Arrest of Cervical Dilatation

Arrest of cervical dilatation is the failure of the cervix to dilate further during the first stage of labour, found on the partograph as a flat line for 4 hours or more despite adequate contractions, or 6 hours or more on oxytocin with inadequate contractions, at 6 cm or more.

It results from a failure of the powers (inadequate or uncoordinated contractions), the passenger (malposition, large fetus, abnormal lie) or the passage (contracted pelvis, soft tissue obstruction).

It matters because the cause decides treatment: oxytocin for weak contractions, but caesarean section for obstruction.

• Risk factors: first pregnancy, obesity, short stature, large fetus, malposition, previous cervical surgery, induction.
• A thick, oedematous cervix with marked caput suggests obstruction.
• Delay in action leads to infection, rupture of the uterus and fistula.

Women have painful contractions with no progress, exhaustion, dehydration and sometimes a distended bladder. Examination may show caput, marked moulding and an oedematous cervix.

• Partograph line flat for 4 hours or more.
• Maternal pulse above 100 per minute and ketosis.
• Differential diagnosis: inadequate uterine activity, cephalopelvic disproportion, malposition, cervical dystocia, abnormal lie, obstructed labour, chorioamnionitis.
• Complications: prolonged labour, exhaustion, infection, uterine rupture, obstetric fistula, fetal hypoxia, caesarean section, postpartum haemorrhage.

The approach is partograph review and a systematic assessment of powers, passenger and passage.

• Cervical examination: dilatation, effacement, station, caput and moulding, position, liquor colour; abdominal palpation for engagement and lie.
• Contraction frequency, duration and strength; maternal pulse, temperature, urine output and ketones.
• Cardiotocography; ultrasound for fetal position (occiput posterior or transverse), estimated weight and presenting part.
• Pelvic assessment; group and cross-match.

The principle is to find the cause: strengthen contractions when they are inadequate and deliver by caesarean section when there is obstruction or the arrest persists.

• Supportive: hydration (Ringer's lactate 1 litre IV over 2 hours); catheterise or empty the bladder; upright and side lying positions; analgesia (epidural or pethidine 50 to 100 mg IM 4-hourly); one to one support; continuous cardiotocography on oxytocin.
• Pharmacological: oxytocin starting at 2 mU/minute and doubling every 30 minutes to a maximum of 32 mU/minute, aiming for 3 to 5 contractions in 10 minutes lasting 40 to 60 seconds, for 4 to 6 hours; stop oxytocin for tachysystole or fetal distress; benzylpenicillin 5 million units IV then 2.5 million units 4-hourly in labour 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 at birth then infusion of 20 IU in 1 litre sodium chloride 0.9 percent at 125 mL per hour for 4 hours.
• Procedures: amniotomy; manual rotation or repositioning of an occiput posterior or transverse head when fully dilated; caesarean section for cephalopelvic disproportion, no progress after 4 to 6 hours of adequate oxytocin, or fetal compromise; no oxytocin for suspected obstruction.
• Special groups: women with a previous caesarean section have oxytocin with senior review and continuous monitoring because of the risk of uterine rupture; grand multiparas avoid oxytocin unless closely monitored; women with cervical scarring may need caesarean section earlier.
• Red flags: tachysystole, fetal heart rate abnormality, fever above 38 degrees Celsius, scar pain or tenderness, bandl ring, maternal exhaustion, bleeding.
• Follow-up: cervical examination every 2 to 4 hours; maternal temperature 4-hourly; postnatal bladder check for fistula symptoms; counselling on the next birth.