Verzögerung der Wehen und instrumentelle Entbindung

The rate of operative vaginal delivery has remained fairly constant at around 10-13%¹. 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 instrumentation². 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 deliveries³.

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 deliveries⁴. It should also be remembered that caesarean section in the second stage of labour is not without considerable morbidity⁵.

The operator should use their skill and judgement to determine the best choice of instrument for the situation⁶. 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 forceps⁴⁷. Forceps delivery may, however, have a lower rate of neurological problems in the neonate than vacuum extraction or caesarean section⁸.

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 delivery⁹.

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 mother¹⁰.

Classification of forceps deliveries

Indications for instrumental delivery

They are used to shorten the second stage of labour.

Fetal

• Presumed, or diagnosed (by fetal blood sampling) compromise.

• To protect the head during breech vaginal delivery¹¹.

Mütterlicherseits

• To avoid Valsalva manoeuvre (eg, maternal cardiac disease - Class 3 or 4).

• Hypertensive crises.

• Cardiovascular disease, particularly uncorrected malformations.

• Myasthenia gravis.

• Verletzung des Rückenmarks.

Inadequate progress⁶

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 atony¹².

• 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.

Kontraindikationen

• 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 weeks¹. 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.

A mediolateral episiotomy should be performed prior to an instrumental delivery to reduce the risk of third- and fourth-degree tears⁶. The evidence to support this, however, is not robust¹.

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 recommended⁸¹³. However, the operator should balance this decision against the risks of subsequent caesarean section¹.

After delivery care

Perineal examination

All women should have a thorough examination of the perineum with careful rectal examination to ensure no third-degree tear is missed³.

Analgesie

Routine paracetamol and diclofenac should be prescribed, if there are no contra-indications¹.

Antibiotika

There is no evidence that these should be routinely prescribed¹⁴.

Thromboseprophylaxe

Each woman should be individually assessed for risk - eg, immobility.

Bladder care

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.

Future deliveries

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 have¹.

Ergebnisse

• Vacuum-assisted delivery has a lower rate of successful delivery¹⁵.

• Vacuum-assisted delivery is associated with less use of anaesthesia and fewer severe maternal injuries¹⁶.

• 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 delivery⁷¹⁷.

• Third- and fourth-degree tears are more common with operative delivery, due to the reduced time for stretching of the perineum³.

• 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 delivery¹⁸¹⁹.

• Cephalohaematomas and retinal haemorrhages are well recognised sequelae of vacuum extraction but usually have no long-term adverse effects⁴.

Audit³

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.