Operative delivery

Published on 09/03/2015 by admin

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Last modified 09/03/2015

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47

Operative delivery

Introduction

The phrase ‘operative delivery’ is used to describe both instrumental vaginal delivery and caesarean section. It may be indicated to expedite delivery in the presence of fetal distress, or for ‘delay’ or failed progress, despite good contractions and maternal effort. The choice between instrumental delivery and caesarean depends partly on the stage of labour, with instrumental delivery possible only in the second stage; even then, specific criteria must be met. Caesarean section can be used in both the first and second stages of labour and after a failed or abandoned attempt at instrumental delivery.

Instrumental vaginal delivery

The most common indications for instrumental delivery are presumed fetal distress (e.g. heart rate abnormalities, meconium, low pH on fetal blood sampling) and second-stage delay. The criteria in Box 47.1 must be fulfilled before the procedure can be carried out.

Box 47.1

Criteria for instrumental vaginal delivery

icon01.gif Consent from the mother obtained

icon01.gif The cervix fully dilated with the membranes ruptured

icon01.gif The head fully engaged, at spines or below, with no head palpable abdominally

icon01.gif The position of the head known

icon01.gif The bladder empty

icon01.gif Analgesia satisfactory (perineal infiltration and pudendal blocks usually suffice for mid-cavity and ventouse deliveries but epidural or spinal analgesia is required for Kielland’s rotational forceps)

A careful assessment is required prior to instrumental delivery, beginning with abdominal palpation. There should be no head palpable above the symphysis pubis although occasionally one-fifth is palpable in occipitoposterior positions. One of the most difficult parts of an instrumental delivery is being completely certain of the fetal head position prior to applying the forceps or ventouse (also known as vacuum-device). A systematic examination should determine the orientation of both the anterior and posterior fontanelles as the most common mistake is diagnosing an occipitoanterior position when in fact it is occipitoposterior. If there is a suspicion from palpation of the sutures that the fetal head is occipitotransverse, it is often helpful to try to feel for an ear anteriorly under the symphysis pubis. Some obstetricians use transabdominal ultrasound to confirm the position of the fetal head, others will seek a second opinion, or re-examine the patient in an operating theatre with good anaesthesia, where early recourse to caesarean section is possible. Incorrect assessment of the fetal head position or station results in a higher rate of failed instrumental delivery and morbidity for the mother and baby.

Operative vaginal delivery requires a multidisciplinary approach to maximize the likelihood of success and minimize maternal and fetal trauma. In addition to the attending midwife, a practitioner experienced in neonatal resuscitation should be present and the anaesthetist is frequently involved in the provision of adequate analgesia. Umbilical artery and vein acid–base status should be routinely recorded immediately after delivery.

The choice is between forceps and the ventouse.

Forceps delivery

There are three main types of obstetric forceps (Fig. 47.1):

f47-01-9780702054082

Fig. 47.1Selected types of forceps and ventouse cups.

The forceps, from left to right, are Kielland’s, Haig Ferguson’s and Wrigley’s. The orange tubing is attached to an O’Neill occipitoanterior metal cup, and the blue ventouse is a silastic cup.

1. Low-cavity outlet forceps (e.g. Wrigley’s, see History box), which are short and light and are used when the head is on the perineum

2. Mid-cavity forceps (e.g. Haig Ferguson’s, Neville-Barnes’, Simpson’s, see History boxes), for use when the sagittal suture is in the anteroposterior plane (usually occipitoanterior)

3. Kielland’s forceps (see History box) for rotational delivery to an occipitoanterior position. The reduced pelvic curve allows rotation about the axis of the handle.

History

Arthur Wrigley (1902–1983) was born in Lancashire and opposed the use of forceps when the fetal head was high. His own forceps, he said, were designed ‘so that it is impossible to exert a tremendous pull’.

History

James Haig Ferguson (1862–1934), from Edinburgh and related to Field Marshall Earl Haig, modified Simpson’s forceps by shortening the handle and placing slots to allow the application of traction tapes; this increased fetal head flexion.

History

William Neville (d. 1904) and Robert Barnes (1817–1907), both from England, first displayed their forceps at the Obstetrical Society of London in 1867. The forceps were designed to grasp the moulded fetal head at or above the pelvic brim as an alternative to craniotomy or caesarean section.

History

James Young Simpson (1811–1870), from Edinburgh, had a huge impact on obstetric practice. In addition to his forceps, he introduced chloroform to obstetric anaesthesia (quoting Galen with ‘pain is useless to the pained’) and developed a forerunner to the ventouse.

History

Christian Kielland (1871–1941) was born in Zululand and was of Norwegian descent. His design of straighter forceps permitted head rotation, and he set strict criteria to ensure their safe use.

Low- or mid-cavity non-rotational forceps

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