Transverse Lie in Obstetrics

Transverse Lie

• Definition: The long axis of the fetus is perpendicular to the maternal spine or central uterine axis.

• Positions: Anterior (most common), Posterior, Superior, Inferior. The positions relate to the fetal surface that is facing the maternal spine (flexor or extensor).

• Incidence: Approximately 1 in 300 births. More common in premature and macerated fetuses, and 5 times more common in mothers who have had multiple pregnancies compared to first-time mothers.

• Etiology: Multiparity (common cause), twins, contracted pelvis, pelvic tumors, congenital malformations of the uterus (arcuate or subseptate), prematurity, hydramnios, placenta previa, intrauterine death.

• Diagnosis:

  • Inspection: Broad and asymmetrical uterus, deviating from a typical pyriform shape.
  • Palpation: Fundal height is usually less than expected for gestational age. Fetal parts (breech or head) are not palpable in the fundal grip.
  • Lateral grip: Soft, broad irregular breech felt on one side, hard globular head on the opposite side. The head is usually lower positioned on one iliac fossa. The back is felt running across the long axis anteriorly in dorso-anterior or dorso-posterior locations.
  • Auscultation: Fetal heart sounds (FHS) easily heard lower down from the umbilicus in dors-anterior positions. FHS are higher and often indistinct in the dorso-posterior position.
  • Ultrasound or X-ray confirms diagnosis.
    • During pregnancy: Presenting parts may be high and soft parts are felt.
    • During labor: Elongated membranes (shoulder located by acromion process, scapula, clavicle and axilla), prolapsed arm.

• Clinical Course of Labor: No typical labor mechanism in transverse lie. Average size baby often cannot pass through average size pelvis.

• Unfavorable Events:

  • PROM (Premature rupture of membranes).
  • Hand prolapse (with or without loop of cord).
  • Cord prolapse.
  • Ascending infection.
  • Obstructed labor.
  • Pathological retraction ring.
  • Maternal distress.
  • Sepsis.
  • Uterine rupture.

• Favorable Events (Very Rare):

  • Spontaneous rectification or version.
    • Occurs in early labor with adequate water and movable, small baby.
    • Contractions shift fetus for longitudinal position.
    • Rectification or version occurs based on the fetal presentation (head or breech).
    • More common in multiparous pregnancies.
  • Spontaneous evolution.
    • The head lies on an iliac fossa, trunk and breech force into cavity, neck elongated.
    • Breech and trunk delivered followed by head. Requires strong uterine contractions.
  • Spontaneous expulsion
    • Extremely rare in premature or macerated fetuses.
    • Fetus delivered doubled up (chest and abdomen apposed). Head and feet delivered last.

• Management:

  • Intact membranes, live fetus: Approach before onset of labor: ECV (external cephalic version) at ~37 weeks. If ECV successful, induce labor. If unsuccessful or declined, Cesarean (~38-39 weeks).
  • Early labor: ECV to achieve longitudinal lie. If successful with enough cervical dilation, allow vaginal delivery. If ECV unsuccessful, Cesarean.
  • Active labor: Cesarean delivery.
  • Rupture of membranes, live fetus (gestational age >34 weeks): Cesarean delivery.
    • Gestational age <34 weeks: Expectant management is reasonable (with possibility of performing cesarean if problems arise).
  • Transverse lie of second twin after delivery of first twin: Internal podalic version and breech extraction.
  • Fetal demise/previable fetus (before or early labor): ECV to achieve longitudinal presentation (for delivery options). In active labor: Internal podalic version or delivery in a way that is appropriate for the circumstances.

Brow Presentation

• Definition: Fetal head is hyperextended. Fetal face is the presenting part lying between orbital ridges and chin.
• Associated with: abnormal positions of the fetus and complications during labor and delivery and potential for injury to the fetus.

Face Presentation

• Definition: Fetal head and neck hyperextended, causing the occiput to present behind the back; the fetal face is the presenting part.

Anteroposterior Diameters of the Fetal Skull

• Table showing various AP diameters of the fetal skull, the attitude, and the presenting part (e.g., vertex, brow, face).