Well yes and no...If you have bloody urine or the catheter insertion has caused a ruptured vessel in the urethra then the bloody urine that is passively draining through the tubing can clot, preventing the flow of urine. However the urethra is not a blood vessel. It is not part of the vascular system. So a clot that may form in the urethra cannot travel into the vascular system and cause a stroke. It will only block the flow of urine, causing the bladder to distend and become very full and painful. Blood clots occur in the vascular system for a number of reasons. Vessel wall irritation caused by IV's, narrowing of vessels from plaque buildup, hardening of the arteries, high blood sugar that causes sticky glycoproteins to form. Anything that slows blood flow can promote platelets in the blood to stick to the narrow vessel. After a while the platelets form a clot. These clots can break loose and travel. Depending their location, if it travels to the heart and block coronary arteries it is called a heart attack, if reaches the lungs it is called a pulmonary embolism, if it hits the brain it's called a stroke, if the clot forms in the legs due to long periods of inactivity then it is called deep vein thrombosis. High cholesterol, high blood pressure are the silent killers. Cholesterol build up forms clots and high blood pressure dislodges them. Hope this helps.
That is true, but one must consider the matter in terms of the probability of a clot forming and the damage the clot might do if it travels. Events involving mortality or stroke are extremely rare. An intravenous line in the medial antecubital, for example, utilizes a plastic flexible catheter, which may vary in diameter, which restricts blood flow. With such a restriction there is a possibility of a clot forming, especially if the line is in place for an extended period of time. There must be co-factors, such as dehydration, high hematocrit, and excessive clotting factor (usually vitamin K).