RECURRENT LOWER LIMB DVT: OUT WITH THE OLD (THROMBUS), IN WITH THE NEW?
By Ellen Cronin, Mallow General Hospital
Background:
This case study follows a 23 year old female who attended the Medical Assessment Unit with a swollen, painful right calf and an elevated D dimer. A few months prior, she presented to the Accident and Emergency department with a comminuted fracture of the proximal right femur, underwent intra-medullary nailing and subsequently developed a right lower limb deep vein thrombosis (DVT).
Ultrasound Findings:
Comparison is made to the initial presentation right lower limb ultrasound after her femoral fracture. Thrombus is evident within the right mid superficial femoral vein. This area was nearly completely occluded on the initial ultrasound. This clot is now relatively echogenic and adherent to one wall. There is further adherent appearing mural thrombus in the right popliteal vein where again previously, there was extensive occlusive thrombus. The thrombus in the popliteal vein appears chronic and partially endothelialised. It is more difficult to label as chronic and partially endothelialised the thrombus within the superficial femoral vein.
Discussion:
There is currently no diagnostic standard for the management of suspected recurrent DVT. Up to 50% of patients who experience a lower limb DVT will develop post-thrombotic syndrome. This high incidence complicates the assessment of recurrent lower limb DVT, as there is significant overlap in the clinical signs and symptoms. Given that a significant proportion of spontaneous DVT does not recanalise on anticoagulation, it is difficult to differentiate acute from chronic thrombus with ultrasound.
Conclusion:
The diagnosis of recurrent lower limb DVT with ultrasound can prove challenging. Ultrasound has limited ability in distinguishing new DVTs from previous post-thrombotic changes. Imaging findings in the diagnosis of a suspected recurrent lower limb DVT must be correlated to current clinical history as regards to whether the lower limb swelling resolved after initial treatment and subsequently, reoccurred rapidly on current presentation, or not.