The functions of a vaginal examination are to:
- Determine if true labour has begun and the stage it has reached, based on measuring the dilatation of the cervix
- Assess the progress of labour in terms of the rate of increase in cervical dilatation and the descent of the fetus down the birth canal
- Identify the fetal presentation and position
- Detect any moulding of the fetal skull bones (the extent to which they overlap under pressure from the birth canal)
- Assess the size of the mother's pelvis and its adequacy for the passage of the fetus
- Check the colour of the amniotic fluid.
In this study session, we will only focus on the first of these reasons for conducting a vaginal examination: assessing the stage of labour by measuring the dilatation of the cervix. All of the other functions of vaginal examination will be covered in later study sessions.
Assessing cervical dilatation
Wash your hands thoroughly with soap and clean water for two full minutes. Then put on new sterile gloves. Tell the mother what you are going to do. Vaginal examination is done using two gloved fingers. Try to collect all the information you need before withdrawing from the vagina, because once you have withdrawn your fingers you should not put them back in again.
Can you explain why not?
Putting your examining fingers back into the vagina could introduce infection.
In particular repeated vaginal examination causes infection: it should not be done more often than every 4 hours, unless there is a justifiable need (e.g. to confirm second stage of labour).
The woman should lie down on her back, bend her legs and open her knees. Gently swab the external genitalia with sterile gauze dipped in antiseptic solution. Separate the labia with two fingers on your non-dominant hand (the dominant hand is the one you write with). Dip your examining fingers (index and middle fingers) into an antiseptic lubricating cream and insert them very gently into the vagina, following the direction of the vagina, upwards and backwards. Ask the woman to take deep breaths and try to relax, as this will help to decrease the discomfort of the procedure.
Cervical dilatation is the increase in diameter of the cervical opening, estimated in centimeters. Dilatation happens after the cervix has effaced (the 3 cm length of the cervix has been drawn up into the uterus, as you saw in Figure 1.1 in the previous study session.) Estimating the diameter of the cervical opening takes practice. Activity 2.1 will help you.
Allow about 20 minutes for this activity. You will need a piece of hard paper or thin card, a ruler, compass (for drawing circles), pencil and scissors.
- Make 10 circles on the hard paper, with increasing diameters: 1 cm, 2 cm, 3 cm, etc. up to 10 cm.
- Leave a wide margin around each circle and cut the card into 10 squares of the same size.
- Remove the inside of each circle with scissors.
- Write the diameter of each circle on the card.
- Choose a circle and place one or both your examining fingers into the hole. Can you get both fingers into the hole? Then cover your eyes and try to estimate the diameter of the hole in centimetres.
- Try to estimate the diameter of each hole with your eyes closed. Then check to see if you are correct. Try this repeatedly.
What diameter will the cervix have reached when the labour progresses from (a) latent to active first stage? (b) active first stage to second stage?
(a) 4 cm; (b) 10 cm (fully dilated).