Epidural anaesthesia in labour is a special form of regional anaesthesia which can be used to numb the area of your chest, abdomen, pelvis and legs.
In obstetrics, epidural anaesthesia is used to temporarily numb the nerves carrying pain sensation from the womb and birth canal. A special epidural needle is inserted into the lower part of the back; a small amount of local anaesthetic may be first injected into the skin of the area. The tip of the epidural needle is advanced into the space which contains the nerves before they enter the spinal cord. Sometimes it is difficult to insert the epidural which results in more discomfort than usual. With the epidural needle in place, a fine plastic tubing can then be passed through the needle. The needle is withdrawn and the plastic tube taped in place so drug doses can be given through it with no further injections.
Epidural injections may not be possible in patients who have had previous spinal surgery, are very overweight, have severe infections, or who have defective blood clotting. There may be additional obstetric reasons to avoid epidural anaesthesia and your obstetrician must therefore agree before epidural anaesthesia is performed.
Before performing an epidural anaesthetic, first your anaesthetist will assess your medical and obstetric condition. If you are in extreme pain when requesting your epidural, then this pre-anaesthesia consultation may be very brief and much of this information may be gathered from your midwife. An intravenous drip will be started which is used to give you extra fluid and for drugs if needed.
No anaesthetic is without risk, but most patients do not suffer any serious complications. When they do occur, complications vary from mild and inconvenient (headache, nausea, vomiting, shivering) to the severe but very rare, such as damage to the spinal cord or nervous system, or death. The risk of developing a serious complication is very remote when the epidural is performed by someone who is experienced, and when ongoing care is provided by staff who are experienced in epidural management.
Once your pain has been relieved, your blood pressure can fall somewhat and this might make you feel a little light-headed or nauseated. A fall in blood pressure is usually not serious and can be easily treated. Sometimes the fall is helpful, if your blood pressure is already high.
Occasionally the epidural needle is inserted a little further than intended, causing a “lumbar puncture” or small leak of the fluid surrounding the spinal cord. This is not serious in itself but can cause a severe headache, which can be treated effectively. Infection following an epidural is extremely rare and if treated early with antibiotics usually recovers completely without complications. Epidurals are very safe when performed and managed properly. Serious complications are extremely rare. Minor complications such as lumbar puncture headache, are uncommon and are easily treated.
Modern epidurals in labour usually combine a low concentration local anaesthetic with a morphine-related pain relieving drug such as fentanyl. This takes away the pain but allows enough sensation for you to still feel your contractions; you can assist in and experience giving birth to your baby.
Only a very small amount of local anaesthetic passes to the baby and it has practically no effect. Morphine-related drugs such as fentanyl can also pass into the baby, but the small amounts used in the epidural usually have no effect on the baby; these drugs can be easily reversed if they do affect the baby.
The intensity of your contractions may be reduced at first, but overall labour is not usually prolonged by the epidural. If all feeling has to be numbed then there is no sensation of pressure in the bowel and the pushing stage may take longer. With a strong epidural block, you may feel little sensation at all. Your legs may be weak for a few hours until your epidural wears off. This feeling can also take away your urge to push. Sometimes it is necessary to assist the birth of your baby using forceps delivery.
The effect is variable in different people. Generally the epidural begins to work within a few minutes and is maximal after fifteen minutes or so. In an hour or two it will begin to wear off. The effect can be prolonged either by a “top up” dose from time to time or by using an infusion device to pump in a constant dose each hour for as long as is needed. A tingling or burning sensation in your legs indicates the epidural is wearing off.