Fetal Spiral Electrode: Vital in Moments that Matter

Aug 25, 2022 . 3 min read

Pioneered in the late 1960s, a fetal spiral electrode (FSE) is a form of internal fetal monitoring used during the labor and delivery process that is typically only necessary when external fetal monitoring proves inadequate. For many patients, monitoring a fetal heart with an external device is sufficient; however, in some cases, the FSE can be an invaluable tool.

This device attaches directly to the fetus via an electrode that is inserted through the opening of the maternal vagina and cervix. Guided by a catheter and connected to a spiral wire, the electrode attaches to the fetal scalp to allow for a more precise heart rate reading. Due to the invasive nature of the FSE, this method is often considered a "last resort" to get critical data regarding the well-being of the fetus.

Let's explore this unique labor and delivery resource.

Determining When to Use an FSE

The use of an FSE may be indicated when external monitoring cannot provide an adequate continuous tracing of a fetal heart rate such as:

When maternal obesity is a factor
When the maternal position must be changed frequently and rapidly
When there is a need to distinguish the fetal tracing from the maternal heartbeat
When fetal decelerations are present

In these situations, an FSE can effectively evaluate fetal heartbeat and its variations—even during uterine contractions—and provide labor and delivery staff with reliable insight into the fetus's condition. In fact, an FSE detects actual beat-to-beat electrical signals of the fetal heart, whereas external monitoring uses an "averaging algorithm" to smooth signals generated from the Doppler, notes Obstetrics & Gynecology.¹

Another feature of an FSE is that it often does not require in-the-moment maintenance; this separates it from the external Doppler, which may need frequent or even constant attention to sustain continuous tracing on some patients. This feature has led to increased use of the FSE during the COVID-19 pandemic, as it can help labor and delivery nurses manage more patients at one time and reduce staff-to-patient exposure.

Learn more about how COVID-19 safety protocols impacted labor and delivery staff and patients.

That being said, there are a handful of reasons to avoid using FSEs, and they certainly should not be used routinely. Because an FSE punctures the skin of the fetus, there is a possibility of spreading blood-borne diseases. Therefore, this clinical accessory should be avoided in the presence of maternal HIV, herpes, hepatitis B or C, or other blood-borne diseases that can be transmitted from birthing parent to fetus. Bleeding can also occur at the site of placement, impeding the use of the FSE for fetal monitoring when there is a known or suspected neonatal clotting disorder. Suspected vasa or placenta previa is also a contraindication.

Examining Possible FSE Complications

Labor and delivery healthcare oversee which medical devices and accessories are appropriate for each birth. Due to the reported risks and complications—which are rare but quite serious—an FSE typically isn't the first tool employed.

A 2016 review published in the British Journal of Obstetrics and Gynecology looked at 37,492 births that utilized an FSE.² The authors found that the use of an FSE was associated with a small increased risk of fetus scalp injury, cephalohematoma, and neonatal sepsis. However, these rates were similar to or less than the rates seen with operative vaginal deliveries, with 1.2% of babies receiving a scalp ulcer. The authors concluded that the increased risk of sepsis seen in the study was likely due to the higher-risk nature of patients receiving an FSE compared to controls.

A 2012 study published in the Journal of Obstetrics and Gynecology Canada that controlled for these factors concluded that the FSE was not independently associated with an increased risk of neonatal sepsis.³More recently, a 2021 study published in the American Journal of Obstetrics & Gynecology on the FSE use in obese patients also concluded that the presence of the FSE didn't increase the patient's risk for infection either.⁴

Reaching for the Right Option

More serious risks to the fetus have been reported, including eyelid laceration, abscess, and even osteomyelitis. However, many of the aforementioned risks and complications can be avoided or minimized by judicious use of the FSE for fetal monitoring, proper training, and good technique during placement. Before placing the FSE, ensure that:

Membranes are already ruptured.
The fetal part is identified and engaged.
The patient is at least 2–3 cm dilated.
Placement will avoid the face or genitals.

Further, if labor and delivery staff need to use this accessory, they should reach for the highest-quality option. With GE Healthcare's labor and delivery accessories⁵, healthcare staff can rely on effective and efficient transducers and fetal spiral electrodes. All of these critical labor and delivery accessories are compatible with GE Healthcare's Corometrics^TMmaternal and fetal monitoring systems⁶, providing a single view on fetal heart rate and uterine activity. Connect these tools to the Corometics^TM174⁷ or the Corometrics^TM250cx Series⁸^, which features two models: the 256cx, a fetal monitoring system, and the 259cx, a fully equipped maternal/fetal monitoring system.

Although turning to a fetal spiral electrode may not be ideal, using an exceptional product with the right patients has proven to be a reliable option for fetal monitoring when other options have failed.