Hyperbaric Prilocaine Compared With Hyperbaric Bupivacaine in Cervical Cerclage?

Patients that have a \"cervical stitch\" (cervical cerclage) require an anaesthetic. The most common choice is a spinal block. This is an injection in the back that makes the lower half of the body become temporarily numb and weak. The key aims when choosing which type of anaesthetic are safety for mother and baby, comfort during and after the procedure as well as patient convenience and satisfaction. There are two commonly available choices for the drug used in spinal anaesthesia, bupivacaine and prilocaine. Both have a long history of being safe and effective. One difference observed in studies of these drugs used for spinal anaesthetics in other surgeries is that prilocaine is shorter-acting and it, therefore, takes less time for the return of full strength and sensation of the lower body. This means patients are able to leave hospital sooner and are less likely to need a urinary catheter. The investigators want to see if these benefits can apply to patients having a cervical stitch too, by comparing the recovery of patients having a spinal anaesthetic with one of these two local anaesthetic medications.