///2010 Abstract Details
2010 Abstract Details2018-05-01T17:52:49+00:00

Ultrasound determination of the level at which the intercrestal line intersects the spine in term pregnant women

Abstract Number: 94
Abstract Type: Original Research

Clarita B Margarido MD, PhD1 ; Rafeek Mikhael MD, PhD2; Cristian Arzola MD, MSc3; Mrinalini Balki MD4; Jose C.A. Carvalho MD, PhD5

Introduction: The intercrestal line, also known as the Tuffiers line, is thought to intersect the spine at the L4-5 interspace, but variations may occur (1). The Tuffiers line was originally described as a radiological concept, not taking into account the subjects body habitus and positioning. Pregnancy is associated with significant subcutaneous tissue gain and accentuation of lumbar lordosis. This study was conducted in term pregnant women to establish at which point a transverse line connecting the superior aspects of the iliac crests, as determined by palpation, intersects the lumbar spine, as determined by ultrasound (US).

Methods: After REB approval and written informed consent, term pregnant patients were recruited. The exclusion criteria were a history of scoliosis and previous spinal surgery. Height, weight, and BMI were recorded. With the patient in the sitting position, using a pen containing ink only visible under ultraviolet light, the attending anesthetist palpated and marked the superior aspects of the iliac crest bilaterally, and then drew a line connecting the two marks and intersecting the spine (Pline). One of the investigators, blinded to the line, performed a lumbar ultrasound assessment to locate the lumbar interspaces (T12-L1 to L5-S1), and marked them on the patients back. Then, ultraviolet light was used to reveal the Pline and determine its intersection point at the spine. The interspaces and the Pline intersection were plotted on a transparent sheet placed on the patients back, and the distance between two consecutive interspaces was divided into three equal sub-segments. Starting from the L5-S1 interspace and counting cephalad, 15 sub-segments were identified, and numbered sequentially from 1 to 15 (1 being the lower 1/3 of the L5-S1 distance, and 15 being the upper 1/3 of the T12-L1 distance).

Results: We have studied 17 cases of our planned sample size of 45. The distribution of the levels of intersection is shown in the figure. There was no correlation between height, weight and BMI and the level of the intersection.

Conclusions: The Tuffiers line determined by palpation is an unacceptable surrogate as a landmark for spinal anesthesia in term pregnant women. Further studies are warranted to determine a safer and more appropriate anatomical landmark. The use of pre-puncture ultrasound is, therefore, encouraged.

References: 1) Anesth Analg 1994; 78 :194-5

SOAP 2010