Spinal anesthesia, also called spinal analgesia, spinal block or sub-arachnoid block (SAB), is a form of regional anaesthesia involving injection of a local anesthetic solution into the subarachnoid space that numbs the nerves from the waist down to the toes for duration of 4 to 6 hours. The local anesthetic solution blocks conduction of impulses along all nerves with which it comes in contact. In prolonged procedures continuous spinal anesthesia may be used. A thin catheter (hollow tube) is left in place in the subarachnoid space for additional injections of the anesthetic agent, which ensures numbness during the length of the procedure. A spinal anesthetic is used for lower abdominal, pelvic, rectal, or lower extremity surgery. Since 1985 Spinal anesthesia has progressed and has successfully been used in various clinical situations. The advantages of spinal anesthesia over general anesthesia are that it avoids the ill effects of general anesthesia such as sore throat, teeth, lips and gum injury and chest infection. The other advantages include the reduced blood clots in the legs, less blood loss during surgery, full control of breathing during surgery, less sickness and drowsiness after surgery and being able to communicate with medical professionals and surgeons during surgery. The drawbacks include the pain during injection, headache, and itching, urinary retention and low blood pressure and there might be a requirement of general anesthesia if the spinal anesthesia does not work satisfactorily or in case the surgery turns out to be more complicated than initially anticipated.