Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial

The following abstracts of articles from leading journals have been selected on the basis of their importance to the practice of obstetrics and gynecology. Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial BACKGROUND: Cervical cerclage has been widely used in the past 50 years to prevent early preterm birth and its associated neonatal mortality and morbidity. Results of randomized trials have not generally lent support to this practice, but this absence of benefit may be due to suboptimum patient selection, which was essentially based on obstetric history. A more effective way of identifying the high-risk group for early preterm delivery might be by transvaginal sonographic measurement of cervical length. We undertook a multicenter, randomized, controlled trial to investigate whether, in women with a short cervix identified by routine transvaginal scanning at 22–24 weeks of gestation, the insertion of a Shirodkar suture reduces early preterm delivery. METHODS: Cervical length was measured in 47,123 women. The cervix was 15 mm or less in 470, and 253 (54%) of these women participated in the study and were randomized to cervical cerclage (127) or to expectant management (126). Primary outcome was the frequency of delivery before 33 completed weeks (231 days) of pregnancy. FINDINGS: The proportion of preterm delivery before 33 weeks was similar in both groups, 22% (28 of 127) in the cerclage group versus 26% (33 of 126) in the control group (relative risk 0.84, 95% confidence interval 0.54–1.31, P .44), with no significant differences in perinatal or maternal morbidity or mortality. INTERPRETATION: The insertion of a Shirodkar suture in women with a short cervix does not substantially reduce the risk of early preterm delivery. Routine sonographic measurement of cervical length at 22–24 weeks identifies a group at high risk of early preterm birth. To MS, Alfirevic Z, Heath VC, Cicero S, Cacho AM, Williamson PR, Nicolaides KH; Fetal Medicine Foundation Second Trimester Screening Group. Lancet 2004;363:1849–53. (http://www.thelancet.com) doi:10.1097/01.AOG. 0000139265.60529. e3 A factorial trial of six interventions for the prevention of postoperative nausea and vomiting* BACKGROUND: Approximately one third of patients who undergo surgery experience postoperative nausea and vomiting. Many different antiemetic routines are used, but the relative benefits are unknown. METHODS: A randomized, controlled trial of factorial design that was powered to evaluate interactions among as many as 3 antiemetic interventions was performed. Of the 5,199 patients who were enrolled in the study, 4,123 were randomly assigned to one of 64 possible combinations of 6 prophylactic interventions: 4 mg of ondansetron or not; 4 mg of dexamethasone or not; 1.25 mg of droperidol or not; propofol or a volatile anesthetic; nitrogen of nitrous oxide; or remifentanil or fentanyl. The remaining patients were randomly assigned to the first 4 interventions. The primary outcome was nausea and vomiting within 24 hours of surgery, which was evaluated blindly. RESULTS: Ondansetron, dexamethasone, and droperidol each reduced the risk of postoperative nausea and vomiting by about 26%. Propofol reduced the risk by 19%, and nitrogen by 12%. All of the interventions acted independently of one another and independently of the patients’ baseline risk. Absolute risk reduction was a function of patients’ baseline risk. CONCLUSIONS: The antiemetic interventions that were studied were similarly effective and acted independently. Therefore, the safest or least expensive should be used first. In low-risk patients prophylaxis is probably not warranted. Moderate-risk patients can benefit from a single intervention. High-risk patients may require multiple interventions. Apfel CC, Korttila K, Abdalla M, Kerger H, Turan A, Vedder I, Zernak C, Danner K, Jokela R, Pocock SJ, Trenkler S, Kredel M, Biedler A, Sessler DI, Roewer N; IMPACT Investigators. N Engl J Med 2004;350:2441–51. (http://www.nejm.org) doi:10.1097/01.AOG. 0000139786.21102. fd Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review OBJECTIVE: To compare the effects of low-concentration epidural infusions of bupivacaine with parenteral opioid analgesia on rates of cesarean delivery and instrumental vaginal delivery in nulliparous women. DATA SOURCES: MEDLINE, EMBASE, the Cochrane controlled trials register, and hand searching of the International Journal of Obstetric Anesthesia. STUDY SELECTION: Randomized controlled trials comparing low-concentration epidural infusions with parenteral opioids. DATA SYNTHESIS: Seven trials fulfilled the inclusion criteria for meta-analysis. Epidural analgesia does not seem to be associated with an increased risk of cesarean delivery (odds ratio 1.03, 95% confidence interval 0.71–1.48) but may be associated with an increased risk of instrumental vaginal delivery (2.11, 0.95–4.65). Epidural analgesia was associated with a longer second stage of labor (weighted mean difference 15.2 minutes, 2.1–28.2 minutes). More women, randomized to receive epi*Modified abstract. VOL. 104, NO. 3, SEPTEMBER 2004 626 © 2004 by The American College of Obstetricians and Gynecologists. 0029-7844/04/$30.00 Published by Lippincott Williams & Wilkins. doi:10.1097/01.AOG. 0000139265.60529. e3 dural analgesia, had adequate pain relief, with fewer changing to parenteral opioids than vice versa (odds ratio 0.1, 0.05– 0.22). CONCLUSIONS: Epidural analgesia using low-concentration infusions of bupivacaine is unlikely to increase the risk of cesarean delivery but may increase the risk of instrumental vaginal delivery. Although women receiving epidural analgesia had a longer second stage of labor, they had better pain relief. Liu EH, Sia AT. BMJ 2004;328:1410.