valsalva maneuver

1- the patient is asked to do valsalva maneuver while the common femoral vein is being imaged transversely.

2-a normal response results in complete retardation of flow within the vein and resultant venous dilatation , the diameter increasing by at least 50%.

3-absence of this normal response is seen in intra luminal venous thrombosis,or external pressure applied on the vein by a pelvic tumor .

4- it could be done also with congestive heart failure

respiratory variations of the spectral wave form

1- the external iliac artery and common femoral veins should have a phasic wave form.

2-if this is lost,and the wave form is flat,then this is suspicious of either external compression from a pelvic mass or a more proximal obstructing intra luminal thrombus.

calf vein imaging

1-this is not routinely performed at every centre.

2-essentially, each of the calf arteries is accompanied with pair of veins.

3-identify first the artery and then apply distal calf compression to visualise the paired veins.

4-spontaneous flow is generally absent below knee.

5-the posterior tibial vein can be visualised by placing the probe to the medial side of the tibia.these veins are more superficially placed than the deeper sets of peroneal veins.

6-the anterior tibial veins can be visualised along the lateral aspect of the tibia.as these veins lie superficially.deeper to it ,we can visualise peroneal veins.

7-peroneal veins could be seen posteriorly through the lower leg.

8-you can visualise the calf veins while the patient is in supine position,or the patient sit up and the legs is suspended over the edge of the table with the foot on a rest.this has the effect to improve visualisation.

9-diagnostic criteria for calf veins is the same as that of the veins above knee.

10-at present,the limitation of this technique as that it will only show global thrombosis either confined to one set of veins, or through out multiple calf veins.it will not reliably and routinely detect small focal segments of thrombosis.therefore,equivocal scans or persistent symptoms may require clarifying venogram.although this could be imperfect in detection of small focal calf thrombi due to poor or non filling of the affected segment.

calf vein imaging

1-this is not routinely performed at every centre.

2-essentially, each of the calf arteries is accompanied with pair of veins.

3-identify first the artery and then apply distal calf compression to visualise the paired veins.

4-spontaneous flow is generally abscent below knee.

lower limb veins thrombosis

a positive diagnosis of deep venous thrombosis using colour flow imaging depend upon a number of factors,which include:

1-lack of spontaneous flow.

2-presence of intra-luminal reflective material.

3-vein dilatation.

4-poor response to augmentation maneuver.

5-non compressibility of the vein.