Written by:

Dr Emily Cornish

Dr Cornish is an academic Obstetrics & Gynaecology trainee in London. She recently returned from a year spent working in South Africa and is looking forward to developing her interests in maternofetal medicine, fertility and high-risk obstetrics.

Instrumental delivery – Assistance when you and your baby need it.

In this article:

  • What is instrumental delivery?
  • What are the devices that might be used?
  • Why might I need to have an instrumental delivery?
  • Where does instrumental delivery take place?
  • What actually happens?
  • What influences the choice of instrument?
  • What are the risks?
  • Recovery
  • Alternatives to instrumental delivery
  • Likelihood of subsequent births requiring similar assistance
  • Main Points
  • References
  • Additional useful resources

Instrumental delivery – Assistance when you and your baby need it.

What is instrumental delivery?

Instrumental delivery (also called “operative vaginal delivery” or “assisted vaginal delivery”) is a technique used by obstetricians to expedite delivery of the baby during the second stage of labour, i.e. once the cervix is fully dilated (10cm). The aim of instrumental delivery is to mimic spontaneous vaginal birth, achieving safe delivery with minimal harm to the mother and baby. Rates of instrumental delivery have remained relatively constant at 10-13% in the UK over the last 20 years (see figure 1).


Figure 1: Rates of instrumental delivery in the UK [https://stratog.rcog.org.uk/tutorial/easi-resource/operative-delivery-rates-4861, accessed 26/11/17]

However, even though more than 1 in 10 women will have an assisted delivery, the possibility is often not discussed antenatally. Being faced with the prospect of instrumental delivery for the first time during labour itself can be very distressing for women and their partners, especially since this often occurs in an emergency setting when there are concerns about the baby’s wellbeing and lots of people are called into the room. This article aims to provide an overview of the scenarios in which instrumental delivery might be recommended, as well as the types, risks, and benefits of the available devices.

What are the devices that might be used?

There are two categories of device used for assisted delivery:

  1. Forceps (spoon-shaped metal blades that slide round the baby’s head): types include Neville-Barnes forceps and Kielland’s forceps.
  2. Vacuum suction cups (applied to the top of the baby’s skull): there is a wide variety of cups available, but the commonest used in the NHS is the plastic Kiwi cup. This type of instrumental delivery is often known as a ventouse delivery.

 

Why might I need to have an instrumental delivery?

Reasons fall into three categories and each one relates to either the mother’s progress in labour, the baby’s condition or pre-existing medical problems in the mother:

Table 1: indications for instrumental delivery [1]

Maternal progress
  1. Slow progress in the second stage of labour (e.g. in a woman having her first baby, no progress for 2 hours – or 3 hours if an epidural is present)
  2. Maternal exhaustion, meaning the mother is no longer able to push
Baby’s condition
  1. Severely abnormal heart trace (CTG) in the second stage of labour
  2. Other evidence that the baby is struggling, e.g. an abnormal FBS (fetal blood sampling) result
Maternal medical problems Any medical condition in the mother that means active pushing might not be able advisable, such as severe heart disease

Where does instrumental delivery take place?

If your midwife thinks that instrumental delivery might be necessary, they will ask an obstetrician to make a full assessment of the situation – this will include a review of any previous deliveries, any significant events or problems in your antenatal history, the onset of your labour (whether spontaneous or induced), the progress of the labour, and a vaginal examination to determine the dilation of the cervix and the position of the baby. If the obstetrician is confident that the baby can be delivered instrumentally, the delivery can take place in your delivery room. However, if there is any doubt about whether the planned instrumental delivery will be successful, then the attempt should be made in the operating theatre – this is called a trial of instrumental delivery. This means that if the instrumental delivery is unsuccessful, the team can proceed quickly to Caesarean section.

What actually happens?

Before any instrumental delivery, the obstetrician should explain their plan to you, including the choice of instrument, the reasons behind their choice and the risks to you and the baby. You will be asked to consent to the procedure, either verbally (if the delivery is happening in your delivery room) or by signing a yellow consent form (if the delivery is taking place in theatre).

The first step is to ensure that you have adequate pain relief. If you already have an epidural, this might be topped up; if not, the obstetrician will inject local anaesthetic around the vagina and perineum (the skin between the vagina and anus) beforehand.

The obstetrician may ask the midwifery team to help reposition you, usually with your bottom at the end of the bed and often with your legs in stirrups. After reviewing your history and performing a vaginal examination as described above, the obstetrician will apply the instrument to the baby’s head. Your midwife will then support you to continue pushing when you are having a contraction, and at the same time the obstetrician will use gentle traction (pulling) to aim to deliver the baby’s head. Ideally, the baby should descend towards the perineum with every pull: if this does not happen, or if the head has not been delivered after three pulls, Caesarean section may be recommended.

An episiotomy is often necessary in order to make the vaginal opening wider and to prevent perineal tears – this will be repaired with stitches after the delivery.

If the delivery is straightforward, your baby can be placed straight on your abdomen and your partner may still be able to cut the cord if they want to. However, if the delivery is difficult or there are any concerns about the baby, the neonatologists may be called in to assess the baby straight after birth.

What influences the choice of instrument?

There are certain scenarios in which forceps delivery should be used.

Specific situations in which forceps delivery is indicated over Ventouse [2]

  • Caput (excessive swelling) on the baby’s head
  • Prematurity (less than 34 weeks)
  • Face presentation
  • Baby’s head is in transverse or occipitoposterior (“back to back”) position
  • Suspected bleeding disorder in the baby
  • Delivery of the head in a breech baby
  • Maternal conditions that prevent pushing e.g. heart disease

If the choice of instrument is not clear-cut, the obstetrician will choose the instrument they feel most skilled in using, in order to give the best chance of a safe, successful delivery.

What are the risks?

The risks of instrumental delivery have been evaluated in a large-scale study

Table 3: risks associated with different forms of instrumental delivery

Forceps Ventouse
Specific risks to mother Vaginal injury Worries about the baby after delivery
Third and fourth degree perineal tears* Requirement for general anaesthetic
Specific risks to baby Facial injury e.g. facial nerve palsy** Scalp injuryCephalhaematoma***Retinal haemorrhage

 

*Third and fourth degree perineal tears involve a degree of injury to the anal sphincter. Providing these are identified and repaired promptly, the risk of long-term complications is low. However, a small minority of women will develop chronic problems that can include incontinence (of faeces or wind), and this risk appears to be independently increased by forceps delivery [1,3].

**Facial nerve palsy can lead to weakness and reduced control of the facial muscles; usually mild and temporary, but in rare cases can persist.

***Cephalhaematoma is a type of scalp haemorrhage in which blood accumulates between the skin and the periosteum, the layer that covers the skull bones. This slightly increases the risk of jaundice in the baby but rarely causes any long-term problems.

Current research [1] suggests that the choice of forceps vs. ventouse has no significant effect on:

  • Requirement for Caesarean section
  • Blood loss
  • Low Apgar scores
  • Requirement for admission to the neonatal care unit
  • Requirement for phototherapy (a treatment for neonatal jaundice)

Recovery

Recovery from an instrumental delivery can be painful, particularly if you have had an episiotomy or perineal tear repaired, and all women who have had an instrumental delivery should be offered regular oral painkillers afterwards.

After an instrumental delivery, your urine output will be monitored closely as you may at increased risk of urinary retention (inability to empty the bladder). If you have had a spinal anaesthetic, or an epidural that was topped up for a trial of instrumental delivery, a catheter (tube into the bladder) should be left in for 12 hours after the delivery to rest the bladder and prevent retention.

Although the majority of instrumental deliveries are uncomplicated, it can be a stressful experience [4]. All women who have had an instrumental delivery should therefore receive psychological support during the postpartum period, including a specific debriefing discussion covering the reasons for instrumental delivery, management plan for any complications and advice for future deliveries [1].

Alternatives to instrumental delivery

The following measures have been shown to reduce the need for instrumental delivery[1]:

  1. Continuous support for the mother during labour
  2. Use of an oxytocin (hormone) drip to augment contractions, when appropriate
  3. Waiting until the baby’s head has descended low into the pelvis before commencing pushing
  4. Upright position during labour and delivery
  5. Delaying the insertion of an epidural until the cervix is more than 3-4cm dilated

Likelihood of subsequent births requiring similar assistance

Women who have previously had an instrumental delivery should be reassured that they have a good chance of achieving a spontaneous vaginal delivery in their next pregnancy (approximately 80%)[1,5]. However, women who have experienced medical or psychological complications of instrumental delivery may wish to discuss the possibility of elective Caesarean section: this discussion should take place as early as possible in the pregnancy in a dedicated Birth Options Clinic.

Main Points

  • Instrumental delivery – i.e the use of forceps or suction cups is also known as operative vaginal delivery or assisted vaginal delivery
  • Rates of assisted delivery have remained at around 10 – 13% for the last two decades in the UK
  • One in ten women will have an assisted delivery in the UK
  • Broadly, there three reasons why an assisted delivery will be required: maternal progress, baby’s condition, maternal medical problems
  • You will be asked for your consent before an instrumental delivery takes place
  • Three traction attempts will be made to deliver the baby using instruments
  • You will be given pain relief before the instrumental delivery takes place
  • The choice of instrument used depends on a number of scenarios and health related factors
  • There are a number of ways to help reduce the need for instrumental delivery, including having continuous support for the mother during labour and being in an upright position during labour and delivery.

References

  1. Bahl RB, Strachan BK and Murphy DJ, Operative vaginal delivery: Green-top Guideline No. 26, Royal College of Obstetricians and Gynaecologists (2011)
  2. O’Mahony F, Hofmeyr GJ and Menon V, Choice of instruments for assisted vaginal delivery. Cochrane Database Syst Rev 11:CD005455 (2010)
  3. MacArthur C, Glazener C, Lancashire R, Herbison P, Wilson D and Grant A, Faecal incontinence and mode of first and subsequent delivery: a six-year longitudinal study. BJOG 112:1075 (2005)
  4. Creedy DK, Shochet IM nnd Jorsfall J, Childbirth and the development of acute trauma symptoms: incidence and contributing factors. Birth 27:104 (2000)
  5. Bahl RB, Strachan BK and Murphy DJ, Outcome of subsequent pregnancy three years after previous operative delivery in the second stage of labour: cohort study. BMJ 328:311 (2004)

Additional useful resources

NHS Choices: Forceps or vacuum delivery [https://www.nhs.uk/conditions/pregnancy-and-baby/pages/ventouse-forceps-delivery.aspx] Accessed 26 November 2017

Patient.co.uk: Assisted Delivery [https://patient.info/health/labour-childbirth/assisted-delivery] Accessed 26 November 2017