OPERATIVE VAGINAL DELIVERY

VACUUM EXTRACTION

 
 
 
Operative Vaginal Delivery Rates.
Delivery with a vacuum cup

Obstetricians should be confident and competent in the use of forceps and vacuum extractor for both rotational and non-rotational operative vaginal deliveries. The anatomy of the birth canal and the fetal head must be understood as a prerequisite to becoming skilled in the safe use of the forceps or vacuum extractor. The RCOG recommends that obstetricians achieve experience in spontaneous vaginal delivery prior to commencing training in operative vaginal delivery. The goal of operative vaginal delivery is to mimic spontaneous vaginal birth, thereby expediting delivery with a minimum of maternal or neonatal morbidity.

There has been an increasing awareness of the potential for morbidity for both the mother and the baby. The risk of traumatic delivery in relation to forceps, particularly rotational procedures, has been long established,7901 although with careful practice overall rates of morbidity are low.8701

In 1998, the US Food and Drug Administration (FDA) issued a warning about the potential dangers of delivery with the vacuum extractor. FDA This followed several reports of infant fatality secondary to intracranial haemorrhage. In addition, there has been a growing awareness of the short- and long-term morbidity of pelvic floor injury following operative vaginal delivery.0101, 0102,0301, 0401, 0501 It is not surprising, therefore, that there has been an increase in litigation relating to obstetric delivery. Caesarean section in the second stage of labour, however, also carries significant morbidity and implications for future births. If we are to offer women the option of a safe operative vaginal delivery, we need to improve our approach to clinical care. The goal should be to minimise the risk of morbidity and, where morbidity occurs, to minimise the likelihood of litigation, without limiting maternal choice.

Reducing operative vaginal delivery rates.

As As operative vaginal delivery can be associated with maternal and neonatal morbidity, strategies that reduce the risk of operative vaginal delivery should be used.

Continuous support for women during childbirth can reduce the incidence of operative vaginal delivery, particularly when the carer was not a member of staff.0302 Use of any upright or lateral position, compared with supine or lithotomy positions is associated with a reduction in assisted deliveries.0402 Epidural analgesia appears to be effective in reducing pain during labour. However, women who use this form of pain relief are at increased risk of having an instrumental delivery. Epidural analgesia had no statistically significant impact on the risk of caesarean section, maternal satisfaction with pain relief and long-term backache and does not appear to have an immediate effect on neonatal status as determined by Apgar scores.0502

Using a partogram leads to fewer operative births and less use of oxytocin.0503 An oxytocin infusion may reduce the high rate of operative delivery in primigravidae associated with epidural analgesia provided that the fetal occiput is in an anterior position at the onset of the second stage of labour8901 Extreme caution should be taken before using oxytocin for the second stage in multiparous women. Each woman should be assessed individually for the management of the second stage.

In the study by Fitzpatrick et al,0202 rates of instrumental delivery were similar following immediate and delayed pushing, in association with epidural analgesia. 0303 The RCOG, however, sites a recent meta-analysis demonstrated that primiparous women with epidurals were likely to have fewer rotational or mid-cavity operative interventions when pushing was delayed for 1?2 hours or until they had a strong urge to push. Upright positions in the second stage with epidurals were associated with a non-significant reduction in the risk of both instrumental delivery (relative risk (RR) = 0.77, 95% confidence interval (CI) = 0.46-1.28) and caesarean section (RR = 0.57, 95% CI = 0.28-1.16).0504

There is no difference between the rates of operative vaginal delivery for combined spinal-epidural and epidural techniques.0304

 

Classification for operative vaginal delivery.

Classification  

Outlet

Fetal scalp visible without separating the labia

Fetal skull has reached the pelvic floor

Sagittal suture is in the antero-posterior diameter or right or left occiput anterior or posterior position

(rotation does not exceed 45 degrees)

Fetal head is at or on the perineum

Low

Leading point of the skull (not caput) is at station plus 2 cm or more and not on the pelvic floor

There are 2 subdivisions:

(a) rotation of 45 degrees or less

(b) rotation more than 45 degrees

 

Mid

Fetal head is 1/5 palpable per abdomen

Leading point of the skull is above station plus 2 cm but not above the ischial spines

Two subdivisions (a) rotation of 45 degrees or less

                              (b) rotation more than 45 degrees

 

High

Not included in classification

Table 1 Classification of Vaginal Operative Delivery

 

Indications for operative vaginal delivery.

Operators should be aware that no indication is absolute and should be able to distinguish standard from special indications.

Operative intervention is used to shorten the second stage of labour. It may be indicated for conditions of the fetus or of the mother (Table 2).

Fetal

Presumed fetal compromise - fetal distress

Maternal

Medical indications to avoid Valsalva (e.g. cardiac disease Class III or IV, a hypertensive crises, cerebral vascular disease, particularly uncorrected cerebral vascular malformations, myasthenia gravis, spinal cord injury)

Inadequate Progress:

The question of when to intervene should involve balancing the risks and benefits of continuing pushing as against operative delivery.

 

  • Nulliparous women: lack of continuing progress for three hours (total of active and passive second stage labour)  with regional anaesthesia, or two hours without regional anaesthesia

In a retrospective cohort study of 15,759 nulliparous, term, cephalic, singleton births at the University of California,0403 San Francisco, between 1976 and 2001, the second stage of labor was divided into 1-hour intervals. Increasing rates of caesarean delivery, operative vaginal delivery, and perineal trauma were associated with the second stage beyond the first hour. In multivariate analysis, the >4-hour interval group had higher rates of cesarean delivery, operative vaginal deliveries, 3rd- or 4th-degree perineal lacerations , and chorioamnionitis. There were no differences in neonatal acid-base status associated with length of second stage. It was concluded that although the length of the second stage of labour was not associated with poor neonatal outcome, a prolonged second stage is associated with increased maternal morbidity and operative delivery rates.

  • Multiparous women: lack of continuing progress for two hours (total of active and passive second stage labour) with regional anaesthesia, or one hour without regional anaesthesia

 

  • Maternal fatigue/exhaustion

Table 2 Indications for operative delivery.

There is no evidence that elective operative delivery for inadvertent dural puncture is of benefit, unless the woman has a headache that worsens with pushing.9301

Contraindications to operative vaginal delivery.

 

Fetal bleeding disorders (e.g. alloimmune thrombocytopenia) or a predisposition to fracture (e.g. osteogenesis imperfecta) are relative contraindications to operative vaginal delivery. However, there may be considerable fetal risk if the head has to be delivered abdominally from deep in the pelvis.

In a postal survey of members and fellows of The Royal College of Obstetricians and gynaecologists,0601 21% thought elective caesarean section is indicated in all fetuses known to be at risk of being affected by haemophilia. Eighty-four percent considered vacuum extraction unsafe in these cases, but 76% would consider the use of low forceps.

The vacuum extractor is contraindicated with a face presentation. It has been suggested that it should not be used at gestations of less than 36 weeks because of the risk of cephalhaematoma and intracranial haemorrhage.

In a retrospective, observational study9501 covered 61 infants delivered vaginally with vacuum extraction versus 122 matched controls delivered spontaneously. All infants were at < 37 weeks of gestation, with birth weights ranging from 1,500 to 2,499 g. Main neonatal outcomes studied were Apgar scores, umbilical artery blood pH and base excess, intraventricular haemorrhage, admission to the neonatal intensive care unit and length of hospital stay. There was a decreased need for episiotomies in the vacuum-assisted deliveries versus the controls (41% versus 57%). Neonatal morbidity was not significantly different in infants with vacuum-assisted deliveries. Vacuum extraction does not seem to increase neonatal morbidity in preterm infants with birth weights of 1,500-2,499 g.

At present, the RCOG recommends avoiding the use of vacuum below 34 weeks because of the susceptibility of the preterm infant to cephalohaematoma, intracranial haemorrhage and neonatal jaundice. There is insufficient evidence to establish the safety of the vacuum at gestations between 34 and 36 weeks.

The risk of vertical transmission of hepatitis C virus appears to be related to the level of viraemia in the pregnant mother and not to the route of delivery. However, it is sensible to avoid difficult operative delivery where there is an increased chance of fetal abrasion or scalp trauma, as it is to avoid fetal scalp clips or blood sampling during labour.

Forceps and vacuum extractor deliveries before full dilatation of the cervix are contraindicated. There are a few exceptions which include a prolapsed cord at 9 cm in a multiparous woman or a second twin. Forceps are indicated for the aftercoming head of the breech and in situations where maternal effort is impossible or contraindicated.

Pre-requisites for operative vaginal delivery.

 

Full abdominal and vaginal examination

 Head is ≤ 1/5 palpable per abdomen

 Vertex presentation

 Cervix is fully dilated and the membranes ruptured

Exact position of the head can be determined so proper placement of the instrument can be achieved

Pelvis is deemed adequate

 

Mother

>Informed consent must be obtained and clear explanation given

>Appropriate analgesia is in place, for mid-cavity rotational deliveries this will usually be a regional block

>A pudendal block may be appropriate, particularly in the context of urgent delivery

>Maternal bladder has been emptied recently

>Indwelling catheter should be removed or balloon deflated

>Aseptic techniques

Staff

>Operator must have the knowledge, experience and skills necessary to use the instruments

>

Adequate facilities and back-up personnel are available

>Back-up plan in place in case of failure to deliver

>Anticipation of complications that may arise (e.g. shoulder dystocia, postpartum haemorrhage)

>Personnel present who are trained in neonatal resuscitation

 Table 3. Pre-Requisites for Operaive Vaginal Delivery

The goal of operative vaginal delivery is to mimic spontaneous vaginal birth, thereby expediting delivery with a minimum of maternal or neonatal morbidity. The complexity of the delivery is related to the type of delivery, as classified in Table 1. Mid-cavity and rotational deliveries, independent of the type of instrument used, demand a high level of clinical and technical skill and the operator must have received adequate training.0503

Inadequate training may be a key contributor to adverse outcomes and training is central to patient safety initiatives.0305 Neonatal trauma is associated with initial unsuccessful attempts at operative vaginal delivery by inexperienced operators.0404 Formal education and training of medical staff did not influence the success rate of instrumental delivery but was associated with improved safety for both mother and baby.

 

Place for operative vaginal delivery.

Operative vaginal births that have a higher rate of failure should be considered a trial and conducted in a place where immediate recourse to caesarean section can be undertaken.

Higher rates of failure are associated with:

  • maternal body mass index greater than 30
  • estimated fetal weight greater than 4000 g or clinically big baby
  • occipito-posterior position
  • mid-cavity delivery or when 1/5 head palpable per abdomen.

At mid-cavity, the biparietal diameter is still above the level of the ischial spines. Failure rates are higher at this station. High maternal body mass index (greater than 30), neonatal birth weight greater than 4000 g, and occipito-posterior positions are also indicators of increased failure.0103 Operative deliveries that are anticipated to have a higher rate of failure, therefore, should be considered a trial of labour and conducted in a place where immediate recourse to caesarean can be undertaken. Failed instrumental delivery performed as a trial of forceps and/or vacuum in a setting where a cesarean section can follow promptly is not associated with increased morbidity of either mother or baby.9701

There is insufficient evidence to assess the benefits and risks of conducting operative vaginal birth in midwifery led units.

Which instrument for operative vaginal delivery?

The operator should choose the instrument most appropriate to the clinical circumstances and their level of skill. Forceps and vacuum extraction are associated with different benefits and risks. The options available for rotational delivery include Kielland forceps, manual rotation followed by direct traction forceps or rotational vacuum extraction. Rotational deliveries should be performed by experienced operators, the choice depending upon the expertise of the individual operator.

Metal cups appear to be more suitable for 'occipito-posterior', transverse and difficult 'occipito-anterior' position deliveries. The soft cups seem to be appropriate for straightforward deliveries.0002 Soft cups are significantly more likely to fail to achieve vaginal delivery (odds ratio 1.65, 95% confidence interval 1.19 to 2.29). However, they were associated with less scalp injury. The soft cups seem to be appropriate for straightforward deliveries.

In the review by Johanson and Menon,0003 ten trials were included. Use of the vacuum extractor for assisted vaginal delivery when compared to forceps delivery was associated with:

  • significantly less maternal trauma (odds ratio 0.41, 95% confidence interval 0.33 to 0.50)
  • and with less general and regional anaesthesia.
  • there were more deliveries with vacuum extraction (odds ratio 1.69, 95% confidence interval 1.31 to 2.19).
  • fewer caesarean sections were carried out in the vacuum extractor group.
  • the vacuum extractor was associated with an increase in neonatal cephalhaematomata and retinal haemorrhages.
  • serious neonatal injury was uncommon with either instrument.

It was concluded that the use of the vacuum extractor rather than forceps for assisted delivery appears to reduce maternal morbidity. The reduction in cephalhaematoma and retinal haemorrhages seen with forceps may be a compensatory benefit.

There is no evidence to suggest that at five years after delivery use of the ventouse or forceps has specific maternal or child benefits or side effects.9901

The data available from the published controlled trials cannot be analysed separately to compare vacuum and forceps in their use for rotational deliveries.

Abandoning operative vaginal delivery.

Operative vaginal delivery should be abandoned where there is no evidence of progressive descent with each pull or where delivery is not imminent following three pulls of a correctly applied instrument by an experienced operator.  Adverse outcomes, including unsuccessful forceps or vacuum delivery, should trigger an incident report as part of effective risk management processes.

The use of multiple instruments was associated with increased neonatal trauma (adjusted OR 3.1, 95% CI 1.5, 6.8; adjusted OR 4.4, 95% CI 1.3, 14.4, for completed and failed deliveries, respectively). Excessive pulls and multiple instrument use were associated with an initial attempt at vaginal delivery by an inexperienced operator, 25/48 (52%) and 34/75 (45%). 0305

The bulk of malpractice litigation results from failure to abandon the procedure at the appropriate time, particularly the failure to eschew prolonged, repeated or excessive traction efforts in the presence of poor progress. Adverse events, including unsuccessful forceps or vacuum extraction, birth trauma, term baby admitted to the neonatal unit, low Apgar scores (Apgar less than 7 at 5 minutes) and cord arterial pH less than 7.1 should trigger an incident report and review, if necessary, as part of effective risk management processes.

Sequential use of instruments for operative vaginal delivery.

The use of sequential instruments is associated with an increased risk of trauma to the infant. However, the operator must balance the risks of a caesarean section following failed vacuum extraction with the risks of forceps delivery following failed vacuum extraction.

The use of outlet forceps following failed vacuum extraction may be judicious in avoiding a potentially complex caesarean section. Caesarean section in the second stage of labour is associated with an increased risk of major obstetric haemorrhage, prolonged hospital stay and admission of the baby to SCBU compared to completed instrumental delivery.0103 Sequential use of instrumental delivery carries a significantly higher neonatal morbidity than when a single instrument is used.0306

Ezenagu et al9901 found that the prudent use of sequential instruments at operative vaginal delivery did not engender higher rates of maternal or neonatal morbidity whereas others concluded that sequential use of vacuum and forceps is associated with increased risk of both neonatal and maternal injury.0104

The sequential use of instruments should not be attempted by an inexperienced operator without direct supervision and should be avoided wherever possible.

Episiotomy and operative vaginal delivery.

   

If obstetric indications necessitate forceps delivery, performance of an episiotomy decreases the risk of perineal tears of all degrees. When analyzing the type of episiotomy, mediolateral episiotomy seems to be more protective against perineal trauma in women undergoing forceps delivery.0307

The role of routine episiotomy for operative vaginal delivery is poorly evaluated and warrants further research.

Post Delivery Management.

   

Mid-cavity delivery, prolonged labour and immobility are risk factors for thromboembolism. Women should be reassessed after delivery for risk factors for venous thromboembolism and considered for thromboprophylaxis if necessary.

Paracetamol and ibuprofen were rated similarly as analgesicsfor perineal pain. Ibuprofen may be the preferred choice because it is less expensive and requires less nursing time to dispense. Further studies need to address improved analgesia for women with forceps-assisted deliveries.0105

Care is required to ensure appropriate bladder function. Clinically overt postpartum urinary retention complicates approximately 1 in 200 vaginal deliveries, with most resolving before hospital dismissal. Factors that are independently associated with its occurrence include instrument-assisted delivery and regional analgesia.0203 Persistent postpartum urinary retention in contemporary obstetric practice is rare but may be associated with long-term bladder dysfunction. Early diagnosis and intervention are required to prevent irreversible bladder damage.0106 The timing and volume ofthe first void urine should be monitored. All women undergoing an operative vaginal delivery should have a fluid balance chart, for at least 24 hours, to detect postpartum urinary retention. A post-void residual should be measured if retention is suspected.

Women who have had spinal anaesthesia or epidural anaesthesia that has been topped up for a trial of labour may be at increased risk of retention and should be offered an indwelling catheter, to be kept in place for at least 12 hours following delivery to prevent asymptomatic bladder overfilling.

Women should be offered physiotherapy-directed strategies to prevent urinary incontinence. Following physiotherapy intervention, at three months after delivery, the prevalence of incontinence in the intervention group was 31.0% (108 women) and in the usual care group 38.4% (125 women); difference 7.4%. At follow up significantly fewer women with incontinence were classified as severe in the intervention group (10.1%) v (17.0%). 0204

Reducing fear of subsequent childbirth.

   

Operative vaginal delivery can be associated with fear of subsequent childbirth and in a severe form may manifest as a post-traumatic stress type syndrome which has been referred to as ?tokophobia?. 

Three per cent of women had post-traumatic stress at least once within 1-11 months postpartum.0602

Operative intervention in first childbirth carries significant psychological risks rendering those who experience these procedures vulnerable to a grief reaction or to posttraumatic distress and depression.9702

Women consider postnatal debriefing and medical review important deficiencies in current care. Those who experienced operative delivery in the second stage of labour would welcome the opportunity to have a later review of their intrapartum care, physical recovery, and management of future pregnancies.0308

Posttraumatic stress disorder after childbirth is a poorly recognized phenomenon. Women who experienced both a high level of obstetric intervention and dissatisfaction with their intrapartum care are more likely to develop trauma symptoms than women who receive a high level of obstetric intervention or women who perceive their care to be inadequate. These findings should prompt a serious review of intrusive obstetric intervention during labor and delivery, and the care provided to birthing women.0004

Following instrumental vaginal delivery, fear of childbirth was a reported by 51% as a reason for avoiding a further pregnancy.0405 This is a surprising thought provoking observation, particularly as we believe that we are using adequate analgesia.

The support, counseling, understanding, and explanation given to women by midwives in the postnatal period provides benefits to psychological well-being. Maternity units have a responsibility to develop a service that offers all women the option of attending a session to discuss their labor.9801 In another study, however, midwife led debriefing after operative birth proved to be ineffective in reducing maternal morbidity at six months postpartum. The possibility that debriefing contributed to emotional health problems for some women could not be excluded.0005

Future deliveries.

Sources:    

Those delivered spontaneously and by vacuum, low forceps and mid-forceps in their first pregnancy had a 96%, 91%, 88% and 82% chance, respectively, of spontaneous delivery in their next pregnancy.0006

  Primary Source    http://www.rcog.org.uk/resources/Public/pdf/operative-vaginal-delivery. Pdf

 

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