Name: Carlos André Daher Santos
Type: MSc dissertation
Publication date: 03/07/2019

Examining board:

Name	Role
Cristiano Ventorim de Barros	External Examiner *
Gustavo Peixoto Soares Miguel	Advisor *
Octávio Meneghelli Galvão	Internal Examiner *

Summary: Introduction: May-Thurner syndrome (MTS) is characterized by compression of the left common iliac vein (LCIV) by the right common iliac artery (RCIA) against the spine, with its clinical range varying from asymptomatic to acute (deep venous thrombosis ) and chronic presentations (pain, edema, feeling of heaviness and signs of chronic venous insufficiency in the left lower limb). There is no consensus today on its diagnosis, and it is done through noninvasive and invasive tests. The present study aims to correlate Doppler ultrasound (DUS) with the intravascular pressure gradient measured between IVC and LCIV.

Methods: We evalueted 41 patients with DUS suggestive of MTS and afterwards submitted to venous angiography and subsequently measured intravascular pressure in IVC e LCIV right after stenosis using a diagnostic catheter. The results were compared, with pressure gradient <3 mmHg (negative) and &#8805;3 mmHg (positive).

Results: 56.1% of patients were between 20 and 49 years old. The mean weight was 72.85 kg and mean height was 1.64 m. 70.7% of normal or overweight body mass index (BMI). The mean pressure in the IVC and LCIV was 10.49 and 11.83 mmHg, respectively, with the mean IVC-LCIV pressure gradient of 1.51 mmHg. Statistical analysis was performed using the t-test, Shapiro-Wilk and Mann-Whitney for age, weight, height and BMI and correlation analysis for IVC pressure, LCIV pressure and gradient, and wich was found p value> 0.05 for all .

Conclusion: DUS is unrelated to pressure in the IVC and LCIV, nor to the pressure gradient between the IVC-LCIV. The DUS is a screening test and diagnostic confirmation of MTS with phlebography is mandatory without pressure measurements.

Keywords: May-Thurner syndrome; gradient; pressure; phlebography.