It The Journal of Obstetrics and Gynaecology - of the British Commonwealth

1 1 VOL. 77 No. 5 NEW SERIES MAY 1970

ACTIVE MANAGEMENT OF LABOUR AND CEPHALOPELVIC DISPROPORTION

BY

KIERAN ODRISCOLL, REGINALD J. A, JACKSON AND JOHN T. GALLAGHER National Maternity Hospital, Dublin

Summary A preoccupation with cephalopelvic disproportion is the main reason for a reluctance to abandon the conservative attitude towards labour which prevails in the United Kingdom and Ireland. In a series of 1000 consecutive primigravidae, in which an active approach to labour was adopted, the incidence of disproportion was less than 1 per cent and there was notable absence of trauma, especially to the child. Oxytocin stimulation is recommended as an essential instrument to define dispro- portion when the natural forces are not adequate. Excessive caution is criticized because a diagnosis of disproportion cannot be made unless uterine action is adequate. 1 t is concluded that the possibility of cephalopelvic disproportion does not justify a passive attitude towards labour in a modern maternity unit.

THE special significance of cephalopelvic dispro- portion is that it commits a young woman to Caesarean section at every delivery. This places a responsibility on the obstetrician to ensure that the initial diagnosis is correct. A wide variation in the reported incidence from similar hospitals suggests that this is often not the case.

An aspect of the problem which has a much wider significance concerns the general manage- ment of labour. It has been stated frequently that disproportion is a common cause of protracted labour and that ocytocin should never be given to accelerate progress unless disproportion has been excluded (Hellman, 19 59 ; Friedman and Sachtleben, 1962 ; Turnbull and Anderson, 1968). The result is that few are willing to apply stimulation effectively lest this should result in injury to mother or child.

During recent years an active approach to labour has been adopted at the National Maternity Hospital in which the emphasis is on stimulation to achieve early delivery (ODriscoll et a!., 1969). Prolonged labour has been elimi-

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nated with the result that disproportion has been isolated as a separate entity. The purpose of this paper is to establish the true incidence of disproportion and to examine the proposition that inefficient labour in primigravidae is often an expression of disproportion.

MATERIALS AND METHODS A prospective study of loo0 consecutive

primigravidae was conducted between 1 st Janu- ary and 16th September, 1968. A policy of active management ensured that every woman had efficient uterine action in labour. This was achieved by early recourse to stimulation and was measured by dilatation of the cervix. When dilatation of the cervix was not progressive the forewaters were ruptured, and if this did not accelerate progress an intravenous infusion of oxytocin was given. A standard concentration of 10 units of oxytocin per litre of 5 per cent dextrose was used and the drip was regulated to ensure dilatation of the cervix. The only factor

386 ODRISCOLL, JACKSON AND GALLAGHER

which limited the rate of infusion was fetal distress. Oxytocin was never withheld because disproportion was suspected.

Cephalopelvic disproportion was suspected on the basis of a free head which could not be made to engage in the pelvis after 38 weeks. X-ray pelvimetry was performed in these cases but assessment of the pelvis by vaginal examination or head-fitting tests under anaesthesia were not practised. Every patient suspected of dispropor- tion was submitted to a trial of labour. Dispro- portion was excluded when delivery occurred in less than 24 hours without injury to mother or child. A presumptive diagnosis of disproportion was made when this was not achieved.

The possibility that disproportion may have been overlooked in some cases not submitted to trial of labour was recognized. These cases would be recorded as Caesarean section per- formed for another reason, or as cases of prolonged labour, laceration of the birth canal or injury to the fetus when vaginal delivery was achieved. A critical assessment was maintained to ensure that disproportion was not concealed under these headings. In the event of a second delivery having occurred during the interval since the series was completed, the outcome has been stated. Malpresentations and malformations were not included as cases of cephalopelvic disproportion; there were 35 breech, 1 brow and I face presentations and 2 cases of hydro- cephal u s .

RESULTS In this series of 1000 consecutive primigravidae

no elective Caesarean section was performed for disproportion and no perinatal death was caused by traumatic intracranial haemorrhage. No mother sustained an injury more severe than a second degree laceration of the perineum and the duration of labour exceeded 24 hours in only one instance. Oxytocin was infused to induce labour in 79 cases with 2 perinatal deaths from congeni- tal malformations and to accelerate labour in 120 cases with one perinatal death from hypoxia in a second twin. Disproportion was suspected in 30 cases, but these were reduced to 22 when the head subsequently engaged in 8 cases.

Trial of Labour A trial of labour was conducted in 22 cases in

which the head was not engaged at the onset of labour. This proved successful on 13 occasions when vaginal delivery was achieved in less than 24 hours without injury to mother or child. The unsuccessful cases included 7 Caesarean sections, 2 perinatal deaths of which one occurred in a case delivered by Caesarean section, and the only prolonged labour in the series. This group of 9 failures included all the cases of cephalo- pelvic disproportion in I000 primigravidae (0-9 per cent). Three of these patients became pregnant again and each had a normal delivery. The extraneous factors which affected the trial of labour in these cases were prolapsed cord, infertility at 35 years of age and prolonged pregnancy. The other six patients have not become pregnant again. Pregnancy was pro- longed to 42 weeks in 10 cases submitted to trial of labour; 5 Caesarean sections and both perinatal deaths were included in these 10 cases.

Oxytocin was infused to induce labour for 4 patients all of whom were subsequently delivered by Caesarean section, and to accelerate labour for 7 patients all of whom achieved vaginal delivery. Neither of the perinatal deaths was associated with oxytocin. There was radiological evidence of contracted pelvis in 13 cases; the antero- posterior diameter of the brim was less than 10 cm. in 4 cases and the transverse diameter less than 12 cm. in 9 cases. Oxytocin was infused in 5 cases with contracted pelvis and 4 of these patients achieved vaginal delivery. The height of the mother was less than 155 cm. in 12 cases and only one mother exceeded 160 cm.

Caesarean Sections There were 40 Caesarean sections (4 per cent).

The operation was performed during labour in 12 cases and before labour in 28 cases. The indications for Caesarean section during labour were: disproportion (9, fetal distress (3), prolapsed cord (l), abruptio placentae (I), brow presentation (1) and breech presentation (1). A diagnosis of disproportion was made in 4 cases when the head did not engage during labour and in one case when trial of labour was cur- tailed by fetal distress. A trial of labour was interrupted by prolapse of the cord in a sixth case. The head was engaged before 38 weeks in the cases of fetal distress and abruptio placentae.

ACTIVE MANAGEMENT OF LABOUR AND CEPHALOPELVIC DISPROPORTION 387

The indications for Caesarean section before labour were : toxaemia (12), breech presentation (8), placenta praevia (2), abruptio placentae (2), ovarian cyst (1) maternal age (l), face presenta- tion (1) and fetal distress (1). Caesarean section was performed because meconium was seen when the membranes ruptured before labour in the case of fetal distress, and this is included as an unsuccessful trial of labour because the head was not engaged. Disproportion was not suspected in any other case.

Perinatal Deaths There were 25 perinatal deaths (2.5 per cent).

Necropsy was performed in every case. Congeni- tal malformations caused 8 deaths. The circum- stances in the other cases were that 10 deaths occurred before labour, 3 during labour and 4 after birth. Two of the liveborn infants, who died from respiratory distress, had been delivered before labour by Caesarean section. All 5 infants who died during or after labour suffered pro- found distress and showed evidence of hypoxia at necropsy.

Two deaths occurred in cases suspected of disproportion ; prolonged pregnancy was a critical factor on both occasions, one occurred at 44 weeks before labour began and Caesarean section was performed subsequently for dispro- portion, the other occurred after the head engaged in labour at 42 weeks.

Brain Damage Four infants (0.4 per cent) showed signs of

brain damage at discharge from hospital. The obstetrical factors were abruptio placentae (2 cases), and prolonged pregnancy (2 cases). Disproportion was not suspected in any case. The infants were examined after six months when three had cerebral palsy, and the only case stimulated with oxytocin was normal.

DIscussioN The incidence of cephalopelvic disproportion

cannot be stated precisely but a reasonable estimate can be made when this is based on objective clinical standards. The simple standard adopted in this series was failure to achieve a vaginal delivery in 24 hours without injury to mother or child. A diagnosis was made on this

basis on 9 occasions in lo00 consecutive primi- gravidae. The diagnosis was influenced in some cases by other factors with the result that the only three patients who became pregnant again had normal deliveries. It is concluded that the incidence of cephalopelvic disproportion was less than 1 per cent.

Safe delivery within a reasonable time is the only proof of the functional capacity of a pelvis, and failure to achieve this in cases suspected of disproportion is due usually to inefficient uterine action (Donald, 1969). Early stimulation to ensure progress in labour corrects inefficient uterine action and therefore isolates dispropor- tion. It has been stated that disproportion is often the cause of delay in labour (Hellman, 1959; Friedman and Sachtleben, 1962) but our experience lends no support to this observation. In this series of 1000 primigravidae there were 120 cases of inefficient labour in which stimula- tion was applied; one patient was subsequently delivered by Caesarean section, one perinatal death occurred in a second twin and one infant suspected of cerebral damage was normal when six months old.

The purpose of stimulation is to ensure normal progress in labour which is measured by dilata- tion of the cervix. A diagnosis of disproportion is established when there is no corresponding descent of the fetal head. Stimulation is exploited in this hospital as an instrument to define disproportion when the natural forces are inadequate. It is never the intention to surmount obstruction by force and fetal distress is of paramount importance i n the conduct of labour, whether or not this is stimulated with oxytocin. The effect has been that, as prolonged labour has been eliminated, the incidence of dispropor- tion has been greatly reduced. Disproportion was suspected in seven cases treated to accelerate labour in the present series and all achieved safe vaginal delivery ; suggestions that disproportion may have been surmounted by force have no meaning in these circumstances.

There is a considerable difference of opinion about the safety of stimulation in primigravidae in whom cephalopelvic disproportion is suspec- ted. Theobald et al. (1956) and Hannah (1965) did not consider this a contraindication, and Goodwin and Reid (1963) concluded that oxytocin demonstrated safely and quickly the

388 ODRISCOLL, JACKSON AND GALLAGHER

limits of uterine ability in trial of labour. Ledger (1969) advocated an aggressive policy towards labour in patients with abnormal patterns of cervical dilatation, provided there was no cephalopelvic disproportion, and Hell- man (1 959) warned that pelvic contraction even of a minor degree was the principal contra- indication to stimulation. Turnbull and Ander- son (1968) were especially concerned about the possibility of injury to the fetus resulting in traumatic intracranial haemorrhage, and recom- mended that only when full clinical and radio- logical assessment excluded disproportion should oxytocin be used.

During the three years 1963-65 when stimula- tion was restricted for conventional reasons, there were 4538 primigravidae delivered in this hospital. Necropsy was performed in all cases of perinatal death and traumatic intracranial haemorrhage was demonstrated in 6 breech and 15 cephalic deliveries; the fetus was mature in 14 cephalic deliveries. During the next three years 1966-68, when stimulation to accelerate ineffi- cient labour became standard practice, 41 53 primigravidae were delivered. Necropsy was performed in all cases of perinatal death and traumatic intracranial haemorrhage was demon- strated in 6 breech and 2 cephalic deliveries; the maturity in the cephalic deliveries was 28 and 30 weeks and oxytocin was not given in either case. Although the indications were not altered the incidence of forceps delivery declined sharply during these years and difficult extrac- tions, when the head was high and not rotated, became rarely necessary. Twelve mature infants died from traumatic intracranial haemorrhage after forceps delivery between 1963 and 1965 but none died between 1966 and 1968. The conclusion is that adequate uterine action reduces the risk of trauma because it protects the fetus from difficult forceps extraction. A reduction in fatal head injuries has implications also for the develop- ment of infants who survive.

Another theoretical contraindication to stimu- lation is the risk of rupture of the uterus. Goldman (1959) could find no report in the literature of ruptured uterus in a primigravida after oxytocin, and ODriscoll et al. (1969) concluded that the primigravid uterus is almost immune to rupture except at manipulation with forceps. Stimulation reduces the need for

manipulation and protects the mother from trauma for the same reason that it protects her child.

In this series of 1000 primigravidae, from which the problem of inefficient uterine action was eliminated, the most important complicating factor in cases suspected of disproportion was prolonged pregnancy. In 12 cases of trial of labour before 42 weeks only 2 were delivered by Caesarean section, but in 10 cases after 42 weeks 5 were delivered by Caesarean section and there were 2 perinatal deaths. Prolonged pregnancy prejudices the outcome of labour because it is associated with fetal hypoxia. It is recommended that when Caesarean section is performed for fetal distress after 42 weeks the mother should not be committed to Caesarean section for disproportion in subsequent pregnancies.

The value of X-ray pelvimetry has been seriously questioned by Hannah (1965) who emphasizes the statement that the result of a trial of labour should depend entirely on progress without regard to radiological appear- ances. We agree that pelvimetry should not influence management except in the rare instance of gross contraction. There was no such case in the present series. An incorrect diagnosis of cephalopelvic disproportion is often made in cases of inefficient uterine action and some feature of pelvic architecture is accepted as evidence in support of this error (Hawksworth, 1952).

The problem of disproportion should be considered separately in primigravidae, because disproportion in multigravidae presents a more complex and dangerous problem. The practice of expressing the incidence in all mothers provides no useful information and offers no basis for comparison between different series. Malpreseiitations and malformations should be excluded because a trial of labour in these circumstances has no place in modern obstetric practice (Donald, 1969).

The problem of cephalopelvic disproportion directly affects comparatively few women, but the indirect effects have much wider implications because it is fear of the possible consequence of stimulation in women in whom disproportion has not been excluded which represents the chief impediment to active management in labour. The result is confusion between inefficient

ACTIVE MANAGEMENT OF LABOUR AND CEPHALOPELVIC DISPROPORTION 389

uterine action and cephalopelvic disproportion and these are the main constituents of prolonged and difficult labour in a primigravida. This confusion, we believe, is the explanation for the relatively high incidence of dystocia reported from other centres.

Active management in labour must be practised under continuous supervision, but sophisticated equipment to control the rate of oxytocin infusion or to monitor uterine activity is not required. An important consequence of active management is high utilization of special care facilities, particularly of skilled nursing personnel.

ACKNOWLEDGEMENTS We are grateful to Dr. Francis Geoghegan

who performed the postmortem examinations and to Dr. Niall O'Brien who assessed the infants for residual brain damage, and especially to the Nursing Sisters in the delivery unit at the National Maternity Hospital to whom most of

the credit for the management of these patients is due.

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Journal of Obstetrics and Gynecology, 85, 209. Hannah, W. J. (1965): American Journal of Obstetrics and

Gynecology, 91, 333. Hawksworth, W. (1952): Proceedings of the Royal Society

of Medicine, 45, 521. Hellman, L. M. (1959): Clinical Obstetricsand Gynecology,

2, 343. Ledger, W. J. (1969): Obstetrics and Gynecology, 34, 114. O'Driscoll, K., Jackson, R. J. A., and Gallagher, J. T.

(1969): British Medical Journal, 2, 411. Theobald, G. W., Kelsey, H. A., and Muirhead, J. M. B.

(1956): Journal of Obstetrics and Gynaecology of the British Empire, 63, 641.

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