|Care in Normal Birth (WHO, 1996, 60 p.)|
|4. CARE DURING THE SECOND STAGE OF LABOUR|
During the second stage of labour the oxygenation of the fetus is gradually reduced because the fetus is being expelled from the uterine cavity, with resulting retraction of the uterus and decrease in placental circulation. Moreover, strong contractions and strenuous pushing may further reduce the uteroplacental circulation. The decrease in oxygenation is accompanied by acidosis. There are however large individual differences in the rate and seriousness of this process, and therefore the caregiver should carefully monitor the condition of the fetus.
The beginning of the second stage is marked by the following symptoms:
· the woman feels the urge to bear down, because the amniotic sac or the presenting part protrudes through the dilated cervix and presses against the rectum;
· often the membranes rupture spontaneously;
· usually there is full dilatation of the cervix, but sometimes the woman feels the urge to push at an earlier stage of dilatation. If a rim of cervix is left it will be pushed aside by the presenting part.
From the above-mentioned it becomes clear that often the onset of the second stage is not exactly known. A woman may feel the urge to bear down before complete dilatation or she may not yet feel it at the moment complete dilatation is diagnosed. If complete dilatation is diagnosed by vaginal examination, it remains uncertain how long this condition has been present before.
In some hospitals it is customary to transport the woman from the labour room to a specific delivery room at the onset of the second stage. The delivery room is usually equipped with large bright lamps, instruments and a delivery bed fitted lithotomy poles and stirrups or metal gutters. Although such a setting is more convenient for the caregiver if an operative delivery is contemplated, for the woman any unnecessary transportation is unpleasant. In normal labour there is no need to move the woman to a different room at the onset of the second stage. Labour and delivery can very well be attended to in the same room.
Caregivers often decide on the onset of the second stage by encouraging the woman to push, either when full dilatation has been diagnosed, or sometimes even earlier. The physiological approach is to wait until the woman feels the urge to bear down herself. At full dilatation sometimes the urge is not yet present, and by waiting ten or twenty minutes the expulsion phase may start spontaneously. There are no controlled trials about early versus late pushing in normal labour, but some trials have been done with epidural analgesia. Because the bearing down reflex is suppressed it is easy to delay the pushing efforts until the vertex is visible in the introitus. This procedure has been compared with pushing as soon as full dilatation was diagnosed (McQueen and Mylrea 1977, Maresh et al 1983, Buxton et al 1988). Delayed pushing did not show any hazardous effect on fetal or neonatal outcome. In the early pushing group significantly more forceps deliveries occurred. Although the results were obtained in women receiving epidural analgesia they are in accordance with clinical experience of midwives who delay pushing until the spontaneous bearing down reflex appears. This practice is easier for the woman and tends to shorten the bearing down phase.
At or before the onset of pushing it is sometimes advised to routinely empty the bladder by catheterisation. This practice is unnecessary and might cause infection of the urinary tract. During the second stage, when the fetal head is firmly engaged, catheterisation may be very difficult and even traumatic. It is advisable to encourage the woman to urinate spontaneously during the first stage of labour; in normal labour this practice will usually suffice.
The practice of encouraging sustained, directed (Valsalva) bearing down efforts during the second stage of labour is widely advocated in many delivery wards. The alternative is supporting the womens spontaneous pattern of expulsive efforts (exhalatory bearing down efforts). These two practices have been compared in several trials (Barnett and Humenick 1982, Knauth and Haloburdo 1986, Parnell et al 1993, Thomson 1993). The spontaneous pushing resulted in three to five relatively brief (4-6 seconds) bearing-down efforts with each contraction, compared with the 10-30 second duration of sustained bearing-down efforts, accompanied by breath holding. The latter method results in somewhat shorter second stages of labour, but may cause respiratory-induced alterations in heart rate and stroke volume. If the woman is lying flat on her back, it may be associated with compression of the aorta and reduced blood flow to the uterus. In the published trials mean umbilical artery pH was lower in the groups with sustained bearing down, and Apgar scores tended to be depressed. The available evidence is limited, but the pattern emerges that sustained and early bearing-down efforts result in a modest decrease in the duration of the second stage, but this does not appear to confer any benefit; it seems to compromise maternal-fetal gas exchange. The shorter spontaneous pushing efforts seem to be superior (Sleep et al 1989).
In many countries the practice of fundal pressure during the second stage of labour is common. It is meant to expedite the delivery, is sometimes performed shortly before delivery, sometimes from the beginning of the second stage. Apart from the issue of increased maternal discomfort, there is suspicion that the practice may be harmful for the uterus, the perineum and the fetus, but no research data are available. The impression is that the method is at least used too often, with no evidence of its usefulness.
In 1930 De Snoo determined the duration of the second stage of labour in 628 primiparous women with the fetus in vertex presentation. He found a mean duration of 1¼ hour, with a median value of 1 hour. These values were strongly influenced by the occurrence of some very long periods (10-14 hours). Since then the mean duration of the second stage has been largely determined by artificial termination of labour after the maximum period allowed by the caregiver. In primiparous women the mean duration of the second stage is now often reported at about 45 minutes. The association of a prolonged second stage with fetal hypoxia and acidosis was an incentive to curtail the second stage of labour even in the absence of overt maternal or fetal problems. This policy has been examined in controlled trials (Wood et al 1973, Katz et al 1982, Yancey et al 1991). The termination of labour after an uncomplicated second stage led to significantly higher umbilical artery pH values, without any other evidence that this policy had a beneficial effect on the baby. The maternal trauma and occasional fetal trauma resulting from the increased surgical interference that the policy involves can hardly be justified. If maternal and fetal conditions are good and if there is progress of labour, there is no reason to rigidly adhere to a stipulated duration of the second stage, of for instance 1 hour.
Several follow-up studies have been published about the neonatal condition after a second stage of various duration. In the Wormerveer study (Van Alten et al 1989, Knuist et al 1989) a cohort of 148 neonates was examined using determination of umbilical artery pH and neurological score (Prechtl) in the second week of life. The second stage of labour varied from <60 min (66% of nulliparous women) to 159 min. No correlation was found between the duration of the second stage and the neonatal condition. Recently a follow-up study has been published of 6759 firstborn infants in cephalic presentation weighing >2500 g; the second stage of labour lasted >3 hours in 11%. No relation was found between second-stage duration and low 5-minute Apgar score, neonatal seizures or admission to the neonatal intensive care unit (Menticoglou et al 1995).
In conclusion, decisions about curtailing the second stage of labour should be based on surveillance of the maternal and fetal condition, and on the progress of labour. If there are signs of fetal distress or if the presenting part fails to descend there is good reason to terminate labour, but if the mothers condition is satisfactory, the fetus is in good condition, and there is evidence of progress in the descent of the fetal head, there are no grounds for intervention. However, after a second stage of >2 hours in nulliparous women and >1 hour in multiparae the chance of spontaneous delivery within a reasonable time decreases, and termination should be contemplated.
All over the world, in developed and developing countries, during the last decades the number of operative deliveries has increased sharply. The causes are not known exactly, but apart from the earlier mentioned rigid adherence to a stipulated duration of the second stage, the incidence of operative deliveries may be influenced by the fear of malpractice suits, by convenience and by financial gain. Research among obstetricians and residents in the Netherlands showed that the tendency to more frequent interventions was counteracted by the presence of midwives in a hospital (Pel et al 1995). Apparently labour attendance by professionals who are not qualified to interfere, but who act towards the preservation of normality can prevent unnecessary interventions. The world-wide epidemic of operative deliveries needs more attention, because unnecessary interventions are harmful to women and infants.
A number of trials (Stewart et al 1983, Liddell and Fisher 1985, Chen et al 1987, Johnstone et al 1987, Gardosi et al 1989ab, Stewart and Spiby 1989, Crowley et al 1991, Allahbadia and Vaidya 1992, Bhardwaj et al 1995) suggest that an upright (vertical) position or a lateral tilt during the second stage of labour show greater advantages than a dorsal position. The upright position gives less discomfort and difficulty in bearing down, less labour pain, less perineal/vaginal trauma and wound infections. In one trial a shorter duration of the second stage was observed in the upright position. With regard to the fetal outcome, in some trials there were fewer Apgar scores below 7 in the upright position.
A vertical or upright position, with or without the use of a birthing chair, can give more labial tears, the results suggest an increase in third degree tears though the numbers available for analysis are very small. An increased percentage of postpartum haemorrhage has been found in women adopting the vertical position. The cause is not yet established; possibly in the upright position the measurement of blood loss is more accurate, but the difference could also be due to increased pressure on the pelvic and vulvar veins (Liddell and Fisher 1985, Gardosi et al 1989, Crowley et al 1991,). In one trial the haemoglobin was lower on the fourth day after birth, though the difference was not significant.
The position of the mother during the second stage of labour affects the condition of the fetus as it does in the first stage. Research shows less frequent abnormal heart rate patterns in upright positions and on average a higher umbilical arterial pH. A few trials asked the women which position they preferred and found greater enthusiasm for the upright postures, producing less pain and less backache. The lithotomy position with the legs in stirrups was experienced as less comfortable and more painful and restricted in movement. Women who had given birth in that position would prefer the option of an upright position in the future (Stewart and Spiby 1989, Waldenstrnd Gottvall 1991).
Much of the positive effect of the vertical position depends on the capacities of the birth attendant and his or her experience with any position other than the supine. A certain amount of knowledge of the advantages and the willingness to attend to women in various positions can make a vast difference to labour.
In conclusion, for both the first and the second stage, this means that women can adopt any position they like, while preferably avoiding long periods lying supine. They should be encouraged to experiment with what feels most comfortable and should be supported in their choice. Birth attendants need training in coaching and performing births in other positions than the supine in order to not be an inhibiting factor in the choice of position.
Perineal damage is one of the traumas most frequently suffered by women during delivery, even during labour and delivery that are considered normal. There are several techniques and practices aimed at reducing the damage, or modifying it to manageable proportions.
Many textbooks describe the practice of guarding the perineum during delivery of the fetal head: the fingers of one hand (usually the right) support the perineum, while the second hand applies pressure to the fetal head to control the speed of crowning, thus trying to prevent or reduce damage to the perineal tissues. It is possible that by this manoeuvre a perineal tear may be prevented, but it is also conceivable that the pressure on the fetal head impedes the extension movement of the head and diverts it from the pubic arch to the perineum, thus increasing the chance of perineal damage. Because there have been no formal evaluations of this strategy or of the opposite: not touching the perineum or the head during this phase of delivery, it is impossible to decide which strategy is preferable. The practice of guarding the perineum by the hands of the accoucheur can be applied more easily if the woman is in the supine position. If she is in the upright position the attendant can support the perineum blindly, or is compelled to follow the no touch strategy.
Another technique aiming at reducing the risk of trauma to the perineum, is massaging the perineum during the last part of the second stage of labour, thus attempting to stretch the tissues. The technique has never been properly evaluated, but there may be doubts about the benefit of the sustained rubbing of tissues that are already highly vascularized and oedematous.
Other manoeuvres about which insufficient evidence exists with respect to their effectiveness are the various methods to deliver the shoulders and the abdomen of the infant after the birth of the head. It is not clear if these manoeuvres are always necessary and if they are appropriate. Research data about this subject are not available. However, the National Perinatal Epidemiology Unit at Oxford is currently conducting a randomised controlled trial of Care of the Perineum at Delivery - Hands On Or Poised, the so-called HOOP study, which should provide data on the effect of different approaches to delivery of the fetal head and shoulders on the perineum (McCandlish 1996).
Perineal tears occur frequently, especially in primiparous women. First-degree tears sometimes do not even need to be sutured, second-degree tears usually can be sutured easily under local analgesia, and as a rule heal without complications. Third-degree tears can have more serious consequences and should, where at all possible, be sutured by an obstetrician in a well-equipped hospital, in order to prevent faecal incontinence and/or faecal fistulas.
Episiotomies are often made, but the incidence is diverse. In the USA they are carried out on between 50 and 90% of women giving birth to their first child, thus making the episiotomy the most commonly performed surgical procedure in that country (Thacker and Banta 1983, Cunningham et al 1989, Woolley 1995). In many centres blanket policies, such as a requirement for all primiparous women to have an episiotomy, are in place. In the Netherlands midwives attain an overall frequency of 24.5% episiotomies, 23.3% of which are mediolateral and 1.2% midline episiotomies (Pel and Heres 1995). Midline episiotomies are more easily sutured and have the advantage of leaving less scar-tissue, whilst mediolateral episiotomies more effectively avoid the anal sphincter and the rectum. Good reasons for performing an episiotomy during a thusfar normal delivery can be: signs of fetal distress; insufficient progress of delivery; threatened third-degree tear (including third-degree tear in a previous delivery).
All three indications are valid, although the prediction of a third-degree tear is very difficult. The incidence of third-degree tears is about 0.4%, and the diagnosis threatened third-degree tear should therefore only be made occasionally, otherwise the diagnosis is meaningless.
In the literature several reasons, besides the above-mentioned, are given for a liberal use of episiotomy. These include the arguments that it substitutes a straight, neat surgical incision for a ragged laceration, it is easier to repair and heals better than a tear (Cunningham et al 1989); that liberal use of episiotomy prevents serious perineal trauma; that episiotomies prevent trauma to the fetal head; and that episiotomies prevent trauma to the muscles of the pelvic floor, and thus prevent urinary stress incontinence.
The evidence to support these postulated benefits of a liberal use of episiotomy has been investigated in several randomized trials (Sleep et al 1984, 1987, Harrison et al 1984, House et al 1986, Argentine episiotomy trial 1993). The data from these trials do not give evidence to support this policy. Liberal use of episiotomy is associated with higher rates of perineal trauma, and lower rates of women with an intact perineum. The groups of women with liberal and restricted use of episiotomy experienced a comparable amount of perineal pain assessed at 10 days and 3 months post partum. There is no evidence of a protective effect of episiotomy on the fetal condition. In a follow-up study up to three years postpartum no influence of a liberal use of episiotomies on urinary incontinence was found. In an observational study of 56.471 deliveries attended by midwives the incidence of third-degree tears was 0.4% if no episiotomy was made, and the same with a mediolateral episiotomy; the incidence with a midline episiotomy was 1.2% (Pel and Heres 1995).
The caregiver who makes the episiotomy should be able to suture tears and episiotomies appropriately. He or she should be trained accordingly. An episiotomy should be made and sutured under local anaesthesia, with proper precautions for the prevention of HIV and hepatitis infection (see 2.8).
In conclusion, there is no reliable evidence that liberal or routine use of episiotomy has a beneficial effect, but there is clear evidence that it may cause harm. In a thusfar normal delivery there may at times be a valid indication for an episiotomy, but a restricted use of this intervention is recommended. The percentage of episiotomies attained in the English trial (10%) without harm to the mother or the infant (Sleep et al 1984) would be a good goal to pursue.