Many women want to know about their pain relief options during labour.

Some women choose to have elective regional anaesthetic, either before labour begins or very early in labour.

Even if they plan to have a completely drug-free birth, some women require regional anaesthetic for a number of reasons, such as pain relief, exhaustion or because of surgery.

Spinal Or Epidural Blocks – What’s The Difference?

There is often confusion when discussing the best method of regional anaesthetic – spinal block or epidural block.

The confusion usually arises because both options involve injections into the spinal area.

There is actually quite a difference between the two methods.

Spinal blocks are rarely used during labour these days; there is a far higher preference for epidurals.

Both terms are used interchangeably, but they aren’t the same procedures, even though they have similar outcomes.

Let’s take a look at the differences between a spinal block and an epidural block.

Difference #1: Injection Site

Both epidurals and spinal blocks deliver anaesthetic to the spinal area, but they do it in different ways.

During a spinal block, a small needle is used to make a tiny hole in the dura, which is the tissue surrounding the spinal cord and cerebrospinal fluid. The anaesthetic drugs are injected directly into the cerebrospinal fluid.

Only a small amount of local anaesthetic is needed because it spreads quite quickly in the spinal fluid. The small needle is removed once the drugs have been injected. The process of injecting a spinal block is quite fast.

An epidural requires a large hollow needle to be inserted outside the dura, in the epidural space. A catheter is then threaded into the needle and drugs are administered.

Compared with a spinal block, an epidural requires much larger amounts of anaesthetic because it takes more to spread through tissues. It also takes longer to put in place – often about 10 to 25 minutes.

Difference #2: Anaesthetic Effects

The effect of a spinal block is noticeable quite quickly, usually within a few minutes of the anaesthetic being injected. It is a single injection, however, so pain relief lasts only for a few hours.

Generally spinal blocks are used for short, simple procedures. When the anaesthetic has taken effect, there is a total loss of sensation in the lower half of the body.

After an epidural it can be up to 20 minutes before you notice the effects. However, because the catheter remains in place, the drugs can be topped up to extend the time the epidural block lasts.

The reason epidurals are more frequently used during labour, is the effects can be continuous for as long labour lasts. Effective epidural anaesthesia allows you to feel sensation without pain.

Difference #3: Side Effects

The most common side effects of spinal blocks are:

Low blood pressure
Headaches
Back pain

Very rarely the needle can be placed in a spinal nerve; this causes damage to the nerve fibres, which can cause infection or seizures.

Epidural blocks are considered safe but there are still potential side effects, such as:

Heart rhythm problems or seizures, due to the catheter tip entering a vein and causing anaesthetic to move into blood vessels
Hematoma (bruising, infection or bleeding) in the epidural space
Headache

Very rarely, air can become trapped between the lung and rib cage, causing what’s known as a pneumothorax. Signs of this rare problem involve respiratory symptoms within 24 hours of the procedure, such as persistent coughing, chest pain, or breathing problems and shortness of breath.

Can Spinal and Epidural Blocks Be Combined?

Some women want the benefits of lower amounts of anaesthetic used in a spinal, but prefer to have the availability of ongoing pain relief that an epidural offers.

There is also a higher risk of interventions with traditional epidurals, including:

Prolonged labour
Use of synthetic oxytocin to speed up contractions
Use of forceps (often involving episiotomies).

To combat these problems, a single spinal injection can be combined with the use of an epidural catheter to provide ongoing pain relief with lower doses of anaesthetic.

The combined spinal-epidural (CSE) offers faster pain relief, but a review of trials comparing CSE with traditional and low dose-epidurals found there was no improvement in the incidence or severity of side effects in mothers and babies.

However traditional epidurals had a significantly higher rate of urinary retention, need for interventions, and instrumental births than CSEs did.

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