultrasound Obstet Gynecol 2017;50:578-583.
In a departure from the usual format, this month’s Alert will feature snippets from the recent literature that may help clinicians in preparing and performing cesarean deliveries — especially since one in three pregnancies in the United States ends this way. Over the last five years, there has been significant interest in fine-tuning operative methods to diminish future complications. The authors of a recent complex meta-analysis dealt with the ability to predict future uterine wound complications in patients who underwent double- vs. single-layer closure of the uterine wall. Di Spiezio et al, who scanned the literature for postpartum ultrasound evaluation of the uterine scars, were interested in the rates of downstream-dependent variables: 1) the rate of cesarean scar defects; 2) postpartum residual myometrial thickness (RMT) as a surrogate for dehiscence (UD) or rupture (UR); and 3) actual incidences of UD or UR in the patients’ subsequent pregnancies.
Five trials showed a nonsignificant increase in the rate of uterine scar defects with two-layer closure vs. the one-layer method (25% vs. 43%; relative risk [RR], 0.77; 95% confidence interval [CI], 0.36-1.4), which was counterintuitive. Four trials showed a significantly thinner RMT in the scar area with single-layer closure, with a mean difference of -2.19 mm (95% CI, 1.57-2.80) in the single layer cohort. In three trials, no significant differences were noted between single- and double-layer closure in the rates of UD (0.4% vs. 0.2%; 95% CI, 0.24-4.82) or UR in one trial (0.1% vs. 0.1%). However, the lower prevalence of adverse outcomes caused the latter studies to be rated as low-quality evidence. In fact, the evidence for conclusive results in every analysis in the paper was rated as low by the commonly used GRADE assessment tool.
In an accompanying referee commentary, Rozenberg, who originally reported the association between uterine wall thickness (UWT) just prior to cesarean delivery with uterine wall complications at delivery, noted that the above meta-analysis provided no solid evidence that the number of layers used to close the uterus had any major effect on the rates of cesarean scar defects.1 The thinner postpartum RMTs with the single-layer closure seem like a no-brainer, but there is no evidence that the RMT is the proper surrogate for future UD or UR, nor does it necessarily even correlate with later UWT in subsequent pregnancies.
In a letter to the editor, Demers and Roberg emphasized the usefulness of assessing UWT prior to repeat cesarean deliveries and cited their previous publications.2 In their meta-analyses of retrospective studies, these authors found a single-layer closure to be associated with a significantly higher rate of UR and UD in subsequent pregnancies and with thinner UWT, obtained just prior to the next deliveries.3,4 The take-home message is that postpartum findings in the meta-analyses did not provide enough evidence to recommend one method of uterine wall closure over another. It is not even clear that postpartum RMT is an appropriate surrogate for later uterine wall complications. However, pending new information to the contrary, the previously published data suggest benefit of taking the extra time to close the uterus with two layers.3,4
Fox et al undertook another retrospective study in patients having higher order (three or more) cesarean deliveries.5 The rates of wound complications were compared before 2011, when staples were used for skin closure, with a cohort collected after 2011, when the members of a large practice closed the skin with subcuticular sutures. The study included 551 patients, 192 of whom had staple closure and 359 had suture closure. Those in the former group had a higher rate of wound complications (separation and/or infection requiring antibiotics; 11.5% vs. 4.7%; 95% CI, 7.7%-16.7%). The authors indicated that no other new variables were introduced in the clinicians’ consistent method of performing cesarean sections before and after 2011.
Interestingly, Zaki et al studied only those patients who were at high risk for wound complications — obese women with body mass index > 40 kg/m2.6 They randomized 119 women to have staples and another 119 were assigned to have sutures for skin closure. Again, the outcome variables were wound separation or infection. There were no significant differences in wound complications, which occurred in 19.3% of the staples group and 17.6% in the suture group (P = 0.74). What was striking in the analysis was the higher rate of wound complications in the study in smokers (RR, 4.37; 95% CI, 1.37-18.03). Also, when asked their preference, fewer women would choose staples again.
The message from these studies is that the superficial tissue of patients undergoing three or more cesarean deliveries was less likely to separate or get infected if the operators took the extra time to close with subcuticular sutures, but that wound complications were no more likely to occur with staples in morbidly obese patients having cesarean deliveries, in general.
This month’s bonus: Drukker et al studied a clever ultrasound maneuver that may help in predicting the degree of difficulty one experiences while performing repeat cesarean deliveries.7 A group from Israel described a pre-cesarean ultrasound maneuver that involves watching (and videotaping) the abdominal peritoneum slide over the underlying uterus during a deep respiration. If there was no movement, it was described as a “negative sliding sign.” During the study, 453 patients had repeat cesarean deliveries and, after exclusions, 370 remained. The operating surgeons, blinded to the results of the ultrasound exam, rated the amount of adhesions and surgical difficulty on a scale of 0 to 3, the latter representing “severe.” The rates of severe adhesions were 6.8%, and 56% of these patients were labeled as having a negative sliding sign. This finding also was associated with significantly longer operating times and more blood loss. It is also of note that adding the history of findings of adhesions in previous operative notes only increased the detection rate to 64%. These findings suggest that this maneuver may help surgeons prepare for potential complications that might require thoughtful preparation in the operating room and ready availability of blood.
Financial Disclosure: OB/GYN Clinical Alert’s Editor Jeffrey T. Jensen, MD, MPH, reports that he is a consultant for and receives grant/ research support from Bayer, Merck, ContraMed, and FHI360; he receives grant/research support from Abbvie, HRA Pharma, Medicines 360, and Conrad; and he is a consultant for the Population Council. Peer Reviewer Catherine Leclair, MD; Nurse Planners Marci Messerle Forbes, RN, FNP, and Andrea O’Donnell, FNP; Editorial Group Manager Terrey L. Hatcher; Executive Editor Leslie Coplin; and Editor Jonathan Springston report no financial relationships relevant to this field of study.