Midwifery 101: Vaginal examination
Most women who have had a baby will have had a vaginal examination at some time. In the UK, they are not routinely done antenatally, because there is absolutely no need. Telling you at 38 weeks that you’re 1cm and fully effaced doesn’t mean anything, except you might go in to labour sometime between that day and the next 4 weeks or so. Which, to be honest, you already know. If you’ve had a baby before, your cervix can be slightly dilated (called multips OS) throughout your pregnancy, so it’s no indication of labour at all.
However, they are offered in labour to assess progress. Some women choose to decline. Other women accept them as part of routine labour care. Some women request them far more frequently, but unless there are indications that something is amiss (e.g. bradycardia), we won’t offer a VE more frequently than every 4 hours once your labour is established.
This midwifery 101 is going to explain what we look for upon VE. Lots of links in this, so get clicking!
Just like during antenatal appointments, the midwife will palpate your bump. This tells us if baby is head or bottom down, what position they’re in and how far into your pelvis they have descended. We also listen in to the fetal heart rate.
Midwives check for any signs of swelling (oedema), infection, warts, scarring, abnormal discharge or any other abnormalities that might need treatment or cause a problem in labour.
Before labour, your cervix is posterior, meaning it is tilted towards your back. As labour begins and progresses, it becomes more central and then anterior (towards your bump).
This relates to the thickness of your cervix. A non-labouring cervix is long like a tube, and thick. It begins to shorten and thin out, until it no longer protrudes into the vagina and is indistinguishable from the lower uterine segment.
First time mothers (primips) usually find that their cervix effaces first, and then dilatation begins. In women who have already had children (multips), the two can happen simultaneously.
This is the “how many centimetres” bit. Here, the midwife inserts her fingers into the opening cervix, and then parts them to assess how many cm dilated the cervix is. A fully dilated cervix is considered to be 10cm. When the cervix is over 6 or so cm, it is often easier to feel how much cervix remains to make an accurate assessment e.g. 2cm rim of cervix left, so the woman is 8cm.
Once the cervix can no longer be felt around the baby’s head, the woman is fully dilated. At this point, the baby’s head can pass through the cervix. A woman undergoing preterm labour may be “fully” dilated at less than 10cm, as the baby’s head can pass through the cervix sooner due to it’s smaller size.
When the baby is well descended into the pelvis, their head puts pressure on the cervix and helps it dilate. This is ‘close’ application, and you can feel the pressure upon VE.
If the head os ‘loosely’ applied, the cervix doesn’t have as much pressure on it, and doesn’t feel as stretched.
A good way to describe the difference is this: make a tight fist. Use two fingers to poke the back of your hand. The skin is tight, stretched, and doesn’t move all that much. That’s like close application.
Now relax your hand, and do the same. The skin is looser, yields to your touch and is easily moveable. That’s like loose application.
If there are membranes still intact over the baby’s head (or bottom if breech!), it feels like a smooth, slippery surface. The membranes are easier to feel if a little amniotic fluid has become trapped between the baby’s head on the cervix and the membranes themselves. This is called ‘bulging’ membranes/forewaters. With continued pressure from the baby’s head, these membranes are likely to spontaneously burst.
The lower image here shows bulging forewaters.
Presentation & Position
A VE is also used to assess what and what part of the baby’s body is on the cervix e.g. head, bum or other (foot, arm, etc).
If the head is presenting, it is called cephalic presentation. If the bum is, it’s breech. If a foot or arm is presenting, it is a malpresentation that can cause problems in labour.
We also look what position the baby is in. This diagram explains the different positions. L means left, R means right, O means occiputo (back of baby’s head), A means anterior (front), p means posterior (back), t means transverse (side).
So LOA means Left Occipito Anterior. The back of the baby’s head is on the front-left side of mum’s pelvis.
This is assessed by feeling for sutures on the baby’s head - bony ridges that we are all born with.
Last of all, we assess how low down in the birth canal baby is in relation to the pelvis. It’s quite hard to describe, so use this image to help.