Fetal scalp blood testing

Fetal Scalp Blood Testing (FSBT) is a diagnostic procedure used in obstetrics to assess the well-being of a fetus during labor. This test is particularly utilized when there are signs of fetal distress or when the fetal heart rate pattern is abnormal. Fetal scalp blood testing involves obtaining a small sample of blood from the fetus's scalp to measure the pH level, which can indicate the fetus's oxygenation and acid-base status.

Indications

Fetal scalp blood testing is indicated in situations where there is concern about fetal well-being during labor, especially when non-invasive monitoring methods, such as cardiotocography (CTG), suggest fetal distress. Indications include:

• Abnormal fetal heart rate patterns
• Prolonged labor
• Suspected fetal hypoxia

Procedure

The procedure for fetal scalp blood testing is performed by an obstetrician and involves the following steps:

1. The mother is positioned in a way to allow access to the fetus, usually with her legs in stirrups.
2. A sterile speculum is inserted into the vagina to visualize the cervix.
3. The fetal scalp is then accessed using an amnioscope, a device that allows the obstetrician to see the fetus.
4. A small incision is made on the fetal scalp, and a blood sample is collected.
5. The blood sample is analyzed immediately to determine the pH level.

Interpretation

The pH level of the fetal scalp blood provides information about the acid-base status of the fetus. A normal pH range is between 7.25 and 7.35. Values below 7.20 suggest fetal acidemia, which can indicate hypoxia (lack of oxygen). Depending on the results, immediate actions may be taken to expedite delivery, such as by cesarean section or instrumental delivery.

Risks

Fetal scalp blood testing is generally considered safe, but it carries some risks, including:

• Infection
• Fetal scalp injury
• Rarely, fetal bleeding

Alternatives

Alternatives to fetal scalp blood testing include:

• Continuous electronic fetal monitoring
• Fetal pulse oximetry
• Fetal ECG ST segment analysis

These alternatives may provide additional or complementary information about the fetal condition during labor.

Conclusion

Fetal scalp blood testing is a valuable diagnostic tool in obstetrics for assessing fetal well-being during labor. It provides direct information about the fetal acid-base status, which can guide clinical decisions to ensure the safety of both the mother and the fetus. However, like all medical procedures, it has its risks and limitations, and its use should be carefully considered by the healthcare team.