Epidurals and spinals are both forms of ‘regional anaesthesia’. They both aim to prevent pain sensations from being felt in the lower ‘region’ of the body.
Both require that a long, hollow needle be placed between two of the backbones in the woman’s lower spine. The epidural space surrounds the spinal cord and is located just outside a layer of tissue called the ‘dura mater’. The dura mater tissue encases the spinal cord and spinal fluid. Large nerves that transmit pain, heat and touch sensations, enter and leave the spinal cord via the epidural space.
With an epidural, the epidural needle is inserted only as far as the epidural space. This space is located just outside a layer of tissue called the ‘dura mater’. The dura mater tissue encases the spinal cord and spinal fluid.
Once the needle is believed to be in the correct location, a fine hollow tube or ‘catheter’ (about the width of fishing line) is passed through the hollow needle, so that the end of the tube rests in the epidural space. The epidural needle is then removed and the catheter is left in place. The catheter is about 90cm long and the remainder of the tube is eventually taped in place, up the length of the woman’s back.
The anaesthetic medication is then injected down the catheter to ‘bathe’ the nerves that lead to the woman’s uterus and lower body, to numb them.
Epidural medication(s) generally take about 10 to 30 minutes to relieve the pain and last for 1 – 2 hours.
Once the initial dose of medication has worn off, the epidural can be ‘topped up’, with more medications being administered down the epidural catheter. This means that the pain relief can be maintained (if the labour is continuing after the epidural wears off), or increased if the woman needs more epidural medications for an instrumental delivery or a caesarean birth. Sometimes lower doses of the epidural medications are given continuously through the catheter, using an automatic electric syringe pump, rather than the caregiver administering ‘top-ups’ every couple of hours.
With a spinal anaesthetic, the spinal needle is inserted a little further than the epidural space. The end of the needle actually pierces the ‘dura mater’ layer of tissue (the dura mater being the tissue that encases the spinal cord and spinal fluid). The end of the needle reaches the cerebral spinal fluid, or ‘CSF’ (the pool of fluid that surrounds the spinal cord and flows around the brain). Once in place, the anaesthetist injects the medications into the spinal fluid. The spinal needle is then totally removed and no catheter is left in place.
Spinal medication(s) only take about 5 to 10 minutes to relieve the pain and can last for 1 – 2 hours.
A spinal is a ‘once only’ procedure subsequent injections cannot be administered and there is no catheter is left in place to give further ‘top ups’ (like an epidural). This is why a spinal tends to be used more for Caesareans rather than for pain relief in labour.
The Availability of epidurals
Epidurals for labour pain are only administered in delivery suites of public and private hospitals. They are not available for women labouring in birth centres or at home.
Epidurals need to be inserted by an anaesthetist. Anaesthetist doctors are available 24 hours a day. However, depending on how busy they are, they may take minutes to be available for the epidural or if the they need to come in from home or is attending another patient or is in the operating theatre with a Caesarean birth, their services may be delayed.
Epidurals can be used in labour for many reasons:
- Pain relief
- Forceps, ventouse or Caesarean
- Long labour
- Anxious or concerned
- High blood pressure
- Twins and VBAC
The most common reason for a woman to request an epidural is for pain relief which is usually given in the active first stage of the labour (when the cervix is opening or dilating past 3 – 5 cm, but before 10 cm).
An epidural is rarely inserted for pain relief in pre-labour or in the early 1st stage of labour, because it is likely to slow down the labour. This means that an oxytocin drip to augment the contractions would then be needed. An epidural is also not usually inserted for pain relief after the woman’s cervix is fully dilated to 10cms (meaning she is in the 2nd stage or the pushing phase of the labour) as this is likely to inhibit her ability to push her baby out, requiring a 1 to 2 hour delay in the pushing phase or, alternatively, a ventouse or forceps birth.
The sensation of needing to urinate is diminished, which often requires the placement of a urinary catheter for the duration of the epidural
Epidural analgesia is a relatively safe method of relieving pain in labor. It provides rapid pain relief in most cases. It is more effective than nitrous oxide, opioids, TENS, and other common modalities of analgesia in childbirth.
Some researchers claim that it is correlated with an increased chance of operational intervention. The clinical research data on this topic is conflicting.
Complications of epidural use
- No pain relief (block failure) or Partial pain relief (partial failure) occurs in about 5% and 15% respectively
- If pain relief is inadequate, another epidural may be attempted
- Bloody tap (about 1 in 30-50). It is easy to injure an epidural vein with the needle. In patients who have normal blood clotting, it is extremely rare for problems to develop. However, in a patient who has a coagulopathy, the patient may be at risk of epidural hematoma
- Dural puncture with headache (about 1-3 in 100 insertions). This may cause cerebrospinal fluid (CSF) to leak out into the epidural space, which may in turn cause headache. This can be severe and last few days. It is caused by a reduction in CSF pressure and is characterised by postural exacerbation when the patient raises their head above the lying position. If severe it may be successfully treated with an epidural blood patch (a small amount of the patient’s own blood given into the epidural space via another epidural needle which clots and seals the leak). Most cases resolve spontaneously with time
- High block (less than 1 in 500). Due to large dose of local anaesthetic in the epidural space. It may present with hypotension, nausea, sensory loss or paraesthesia or difficulty breathing. These symptoms can be very distressing to the patient
- Catheter misplaced into a vein (less than 1 in 300). Results in all the anaesthetic being injected intravenously, where it can cause seizures or cardiac arrest (about 1 in 10,000 insertions). This also results in block failure
- Catheter misplaced into the subarachnoid (subdural) space (less than 1 in 1000). Large doses of anaesthetic may be delivered directly into the cerebrospinal fluid. This may result in a high block, or, more rarely, a total spinal, where anaesthetic is delivered directly to the brainstem, causing unconsciousness and sometimes seizures.
- Epidural abscess (about 1 in 145,000). Infection risk increases with the duration catheters are left in place.
- Neurological injury (about 1 in 240,000)
Effects on the baby
- There is a noticeable lack of research and information about the effects of epidurals on babies. Drugs used in epidurals can reach levels at least as high as those in the mother, and because of the baby’s immature liver, these drugs may take a long time to be cleared from the baby’s body.
- One study concluded that women whose epidurals contain the drug fentanyl were less likely to fully breastfeed their infant. However, this study has been criticised for several reasons, one of which is that all patients who used epidurals in labor had also used systemic pethidine, which would be much more likely to be the cause of any effect on breastfeeding due to the higher amounts of medication used via that route. If that were the case, then early epidurals which avoided the need for pethidine may actually improve breastfeeding outcomes, not worsen them.
Cost involved in having Epidural or Spinal anaesthetics
- A specialist anaesthetist will administer your epidural or Spinal anaesthetics and he/she will charge a separate fee for the service. You will be responsible for paying the account that will be forwarded directly to you.
You will be asked to sign a consent.
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