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.
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.
There are two categories of device used for assisted 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 |
|
| Baby’s condition |
|
| Maternal medical problems | Any medical condition in the mother that means active pushing might not be able advisable, such as severe heart disease |
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 with an instrument, 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.
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 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 dissolvable 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.
There are certain scenarios in which forceps delivery should be used.
Specific situations in which forceps delivery is indicated over Ventouse [2]
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.
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 | Vaginal Injury |
| Third and fourth degree perineal tears* | Third and fourth degree perineal tears* | |
| Specific risks to baby | Facial injury e.g. facial nerve palsy** | Scalp injury, Cephalhaematoma***, Retinal haemorrhage |
*Third and fourth degree perineal tears involve a degree of injury to the anal sphincter. There is a risk with any delivery, but this is higher with an instrumental delivery, particularly with the forceps. Having an episiotomy with a forceps delivery significantly reduces this risk. Providing the tear is 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][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:
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].
When an instrumental delivery is needed, there really isn’t another alternative other than caesarean section, which at full dilatation and a low head in the birth canal, comes with its own challenges and risks. However, you can reduce your chance of needing an instrumental delivery.
The following measures have been shown to reduce the need for instrumental delivery[1]:
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.
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