Participants and sampling procedures
painless, abortion
DILATION, CONTRACTION, PREMATURE DELIVERY, CONTRACTIONS
This study used a case-control method and was approved by the Ethics Committee of the Xiamen Maternity and Child Health Care Hospital (XMCH) (Approval No. KY-2020-007). Written informed consent was obtained from all the participants. The study design and sampling plan are shown in The workflow of study design.Pregnant women’s baseline demographic and clinical data undergoing cerclage.Indications for cerclage can be summarised based on one of the following conditions: i) nonemergency cerclage, including a history of medical indication (one or more painless dilatations of the cervix without uterine contraction and then abortion or premature delivery in second/third trimesters) and ultrasound indication (the cervical canal length is less than 25 mm during the second trimester); ii) emergency cerclage, including cervical canal dilation, no noticeable contractions, and with or without amniotic membrane sac exposure to the outer cervix. The patients underwent McDonald’s cerclage with braided Mersilene 5-mm tape. The Trendelenburg position was used to relieve pressure on the membranes of all patients under spinal anaesthesia. The membranes were gently pushed back into the internal os with a sponge stick or Foley balloon after gently pulling the cervical lips with ring forceps. Sutures were placed near the vaginal-cervical junction. Once the suture closed the internal os or endocervical canal, alternating knots were tied to prevent slippage.Patients with indications for cerclage (n = 30) underwent cerclage performed by the same surgical team. Vaginal swabs were obtained pre-surgery and seven days post-surgery. The sample before cerclage surgery was defined as Cerclage1. After cerclage surgery, the sample was defined as Cerclage2. A gestational age-matched cohort of healthy pregnant women (n = 20) (no particular abnormality during pregnancy, without CIC, delivery at term; 