This study will investigate whether an ultrasound-assisted technique is better than a classical land-mark technique to facilitate spinal anesthesia in the sitting position in super obese pregnant women with BMI ≥ 50 who will undergo elective cesarean section. The primary objective of this study is the rate of successful dural puncture at the first attempt. It was assumed that ultrasound could facilitate neuraxial blockade in super obese (BMI ≥ 50 kg/m2), pregnant women, according to the Who classification, whose topographic anatomy is difficult.