Spinal anesthesia is the most commonly used anesthetic technique for cesarean section. However, in obese parturients, identification of the optimal puncture site using anatomical landmark palpation can be challenging because of altered anatomy. Preprocedural ultrasound has been proposed as a tool to improve localization of the puncture site and facilitate neuraxial access.

This is a prospective comparative study included 100 obese parturients undergoing cesarean section under spinal anesthesia. Participants were allocated to one of two comparison groups according to the puncture site localization technique: a preprocedural ultrasound group and an anatomical landmark palpation group.

The primary outcome is the first-attempt success rate, defined as successful cerebrospinal fluid return after the first needle insertion without needle redirection or a new skin puncture. Secondary outcomes include the number of puncture attempts, needle redirections, need for rescue interventions, incidence of paresthesia and vascular puncture during the procedure, and procedural times.

This prospective comparative study aims to evaluate the effectiveness of preprocedural ultrasound-guided marking compared with the conventional anatomical landmark palpation technique for spinal anesthesia in obese parturients undergoing cesarean section.

A total of 100 parturients with a body mass index (BMI) ≥ 30 kg/m² were prospectively allocated to one of two comparison groups according to the puncture site localization technique. In the ultrasound group, the puncture site was identified using preprocedural ultrasound to determine the optimal intervertebral space and needle insertion trajectory. In the landmark group, the puncture site was identified using conventional anatomical landmark palpation.

The primary outcome was the first-attempt success rate, defined as successful cerebrospinal fluid return after the first needle insertion without needle redirection or an additional skin puncture. Secondary outcomes included the number of puncture attempts, needle redirections, need for rescue interventions, incidence of paresthesia and vascular puncture during needle insertion, and procedural times (site identification time, puncture time, and total procedure time).

This study evaluated whether preprocedural ultrasound-guided marking improves the technical performance of spinal anesthesia compared with conventional anatomical landmark palpation in obese parturients undergoing cesarean section.

Inclusion Criteria:

• Age ≥ 18 years
• Pregnant women undergoing cesarean section
• Body mass index (BMI) ≥ 30 kg/m² at the time of cesarean section
• Scheduled for cesarean section under spinal anesthesia

Exclusion Criteria:

• Congenital spinal deformities
• History of spinal surgery
• Coagulopathy
• Infection at the puncture site
• Allergy to local anesthetics
• Emergency cesarean section (NICE category 1)

URL address will be offered or information will be sent by email.

Beginning 3 months after publication and ending 12 months after publication

Access will be granted to researchers who provide a methodologically sound proposal. Proposals should be directed to the corresponding author via email. Data will be shared after approval of the proposal and signing of a data access agreement.

Due to the nature of the intervention, blinding of the operators was not feasible.