A spinal block is similar to the epidural but without the catheter.  Medication is injected into the spinal fluid.  Pain relief occurs almost immediately but only lasts for an hour or two.  A spinal block is generally given only once during labor, as close to delivery as possible.  Medications used for a spinal block are typically the same as those used for an epidural and thus carry many of the same risks.  The benefit to a spinal block over the epidural is the shorter duration which may reduce the risks to mother and baby of the medications used.