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Updated: Oct 30, 2025
Image Acquisition Method for the Sonographic Assessment of the Inferior Vena Cava
Published on: January 13, 2023
Ultrasound evaluation of inferior vena cava compression in tilted and supine term parturients
Marie-Pierre Gagné1, Philippe Richebé1, Christian Loubert1
1Department of Anesthesiology and Pain Medicine, Maisonneuve-Rosemont Hospital, CIUSSS de l'Est de l'Ile de Montreal (CEMTL), University of Montreal, 5415 boul. de l'Assomption, Montreal, QC, H1T 2M4, Canada.
Purpose:
Hypotension is common following spinal anesthesia (SA) during elective Cesarean delivery (CD). Although common practice is to alleviate inferior vena cava (IVC) compression, limited evidence supports a 15° tilt for CD. We measured collapsibility of the IVC in supine and 15° left lateral tilt positions with ultrasound before and after SA and phenylephrine infusion in term parturients.
Methods:
Twenty term parturients scheduled for CD were recruited for this prospective study. Ultrasound measurements of the IVC were taken 1) supine before SA, 2) tilted 15° before SA, 3) supine after SA, and 4) tilted 15° after SA. A phenylephrine infusion was begun after injection of SA. The primary outcome was to evaluate the impact of position on the IVC collapsibility index (IVCCI): a measure of the difference between the maximum and minimum IVC diameter with respiration.
Results:
The mean (standard deviation) IVCCI (%) before SA was higher in the supine 19.5 (8.0) than in the tilted 15.0 (6.4) position (mean difference, 4.5; 95% confidence interval [CI], 0.1 to 8.9; P = 0.04). After SA, there was no significant difference between IVCCI (%) in the supine 17.8 (8.3) and tilted 14.2 (6.9) position (mean difference, 3.5; 95% CI, -0.9 to 7.9; P = 0.13). There was no correlation between the pre-spinal IVVCI measurements and the quantity of phenylephrine used during the surgery.
Conclusion:
The IVCCI was lower in the 15° tilt position than in the supine position, but not after SA with a phenylephrine infusion. Ultrasound imaging can help identify IVC compression.
Trial Registration:
www.clinicaltrials.gov (NCT03410199); registered 18 January 2018.
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