Scalp Lead Placement Technique

Updated: Dec 28, 2015
  • Author: Michael G Ross, MD, MPH; Chief Editor: Christine Isaacs, MD  more...
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Technique

Approach Considerations

Significant debate surrounds the value of fetal heart rate recording in labor. A meta-analysis suggested that performance of continuous fetal heart rate monitoring in labor is associated with a decrease in neonatal seizures, but not a reduction in other newborn morbidities, including cerebral palsy or infant mortality. [12] However, fetal heart rate monitoring in labor is associated with an increased incidence of both cesarean and operative vaginal deliveries. Despite this lack of convincing evidence of efficacy, fetal heart rate monitoring in labor has become the standard of care in most parts of the United States. Efforts to improve efficacy have included establishment of standards for fetal heart rate tracing assessment and intervention.

Numerous refinements of the technique have been proposed in an attempt to improve the predictive power of the test. In the past, continuous fetal tissue pH and fetal O2 saturation have been used for the prediction of fetal status in labor, although neither of these is currently in use. A promising technology is computerized analysis of the fetal ECG waveform (S-T segment analysis).

Some reports suggest that S-T segment analysis is associated with better fetal outcome (less neonatal encephalopathy, fewer infants with severe metabolic acidosis), with a similar operative delivery rate when compared with conventional continuous monitoring in labor. [13, 14] Additionally, another product measures fetal heart ECG via electrode patches placed on the maternal abdomen with close correlation with the direct fetal ECG. [15]

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Scalp Lead Placement

Placement of a fetal electrode requires that the fetal membranes are ruptured, and that the cervix is sufficiently dilated to allow insertion of the device. The fetal presentation should be known, and the mother should consent verbally to the procedure. Placement of the electrode is performed as follows (see the image below).

Application of the scalp electrode: after introduc Application of the scalp electrode: after introduction of the system into the maternal vagina, the introducer is placed against the fetal head, over the parietal or occipital bone (inset). Pressure is applied to the electrode, and a rotary motion is used to drive the needle electrode into the fetal scalp. The introducer is then removed, leaving the electrode in place.

See the list below:

  • Counsel the patient about the procedure.
  • Prepare supplies.
  • Apply the leg plate to the maternal thigh.
  • Prepare for sterile vaginal examination (eg, wash hands, don sterile gloves).
  • Insert fingers into the vagina and palpate the fetal scalp. Ensure membranes are ruptured. Some authors have reported using the scalp electrode to rupture the membranes, in cases in which the usual means for membrane rupture were unsuccessful.
  • Ensure fetal position. Choose a location over parietal or occipital bone, away from sutures and other fetal or maternal structures. Application to the fetal buttocks may also be considered if the patient is to attempt breech vaginal delivery.
  • Retract the electrode into the introducer until the needle is not exposed. Insert the introducer into the vagina up to the fetal scalp.
  • Maintaining pressure on the fetal scalp, turn the electrode assembly clockwise. Take care not to elevate the fetal head out of the pelvis (risk of cord prolapse).
  • Disengage the wires from the introducer and remove the introducer assembly. Insert wires into the leg plate.
  • Document procedure and result (fetal heart rate pattern).
  • Electrode removal requires that the electrode be rotated counterclockwise so as to safely detach the needle from the fetal scalp; this is accomplished by turning the wires in the desired direction.

At times, removing the electrode prior to delivery of the fetus is difficult to impossible; often this is due to tangling of the electrode in fetal hair. In these cases, the electrode wires may be cut off short and removal of the electrode left until after delivery.

Attempting to detach the electrode by pulling is not appropriate because this may lacerate the fetal scalp.

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