A CTG is categorised as pathological in the first stage of labour, but immediate delivery is not yet decided. Which single test can help assess fetal acid-base status directly?

Answer: B. Fetal scalp blood sampling

Fetal scalp blood sampling

When the CTG is pathological but the overall picture does not mandate immediate delivery, a direct assessment of fetal status can guide management.

Fetal scalp blood sampling

• A small sample of fetal capillary blood is taken from the scalp to measure pH (and lactate), assessing for acidosis/hypoxia.
• A normal result allows labour to continue with monitoring; an abnormal (acidotic) result indicates the need for expedited delivery.

Prerequisites

• Requires sufficient cervical dilatation, ruptured membranes, and no contraindication (for example certain fetal bleeding disorders or maternal infections).

So fetal scalp blood sampling directly assesses fetal acid-base status.