Gathering the evidence: cord gases and placental histology for births with low Apgar scores

Background: Acute intrapartum hypoxia is an uncommon cause of cerebral palsy. The exclusion of acute intrapartum hypoxia utilizes two vital pieces of information that can be obtained at the time of birth: (i) cord blood gas to exclude a severe metabolic acidosis, and (ii) placental histology to suggest an alternative aetiology other than acute intrapartum hypoxia. Although recommendations exist to encourage this practice in high-risk deliveries, their compliance in an Australian setting is not known.

Aims: To evaluate the frequency and utility of cord blood gases and placental histology following delivery with an Apgar score ≤6 at five minutes.

Methods: A retrospective study of 12,887 consecutive deliveries at a tertiary obstetric centre, of which 100 live births had Apgar scores ≤6 at five minutes. Cord blood gases and placental histology were examined. There were also 132 stillbirths where placental histology was sought.

Results: Cord gases were measured in 52 of 100 live births with a low Apgar score. Seven of these had severe metabolic acidaemia and 26 had normal cord gases. Placental histology was requested in 40 of these births and 30 showed abnormal histology, suggesting alternative aetiologies. Of the 132 stillbirths, placental histology was available in 50. Abnormal histology was present in 39 of these stillbirths.

Conclusions: Cord gases and placental histology should be sought in all babies with low Apgar scores for the benefit of understanding causation, counselling of the parents, research and professional liability assessment. Heightened awareness for adverse perinatal outcomes is required by health care professionals when a neonate requires resuscitation.