Management of delivery

Normal vaginal delivery

Normal vaginal delivery marks the end of the second stage of labour.

The second stage of labour is defined as the period from the time of complete cervical dilatation to the baby’s birth. It is convenient to consider the second stage in two phases: the descent in the pelvis, i.e. the pelvic or ‘passive’ phase, and the perineal, or ‘active’, phase of the second stage. During the descent phase the mother does not normally experience the sensation of bearing down and, from a management point of view, this phase may be regarded as an extension of the first stage of the labour. In the perineal phase the urge to bear down is present, although this may be masked or diminished if epidural analgesia has been provided for the woman. Therefore, unless the head is visible with contractions, the dilatation of the cervix and the station of the presenting part should be confirmed by vaginal examination before encouraging the woman to bear down.

Provided no adverse clinical factors are present, a normal duration of the second stage is commonly regarded as lasting up to 2 hours in the nulliparous woman and 1 hour in the multipara. If the woman has received epidural analgesia, these times are extended by 1 hour for each group, respectively. Progress in the second stage is monitored by descent of the fetal head assessed by an abdominal and vaginal examination. The fetal head is engaged and it is favourable for mother to bear down when no more than one-fifth of the head is palpable abdominally and the bony part of the vertex has descended to the level of the ischial spines.

If the labour is normal, women may choose a variety of positions for delivery, but the supine position should be discouraged because of the risk of supine hypotensive syndrome. Many women adopt a semi-reclining position, which has the advantage of reducing the risk of supine hypotension and is a suitable position for assisted delivery or perineal repair should these procedures be required.

Normal vaginal delivery

Women should be guided by their own urge to push. Pushing effort should allow for an unhurried, gentle delivery of the fetal head, and this can be achieved by combining short pushing spells with periods of panting, thus giving the vaginal and perineal tissues time to relax and stretch over the advancing head ( Fig. 12.1 ). Several contractions may occur before the head crowns and is delivered. For the delivery of the head, either the ‘hands-on’ technique – supporting the perineum and flexing the baby’s head – or the ‘hands-poised’ method – with the hands off the perineum but in readiness – can be used to facilitate spontaneous birth.

Episiotomy is not routinely required for spontaneous vaginal birth but may be indicated if the perineum begins to tear, if the perineal resistance prevents delivery of the head or if concern for the wellbeing of the fetus requires that the birth be expedited. Where an episiotomy is performed, the recommended technique is a mediolateral incision at the time of crowning, originating at the vaginal fourchette and directed usually to an angle of 60 degrees, which becomes a cut of 45 degrees when the head is delivered ( Fig. 12.2 ).

With the next contraction, the head is gently pulled downwards along the longitudinal axis of the baby until the anterior shoulder is delivered under the sub-pubic arch, and then the baby is pulled anteriorly to deliver the posterior shoulder and the remainder of the trunk whilst protecting the perineum from tearing by the emerging posterior shoulders.

The infant will normally cry immediately after birth, but if breathing is delayed, the nasopharynx should be aspirated and, if needed, the baby’s lungs inflated with oxygen using a face mask. If the onset of breathing is further delayed, intubation and ventilation may become necessary. The condition of the baby is assessed at 1 and 5 minutes using the Apgar scoring system ( Table 12.1 ) and again at 10 minutes if the baby is depressed. If the baby is born in poor condition (Apgar score of less than 4 at 1 minute and less than 7 at 5 minutes), the cord should be double-clamped for paired cord blood gas analysis.

Table 12.1

Evaluation of Apgar score at 1 and 5 minutes

	0	1	2
Colour	White	Blue	Pink
Tone	Flaccid	Rigid	Normal
Pulse	Impalpable	<100 beats/min	>100 beats/min
Respiration	Absent	Irregular	Regular
Response	Absent	Poor	Normal

Management of the third stage

Active management of the third stage of labour is recommended, which includes the administration of oxytocin (10I/U) intramuscularly to the mother, followed by late clamping (>2 minutes) and cutting of the cord. When the signs of placental separation are seen, i.e. the lengthening of the cord, trickle of blood and the uterus becoming globular and hard due to contraction and extruding the placenta into the lower segment, the placenta is delivered by controlled cord traction, a method commonly referred to as the Brandt – Andrews technique ( Fig. 12.3 ).

Repair of episiotomy or perineal injury

A careful examination of the mother’s perineum should be made as soon as possible to identify the degree of perineal or genital tract trauma sustained during the birth. Perineal trauma caused either by episiotomy or tearing may be classified as first-, second-, third- or fourth-degree tears. A first-degree tear describes laceration to vaginal and perineal skin only. A second-degree tear involves the posterior vaginal wall and underlying perineal muscles but not the anal sphincter. Third-degree injury to the perineum is damage that involves the anal sphincter complex, and a fourth-degree laceration is injury to the perineum that includes the ano/rectal mucosa.

In the case of a first-degree perineal tear, there is no need for suturing if the skin edges are already apposed, provided the wound is not bleeding. Episiotomies and second-degree lacerations should be sutured to minimize bleeding and to expedite healing. Third- and fourth-degree perineal lacerations should be repaired under epidural/spinal or general anaesthesia by an experienced surgeon in an operating theatre under good lighting conditions. This is discussed in more detail in the next section.

Episiotomy repair

For episiotomy repair, the woman should be placed in the lithotomy position so that a good view of the extent of the wound can be obtained ( Fig. 12.4 ). Repair should only be undertaken with effective analgesia in place using either local anaesthetic agent infiltration or epidural or spinal anaesthesia. Closure of the vaginal wound requires a clear view of the apex of the incision. It is recommended that an absorbable synthetic suture material be used for the repair, using a continuous technique for the vaginal wall and muscle layer and a continuous subcuticular technique for the skin.

On completion of the procedure, it is important to ensure that the vagina is not constricted and that it can admit two fingers easily. In addition, a rectal examination should be performed to confirm that none of the sutures have penetrated the rectal mucosa. If this occurs, the suture must be removed, as it may otherwise result in the formation of a rectovaginal fistula.

Malpresentations

More than 95% of fetuses present with the vertex and are termed normal . Those presenting with other parts of the body (breech, face, brow, shoulder, cord) to the lower segment and cervix are known as malpresentations . There may be a reason for malpresentation, although in most instances there is no identifiable cause. They also present with specific problems in labour and during delivery. In modern obstetrics, the presentation needs to be diagnosed early in labour and appropriate management instituted to prevent maternal or fetal injury.

Breech presentation is discussed in Chapter 8 .

Face presentation

In face presentation, the fetal head is hyperextended so that the part of the head between the chin and orbits, i.e. the eyes, nose and mouth, that can be felt with the examining finger is the presenting part. The incidence is about 1 in 500 deliveries. In most cases, the cause is unknown but is associated with high parity and fetal anomaly, particularly anencephaly. In modern obstetric practice where most pregnant women have an ultrasound scan for fetal abnormalities, it is rare to see such conditions as a cause of face presentation.

Diagnosis

Face presentation is rarely diagnosed antenatally, but rather is usually identified during labour by vaginal examination when the cervix is sufficiently dilated to allow palpation of the characteristic facial features. However, oedema may develop that may obscure these landmarks. If in doubt, ultrasound will confirm or exclude the diagnosis. The position of a face presentation is defined with the chin as the denominator and is therefore recorded as mentoanterior, mentotransverse and mentoposterior ( Fig. 12.5 ).

Management

If the position is mentoanterior, progress can be followed normally with the expectation of spontaneous vaginal delivery. However, if progress is abnormally slow, it is preferable to proceed to caesarean section. In cases of persistent mentoposterior positions, vaginal delivery is not possible without manual or forceps rotation. Because the risk associated with these manoeuvres to the mother and infant is considerable, most obstetricians will perform a caesarean delivery.

Brow presentation

A brow presentation is described when the attitude of the fetal head is midway between a flexed vertex and face presentation ( Fig. 12.6 ) and is the most unfavourable of all cephalic presentations. The condition is rare and occurs in 1 in 1500 births. If the head becomes impacted with a brow as the presenting diameter, the mentovertical diameter (13cm), this is incompatible with vaginal delivery.

Diagnosis and management

The diagnosis is almost always made in labour when the anterior fontanelle, supraorbital ridges and root of the nose are palpable. In the normally grown term fetus, vaginal delivery is not possible as a brow because of the large presenting diameters. Therefore in the vast majority of cases with brow presentation, caesarean section is the method of choice for delivery.

Malposition of the fetal head

Position of the fetal head is defined as the relationship of the denominator to the fixed points of the maternal pelvis. The denominator of the head is the most definable prominence at the periphery of the presenting part. In 90% of cases, the vertex presents with the occiput in the anterior half of the pelvis in late labour, and hence is defined as the ‘normal’ or ‘occipitoanterior’ (OA) position. In about 10% of cases, there may be malposition of the head; i.e. the occiput presents in the posterior half of the pelvis with the occiput facing the sacrum or one of the two sacroiliac joints – the occipitoposterior (OP) position – or the sagittal suture is directed along the transverse diameter of the pelvis – the occipitotransverse (OT) position. Malposition of the vertex is frequently associated with deflexion of the fetal head or varying degrees of asynclitism, i.e. one parietal bone, usually the anterior, being lower in the pelvis with the parietal eminences at different levels. Asynclitism is most pronounced in the OT position. Deflexion and asynclitism are associated with larger presenting diameters of the fetal head, thereby making normal delivery more difficult.

The occipitoposterior position

Some 10–20% of all cephalic presentations are OP positions at the onset of labour, either as a direct OP or, more commonly, as an oblique right or left OP position. During labour, the head usually undertakes the long rotation through the transverse to the OA position, but a few, about 5%, remain in the OP position. Where the OP position persists, progress of the labour may be arrested due to the deflexed attitude of the head that results in larger presenting diameters (11.5cm × 9.5cm) than are found with OA positions (9.5cm × 9.5cm). Prolonged and painful labour associated with backache is a characteristic feature of a posterior fetal position ( Fig. 12.7 ).

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here