Many hospitals will have a policy of performing regular vaginal examinations (VE) throughout labour, regardless of the risk status of the woman. Midwives are increasingly working in an environ-
ment in which the evidence from VE supersedes all other indications of progress. There is thus a risk that midwives and students will lose confi dence in other means of assessing progress (Sookhoo and Biott 2002).
The fi rst VE is often carried out soon after admission to the deliv- ery suite. However, depending on local policy, the midwife may wait until she is sure that the woman is in active labour. It is common practice to carry out a VE to confi rm onset of the second stage of labour, though this may not be necessary if the presenting part is already visible. However, if the woman displays an urge to push when there is doubt about progress in labour, a vaginal examination should be carried out (Enkin et al. 2000). All VE are invasive proce- dures and risk introducing bacteria to the genital tract. They also compromise the woman’s dignity and sense of autonomy, so should not be undertaken without good reason. Many midwives working in the community or birth centres will operate a policy of conducting a VE only if there is a clear indication to do so.
VE allows the progress of labour to be assessed through a number of indicators. These are:
The state of the cervix
The midwife will assess the position, effacement, consistency and dilatation. In early labour, these fi ndings may be expressed using the Bishop’s Score system, a tabular representation which allocates points to each factor (see Table 5.3). The higher the number of points, the more advanced the state of cervix towards established labour.
The station of the presenting part
Even if the cervix is closed, the midwife will be able to ascertain the descent of the presenting part (PP) through the pelvis. This should have been estimated by abdominal palpation prior to commencing the VE. The PP is measured in relation to the ischial spines (see Figure 5.2) and is estimated in centimetres. The ischial spines may
Table 5.3 Bishop’s score
Parameter 0 1 2 3
Dilatation <1 cm 1–2 cm 2–4 cm >4 cm
Length >4 cm 2–4 cm 1–2 cm <1 cm
Consistency Firm Average Soft −
Position Posterior Mid Anterior
Station −3 −2 −1, 0 +1, +2
http://www.perinatal.nhs.uk/main.htm accessed 22.10.07
be felt as blunt, bony prominences on stretching the examining fi ngers to the sides of the vaginal wall. Thus a position of 0 means that the PP is level with the ischial spines: −1 means one cm above the ischial spines; +1 means 1 cm below (Allotey 1996) (see Figure 5.2). The midwife would expect the PP to descend steadily through- out labour as the cervix dilates. However, midwives may have dif- fi culty locating the ischial spines and the use of this landmark is highly subjective and therefore may not be a very accurate tool for measuring descent (Allotey 1996).
Position of the cervix
Prior to the onset of labour, the cervix points towards the posterior vaginal wall. On VE it may be very diffi cult to locate. From the end of pregnancy until the onset of established labour, it gradually becomes central and eventually anterior facing. Thus the ease with which the cervix can be reached is an indicator of progress in the latent or early phase of labour.
The size and shape of the bony pelvis
The midwife conducting the VE will note any unusual fi ndings such as a narrow pubic arch or a prominent sacrum, either of which might impede the progress of labour. A higher than expected PP coupled
Ischial spines 5 cm4
32 1 12 34 –– –– –
++ ++
Figure 5.2 Ischial spines
with an unusual pelvic structure is a likely indicator that labour will not progress to delivery, regardless of the strength of contractions.
This must be reported urgently to the senior obstetrician as a cae- sarean section is likely to be needed.
The position of the presenting part
If the cervix is suffi ciently dilated, it will be possible for the midwife to assess the attitude (fl exed or defl exed) of the fetal head by feeling for the fontanelles. A defl exed head at the start of labour would be expected to gradually fl ex, so that the posterior fontanelle becomes readily palpable. Lack of fl exion may be an indicator of poor progress due to an unfavourable fetal position or to ineffi cient contractions.
The position of the fetus can be determined through palpation of the sutures on the fetal skull. By noting the position and direction of the sutures, the midwife can assess whether the fetus has rotated into a good position for birth. If VEs are repeated over a period of time, the midwife should be able to track the progress of the fetus as it rotates and descends through the birth canal. These are impor- tant signs of progress in labour and a lack of rotation, fl exion and descent may indicate an obstruction to normal labour.