What steps are needed to prepare a pregnant woman ≤24 weeks gestation with a short cervix (≤25 mm) and a history of painless cervical dilation or prior second‑trimester loss for cervical cerclage?

Preparation for Cervical Cerclage in High-Risk Pregnancy

In a pregnant woman ≤24 weeks with a short cervix (≤25 mm) and a history of painless cervical dilation or prior second-trimester loss, prepare for cerclage by confirming gestational age, performing transvaginal ultrasound to document cervical length and assess for dilation, obtaining vaginal cultures and urinalysis to rule out infection, counseling the patient on risks and benefits, and ensuring the cervix is not dilated ≥4 cm before proceeding. 1, 2

Pre-Procedure Assessment Requirements

Confirm Eligibility Criteria

• Verify gestational age is <24 weeks – Cerclage should be offered up to 24 0/7 weeks of gestation; placement after this threshold cannot be recommended based on current evidence. 3
• Document singleton pregnancy – Cerclage is contraindicated in multiple gestations even with short cervix, as literature does not support its use in twins. 2, 4
• Confirm qualifying history – The patient must have either three or more prior second-trimester losses/extreme premature deliveries (for history-indicated cerclage) OR one or more prior spontaneous preterm births with current cervical length ≤25 mm (for ultrasound-indicated cerclage). 1, 2, 5

Diagnostic Imaging

• Perform transvaginal ultrasound with standardized technique – Cervical length must be measured by transvaginal (not transabdominal) ultrasound using Perinatal Quality Foundation or Fetal Medicine Foundation protocols to confirm length ≤25 mm. 6, 4
• Assess for cervical dilation on physical examination – If cervical length is <11-15 mm on ultrasound, perform speculum and digital examination, as 30-70% of these patients will have cervical dilation ≥1 cm, making them candidates for examination-indicated cerclage. 1
• Exclude dilation ≥4 cm – Emergency cerclage may be considered only if cervical dilation is <4 cm without contractions before 24 weeks. 2

Infection Screening and Treatment

• Obtain urinalysis with culture and sensitivity – All women with history of cervical insufficiency should have urine cultures at the first obstetric visit, with treatment of any identified infections before cerclage placement. 2
• Perform vaginal cultures for bacterial vaginosis – Screen for and treat bacterial vaginosis prior to cerclage, as infection increases risk of procedure-related complications. 2
• Consider amniocentesis in examination-indicated cases – When membranes are visible or cervix is dilated, amniocentesis to rule out intra-amniotic infection before rescue cerclage remains debated but may be considered on a case-by-case basis. 7

Patient Counseling and Consent

• Discuss procedure-related complication rates – Inform the patient that randomized trials report a 0.3% complication rate for ultrasound-indicated cerclage and 0.9% for physical examination-indicated cerclage. 3
• Explain expected benefits – Cerclage significantly decreases preterm delivery and improves perinatal outcomes in appropriately selected women with singleton pregnancy, prior spontaneous preterm birth, and cervical length <25 mm before 24 weeks. 3, 5
• Review post-procedure management – Counsel that routine bed rest, prophylactic antibiotics, and routine tocolysis are not recommended after cerclage placement. 7

Adjunctive Therapy Planning

• Plan to prescribe vaginal progesterone 200 mg daily after cerclage – Adding vaginal progesterone after cerclage placement reduces spontaneous preterm birth at <34 weeks (2.2% vs 18.4%) and <37 weeks (9.1% vs 29.7%). 1
• Do NOT use 17-alpha hydroxyprogesterone caproate – 17-OHPC (including compounded formulations) should not be prescribed for short cervix treatment (GRADE 1B). 8, 6
• Do NOT place cervical pessary – Pessary is not recommended for singleton pregnancies with short cervix due to conflicting data and safety signals (GRADE 1B). 6, 1

Timing and Technique Selection

• Schedule history-indicated cerclage at 12-14 weeks – For women with three or more prior losses without other identifiable causes, place elective cerclage at 12-14 weeks of gestation. 2, 5
• Place ultrasound-indicated cerclage when cervix shortens to ≤25 mm – In women with prior spontaneous preterm birth, offer cerclage when serial ultrasound (starting at 14-16 weeks) documents cervical length ≤25 mm before 24 weeks. 1
• Use McDonald or Shirodkar technique – These are the standard vaginal cerclage techniques; abdominal cerclage is reserved only for women with failed prior vaginal cerclage (delivery before 28 weeks) or after trachelectomy. 9, 2, 5

Critical Pitfalls to Avoid

• Do not place cerclage in asymptomatic women without prior preterm birth history – Even with incidental finding of short cervix on ultrasound, cerclage shows no benefit in women without risk factors (GRADE 1B). 6, 2
• Do not delay for arbitrary gestational age cutoffs – Cerclage should be guided by objective cervical shortening, not performed prophylactically at predetermined gestational ages without assessment. 1
• Do not proceed if active labor or rupture of membranes is present – These are absolute contraindications to cerclage placement. 7

Post-Placement Monitoring Instructions

• Instruct patient to report preterm labor signs immediately – Patients must promptly report uterine contractions, pelvic pressure, vaginal bleeding, or fluid leakage for early intervention. 1
• Advise watching for infection indicators – Fever, uterine tenderness, or purulent vaginal discharge require immediate evaluation. 1
• Permit routine daily activities but avoid vigorous exercise – Light upper-body resistance exercise is allowed, but moderate-to-vigorous physical activity should be avoided; bed rest is explicitly not recommended and may be harmful. 1