How long does a fetal scalp blood sample take?

The study aim was to identify the time from a decision to perform a fetal blood sample to the result of the test being available. A total of 100 consecutive fetal scalp blood samples taken on women in labour were identified from the blood gas analysers on the delivery suite. Eighty-nine percent of attempts yielded a result. The median time taken was 18 minutes (interquartile range 12-25 minutes). In 9% of women, the result took longer than 30 minutes. This is important clinically when repeated testing is required or in the second stage when operative vaginal delivery is achievable. Furthermore, when retrospectively analysing cases with a poor outcome, the time to obtain a result needs to be taken into account when determining the time at which a baby could have been delivered.