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Assessing the start of labour is one of the most important aspects of the management of labour. Signs of the start of labour are:
- painful contractions with a certain regularity
- effacement and/or dilatation of the cervix
- leakage of amniotic fluid
- bloody discharge
Rupture of the membranes is a clear sign that something irreversible has occurred. The other symptoms are less obvious: contractions may be felt long before labour actually starts, and cervical dilatation may be present weeks before the end of pregnancy, and may progress slowly to the time of labour (Crowther 1989). Notwithstanding these difficulties the birth attendant should be able to distinguish between false labour and the beginning of labour; usually a vaginal examination is necessary to detect alterations of the cervix. The establishment of the onset of labour is, inevitably, the basis for identifying prolonged labour requiring action. If the diagnosis “start of labour” is made erroneously, the result may be unnecessary interventions, such as amniotomy or oxytocin infusions. The diagnosis “prolonged latent phase” is usually better substituted by “false labour”, because actually labour has not yet started. Sometimes the distinction between “start of labour” and “false labour” can only be made after a short period of observation. In the WHO multicentre trial of the partograph (WHO 1994b) only 1.3% of the women were reported to have a prolonged latent phase. The cause of this small percentage can be twofold: at the introduction of the partograph in the hospitals a discussion of labour management took place which may have affected the way the latent phase is perceived. Also, active intervention in the latent phase is postponed by 8 hours in the partograph.
Spontaneous prelabour rupture of the membranes (PROM) at term provokes a lively discussion about the risk of vaginal examination (Schutte et al 1983), induction of labour and prophylactic antibiotics. In a recent randomized study on induction after 12 hours versus expectant management during 48 hours, in the induction group the need for pain medication was significantly greater and there were more interventions, while mild neonatal infection occurred in 1.6% in the induction group versus 3.2% in the group with expectant management. No routine prophylactic antibiotics were used and vaginal examination was only performed if labour had started (Ottervanger et al 1996). A conservative approach, which is supported by the existing evidence, would indicate a policy which requires observation without vaginal examination and without antibiotics, during the first 48 hours after PROM. If labour has not commenced spontaneously during that period (in about 20% of the women), consideration could be given to oxytocin induction. However, these results are obtained in populations of women from developed countries in good health, and in hospitals where it was possible to maintain high standards of hygiene at all times. In different populations a more active management may be advisable, with the use of antibiotics and earlier induction of labour. Given that in the developing world puerperal sepsis is often the third or fourth cause of maternal mortality all efforts should be made to prevent it, whatever its source.
Several studies show that, during the first stage of labour, the supine position affects the blood flow in the uterus. The heavy uterus can cause aortocaval compression and the reduced blood flow can compromise the condition of the fetus. The supine position is also found to reduce the intensity of the contractions (Flynn et al 1978, McManus and Calder 1978, Williams et al 1980, Chen et al 1987), and thus interferes with the progress of labour. Standing and lying on the side are associated with greater intensity and greater efficiency of the contractions (their ability to accomplish cervical dilatation).
Despite the continued prevalence of the supine position many options are open to women in labour. However, various constraints frequently limit those options, from the design of the delivery-suite bed to delivery protocols or the presence of routine intravenous lines or monitoring equipment. Where such constraints are kept to a minimum women can stand, walk, sit upright or on hands and knees, take a shower or a bath to relax or adopt each position alternately as they choose. Trials that have compared these positions to the supine have found that, on average, labour was experienced as less painful (there was less need for analgesia) and augmentation was used less frequently in the non-supine positions (Chan 1963, Flynn et al 1978, McManus and Calder 1978, Diaz et al 1980, Williams et al 1980, Hemminki 1983, Melzack 1991). One trial (Flynn et al 1978) found a significantly lower incidence of fetal heart rate abnormalities in the upright position, but other trials detected no significant differences in neonatal outcomes.
In conclusion, there is no evidence to support the encouragement of the supine position during the first stage of labour. The only exception is where the membranes have ruptured in the presence of a non-engaged fetal head. If and when the membranes are ruptured and the birth attendant has established a sufficient engagement of the fetal head, women should be free and encouraged to choose the position they prefer during labour. They will often change positions, as no position is comfortable for a long period of time.
This is one of the essential diagnostic actions in the assessment of the start and the progress of labour. It should only be conducted by trained birth attendants, with clean hands, covered by sterile gloves. The number of vaginal examinations should be limited to the strictly necessary; during the first stage of labour usually once every 4 hours is enough, as prescribed in the manual for the use of the partograph (WHO 1993). If labour passes off smoothly, experienced birth attendants can sometimes limit the number of examinations to one. Ideally, that would be the one examination necessary to establish active labour, i.e. to confirm the fact that there is dilatation of the cervix (the most objective criterion of active labour). Another practice in the management of labour is to only perform a vaginal examination when there is an indication for the need, for example when the intensity and frequency of the contractions decrease or at signs of heavy show or the urge to push, or before the administration of analgesia.
Something can be said for each of the above-mentioned approaches, but considering our theorem: “In normal childbirth there should be a valid reason to interfere with the natural process” maybe the latter two policies outweigh the former. Yet many questions remain, as there is no clear evidence to support any specific policy. Perhaps more strict guidelines are necessary in those countries where birth attendants have a limited training and are isolated, with great distances to the referral centres. These guidelines would then be country-specific.
In institutions where caregivers are trained a vaginal examination by a student sometimes will have to be repeated and checked by the supervisor. This may only be done after the woman has consented. Under no circumstances should women be compelled to undergo repeated or frequent vaginal examinations by a number of caregivers or students.
In the past rectal examination has been advised to avoid contamination of the vagina. This practice is not recommended. Studies comparing vaginal and rectal examinations showed a similar incidence of puerperal infection whether rectal or vaginal examinations were employed during labour (Crowther et al 1989). Women’s preference for vaginal over rectal examinations was clearly demonstrated in a randomized clinical trial (Murphy et al 1986).
The assessment of the progress of labour is made by observation of the woman; her appearance, behaviour, contractions, and the descent of the presenting part. The most accurate measure is dilatation of the cervix. Deviation from an arbitrarily defined normal rate of dilatation should be an indication for review of the labour management plans. In the partograph method of WHO (WHO 1993) the alert line is passed if the dilatation is slower than 1 cm per hour; if the woman is in a health centre this is reason to refer her to a hospital. The action line is passed if delay in progress continues for four more hours. Then a critical assessment of the cause of delay should be made, and a decision taken about the appropriate management. Although these strict rules are not followed in all countries, they form valuable guidelines, especially in those situations where distances to a referral centre are great, and birth attendants are isolated. Research about the effect of the use of the partograph showed that over a fifth of the graphs of primigravidae crossed the alert line, and 10-11% crossed the action line (Philpott and Castle 1972, WHO 1994b). In Latin America a different partograph is in use, differentiating between nulliparous and multiparous women, intact and ruptured membranes, and upright or lying position (Schwarcz et al 1987-1995).
The relationship between prolonged labour and adverse maternal and fetal outcome is the reason why it is so important to monitor the progress of labour accurately. The extent to which that relationship is causal is by no means certain. Slow progress should be a reason for evaluation rather than for intervention. Cephalopelvic disproportion must be considered when progress is slow. Intrapartum X-ray pelvimetry has not proven to be useful. The available trials of X-ray pelvimetry show an increase of interventions like caesarean section, but no benefits in terms of reduced neonatal morbidity (Parsons and Spellacy 1985). X-ray pelvimetry during pregnancy and labour increases the incidence of leukaemia in infancy, and should be abolished (Stewart et al 1956, MacMahon 1962). In experienced hands manual pelvimetry may be useful. If the membranes are still intact during labour slow progress is usually not caused by disproportion. Expectant management would then be an option (Albers et al 1996). As no solid research evidence is available about expectant management versus active management in case of slow progress without signs of disproportion, no definite conclusions can be drawn. When the membranes are ruptured slow progress is more likely to be the consequence of mechanical problems. The management in cases of abnormal labour is beyond the scope of this report.
Several measures have been proposed to prevent delay in the progress of labour; sometimes these actions are taken long before the action line or even the alert line of the partograph are reached. The most active interventions are early amniotomy and early oxytocin infusion, or a combination of the two. Early amniotomy interferes with the physiological timing of fetal membranes’ rupture. Under normal conditions, the membranes remain intact until full dilatation in 75% of the cases (Schwarcz et al 1995). Amniotomy before full dilatation is frequently practised as a method to expedite labour.
This intervention has been recommended as a routine procedure 1 hour after admission in labour (O’Driscoll et al 1973). In a controlled study a considerable increase of type I decelerations of the fetal heart rate was found after early amniotomy (Schwarcz et al 1973). Several randomized trials suggest that amniotomy early in labour leads to a reduction, on average, of between 60 and 120 minutes in the duration of labour, without effects on the use of analgesia and rates of operative delivery. The trials provide no evidence that early amniotomy has a favourable or unfavourable effect on the condition of the neonate (Fraser et al 1991, 1993, Barrett et al 1992). It is not possible to conclude that early amniotomy has a clear advantage over expectant management, or the reverse. Therefore, in normal labour there should be a valid reason to interfere with the spontaneous timing of the rupture of the membranes.
This is frequently used to expedite labour after either spontaneous or artificial rupture of the membranes. The combination with early amniotomy is often called “active management of labour”, and as such it was first advocated in Ireland (O’Driscoll et al 1973, O’Driscoll and Meagher 1986). In more or less modified form the technique has been widely adopted across the world. According to the original protocols for the active management of labour, after early amniotomy hourly vaginal examinations are performed, and oxytocin is administered if the rate of cervical dilatation is less than 1 cm per hour. The practice has been investigated in a number of randomized trials (Read et al 1981, Hemminki et al 1985, Bidgood and Steer 1987, Cohen et al 1987, Lopez-Zeno et al 1992). Of the three trials providing data on the length of labour after oxytocin augmentation compared to control groups, only one showed a shorter mean duration with oxytocin. In one trial the women in the control group were encouraged to get out of bed and walk around, stand or sit as they wished. In this control group the mean duration of labour was slightly shorter than in the augmented group. Neither Apgar scores nor the incidence of admission to a special care nursery were different between oxytocin augmentation and control groups (Hemminki et al 1985). This study reported on the women’s views on the procedure. The majority said the augmentation procedure was unpleasant. More than 80% felt that augmentation had increased their pain. Half of the women in the control group who were ambulant said that this mobility had decreased their pain while 24% felt no difference.
In conclusion, it is not clear from the available data that liberal use of oxytocin augmentation (“active management of labour”) is of benefit to women and babies. Of course this does not mean that oxytocin is useless in the therapy of prolonged labour. However, there is no evidence that the prevention of prolonged labour by the liberal use of oxytocin in normal labour is beneficial. It is fair to ask whether labour augmented by oxytocin infusion can still be considered normal. In many places oxytocin infusions are only administered in hospital under the responsibility of the obstetrician. This is a reasonable precaution, given the unpredictable nature of artificially managed labour. As a general rule oxytocin should only ever be used to augment labour in facilities where there is immediate access to caesarean section should the need arise. The need for augmentation is considered an indication for referral to obstetric services with surgical facilities. Where available, subsequent fetal surveillance is not by intermittent auscultation but by electronic monitoring. The experience in Dublin during the randomized trial of intrapartum fetal heart rate monitoring also points in this direction: in the group monitored with auscultation the number of neonatal seizures was increased, but the majority of these infants were born from mothers who had augmentation with oxytocin during labour (MacDonald et al 1985). See also 2.7 Oxytocin augmentation is a major intervention and should only be implemented on a valid indication. The same holds true for the more modern variation of augmentation with prostaglandins, and for the induction of labour with these substances.
Use of any intramuscular oxytocic before the birth of the infant is generally regarded as dangerous, because the dosage cannot be adapted to the level of uterine activity. Hyperstimulation may result and is harmful to the fetus. An increase in the incidence of ruptured uterus, with corresponding grave sequelae, has also been linked to this practice (Kone 1993, Zheng 1994). Nevertheless intramuscular oxytocin administration is still practised, sometimes at the request of pregnant women or her family expecting a more rapid delivery. In some developing countries the drug can be bought on the market. This harmful practice should be abandoned. The same holds true for the administration of other oxytocics, like prostaglandins, at any time before delivery in such a way that their effect cannot be controlled.
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