Fetal Malpresentation and Malposition

Introduction and Definitions

• Fetal malpresentation describes any situation in which the presenting part of the fetus is not the vertex (head). Understanding key anatomic terms is essential for describing fetal orientation at delivery (Table 1).

• Diagnosis: Presentation and lie are typically assessed by abdominal palpation and confirmed by ultrasound in the late third trimester or during labor.
• Clinical relevance: Malposition (e.g., persistent occiput posterior) may result in prolonged or arrested labor and increase the likelihood of operative or cesarean delivery.
  • When occiput posterior positioning is observed, only 29% of nulliparous and 55% of multiparous women will have a vaginal delivery.¹
• Terminology reminder: Malpresentation refers to any noncephalic presentation, while malposition refers to abnormal orientation of a cephalic presentation (e.g., occiput posterior or transverse).

Breech Presentation

• Breech presentation describes any instance when the presenting portion of the fetus is the lower extremities or buttocks.
• Breech presentation is the most common type of malpresentation encountered at term.²
• There are three different types of breech presentation:
  • Complete – both lower extremities are flexed at the hips and knees
  • Incomplete – one or both lower extremities are extended at the hips
  • Frank – both hips are flexed, but knees are extended
• Breech presentation can be observed during the cervical exam by palpating the presenting part and confirmed with ultrasonography.
• Fetal position is often dynamic, with many fetuses initially being breech early in pregnancy and rotating by the middle of the third trimester. It’s estimated that 3-4% remain breech at term.³
• Some predisposing factors include⁴:
  • Uterine – multiple gestation, polyhydramnios, multiparity, anomalies
  • Fetal – hydrocephalus, anencephaly
  • Obstetric – history of breech presentation, growth restriction, oligohydramnios

Complications and Risks of Malpresentation and Malposition

Maternal Risks

• Increased likelihood of operative delivery, particularly cesarean delivery.
• Higher rates of labor dystocia and prolonged labor, especially with occiput posterior or transverse positions.
• Increased risk of postpartum hemorrhage and genital tract trauma due to difficult extraction or manipulation.

Fetal and Neonatal Risks

• Asphyxia or hypoxia from cord compression, head entrapment, or delayed delivery of the head in breech presentation.⁵
• Birth trauma of the fetus, including brachial plexus injury, skull fracture, or soft tissue injury.
• Umbilical cord prolapse is more likely when the presenting part does not fill the pelvis (e.g., breech, shoulder, or face presentations).
  • Risk is highest with a footling breech and a transverse lie.
• Perinatal morbidity and mortality remain higher in malpresentation even when cesarean delivery is performed.⁶

Pathophysiologic Considerations

• In breech or shoulder presentations, incomplete coverage of the cervix allows cord descent and compression.
• In occiput posterior malposition, the fetal head often enters the pelvis at a larger diameter, predisposing to arrest of descent.

Obstetric Management of Malpresentation and Malposition

• Management of fetal malpresentation and malposition focuses on optimizing fetal position before and during labor to facilitate safe delivery.
• Options include ECV to convert to cephalic presentation, planned cesarean delivery, or carefully selected vaginal breech delivery in centers with experienced providers and immediate surgical backup.²

ECV

• The purpose of ECV is to attempt to manually rotate the fetus from breech or transverse lie to a cephalic presentation before labor.
• Performed under ultrasound guidance with continuous fetal heart rate monitoring.
• Should occur in a setting capable of emergency cesarean delivery.
• Tocolytics (e.g., terbutaline) and neuraxial analgesia may improve success rates.

Key Considerations

• ECV should only be attempted with full resuscitation capability available.
  • Success rate: 35-86% in nonlaboring women at term⁴
  • Optimal timing of ECV is unclear; however, if performed too early, there is a greater chance that the fetus may become breech again. Many obstetricians recommend 37-39 weeks’ gestation.⁹
• Vaginal breech delivery carries increased risk and should be reserved for carefully selected cases.
• Cesarean delivery remains the safest option for most noncephalic presentations.
• Management after failed ECV
• Repeat attempt: May be considered if fetal and maternal conditions remain stable and there are no new contraindications.
• Timing: A second attempt may be performed the same day after rest and tocolysis, or at a later date if gestational age allows.
• Ongoing breech presentation:
• Plan for scheduled cesarean delivery at 39 weeks in most cases.
• Vaginal breech delivery may be considered only in centers with:
  • Experienced obstetric and anesthesia teams
  • Immediate access to cesarean capability
  • Favorable maternal pelvis and estimated fetal weight <3,800 g
• Labor onset before scheduled delivery: Proceed with urgent or emergency cesarean delivery if breech persists and vaginal delivery is not preapproved.

Anesthetic Management of Malpresentation and Malposition

ECV

• Goal: Optimize maternal comfort and uterine relaxation to increase procedural success and minimize fetal stress.
• Analgesic options:
  • Neuraxial anesthesia (epidural or spinal): Shown to increase ECV success and maternal tolerance compared to no anesthesia or IV opioids.²
  • IV or inhaled agents: Short-acting opioids, nitrous oxide, or low-dose volatile anesthetics may be used when neuraxial techniques are unavailable.
• Adjuncts: Tocolytics (e.g., terbutaline) and left uterine displacement improve fetal oxygenation and ease of manipulation^.2
• Preparation: Full resuscitation capabilities, continuous fetal monitoring, and immediate access to cesarean delivery are mandatory.

Cesarean Delivery for Malpresentation

• Technique: Standard neuraxial (spinal, epidural, or combined spinal-epidural) anesthesia preferred; general anesthesia reserved for contraindications or emergencies.
• Anticipated challenges:
  • Difficult fetal extraction or head entrapment (breech) — consider uterine relaxation with nitroglycerin or volatile anesthetics if needed.²
  • Increased risk of uterine incision extensions and hemorrhage due to abnormal fetal lie.²
• Anesthesia goals: Maintain uteroplacental perfusion, anticipate rapid conversion to general anesthesia if fetal distress occurs.

Vaginal Breech Delivery

• Indications: Rare; only in centers with experienced obstetric and anesthesia teams.
• Anesthetic plan: Early placement of a functioning epidural catheter to allow conversion to surgical anesthesia if emergent cesarean becomes necessary.
• Monitoring: Continuous fetal heart rate and readiness for neonatal resuscitation.

Emergency Considerations

• Cord prolapse, fetal bradycardia, or failed ECV may require immediate cesarean delivery.
• Rapid-sequence induction and preparedness for difficult fetal extraction are essential.

Summary Points

• Successful management of fetal malpresentation requires close coordination between anesthesia, obstetrics, and neonatal teams.
• Anesthesia providers play a pivotal role in optimizing maternal comfort, ensuring readiness for rapid operative delivery, and maintaining maternal-fetal safety during both planned and emergent interventions.
• A structured, team-based approach improves ECV success, minimizes complications, and enhances perinatal outcomes.