Internal monitoring differs from external monitoring. Instead of both leads being strapped to the outside of the woman's body, the
Doppler lead is replaced by a smaller lead that is placed inside the woman's vagina and attached to the head of the baby. The internal lead is called a 'fetal scalp electrode' (or FSE). It is only used to monitor the baby's heart rate during labour, usually if external monitoring is not being reliable (but sometimes if the caregiver prefers internal to external monitoring).
A fetal scalp 'clip', or electrode, is a small, circular, corkscrew-shaped needle attached to a coated wire. The clip is covered with a long, protective, flexible, plastic covering and guided up through the mother's vagina by the caregiver doing an internal examination. This procedure should not be any more uncomfortable than a normal vaginal examination. The waters need to be broken to attach an FSE to the baby's head. If they are not already broken, this will need to be done to allow the electrode to be attached.
Image 3-32 shows a Fetal Scalp Electrode with its long, flexible, plastic coating before being placed on the baby's head.
The needle is gently rotated into the skin on the baby's scalp (or bottom if the baby is breech). The internal electrode monitors the baby's heart rate more accurately than an external
Doppler. Once the clip is attached, the plastic cover is removed, leaving just the wire.
The fetal scalp clip has 2 coloured wires attached. The wires are connected to the lead with a small conducting device (about the size of a match-box), strapped to the woman's thigh. The conducting device has conducting gel applied to it (like the gel used in ultrasounds). The lead is then plugged into the monitor to produce the readouts.
Image 3-30 shows the end of an uncovered fetal scalp electrode that is attached to the baby's head.