Operative delivery

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Chapter 40 Operative delivery

Michael Flynn

Caesarean section

Caesarean section births constitute approximately one-quarter of births in many countries. Although now a relatively safe procedure, emergency caesarean section carries an increased risk of maternal mortality and morbidity.

Indications for caesarean section

Elective

• repeat caesarian section
• abnormal fetal lie
• malpresentation: breech, twins
• placenta praevia
• maternal conditions, including pre-eclampsia, diabetes, neurological disease

Emergency

• presumed fetal distress
• failure to progress

Risk of uterine rupture with labour after caesarean section

Classical caesarean section

The overall risk of rupture after a classical caesarean section is about 6%, with 2% scar dehiscence before labour.

Lower segment caesarean section

There is a 0.3% risk of dehiscence overall, increasing to 0.7% with labour and 0.1% at elective caesarean section.

Trial of vaginal delivery after lower segment caesarean section

Up to 40% of women undergo a repeat caesarean section after one lower segment caesarean section for a non-recurring cause. The risks and benefits of repeat caesarean section and trial of vaginal delivery require consideration when deciding on the mode of delivery.

Risks of caesarean section

Maternal risks

• higher overall maternal mortality rate compared with vaginal delivery, although comparable rates with elective caesarean section
• higher febrile morbidity
• increased blood loss
• anaesthetic risks
• increased risk of deep venous thrombosis

Neonatal risks

• increased risk of respiratory distress secondary to retained lung fluid
• birth trauma

Factors to consider in deciding the mode of delivery

• Number of previous lower segment caesarean sections: only small numbers have been reported regarding trial of vaginal delivery after two caesarean sections.
• Indications for the first caesarean section: the vaginal delivery rates are lowest when the initial indication was for failure to progress.
• Previous vaginal delivery: if the woman has had a previous vaginal delivery, there is a greater likelihood of delivering vaginally again.
• Vaginal delivery can be achieved in up to 75% of trials of labour. There is a tendency for higher vaginal delivery rates if oxytocin is used for augmentation and longer labour is allowed. The use of oxytocin remains controversial.

Symptoms and signs of uterine rupture

• acute continuous abdominal pain
• acute fetal distress
• reduction in contractions
• vaginal bleeding

Complications of caesarean section

Haemorrhage

• Haemorrhage accounts for 6% of maternal deaths associated with caesarean section.
• There are higher risks with placenta praevia, placental abruption, atonic uterus, multiparity and prolonged labour.

Urinary tract

• The risk of bladder injury at caesarean section is lower than 1%.
• This is higher in emergency caesarean sections for prolonged obstructed labour or repeat caesarean section with the bladder adherent to the lower segment.
• Ureteric injuries are very uncommon.

Anaesthetic complications

• Regional anaesthesia is a safer alternative to general anaesthesia.
• Anaesthetic complications include supine hypotension and Mendelson’s acid aspiration syndrome.

Infections

• Wound infections occur in 1%–9% of caesarean sections. There is a higher risk of infection with premature rupture of membranes and prolonged labour.
• Endometritis: there is a 10–20 times higher risk of endometritis after caesarean section compared with vaginal delivery. The higher risk is associated with increased length of labour and chorioamnionitis. The common pathogens include group B streptococcus, Escherichia coli and anaerobes.
• Chest infections are complications for 10% of patients after abdominal surgery. High-risk factors for chest infection include obesity, general anaesthetic, smoking and upper respiratory tract infection.
• Urinary tract infection: there is a 2% risk of urinary tract infection with single catheterisation.
• Antibiotic prophylaxis, given after the clamping of the umbilical cord, has been shown to decrease the risk of postoperative febrile morbidity. This is irrespective of whether the caesarean section was emergency or elective. The choice of antibiotics includes broad-spectrum penicillins and early-generation cephalosporin.
• Thromboembolism accounts for 17% of deaths after caesarean section. The recurrence risk after one episode of deep venous thrombosis is 12%.

Indications for classical caesarean section

• absence of the lower uterine segment (this may occur with extreme prematurity, placenta praevia, or fibroids obscuring the lower segment)
• transverse lie or shoulder presentation
• presence of a uterine constriction ring
• large abnormal baby
• caesarean hysterectomy (commonly for tumours of the cervix)
• conjoint twins

Instrumental delivery

This includes the forceps and vacuum extractor. The indications and prerequisites are similar for both.

Indications

• failure to progress in the second stage
• malposition of the fetal head
• fetal distress during the second stage
• maternal conditions, including pre-eclampsia, neurological conditions and cardiorespiratory diseases

Prerequisites for instrumental delivery

• an indication for the use of instruments
• suitable presenting part
• fully dilated cervix
• membranes ruptured
• clinical assessment not suggestive of absolute cephalopelvic disproportion
• station of presenting part below the ischial spines
• no fetal head palpable abdominally
• position of fetal head (must be known)
• adequate uterine contractions
• empty bladder
• adequate analgesia

Forceps

Types of forceps

• outlet forceps: Wrigley’s forceps
• non-rotational: Neville Barnes’ forceps
• rotational: Kielland’s forceps

Complications

• maternal: genital tract soft tissue injury, increased incidence of episiotomy, bladder and rectal injury
• fetal: facial soft tissue damage, intracranial haemorrhage

Vacuum extractor

Complications

• maternal: genital tract injury
• fetal: swelling on the scalp produced by the vacuum cup (the chignon), which disappears over 1–2 days; scalp markings and abrasions; cephalohaematoma (a collection of blood under the periosteum) in up to 6% of babies delivered with vacuum extraction; subgaleal haemorrhage

Perineal lacerations

Lacerations can occur anywhere along the birth canal, including the uterus, cervix, vagina and perineum.

• First-degree perineal laceration means tearing of the skin of the perineum and mucous membrane of the vagina.
• Second-degree laceration involves the skin and musculature of the perineum. It can involve the external anal sphincter.
• Third-degree laceration involves at least the anal mucosa.

The centrepoint of the perineum is the perineal body. The muscles that blend into this point are the external anal sphincter, levator ani, transverse perineal muscles and bulbocavernosus. The anal sphincter consists of the internal and external layers. The internal sphincter is circular and is situated in the upper two-thirds of the anal canal. The external sphincter consists of three layers. In perineal lacerations, the deep layer is important, as it plays a major role in the continence of flatus and faeces.

Repair of perineal trauma

Up to 70% of women are likely to require perineal repair.

Technique

• The vaginal skin may be repaired with continuous or interrupted sutures.
• The perineal skin closure may be subcuticular or interrupted.
• Comparing the two techniques, studies have shown no difference in the long-term complaints of pain or dyspareunia. However, there appears to be a significant advantage in the reduction of pain, in the short term, when using subcuticular sutures.

Choice of suture

Reports comparing polyglycolic acid and chromic catgut show a definite reduction of pain in the short term when using polyglycolic acid, although no long-term differences were found. Therefore, it appears that the optimal choice in the repair of perineal trauma is the use of polyglycolic acid sutures and subcuticular sutures to the skin.

Episiotomy

Tissues cut by an episiotomy include:

• vaginal epithelium and perineal skin
• bulbocavernosus muscle
• transverse perineal muscles: superficial and deep
• occasionally, the external anal sphincter and levator ani

Therefore, an episiotomy is at least a second-degree perineal laceration.

Indications for episiotomy

• vaginal breech deliveries
• in fetal distress, to expedite delivery
• past history of pelvic floor repair or third-degree tear
• imminent perineal tear
• instrumental delivery

Types of episiotomy

• mid-line
• mediolateral
• J-shaped

Repair of an episiotomy

This has three stages:

• The initial stage of repair commences at the apex of the vaginal laceration. The laceration is repaired down towards the fourchette.
• The second stage consists of repairing the deep muscles of the pelvic floor.
• The final stage is to repair the superficial perineal muscles and skin.

If the anal sphincters are involved, both ends need to be isolated and repaired.

Further reading

Enkin M., Keirse M., Chalmers I. A guide to effective care in pregnancy and childbirth. Oxford: Oxford University Press; 2000.

O’Grady J.P., Gimovsky M.. Instrumental delivery: a lost art?. Progress in obstetrics and gynaecology, Vol. 10. Churchill Livingstone, London, 1992. 183–211

Spong C.Y., Landon M.B., Gilbert S., et al. Risk of uterine rupture and adverse perinatal outcome at term after cesarean delivery. Obstetrics and Gynecology. 2007;110:801-807.

Vacca A. Handbook of vacuum extraction in obstetric practice. London: Edward Arnold; 2003.

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