<prompt> Investigation of choice for DVT isDuplex USGVQ scanPlethysmographyD-dimer assay  <response>: . Duplex scanning shows noncompressible vein which is wider than normal.On compression over calf muscles,it does not show any augmentation of flow.Normal venous sound atg the area of femoral vein which disappears during inspiration is conspicuously absent in DVT. Refer page no 224 of SRBs manual of surgery 5 th edition. 