Fetal scalp blood testing is a technique used in obstetrics during active labor to confirm whether a fetus is receiving enough oxygen.
Potential risks include bleeding from the fetal blood sampling site, infection, changes to heart rate, and death.
[1] As one of the first methods of monitoring fetal wellbeing during labor, there were many disadvantages including the need for at least 3 cm dilation of the mother and extreme precision from the physician performing the procedure.
Fetal scalp stimulation is a second-line test that helps provide specialists reassurance that the labor process can safely continue.
This is caused by an increase in pressure on the umbilical cord, but is quickly corrected upon childbirth as carbon dioxide levels return to normal once the baby begins breathing.
[17] Uterine contractions during labor and delivery decrease placental blood flow, therefore the fetus is at an increased risk of hypoxia.
[19] This is considered as one of the causes of acute fetal hypoxia among the likes of umbilical cord compression and myometrial contractures.
[18] Conditions which have been reported in newborns who suffered fetal acidemia include hypoxic-ischemic encephalopathy and periventricular leukomalacia.
Analysis of pH requires a relatively large amount of blood (30–50 μl), and sampling failure rates of 11–20% have been reported.
[21] Analysis of lactate only requires 5 μl of blood and can more accurately identify the cause of acidosis if metabolically induced.
The advantages of lactate measurement is that it is required 5 μl of fetal blood for analysis and provided immediate results compared to pH scalp testing.
[9][13] Using scalp lactate measurements compared to pH helps provide an easier and more affordable method than continuous electronic fetal monitoring.
Nevertheless, literature has shown that both methods has no significant difference in measuring oxygen deprivation as well as in fetal outcome after delivery.
Researchers have created a portable oximeter device which attaches to the hand of a physician and allows for the measurement of fetal oxygenation status.