How do we suspect uterine rupture during a Vaginal Birth After Cesarean (VBAC)?

Recognizing Uterine Rupture During VBAC

Uterine rupture during VBAC is primarily a clinical diagnosis requiring immediate recognition of specific warning signs, with delivery ideally within 18 minutes of suspicion to prevent permanent neonatal injury and maternal mortality. 1

Classic Clinical Signs (Most Reliable)

The most predictive intrapartum signs of uterine rupture include:

• Fetal heart rate abnormalities - particularly mild to severe variable decelerations appearing within 2 hours of delivery, which have statistically significant positive likelihood ratios for rupture 2
• Persistent abdominal pain - especially when combined with variable decelerations, this is highly predictive of rupture 2
• Loss of fetal station - the presenting part suddenly becomes higher on examination 3
• Cessation of previously effective labor contractions 3
• Vaginal bleeding - though not always present 3, 4

Additional Warning Signs

• Hyperstimulation - excessive uterine activity preceding rupture 2
• Maternal tachycardia and hypotension - indicating hemorrhagic shock 4, 5
• Sudden onset of severe abdominal pain - may occur even with smooth labor progression 4, 5
• Hematuria or vernixuria - vernix caseosa in bladder catheter tubing indicates bladder involvement in the rupture 3

Critical Time-Sensitive Response

When uterine rupture is suspected, immediate cesarean delivery is mandatory: 1

• Infants delivered within 18 minutes of suspected rupture have normal umbilical pH and 5-minute Apgar scores >7 1
• Delivery >30 minutes after suspected rupture results in significantly worse long-term neonatal outcomes 1
• This narrow window demands that VBAC only be attempted in facilities with immediate cesarean capability 6

Important Clinical Pitfalls

Uterine rupture can occur without prominent warning signals: 5

• Rupture may happen during smooth labor progression without use of augmentation medications 5
• Posterior uterine wall ruptures are particularly difficult to detect as they may not present with typical anterior scar dehiscence signs 5
• Approximately one-fifth of uterine ruptures are diagnosed after successful vaginal delivery during the immediate postpartum period 7
• Routine postpartum intrauterine exploration is not beneficial and may actually increase rupture risk 7

Imaging Considerations (Limited Role)

Ultrasound has minimal utility during active labor for rupture diagnosis: 1

• Uterine rupture remains primarily a clinical diagnosis 1
• Transabdominal ultrasound may show myometrial disruption or lower uterine segment thickness <2.5mm (predictive of dehiscence) 1
• Imaging should never delay emergency cesarean delivery when clinical suspicion exists 4

High-Risk Scenarios Requiring Heightened Vigilance

Maintain extreme vigilance in patients with: 1

• Labor induction with prostaglandins (2% rupture risk with PGE2, 13% with misoprostol) 1
• Oxytocin augmentation (1.1% rupture risk) 1
• Multiple prior cesarean deliveries (0.87% rupture risk after 3 cesareans) 6
• Inter-delivery interval <18 months 1, 6
• Classic uterine scar from prior cesarean 1, 6

Postpartum Monitoring

Continue surveillance for 12-24 hours postpartum: 7

• Progressive abdominal pain developing hours after successful VBAC may indicate delayed rupture recognition 7
• Maintain low threshold for imaging or surgical exploration if symptoms develop 7