The following is adapted from an addendum jointly prepared by the Singapore Society of Anaesthesiologists, Obstetrical Gynaecological Society of Singapore and College of Obstetricians and Gynaecologists Singapore.
Regional anaesthesia involves either:
Spinal anaesthesia - Local anaesthetic medications are injected into the fluid space around the spinal cord to numb the lower half of the body. It starts to work very quickly and generally is adequate for operations lasting less than 2 hours.
Epidural anaesthesia - A thin plastic tube is inserted into the epidural space, near the nerves of the spine, through a needle. Local anaesthetic and other medications are given through this tube to keep the lower half of the body numb. It starts to works about 15 minutes after the medications are put into the tube, and is effective for operations or pain relief that need to last longer.
Combined spinal-epidural anaesthesia - This involves a combination of the spinal anaesthesia and epidural anaesthesia. It combines the advantage of the quick onset of action of the spinal anaesthesia and the ability to work for a longer period of time with the epidural anaesthesia.
Benefits of regional anaesthesia
Generally, regional anaesthesia provides excellent pain relief, less nausea and vomiting after surgery and earlier return of oral intake.
However if you have had previous back surgery, deformity / abnormality of the spine, problems with blood clotting or you are on medications that reduce clotting, regional anaesthesia may not be suitable for you.
Risks from regional anaesthesia
These include, but are not limited to, the following:
Common side-effects which are usually temporary: numbness of lower limbs or lower half of body, weakness and temporary loss of muscle control over numbed areas, shivering, body itch, drop in blood pressure, making you nauseous, transient tenderness around injection site at lower back.
Serious but uncommon side-effects: headache (which may last days to weeks but is treatable), nerve damage (which may be transient at 1:10,000 or permanent at 1:100,000) which may cause paralysis, failure of regional anaesthesia to work optimally (in which case, supplementary pain relief or general anaesthesia may be administered), breathing difficulties from high block, and seizures.