LAB TEST
Fetal scalp pH testing
Fetal scalp pH testing is a procedure performed when a woman is in active labor to determine if the baby is getting enough oxygen.
How the Test is Performed
The procedure takes about 5 minutes. The mother lies on her back with her feet in stirrups. If her cervix is dilated at least 3 to 4 centimeters, a plastic cone is placed in the vagina and fit snugly against the scalp of the fetus. The scalp of the fetus is cleansed and a small blood sample is taken for examination.…
How to Prepare for the Test
The health care provider will explain the procedure and its risks. There isn't always a separate consent form for this procedure because many hospitals consider it part of the general consent for delivery form you signed at admission.
How the Test will Feel
The procedure should feel like a long pelvic exam. At this stage of labor, many women have already had epidural anesthesia and may not feel the pressure of the procedure at all.
Why the Test is Performed
Sometimes fetal heart monitoring doesn't provide enough information about the well-being of a baby. In these cases, testing the scalp pH can help the doctor decide whether the fetus is getting enough oxygen during labor. This helps determine whether the baby is healthy enough to continue labor, or if a forceps…
Normal Results
Normal fetal blood sample results are: Normal pH: 7.25 to 7.35 Borderline pH: 7.20 to 7.25 The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about…
What Abnormal Results Mean
A fetal scalp blood pH level of less than 7.20 is considered abnormal. In general, low pH suggests that the baby does not have enough oxygen. This may mean that the baby is not tolerating labor very well. The results of a fetal scalp pH sample need to be interpreted for each labor. The provider may feel that the…
Risks
Risks include the following: Continued bleeding from the puncture site (more likely if the fetus has a pH imbalance) Infection Bruising of the baby's scalp
References
Cahill AG. Intrapartum fetal evaluation. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies . 8th ed. Philadelphia, PA: Elsevier; 2021:chap 15. Marcdante KJ, Kliegman RM, Schuh AM. Assessment of the mother, fetus, and newborn. In: Marcdante KJ, Kliegman RM, Schuh AM,…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 02/07/2022).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.