A 38 year old woman booked for antenatal care in her second pregnancy. Her first baby had been delivered by emergency caesarean section after failed induction of labour. She had an uncomplicated antenatal course and hoped to achieve a vaginal delivery. At 39 weeks’ gestation she presented in spontaneous labour with regular uterine contractions. The fetus was of average size and in a cephalic presentation, with two fifths of the head palpable abdominally. On vaginal examination, the cervix was 5 cm dilated and clear liquor was draining. She was reassessed after two hours and had progressed to 9 cm dilation with the vertex 2 cm above the ischial spines. The cardiotocograph at that time was reassurring.

The obstetric registrar was called to review the patient 20 minutes later because of deep late decelerations on the cardiotocograph and fresh vaginal bleeding. On abdominal examination, four fifths of the head was palpable but no scar tenderness was noted. Vaginal examination showed a high presenting part and findings otherwise unchanged from the previous examination.

A liveborn female infant weighing 4.1 kg was delivered by emergency caesarean section. Apgar scores were 5 at one minute and 8 at five minutes. The cord blood results were abnormal (pH artery 6.9, base excess −14.6; pH vein 7.0, base excess −12.4).

The mother was transferred to the high dependency unit after delivery for 24 hours and made a good recovery. She was discharged on day 6. The baby was discharged on day 12 with arrangements for neurodevelopmental follow-up.