The rate of operative vaginal delivery has remained fairly constant at around 10-13%. However, there are emerging trends - for example, an increased tendency to conduct the delivery in the operating theatre, increased rate of caesarean section at full dilatation, increasing failures of operative vaginal delivery (especially using the ventouse) and reduced attempts at instrumentation. There has also been a significant increase in the use of vacuum extraction compared with forceps delivery, so that in 2011/12 it accounted for half of the instrumental deliveries.
Although it is now generally well established that there are significant risks associated with rotational and mid-cavity deliveries, there are low morbidity rates with most operative deliveries. It should also be remembered that caesarean section in the second stage of labour is not without considerable morbidity.
The operator should use their skill and judgement to determine the best choice of instrument for the situation. Vacuum extraction and forceps have different risks and benefits. Vacuum extraction can have a higher failure rate and increased risks of cephalohaematoma; it has, however, been shown to be associated with less maternal trauma (particularly pelvic floor injuries and subsequent faecal incontinence) than forceps[4, 7]. Forceps delivery may, however, have a lower rate of neurological problems in the neonate than vacuum extraction or caesarean section.
Preventing assisted delivery
The following factors have been shown to be favourable in avoiding assisted delivery:
- The presence of someone to support the woman during childbirth, especially if they are not a member of staff.
- The mother labours in an upright or left lateral position.
- Avoidance of use of epidural anaesthesia.
NB: there is no evidence that discontinuing an epidural in the second stage of labour or using a partogram to monitor progress will decrease the risk of assisted delivery.
The following factors can reduce the number of mid-cavity or rotational deliveries:
- Using oxytocin in a nulliparous mother with an epidural.
- Delaying active pushing in a nulliparous mother.
Classification of forceps deliveries
Indications for instrumental delivery
They are used to shorten the second stage of labour.
- Presumed, or diagnosed (by fetal blood sampling) compromise.
- To protect the head during breech vaginal delivery.
- To avoid Valsalva manoeuvre (eg, maternal cardiac disease - Class 3 or 4).
- Hypertensive crises.
- Cardiovascular disease, particularly uncorrected malformations.
- Myasthenia gravis.
- Spinal cord injury.
Maternal morbidity increases significantly after three hours of the second stage and further increases after four hours. The most frequent adverse effects in the woman of a prolonged second stage are chorioamnionitis, third- and fourth-degree perineal tears and uterine atony.
- Nulliparous women:
- Delay diagnosed if active second stage ≥2 hours. Most nulliparous women will have delivered after 3 hours
- Multiparous women:
- Delay diagnosed if active second stage ≥1 hour. Most multiparous women will have delivered after 2 hours.
- Maternal fatigue/exhaustion.
- Predisposition to fractures in the fetus.
- Bleeding tendency or active bleeding in the fetus.
- Face presentation and vacuum extractor.
- Vacuum extractor should not be used for gestation of ≤34 weeks. Use with caution at 34-36 weeks of gestation.
Requirements for instrumental delivery
Full discussion and consent should take place with mother/parents.
(Acronym = FORCEPS):
- Fully dilated cervix.
- Occipito-anterior position preferably - OP delivery is possible with Kielland's forceps and vacuum.
- Ruptured membranes.
- Cephalic presentation.
- Engaged presenting part, ie the greater diameter of the baby's head has passed the pelvic brim.
- Pain relief is adequate:
- Vacuum extraction or low forceps - minimum of perineal nerve block.
- Mid-forceps - epidural or pudendal nerve block, or general anaesthetic.
- Sphincter (bladder) empty.
Higher failure rates
These are associated with:
- Maternal body mass index >30.
- Estimated fetal weight >4 kg.
- OP position.
- Mid-cavity deliveries.
These factors should prompt trial of delivery, with preparations to proceed to caesarean section immediately if unsuccessful.
- The procedure should be abandoned if no descent is seen with three pulls.
- An incident report should be completed.
- Using differing instruments sequentially is not recommended[8, 13]. However, the operator should balance this decision against the risks of subsequent caesarean section.
After delivery care
All women should have a thorough examination of the perineum with careful rectal examination to ensure no third-degree tear is missed.
Routine paracetamol and diclofenac should be prescribed, if there are no contra-indications.
There is no evidence that these should be routinely prescribed.
Each woman should be individually assessed for risk - eg, immobility.
The woman should have a fluid volume chart for the first 24 hours, to assess for retention and function. Referral to physiotherapy may be appropriate.
The woman should be reassured that there is a high chance that any future delivery will be vaginal. Some women are very traumatised by an operative vaginal delivery and have a fear of subsequent childbirth. If this is severe they may have a form of post-traumatic stress disorder named tocophobia. There is no evidence on how to prevent psychological problems following instrumental delivery. However, it is recommended that the woman be reviewed by the obstetrician who conducted the delivery, to discuss the reasons for it and any concerns she may have.
- Vacuum-assisted delivery has a lower rate of successful delivery.
- Vacuum-assisted delivery is associated with less use of anaesthesia and fewer severe maternal injuries.
- However, use of forceps following failed vacuum extraction can lead to a high level of damage to the mother. Adverse symptoms such as urinary and faecal incontinence are common in mothers with both forms of assisted delivery[7, 17].
- Third- and fourth-degree tears are more common with operative delivery, due to the reduced time for stretching of the perineum.
- The risk of pelvic organ prolapse following operative delivery is still unclear: it is associated with pregnancy; it is less likely following caesarean delivery than a vaginal delivery; it may be more common after forceps delivery[18, 19].
- Cephalohaematomas and retinal haemorrhages are well recognised sequelae of vacuum extraction but usually have no long-term adverse effects.
Suitable subjects may include:
- Rate of use.
- Ratio of vacuum extraction to forceps delivery.
- Rate of failures.
- Incidence of maternal tears.
- Neonatal trauma.
- Standard of documentation.
Did you find this information useful?
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