Obstetrics: Abnormal Labour

Abnormal Labour

• Abnormal labour, also known as labour dystocia, refers to a situation where there is slow or no progress in labour, associated with an increased risk of adverse perinatal outcomes for both mother and baby.

Poor Progress in Labour

• Progress in labour depends on three variables: power (efficiency of uterine contractions), passenger (fetus size, presentation, and position), and passage (uterus, cervix, and bony pelvis).
• Abnormal progress in labour is diagnosed when the rate of dilatation falls to the right of the projected normal labour curve plotted on the partogram.
• Delay in the first stage of labour is suspected if there is cervical dilatation of less than 2 cm in 4 hours.
• Delay in the second stage of labour is diagnosed once the timelines have been exceeded.

Dysfunctional Uterine Activity

• Dysfunctional uterine activity is the most common cause of poor progress in labour, and is more common in primigravida and older women.
• The assessment of uterine contractions is most commonly carried out by clinical examination and by using external uterine tocography.
• Ineffective contractions can be managed by:
  • Hypertonic uterine contractions: analgesia, stop oxytocin, IV fluid.
  • Hypotonic uterine contractions: augmentation – ARM, oxytocin.

Cephalopelvic Disproportion (CPD)

• CPD implies anatomical disproportion between the fetal head and maternal pelvis, which can be due to a large head, small pelvis, or a combination of the two.
• Women of small stature (1.60 m) with a large baby in their first pregnancy are likely candidates to develop this problem.
• Rarely, a fetal anomaly will contribute to CPD.
• CPD is suspected in labour if:
  • Progress is slow or actually arrests despite efficient uterine contractions.
  • The fetal head is not engaged.
  • Vaginal examination shows severe moulding and caput formation.
  • The head is poorly applied to the cervix.

Malpresentations

• Malpresentation is a presentation that is not cephalic, and is more common at earlier gestations.
• Breech presentation is the most commonly encountered malpresentation, and occurs in 3-4% of term pregnancies.
• Etiology of malpresentation includes:
  • Maternal risk factors: pelvic tumours, abnormal placental site, nulliparity, and old age group.
  • Fetal factors: prematurity, multiple pregnancies, fetal abnormalities, and short umbilical cord.

Breech Presentation

• Breech presentation is when the fetal buttocks or lower extremities present into the maternal pelvis.
• The most common type of malpresentation, accounting for 4% of all deliveries.
• Types of breech presentation:
  • Frank breech: both fetal thighs are flexed and both lower extremities are extended at the knees.
  • Incomplete (footling) breech: one of the baby's knees is bent and his foot and bottom are closest to the birth canal.
  • Complete breech: both thighs are flexed and one or both knees are flexed, sitting in a squat position.

Management of Breech Presentation

• If breech presentation is clinically suspected at or after 36 weeks, it should be confirmed by ultrasound scan.
• The three management options available are:
  1. External cephalic version (ECV)
  2. Vaginal breech delivery
  3. Elective cesarean section

External Cephalic Version (ECV)

• Manually convert breech fetus to vertex presentation through external uterine manipulation with ultrasonic guidance.
• Success rates vary according to the experience of the operator, but are around 50% in most units.
• Contraindications to ECV include:
  • Uteroplacental insufficiency
  • Placenta previa
  • Non-reassuring fetal monitoring
  • Hypertension
  • IUGR
  • Oligohydramnios
  • Previous uterine surgery

Vaginal Breech Delivery

• Although evidence suggests that it is probably safer for breech babies to be delivered by cesarean section, there is still a place for a vaginal breech delivery in certain circumstances.
• Factors that contribute to increased perinatal morbidity and mortality include:
  • Lethal congenital anomalies
  • Prematurity
  • Birth trauma
  • Cord prolapse
  • Head entrapment
  • Asphyxia and perinatal loss

Precipitate Labour

• Precipitate labour refers to abnormally rapid progress of delivery within 1 hr in Multipara and 3 hrs in Primipara.
• Risk factors include:
  • Strong uterine contractions
  • Small sized baby
  • Minimal soft tissue resistance
  • Previous history of precipitate labour
• Maternal complications include:
  • Laceration: Cervix, vagina, and perineum
  • Uterine inversion and Uterine atony – PPH
  • Amniotic fluid embolism
  • Infection: as a result of unsterile delivery
• Fetal complications include:
  • Intracranial hemorrhage
  • Fetal distress
  • Delivery in inappropriate place