Obstetricwere first used about 400 years ago. The modern types consist of two blades, each curved to fit snugly around the baby’s head, with edges contoured to fit the curve of the mother’s sacral region.
The blades have openings (windows) in them for lightness, handles by which they are manipulated, and catches so they can be locked together.
There are several models in current use, but the light, short-shanked version is most commonly employed. The reasons for using forceps include:
- the baby shows signs of distress during the second stage of labour and needs to be delivered quickly,
- the second stage is taking a long time, over one-anda-half hours in a first delivery or 45 minutes in a second or subsequent , thus putting the baby at risk,
- the mother has a condition such as heart disease or severe and should not spend a long time pushing,
- the head of a premature baby needs protection. Forceps are used only when the cervix is fully dilated, the baby’s head is well engaged in the pelvis, and the amniotic membrane is ruptured.
The obstetrician examines the mother to check these conditions and the baby’s position, and to insert a catheter (tube) into the mother’s bladder to ensure it is empty. The mother is usually placed in the lithotomy position, lying on her back with her feet held up in stirrups, to make the technique effective and easily carried out.
The obstetrician then injects a local anaesthetic and performs an episiotomy, which is always needed in.
The forceps are introduced into the vagina and manipulated alongside the baby’s head, one blade at a time, so that they lie comfortably. The blades are locked in position. Then, when a contraction is felt and while the mother is pushing, the forceps are pulled firmly but gently, downwards and backwards, to help the baby’s head to emerge. Usually only one or two contractions are required, and once the head is delivered the forceps are unclipped and removed and the rest of theproceeds as normal.
One model of forceps, Kielland forceps, are different in that the blades can slide over each other. They are applied in the same way as described above, but because the blades slide, the baby’s head can be turned into a more suitable position for delivery. They tend to be used when the baby becomes stuck in the mother’s pelvis in an awkward position, such as a persistent occipito-posterior presentation.
This technique was developed in the 1950s as an alternative to forceps; it is used under similar circumstances, particularly when there is a delay in the second stage of labour. The instrument consists of a flexible suction-cup attached by a long tube to a pump, with a traction chain also fitted to it. The suction-cup is applied to the baby’s scalp (the preliminaries being much the same as in) and the pump sucks air from the cup to create a vacuum. The baby’s head becomes firmly attached to the cup, which is then pulled out by the traction chain, using the mother’s contractions in much the same way as forceps.
Advantages of the vacuum extractor orover forceps is that it is usually more comfortable for the mother, and less bulky so it causes less damage to the vagina. One disadvantage is that the vacuum must be built up slowly, so it is not advised if the situation is urgent. Also the suction often produces a large swelling (chignon) on the baby’s scalp, but this goes down after a couple of days.