The Effectiveness of Cervical Pessary Compared to Cervical Cerclage With or Without Vaginal Progesterone for the Prevention of Preterm Birth in Women With a Twin Pregnancy and a Short Cervix: a Two-by-two Factorial Randomised Clinical Trial

This open label, multi-center, two-by-two factorial, randomised controlled trial aims to compare the effectiveness of cervical pessary to cervical cerclage and also to determine the effectiveness of vaginal progesterone for the prevention of PTB in women with a twin pregnancy and a cervix ≤28 mm.

All women with a twin pregnancy will undergo cervical length measurement and digital examination at screening. Prior to CL measurement, women will be given a short brochure outlining risk factors and available PTB prevention methods. Only women with a CL ≤28 mm will be eligible for the study. Eligible participants will be screened by midwives or gynaecologists, then participants will be provided a full participant Information Sheet, Consent Form and will be invited to a full discussion with investigators about the study. Eligible women will further undergo a speculum examination to assess the feasibility of treatment with either cerclage or cervical pessary with or without progesterone and to exclude premature rupture of the membranes (PROM), acute vaginitis and cervicitis. All eligible women will be invited to participate in the study.

After written informed consent, women will be randomly assigned in a 1:1:1:1 ratio to receive a cerclage, pessary, cerclage plus progesterone or pessary plus progesterone. Assignment to treatment allocation will be done via a web portal hosted by HOPE Research Center, Vietnam. The randomisation schedule will be computer-generated at HOPE Research Center, with a permuted random block size of 4 or 8. Blinding will not be possible due to the nature of interventions. However, neonatologists assessing the children will be unaware of treatment allocation. Apart from randomisation, patients will be followed up and treated according to local protocol.

Women allocated to a cervical cerclage will be receiving the intervention according to local protocol, within a week after randomisation. Briefly, 2 to 3 senior clinicians, who had experienced with cerclage, will perform cervical cerclage, using Mc Donald technique, under spinal anaesthesia with a single dose of prophylactic antibiotics.

For those who randomised to pessary group, a soft, flexible, silicone pessary, purchased from the manufacturer (Arabin®, Dr Arabin GmbH & Co KG, Germany), will be inserted through the vagina, upward around the cervix by 4 senior clinicians, who had experienced with pessary used, within one week of randomisation. The size of the pessary will be determined at the time of speculum inspection (Arabin and Alfirevic, 2013).