After pre aneasthestic evaluation and 6 -8 hours of fasting , informed written consent will be taken from the patient .Then patient will be taken inside operation theatre , multipara monitors will be attached and all baseline vital parameters will be recorded .Premedication and Adequate pre loading will be done. Patient will be kept in sitting position on a level table with feet resting on foot rest with an assistant holding the patient.

Grouping of patient : The study population will be randomly devided in two groups

GROUP P: Pre -procedural ultrasound scanning group

                 In this group low frequency curvilinear probe will be placed vertically in paramedian plane to visualise sacrum which appeared as linear hyperechoic line with acoustic shadow anteriorly, now probe will be slide cranially to first visualise L5-S1 Interlaminarspace then L5-L4 and L3-L4 interlaminar space these space will be marked using surgical marker pen . Now the probe will be rotated 90 degree and placed transversly in midlineto visualise spinous process which appeared as linear hypoechoic shadow, now the central point of probe will be marked and this point will be extended as a vertical line using surgical marking pen. The point where these two line intersect will be our point of indertion of spinal needle.now under all aseptic precaution subarachnoid block will be given in marked point of insertion using 23 G Spinal needle.

GROUP L: Landmark guided Group

                In this group conventional landmark guided technique will be used to identify the intervertebral space. under all sterile aseptic precaution subarachnoid block will be given with 23 G Spinal needle.

Followimg parameter will be recorded in both the group:

1) Number  of attempts

2) Number of needle passes

3) Time taken to identify the intervertebral space

4) Time taken for subarachnoid block 

5) Time to achieve successful block