Can a patient with an oblique fetal lie be induced?

Induction of Labor in Patients with Oblique Fetal Lie

Induction of labor is contraindicated in patients with oblique fetal lie due to significant risks of maternal and fetal morbidity and mortality. This presentation requires conversion to a longitudinal lie before any attempt at vaginal delivery.

Understanding Oblique Lie

An oblique lie is an abnormal fetal presentation where the fetal long axis is diagonal to the maternal spine, rather than parallel (longitudinal) or perpendicular (transverse). This presentation:

• Is unstable and often converts to either a longitudinal or transverse lie
• Carries similar risks to transverse lie if it persists at term
• Cannot safely progress through the birth canal without conversion

Risks Associated with Persistent Oblique Lie

• Cord prolapse
• Uterine rupture
• Obstructed labor
• Increased risk of birth trauma
• Higher rates of fetal acidosis and birth injuries 1, 2
• Increased maternal morbidity including hemorrhage and infection 1

Management Approach

Assessment

• Confirm presentation via ultrasound (transabdominal or transvaginal if needed)
• Identify any underlying causes:
  • Placenta previa (present in approximately 29-36% of persistent abnormal lie cases) 1, 3
  • Uterine anomalies
  • Multiple gestation
  • Polyhydramnios
  • Fetal anomalies

Management Options

1. External Cephalic Version (ECV)

   • Should be attempted at approximately 37-38 weeks if no contraindications
   • Success allows for potential vaginal delivery if version is successful and stable

2. Scheduled Cesarean Delivery

   • Indicated if:
     • ECV is unsuccessful or contraindicated
     • Oblique lie persists at term (≥37 weeks)
     • Any signs of labor with persistent oblique lie

3. Contraindications to Induction

   • Oxytocin is explicitly contraindicated in "unfavorable fetal positions or presentations which are undeliverable without conversion prior to delivery" 4
   • Induction with persistent oblique lie increases risks of:
     • Cord prolapse
     • Obstructed labor
     • Emergency cesarean under suboptimal conditions
     • Maternal and fetal trauma

Natural History of Abnormal Presentations

• At 28-30 weeks, approximately 21% of fetuses have abnormal presentations 5
• By term, about 22% of these abnormal presentations persist 5
• The likelihood of persistence increases as term approaches 3
• Only 0.75% of fetuses in cephalic presentation at 28-30 weeks convert to abnormal presentation by term 5

Key Clinical Considerations

• Regular assessment of fetal position in the third trimester is essential
• Ultrasound confirmation of presentation should be performed before any induction attempt
• If oblique lie is detected at term, preparation for cesarean delivery is prudent
• Active intervention at 38 weeks is recommended for persistent abnormal lie 2

Conclusion

The evidence clearly demonstrates that induction of labor in a patient with oblique fetal lie is contraindicated due to significant risks to both mother and fetus. The appropriate management is either successful external cephalic version followed by spontaneous or induced labor, or cesarean delivery if version fails or is contraindicated.