Sensor warns of foetal hypoxia

A new sensor will give earlier and more accurate warnings of foetal hypoxia, a dangerous condition in the birth process when the unborn child’s brain is starved of oxygen.

Researchers at the University of Warwick, and the University Hospitals Coventry and Warwickshire NHS Trust, have developed a sensor which is smaller and more portable than current equipment and measures the presence of a specific chemical rather than pH.

Current tests require a blood sample to be taken to a blood analysis machine which is usually in a different location to the delivery room. A blood sample is taken from the baby’s head using a capillary and measured for pH. If the pH has dropped to levels that concern the doctor but not sufficiently to warrant an immediate caesarean, the time it would take for a repeated test means doctors decide to proceed with a caesarean rather than take the risk of waiting for a full analysis.

Professor Nick Dale at the University of Warwick has developed a probe to measure a blood analyte called hypoxanthine. An unborn child with more than 5 micromoles of hypoxanthine per litre of their blood is at severe risk of foetal hypoxia. The probe is cheaper to make than existing blood analysis machines, and is sufficiently portable to use in the delivery room so results can be obtained quickly.

Warwick Medical School researchers say that the use of Professor Dale's probes to test for hypoxanthine would give doctors in delivery rooms almost instant data on whether the unborn child faced foetal hypoxia. This would allow doctors to take more informed decisions as to whether to proceed to a caesarean section and probably therefore reduce the number of caesareans conducted.

The sensor has generated a great deal of medical interest. It is awaiting regulatory approval and will initially undergo a clinical trial alongside current testing methods.