[Value of plain abdominal radiography for evaluating the patency of LGM caval filters]

To evaluate the value of plain abdominal X-Ray to detect vena Tech LGM filter occlusion or patency during follow-up.

Eighty-nine patients were followed in a prospective study for 2 to 6 years after vena Tech LGM filter implantation. The control examination consisted in a clinical examination, a plain abdominal X-Ray (to measure expansion index = diameter/height of the filter and to detect migration and angulation) and a Doppler ultrasonography and/or a cavography to appreciate filter patency.

175 plain abdominal X-Ray, 172 Doppler ultrasonographies and 28 cavographies were done. Sensitivity and specificity of retraction to suspect a filter obstruction were respectively: 82.3% and 86.1%; if expansion index was lower or equal to 0.34 its sensitivity and specificity were 100% and 92.1%. The negative predictive values of retraction and of the association retraction-migration to exclude a filter obstruction were 85.1% and 96%.

Absence of migration or retraction on plain abdominal X-Ray during the follow-up is highly predictive of filter patency. This limits the use of Doppler ultrasonography and cavography.