No working epidural
Good expulsive efforts
Good contractions
No marked caput/moulding
Birth canal is roomy
Favour forceps if:
Dense epidural block
No good expulsive efforts
Contractions not good
Marked caput/moulding
Birth canal is not roomy
Select manual rotation and traction forceps if:
Good analgesia
Rotational movement is possible
Descent of fetal head with maternal effort
Birth canal is roomy
Absence of signs of true CPD
Select Kielland’s if:
Dense regional block
Descent of fetal head with maternal effort
Birth canal is roomy
Absence of signs of true CPD
Select vacuum (with metal cup or Kiwi Omnicup) if:
No dense regional block
Good maternal effort
Descent of fetal head with maternal effort
No significant caput/moulding
No signs of true CPD
1 A method should only be used if the operator is adequately trained. The operator should use the instrument he or she prefers.
2 The mother’s preferences should be taken into account where appropriate.
3 Vacuum delivery is contraindicated at gestational age <34 weeks and face presentation.
4 Fetal status in itself should not determine the choice of instrument. There is no evidence that one instrument leads to quicker delivery than another.
There have been no recent RCTs comparing vacuum and forceps, but a systematic review of existing RCTs reported that use of the vacuum extractor was associated with significantly less maternal trauma (OR 0.41 [95% CI 0.33–0.50]), and this is one of its main advantages. It also reported that vacuum was associated with more completed deliveries (OR 1.69 [95% CI 1.31–2.19]) than forceps delivery [25]. However, this is potentially misleading, as attempted vacuum delivery has a higher failure rate than forceps as a first line instrument, with failed vacuum deliveries frequently completed by forceps. Vacuum failure rates of between 20% and 30% have been reported in two RCTs comparing different vacuum devices, with higher failure rates for the handheld disposable vacuum device [26,27]. Failure of vacuum delivery is three to four times more likely with a fetal malposition. An updated Cochrane review places a greater emphasis on choosing an appropriate instrument based on differing risks and benefits [28]. In a prospective cohort study of women with complex deliveries transferred to theatre for arrested progress in the second stage of labour, attempted forceps was more likely to result in completed vaginal delivery than attempted vacuum (63% vs. 48%, p < 0.01) [18].
Operative vaginal delivery is associated with increased pelvic floor morbidity. Forceps delivery incurred a higher risk of third-degree laceration than vacuum in two population-based studies (OR 1.94 [95% CI 1.30–2.89] and OR 3.33 [95% CI 2.97–3.74], respectively) [29,30]. In a randomized trial assessing anal sphincter function, symptoms of altered faecal continence were significantly more common following forceps delivery than vacuum [31]. More reassuringly, there was no difference in rates of urinary and bowel dysfunction at five-year follow-up of a previous randomized controlled study comparing forceps and vacuum delivery [32].
The neonatal outcome is critical to the debate on the role of OVD in modern obstetric practice and on the choice of instrument. The operator’s expertise may ultimately determine the preferred mode of delivery, but each obstetrician should have the necessary skills to deliver the baby by the safest means according to the degree of fetal urgency. The neonatal morbidity related to operative delivery needs to be evaluated where OVD is successfully achieved, where a failed attempt at OVD results in CS, and where delivery is by immediate CS. In a systematic review of trials comparing vacuum extraction with forceps delivery, the use of the vacuum extractor was associated with an increase in neonatal cephalhaematoma and retinal haemorrhages, whereas forceps delivery was associated with an increase in facial palsy [25]. If speed is of the essence, particularly in the presence of suspected fetal hypoxia, then there is a higher chance of completed OVD with forceps as a single instrument than vacuum, thereby avoiding the risks of sequential use of instruments [33]. However, a population-based cohort study in Scotland (n = 1021) reported no difference between the decision-to-delivery intervals (DDIs) for forceps and vacuum deliveries but a 15 min difference between the DDIs for deliveries completed in a labour room compared to those requiring transfer to an operating theatre [34]. Different types of morbidity occur with vacuum and forceps and in all cases a backup plan needs to be in place in the event of abandoning or failing an attempted OVD [2].
In situations where the baby is born in poor condition, fears about early morbidity are quickly replaced by concerns about survival and long-term neurological disability. A large Australian population-based study reported an increased risk of neonatal encephalopathy following both OVD and emergency CS (OR 2.3 [95% CI 1.2–4.7] and OR 2.2 [95% CI 1.0–4.6], respectively) [35]. Moderate and severe neonatal encephalopathy are strongly associated with cerebral palsy and death. The use of sequential instruments, particularly vacuum and forceps, has been associated with scalp trauma, intracranial haemorrhage and neonatal death [33]. Reassuringly, a five-year follow-up of the UK second stage prospective cohort study reported low overall rates of neurodevelopmental morbidity with comparable outcomes for each mode of delivery [36].
The relative merits of vacuum extraction and forceps are summarized in Table 8.2 [2,25].
| Vacuum compared to forceps is: | |
| More likely to fail at achieving vaginal delivery | OR 1.7; 95% CI 1.3–2.2 |
| More likely to be associated with cephalhaematoma | OR 2.4; 95% CI 1.7–3.4 |
| More likely to be associated with retinal haemorrhage | OR 2.0; 95% CI 1.3–3.0 |
| More likely to be associated with maternal worries about baby | OR 2.2; 95% CI 1.2–3.9 |
| Less likely to be associated with significant maternal perineal and vaginal trauma | OR 0.4; 95% CI 0.3–0.5 |
| No more likely to be associated with delivery by caesarean section | OR 0.6; 95% CI 0.3–1.0 |
| No more likely to be associated with low five minute Apgar scores | OR 1.7; 95% CI 1.0–2.8 |
| No more likely to be associated with the need for phototherapy | OR 1.1; 95% CI 0.7–1.8 |
Manual rotation either with or without traction forceps has been explored as a strategy to correct fetal malpositions and is recommended in the guideline of the Society of Obstetricians and Gynaecologists of Canada [37]. A large, retrospective cohort study reported a reduction in caesarean delivery associated with the use of manual rotation (9% versus 41%, p < 0.001) [38]. Of the 731 women in this study who underwent manual rotation, none experienced an umbilical cord prolapse and there was no difference in either birth trauma or neonatal acidaemia between neonates who had experienced an attempt at manual rotation versus those who had not. Given these data, manual rotation of the fetal occiput in the setting of fetal malposition in the second stage of labour warrants further evaluation as a potential strategy to consider before moving to OVD or caesarean delivery.
Kielland’s rotational forceps has decreased in popularity, reflecting concerns about morbidity but perhaps more realistically as a result of the need for greater obstetric skill. Two recent studies compared rotational vacuum, manual rotation with forceps and Kielland’s rotational forceps and reported similar maternal and neonatal morbidity rates but a higher failure rate with attempted rotational vacuum delivery [39,40].
Deciding Between Operative Vaginal Delivery and Caesarean Section
Rotational delivery and mid-cavity arrest in the second stage of labour present the obstetrician with a choice between a potentially difficult operative vaginal delivery and CS at full dilatation, each with inherent risks. In a prospective cohort study of women transferred to theatre for second stage arrest, CS was associated with an increased risk of major haemorrhage (adjusted OR 2.8 [95% CI 1.1–7.6]) and prolonged hospital stay (OR 3.5 [95% CI 1.6–7.6]) [18]. However, caesarean delivery (OR 0.63 [95% CI 0.38–1.00]) and major haemorrhage were less likely with delivery by an experienced obstetrician (OR 0.5 [95% CI 0.3–0.9]). High rates of third- and fourth-degree tears are reported following OVD and there was a three-fold increased risk of urinary incontinence at three years following OVD compared to second stage CS [41]. The comparable morbidity at CS relates to extension of the uterine incision into the cervix, vagina or broad ligaments. Long-term follow-up studies will determine whether this results in subsequent difficult deliveries or an increased risk of uterine rupture.
To date, there has been inconsistency in the reported early neonatal morbidity when comparing OVD with CS in the second stage of labour. In a prospective cohort study of women transferred to theatre in the second stage of labour, delivery by CS was associated with an increased risk of admission to the special care baby unit (SCBU) compared to OVD (OR 2.6 [95% CI 1.2–6.0]) [18]. Of note, there were equal rates of pathological FHR tracings in the two groups. However, neonatal trauma was significantly less common following caesarean delivery compared to operative vaginal delivery (OR 0.4 [95% CI 0.2–0.7]). A low umbilical artery pH was more frequently recorded following failed operative vaginal delivery, but there was no increase in admissions to SCBU. Similarly, a recent US study found no increase in neonatal morbidity among women who had a failed OVD when non-reassuring fetal heart rate tracings were accounted for [42]. In a further large North American population-based study, the sequential use of vacuum and forceps was associated with an increased need for mechanical ventilation in the infant [43]. These findings suggest that neonatal complications could be reduced, with careful selection of cases for attempted operative vaginal delivery and a judicious choice of instrument.
A previous delivery experience can have important implications for future pregnancies, not least whether a woman would contemplate another pregnancy. In the UK second stage prospective cohort study, women were far more likely to aim for a future vaginal delivery (79% vs. 39%) and to achieve a subsequent vaginal delivery (78% vs. 31%) following OVD than CS, although fear of childbirth was a frequently reported reason for avoiding a further pregnancy in both groups [44,45]. Women who have experienced a previous CS at full dilatation generate anxiety in subsequent labours relating to the risk of further emergency CS and potential uterine rupture. Mid-cavity and rotational OVD have become unpopular in the United States and are increasingly abandoned in favour of CS. This may be a short-sighted view, however, if one fails to consider the outcome of future deliveries in the assessment of overall morbidity.
Clearly, choice of operative delivery in the second stage of labour presents a difficult risk–benefit dilemma in terms of short- and long-term maternal and infant outcomes. Caesarean section at full dilatation with anhydramnios and a deeply engaged fetal head is a difficult procedure. This is reflected in high rates of major obstetric haemorrhage, extension of the uterine incision and prolonged hospital admission. These risks must be balanced with the potential for pelvic floor trauma and neonatal injury with OVD. Although there is a published protocol for a Cochrane systematic review comparing OVD with CS for difficult deliveries in the second stage of labour, as yet there have been no RCTs addressing this important question. At present, the decision relies on experience, judgement and clinical skill.
Conclusion
Decisions regarding the most appropriate management of prolonged second stage of labour continue to be challenging. Individual clinical circumstances, maternal preferences and the skill of the obstetric team will influence the approach taken. A balance needs to be achieved between avoiding unnecessary intervention and preventing avoidable morbidity. Every woman has a right to expect high-quality care in labour, and in the event of a prolonged second stage she should be assessed carefully and advised on a course of action that will result in a safe and timely delivery. Most women who have reached the second stage of labour will prefer an OVD to a CS if this can be achieved safely with a minimum of morbidity. In such circumstances women should be encouraged that the probability of a spontaneous vaginal birth in a subsequent pregnancy is very high. Some women will express a preference for a CS and should be counselled on the differences between lift-out, low-cavity, mid-cavity and rotational OVDs, and on the implications of a second stage CS for subsequent births. Good decision making is founded on mutual respect and trust between the labouring woman and her care givers. The skilled obstetrician will demonstrate competency in both the technical and non-technical aspects of care in the second stage of labour.
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