Diff between non occlusive thrombus and dvt? what can cause random blood clot? no family hist that i know of. can a really bad muscle strain cause it?

No real difference: Dvt on its own can be occlusive if the whole circumference of the blood vessel is involved or if there is passage of blood through it is non occlusive. Clots develop as a result of abnormality of flow such as in immobilization during flights or surgery, abnormality of blood vessel as in trauma or abnormality of the blood itself as in hyper coagulability due to cancer.

Anyone can get clot: If the clot is in the deep vein system it's dvt. Non- occlusive just means there's still some flow in the vein around the clot. Clot is caused by poor blood flow (stasis) damage to the vein lining (trauma) and/or an abnormal ability to make clot which can result from a clotting factor problem (hereditary). Muscle strain can cause clot, typically in arm veins in athletes/weight-lifters.

Some difference: Non occlusive thrombus is blood clot in arteries/veins around which there is some flow. Dvt is blood clot in veins of arms/legs and most are occlusive (totally blocking a segment of vein). Important to know if DVT is provoked (recent surgery, long trip) or unprovoked (random) especially in terms of length of anticoagulation and evaluation. Muscle strain is not a cause. Effort clot seen in arms.