What is the procedure and timing for cervical cerclage placement and removal?

Cervical Cerclage: Procedure and Timing

Cervical cerclage is a surgical procedure where a stitch is placed around the cervix to provide mechanical support and keep it closed, typically performed between 12-24 weeks of gestation depending on indication, and routinely removed at 36-37 weeks of gestation or earlier if complications arise. 1

Surgical Technique

Transvaginal Approach (Standard Method)

• The McDonald or Shirodkar technique involves placing a purse-string suture around the cervix transvaginally, which is the most common approach for cerclage placement 1
• The procedure requires adequate cervical length to allow suture placement—if the cervix is too short or severely damaged, the transvaginal route may not be feasible 2
• Regional or general anesthesia is typically used for the procedure 1

Transabdominal Approach (Alternative Method)

• Reserved for patients whose cervix is too short or damaged for transvaginal cerclage 2
• Involves laparotomy with placement of a nylon tape around the uterine isthmus medial to the uterine vessels, fixed to the anterior isthmus and supporting ligaments 2
• This approach requires cesarean delivery and is technically more complex 2

Emergency Cerclage with Bulging Membranes

• When membranes are bulging through a dilated cervix, a metreurynter (balloon device) can be used to push the membranes back into the uterine cavity before suture placement 3
• This technique is most successful when cervical dilation is ≤5 cm, with average pregnancy prolongation of 60 days versus only 5.4 days when dilation is ≥6 cm 3

Timing of Cerclage Placement

History-Indicated Cerclage

• Placed at 12-14 weeks of gestation in patients with three or more second-trimester pregnancy losses or extreme premature deliveries without other identifiable causes 4
• This prophylactic approach is reserved for classic cervical insufficiency with multiple prior losses 4

Ultrasound-Indicated Cerclage

• Placed when cervical length shortens to ≤25 mm before 24 weeks of gestation in patients with prior spontaneous preterm birth 4, 1
• Serial transvaginal ultrasound assessment should begin at 14-16 weeks to detect cervical shortening 4
• Particular benefit exists when cervical length is <10 mm, with decreased preterm birth at <35 weeks (39.5% vs 58.0%) 4, 5

Examination-Indicated Cerclage

• Placed when cervical dilation is detected on physical examination before 24 weeks of gestation 1
• When cervical length measures <11-15 mm on ultrasound, 30-70% of patients will have cervical dilation of ≥1 cm, making physical examination essential 6

Timing of Cerclage Removal

Routine Removal

• Cerclage is routinely removed at 36-37 weeks of gestation to allow for spontaneous labor 5
• Removal is typically performed in an outpatient setting without anesthesia

Early Removal Indications

• Preterm premature rupture of membranes (PPROM): Management is controversial—it is reasonable to either remove the cerclage or leave it in place after discussing risks and benefits with the patient 5
• Preterm labor with contractions: Cerclage should be removed to prevent cervical laceration
• Chorioamnionitis or other infection: Immediate removal is indicated
• Vaginal bleeding: May warrant removal depending on severity and etiology

Post-Cerclage Management

Adjunctive Therapy

• Vaginal progesterone (200 mg daily) after cerclage placement significantly reduces spontaneous preterm birth at <34 weeks (2.2% vs 18.4%) and <37 weeks (9.1% vs 29.7%) 6, 5
• This benefit applies to both ultrasound-indicated and examination-indicated cerclage 6

Follow-Up Monitoring

• Serial cervical length assessments after cerclage placement are NOT routinely recommended due to insufficient evidence supporting clinical benefit 5
• Focus should be on monitoring for signs of preterm labor, rupture of membranes, or infection rather than repeated ultrasound measurements 5

Critical Clinical Pitfalls

• Do not place cerclage at arbitrary gestational ages without objective cervical assessment—transvaginal ultrasound provides superior risk stratification compared to clinical examination alone 4
• Avoid cerclage in patients without prior preterm birth history who have cervical length 10-25 mm, as meta-analysis shows no benefit in this population 6, 5
• Consider physical examination when ultrasound shows cervical length <11-15 mm, as 30-70% will have cervical dilation making them candidates for examination-indicated cerclage 6
• Transabdominal cerclage requires cesarean delivery—counsel patients appropriately before choosing this approach 2