BACKGROUND AND OBJECTIVES: An imaginary line connecting both iliac crests is used to determine the vertebral level for lumbar puncture. This line crosses the spine at the level of L4 or the L4-L5 space. This anatomical reference can be inaccurate in a large proportion of patients. The objective of the present study was to determine whether the identification of the L3-L4 space by the physical exam differs from that of the ultrasound in obese and non-obese pregnant women. METHODS: Adult patients undergoing elective cesarean sections under spinal block participated in this study. Patients were divided in two groups: obese and non-obese. The L3-L4 space was determined by physical exam with the patient in the sitting position. This was followed by a lumbar ultrasound. After the sacrum was identified, the transducer was directed in the cephalad direction to identify the spinous processes of the lumbar vertebrae. The clinically estimated L3-L4 level was recorded. RESULTS: Ninety patients, 43 obese and 47 non-obese, were included in this study. Lumbar intervertebral spaces were identified by ultrasound in all patients. The L3-L4 space clinically identified corresponded to the ultrasound identification in 53% and 49% of the cases in the non-obese and obese groups, respectively. There was no significant difference between groups. CONCLUSIONS: The L3-L4 space is correctly identified in a low percentage of obese and non-obese pregnant women. Spinal ultrasound can reduce the incidence of mistaken identification of the L3-L4 space in obese and non-obese pregnant women.
ANESTHETIC TECHNIQUE, Regional; EQUIPMENT; PREGNANCY
