Although most vaginal deliveries result in the delivery of a healthy baby without any significant intervention by your obstetrician, there are some circumstances in which we need to deliver your baby before you can push it out without assistance. Generally speaking if we need to deliver your baby before your cervix is fully open we do so by caesarean. However if your cervix is open and your baby is well down the birth canal we can deliver your baby more safely (both for you and your baby) via the vagina than by caesarean. If we do intervene to deliver your baby vaginally we use either:

  • The vacuum device or ventouse (I call it the sink plunger), or
  • The obstetric forceps (that look like salad servers). There are different types of forceps that are used in different situations.

The ventouse or forceps are used in around 1 in 10 vaginal births, although they are far more commonly used in women having their first baby than in those having their subsequent babies. The ventouse is now the more commonly used instrument.  While the ventouse is a relatively recent invention – it was first used in the mid-1800s – forceps were a feature of obstetric practice as far back as 1,500 BC in ancient Rome (but obstetrics has come a long way since then.)

For the purposes of this information sheet I will use the abbreviation IVD (or Instrumental Vaginal Delivery) to indicate these types of assisted births.

Reasons for an IVD

Because an IVD carries some (admittedly very small) risks, it should only be undertaken when these risks are less than the risks of allowing the birth to proceed unassisted. Broadly speaking there are three types of situations in which we consider an IVD – although one of these is rare and often we can have two reasons occurring in the same labour.

“Fetal Distress”

The first and most obvious reason to perform an IVD is when we suspect your baby may be running out of oxygen – so called “fetal distress”. The vast majority of babies tolerate labour – including the second stage – with no difficulties. However the second stage of labour is a potentially vulnerable time for babies for a number of reasons:

  • You may have been in labour for some time so quite simply the baby may become tired.
  • Your contractions are more frequent and more prolonged than at any other time in your labour. During all uterine contractions in labour there is no blood (and hence oxygen) flowing from you through the uterus to the placenta – the only time your baby is receiving oxygen is in between your contractions. If the functioning of your placenta has been previously compromised (for example if you have high blood pressure, an unduly small for dates baby or there has been bleeding from behind the placenta) your placenta may not transfer an already limited amount of oxygen to your baby.
  • The umbilical cord may be either stretched or pressed upon further reducing oxygen supply to your baby. While we all fear the umbilical cord being wrapped around the baby’s neck, the only time this is really a problem is during late labour when the cord starts to be pulled upon.
  • Other factors may also supervene at this time. One such instance is infection if your membranes have been broken for some time and you have undergone a number of internal examinations. If you have a previous caesarean your uterine scar may be under some strain from your contractions.

The signs of “fetal distress” include:

  • Your baby passing a bowel movement (“meconium”) before birth
  • Abnormalities in your baby’s heart rate pattern that include:
  • The heart rate being too fast between contractions,
  • The baby’s heart rate being very slow during contractions and then taking some time to recover to a normal heart rate, and
  • The baby’s heart rate dropping very low (below 100 beats per minute) and remaining low for more than 3 minutes – we call this a fetal bradycardia and it is an emergency because the baby is at risk of a brain injury if it goes on for more than 10 minutes or so.

During the second stage of labour your baby’s condition may deteriorate quite rapidly so we occasionally have to act very quickly to expedite their birth.

Slow – or no – progress with pushing

We used to call this problem “failure to progress” but I think the negative connotations of the word “failure” are a bit much – it is not as if a baby not coming out is anyone’s fault!

There are no hard-and-fast rules about when to intervene with the ventouse or forceps for slow progress with pushing, but there are one or two rules of thumb.

If you have been pushing with your first baby for more than one hour and the baby is not coming out then we would at least think about offering to help to deliver your baby, especially if the baby’s head was in a slightly unusual position (such as the “posterior” position). The reason for this intervention is that if you have been pushing for more than one hour and your baby is not moving down well you are unlikely to give birth naturally within the foreseeable future.

Please remember I am not talking about intervening after you being in the second stage of labour for one hour or so. Usually once you are fully dilated we try to wait – sometimes for an hour or more – and let the head come down without you pushing.

Maternal Conditions

There are a few very rare situations where it is not appropriate for a woman to push for very long because of medical conditions that can deteriorate with pushing. These include but are not limited to high blood pressure and some heart conditions. Under these circumstances we usually use an epidural to block the urge to push and allow the head to descend before performing an IVD after a few pushes.

What’s involved with an IVD?

We begin the IVD process by placing your legs on supports (we don’t use stirrups any more) so that your pelvis is in a position to allow as much room as possible for your baby to fit out. We also usually ask a paediatrician to attend the birth so that should your baby require any support or resuscitation fully qualified help is right on hand.

In some circumstances we may be a little unsure that your baby will be born by an IVD and we may be concerned that a caesarean may yet be required. Under these circumstances I prefer to move you into a full operating room just in case we need to quickly change from an IVD to a caesarean. We call this process a “trial” of IVD in theatre.

Of course all of these doctors, equipment, theatres etc can be bewildering (to say the least) but I think you always need to bear in mind that safety is our first priority.

Because instrumental delivery is potentially more painful than a spontaneous vaginal birth, a strong form of pain relief is generally advisable (although this is not always necessary and is certainly compulsory).  This can be either an epidural (anaesthetic injection into the back) or a pudendal nerve block (injection into or around the vagina).  Some cases – usually forceps births – require an episiotomy in order to prevent serious vaginal tearing. This is a small cut made in the side of the vagina, under anaesthetic, in order to provide more room for the baby; this is stitched up after the delivery.

A ventouse delivery involves placing a small cup on the baby’s scalp and creating a vacuum seal.  With the next few contractions, pulling on the cup helps to deliver the baby.  Forceps are curved metal instruments, much like salad servers, designed hold the baby’s head and speed up the delivery by pulling the baby out during contractions. However it is important to remember that IVDs are not about “brute force”. The reasons both instruments are successful is that they help with the DIRECTION of the birth and they also help to correct abnormal positions of the baby’s head in order to facilitate the birth.

Complications of IVDs

There are usually no adverse consequences for mothers or their babies when forceps or ventouse is used.  However, you should be aware of the following potential risks:

  • Episiotomies and vaginal / perineal tears are more common with IVDs (especially forceps) than with spontaneous vaginal births.
  • In some cases, ventouse delivery may not succeed so we will proceed to use forceps.  If this is also unsuccessful, you will require a caesarean.
  • Bruising of the baby’s face or scalp, which affects 1 in 6 babies, resolves over a few days and poses no long-term risk. Most babies born with forceps have marks on the side of their heads and cheeks. All babies born with the ventouse have a lump on their heads where the cup was positioned. This is called a chignon (a nice French word for you) and it always resolves over the first few days after the birth. Very rarely babies can have small cuts to the back of their head (ventouse) or face (forceps).
  • Injury to one of the baby’s facial nerves occurs in 1 in 200 babies and is more common with forceps than ventouse.  This also resolves in virtually all babies.
  • Cephalhaematoma: this is an accumulation of blood between the baby’s skull and scalp due to the pressure of the ventouse cup (it does not occur with forceps).  Cephalhaematomas tend to resolve over a number of months and may be associated with jaundice, but have no long-lasting effects.
  • More serious complications, such as permanent eye damage, spinal cord injury, skull fractures and bleeding within the brain are very rare (occurring in less than one in one thousand IVDs). Broadly speaking the risks of these very serious adverse complications are approximately as likely with one instrument as the other.

There’s been some debate in obstetric circles over the centuries about whether ventouse or forceps should be the preferred instrument.  The evidence suggests that ventouse has several advantages over forceps, including a lower risk of maternal injury and less need for an epidural. However, forceps are typically more effective in actually delivering the baby which, after all, is the whole point of an IVD.

There are some circumstances where I use one instrument or the other. These are:

  • If there is an abnormality in the rotation of the baby’s head – in other words if the baby is looking in any other direction than straight backwards (so this includes the “posterior position” – I use the ventouse because I can best assist to rotate the baby’s head with the ventouse.
  • I use the ventouse when a woman does not have an epidural on board because the ventouse is less painful than forceps.
  • I occasionally prefer the forceps when there is severe fetal distress because I believe I can deliver a baby more quickly with the forceps than the ventouse in a situation where minutes matter
  • If a woman has a very dense epidural block, a biggish baby and / or is not pushing effectively I prefer to use the forceps because – and there is no easy way to put this – you can put more traction on a baby with the forceps than the ventouse.

I know what you are thinking

“Oh my God, just give me a caesarean rather than an IVD!”

However you need to remember that:

  1. Really bad things happening as a result of an IVD are extremely rare (and really bad things can happen with normal births sometimes too),
  2. Caesarean sections – particularly when performed very late in labour – have significant risks for mothers and are not without risk for babies (remembering that we sometimes have to use the forceps when we do caesarean sections),
  3. The medical scientific literature on this topic does NOT support performing caesareans instead of IVDs because of the risks of caesareans, and
  4. If you have an IVD with your first birth you have a greater than 95% chance of a NORMAL birth with your subsequent children. If you have a caesarean you have a high chance of a caesarean for your subsequent births. See my information about Caesarean Childbirth for more information on the long term implications of having a caesarean.

Acknowledgement:

This information sheet was written by Dr Alex Owen and I have edited it and added some material. Any omissions or errors are mine alone.