Dysfunctional Labour

Dysfunctional labour is labour in which cervical dilatation or descent is slow or stops because of abnormal uterine action (hypotonic, hypertonic or incoordinate contractions), with or without malposition. It is a leading cause of prolonged labour and caesarean section. It matters because the pattern of contractions decides whether the right treatment is oxytocin, analgesia or operation, and the wrong choice causes harm.

• Risk factors: first labour, occiput posterior position, obesity, large baby, dehydration, early epidural, anxiety, grand multiparity.
• Disproportion and obstruction must be excluded before oxytocin.
• Most cases respond to hydration, amniotomy and the right drug.

Women have painful contractions with little progress, exhaustion and distress. The pattern may be weak and infrequent, strong with high resting tone, or irregular and asymmetrical.

• Partograph line crossing the alert or action line.
• Backache and early rupture of membranes with occiput posterior position.
• Differential diagnosis: hypotonic dysfunction, hypertonic dysfunction, incoordinate action, cephalopelvic disproportion, malposition, cervical dystocia, abruption, chorioamnionitis, obstructed labour.
• Complications: prolonged labour, exhaustion, ketosis, chorioamnionitis, fetal distress, uterine rupture with injudicious oxytocin, postpartum haemorrhage, caesarean section.

The approach is to define the contraction pattern and then the powers, passenger and passage.

• Contractions: frequency, duration, strength by palpation, resting tone between contractions (a soft uterus between contractions is normal); 3 to 5 in 10 minutes lasting 40 to 60 seconds is adequate.
• Cervical dilatation and descent over time; position, caput, moulding, liquor colour; bony pelvis.
• Cardiotocography with tocography; maternal pulse, temperature, urine output and ketones.
• Ultrasound for position and estimated weight; exclusion of abruption by pain pattern and bleeding.

The principle is to match treatment to the pattern: oxytocin for weak contractions, rest and analgesia for hypertonic or incoordinate action, and caesarean section for obstruction or fetal compromise.

• Supportive: Ringer's lactate 1 litre IV over 1 to 2 hours; empty the bladder; position change and walking; one to one support; analgesia (epidural, or pethidine 50 to 100 mg IM 4-hourly); continuous cardiotocography.
• Pharmacological: hypotonic pattern: oxytocin 10 IU in 1 litre Ringer's lactate (10 mU/mL) started at 12 mL per hour (2 mU/minute) and doubled every 30 minutes to a maximum of 192 mL per hour (32 mU/minute); hypertonic or incoordinate pattern: morphine 10 mg IM plus promethazine 25 mg IM for therapeutic rest, or hyoscine butylbromide 20 mg IV or IM repeated once after 30 minutes (maximum 100 mg in 24 hours), with no oxytocin until the pattern is regular; terbutaline 0.25 mg subcutaneous once for tachysystole with fetal distress; benzylpenicillin 5 million units IV then 2.5 million units 4-hourly for group B streptococcus or rupture for 18 hours or more; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily for chorioamnionitis; cefazolin 2 g IV before caesarean section; oxytocin 10 IU IM after birth, then 20 IU in 1 litre at 125 mL per hour for 4 hours.
• Procedures: amniotomy when the head is engaged; manual rotation of a malpositioned head; caesarean section for obstruction, failure of progress after 4 hours of adequate contractions, or fetal compromise.
• Special groups: a uterine scar or grand multiparity uses oxytocin only with senior review and continuous monitoring because of uterine rupture.
• Red flags: tachysystole, abnormal fetal heart rate, fever above 38 degrees Celsius, scar pain, bandl ring, bleeding, maternal exhaustion.
• Follow-up: cervical examination every 2 to 4 hours; maternal temperature 4-hourly; postnatal review for bladder and perineum; counselling about the next birth.