Amniocentesis Before rescue Cerclage

INTERVENTION: Women will be randomised to either: 1. Cerclage group 2. Amniocentesis and cerclage group Randomisation will be organised by a random numbers table and assigned by telephone. Women randomised to the amniocentesis group will undergo an aseptic aspiration of amniotic fluid under ultrasound guidance by a single operator. Briefly, the abdomen will be prepared with antiseptic solution and draped with sterile towels. The ultrasound transducer probe will be draped with a sterile plastic cover. Using a sterile water‐based ultrasound gel to facilitate visualisation, the operator will identify a pocket of amniotic fluid suitably away from the foetus and placenta. A sterile 22 gauge needle will be passed into the uterine cavity under direct visualisation and approximately 15 cc of amniotic fluid will be aspirated. Post procedure, Rhogam™ will be administered to Rhesus negative patients as indicated. Amniotic fluid will be tested for lactate dehydrogenase level (2 cc), glucose level (2 cc), cell count (2 cc), haemoglobin level (2 cc) and Gram staining (2 cc). Amniotic fluid will be sent for confirmatory aerobic, anaerobic and myoplasma/ureaplasma culture (4 cc per culture). All tests will be performed by the respective Departments of Biochemistry, Haematology and Microbiology (Mount Sinai Hospital, Canada) using established protocols. While waiting for the fluid test results (approximately 90 ‐ 120 minutes), a tocodynometer will be placed over the uterine fundus to confirm the absence of uterine activity. Those women without evidence of subclinical infection following amniocentesis and those women who were randomised to the cerclage group will have a rescue cerclage placed. Rescue cerclage placement will be performed under general anaesthesia. Women will be placed in the lithotomy position with a steep Trendelenberg tilt. The prolapsed membranes will be gently pushed back into the uterine cavity with an inflated Foley catheter. A single purse string suture (#5 Ticron™) CONDITION: Cervical incompetence ; Pregnancy and Childbirth ; Maternal care for cervical incompetence PRIMARY OUTCOME: The primary comparison will be the prolongation of gestation to greater than 34 weeks of gestation, defined as rescue cerclage success. SECONDARY OUTCOME: 1. Maternal morbidity: will include complications of cerclage insertion, through gestation and at the time of the delivery; 2. Neonatal morbidity: will include complications during the initial admission to the nursery following the delivery INCLUSION CRITERIA: 1. Singleton gestation 2. Presence of cervical dilatation 3. Membranes visible at or protruding through the cervical opening 4. Absence of any uterine activity 5. Absence of any overt signs of maternal infection: 5.1. Maternal temperature greater than 37.8°C 5.2. Diffuse abdominal pain 5.3. Foul/pus like discharge 5.4. Maternal or foetal tachycardia