Mrs Jones was a 20-year-old primiparous woman, blood group A, rhesus negative and rubella immune. She had normal antenatal ultrasound scans at 16, 20 and 34 weeks’ gestation. The risk of her fetus having Down’s syndrome was 1:3810. She reported good fetal movements throughout the pregnancy and there was no family history of note. She was admitted to hospital in labour at full-term with intact membranes. The fetal heart rate was normal.

CASE STUDY

A male infant, John, was born by vaginal delivery at 41 weeks’ gestation. Thick meconium was present in the liquor at delivery but none was seen below the vocal cords. At birth, he had poor respiratory effort and a heart rate of 60/minute. He was treated with bag and mask ventilation and his respiratory effort improved. The APGAR scores were 5 at 1 minute and 9 at 5 minutes of age. Cord blood gas analysis was not performed.

At 1 h of age, he was noted to be pale, with poor respiratory efforts and an oxygen saturation of 80% in air. He also had decreased movements. He was sedated, intubated, ventilated and transferred to the neonatal unit. At 75 minutes of age an arterial blood gas in air was: pH 7.01, pCO₂ 8.0 kPa, pO₂ 7.7 kPa, HCO₃ 15 mmol/l and base excess −17 mmol/l. The ventilation was adjusted (FiO₂ 40%, maximum pressure 26/5 cmH₂O) and at 120 minutes of age an arterial blood gas was: pH 7.23 pCO₂ 4.0 kPa, pO₂ 20 kPa, HCO₃ 12 mmol/l and base excess −13 mmol/l.

INITIAL DIAGNOSIS

The history of meconium in the liquor, the need for resuscitation at birth, and the metabolic acidosis led the admitting senior house officer to make a working diagnosis of perinatal asphyxia. Since oxygenation was relatively easy, he …