What is the management plan for a patient at risk of cesarean (C-) scar rupture?

Risk Assessment and Management of C-Scar Rupture

For patients at risk of cesarean scar rupture, immediate ultrasound assessment of scar integrity is mandatory, followed by risk stratification based on inter-delivery interval, number of prior cesareans, and scar type to determine whether conservative management with close surveillance or surgical intervention is indicated. 1

Initial Risk Stratification

High-Risk Features Requiring Immediate Action

• Inter-delivery interval <18 months significantly increases rupture risk 2, 1
• Classic uterine scar (vertical incision) carries substantially higher rupture risk than low transverse scars 2
• Multiple prior cesarean sections: Risk escalates with each additional cesarean (placenta accreta risk increases from 12.9/10,000 after one CS to 78.3/10,000 after three CS) 1
• Cesarean scar pregnancy (CSP) identified on ultrasound represents an obstetric emergency with high rupture potential 3, 4

Ultrasound Assessment Parameters

• Scar defect (niche) evaluation: Present in 24-88% of women with prior cesarean section 1
• Gestational sac location: If implanted in the cesarean scar, this is CSP and requires immediate intervention 3, 4
• Myometrial thickness at scar site: Thinning indicates increased rupture risk 5
• Type of CSP if present: Exogenous type II (deeper implantation) has higher rupture risk than endogenous type I 6

Management Algorithm by Clinical Scenario

For Cesarean Scar Pregnancy (CSP)

Termination of pregnancy is the treatment of choice when diagnosed in first trimester due to catastrophic hemorrhage risk from trophoblastic invasion 4

If Patient Desires Future Fertility:

• Systemic methotrexate 1 mg/kg intramuscularly (two-dose regimen) can achieve successful resolution 3
• Monitor β-hCG levels weekly until undetectable 3
• Caution: Conservative treatment carries high failure risk; surgical backup must be immediately available 3

If Patient Does Not Desire Future Fertility or Conservative Treatment Fails:

• Hysterectomy is definitive management for CSP with multiple prior cesareans 3, 4
• Minimally invasive surgical approach should be standard of care when surgical management is required 3

For Intact Pregnancy with Scar Concerns (No CSP)

Gestational Age <20 Weeks:

• Document exact number of prior cesarean sections to quantify risk 1
• Measure inter-delivery interval: If <18 months, counsel on significantly elevated rupture risk 2, 1
• Serial ultrasound monitoring of scar integrity every 2-4 weeks 1

Gestational Age ≥20 Weeks:

• Left uterine displacement must be maintained during any procedures to prevent aortocaval compression 1
• Ensure optimal uteroplacental perfusion and maternal oxygenation during any intervention 1
• Overall rupture risk: 0.22% baseline, increasing to 0.35% when labor occurs 1

For Trial of Labor After Cesarean (TOLAC) Consideration

Contraindications to TOLAC:

• Classic uterine scar (absolute contraindication) 2
• Inter-delivery interval <18 months (relative contraindication requiring individualized assessment) 2
• Three or more prior cesarean sections (significantly increased rupture risk) 1

If TOLAC Attempted:

• Avoid misoprostol entirely: 13% rupture rate in third trimester 2
• Prostaglandin E2 carries 2% rupture risk (95% CI, 1.1-3.5%) 2
• Oxytocin induction has 1.1% rupture risk (95% CI, 0.9-1.5%) 2
• Mechanical methods (Foley catheter): No ruptures reported in available studies 2
• **Decision-to-delivery time <18 minutes** after suspected rupture results in normal neonatal outcomes; >30 minutes causes worse long-term outcomes 2

Surgical Technique to Reduce Future Rupture Risk

If Cesarean Delivery Required:

• Two-layer hysterotomy closure is associated with lower rate of uterine rupture in subsequent pregnancies 2
• Blunt expansion of transverse uterine hysterotomy reduces surgical blood loss 2
• Subcutaneous tissue reapproximation if ≥2 cm thickness 2
• Subcuticular suture for skin closure reduces wound complications compared to staples 2

Critical Pitfalls to Avoid

• Never use misoprostol for cervical ripening or labor induction in women with prior cesarean section in third trimester 2
• Do not delay surgical intervention for ruptured CSP; expectant management has poor prognosis and leads to hysterectomy 4
• Do not miss CSP diagnosis: High index of suspicion required for any first-trimester pregnancy with prior cesarean section 3, 4, 5
• Do not proceed with TOLAC without immediate surgical capability for emergency cesarean within 18 minutes of suspected rupture 2

Counseling Points

• Perinatal mortality is higher with TOLAC/VBAC compared to repeat cesarean delivery 2
• Maternal mortality is lower with TOLAC compared to repeat cesarean delivery 2
• Each additional cesarean increases future pregnancy risks: abnormal placentation, hysterectomy, and surgical complications 2
• Placenta previa incidence: 9/1,000 after one CS, 17/1,000 after two CS, 30/1,000 after three or more CS 2