Nordic randomised trial on laparoscopic versus vaginal cerclage (NORACT): trial protocol for an international, multicentre, randomised controlled trial.

introductionTransvaginal and transabdominal cerclage procedures have become established interventions to prevent mid-trimester pregnancy loss and preterm birth. Transabdominal cerclage seems to be superior to transvaginal cerclage in women with a history of a failed transvaginal cerclage. However, with the availability of a less invasive laparoscopic procedure, there is limited evidence concerning which type of cerclage to recommend to many other risk groups. The objective of this trial is to compare laparoscopic abdominal cerclage and transvaginal cerclage in women at moderate to high risk of spontaneous preterm birth. METHODS AND ANALYSIS: The trial is an open, multicentre, superiority, parallel arm randomised controlled investigator-initiated trial with an embedded internal pilot. Women in whom the clinician has clinical equipoise between laparoscopic and transvaginal cerclage are randomised to either laparoscopic abdominal or transvaginal cerclage in a ratio of 1:1. The trial extends from sites in Denmark, Finland and Norway. The primary outcome is birth <32 weeks of gestation. A total sample of 188 participants will be included to detect an absolute difference of 15% in the primary outcome between the two groups. Analysis will be by intention-to-treat. ETHICS AND DISSEMINATION: The Central Denmark Region Committee on Biomedical Research Ethics, Denmark, Helsinki University Hospital Ethics committee, Finland and the Regional Committees for Medical and Health Research Ethics, Norway approved the trial. This protocol is published prior to complete data collection and analysis. Important protocol changes will be made publicly available on ClinicalTrials.org, on the trial website and distributed electronically to all active sites. Positive, inconclusive as well as negative results from the trial will be published in peer-reviewed international scientific journals. TRIAL REGISTRATION NUMBER: NCT06122506.