Patency

Patency refers to the openness or unobstructed state of a hollow organ or vessel, allowing free flow through a lumen. In medicine, patent lumens enable normal passage of blood, air, bile, urine, or gastrointestinal contents. Patency is a key consideration for vessels, ducts, and conduits after surgery or injury, and it may be described as fully or partially patent depending on the adequacy of flow.

Common contexts include arterial and venous vessels, the airway (trachea and bronchi), the biliary tract, the urinary tract, and the gastrointestinal tract. A lumen is considered patent if flow is sufficient for its function; occlusion can be partial or complete and may compromise organ performance.

Loss of patency can result from thrombosis, embolism, atherosclerosis, stenosis, tumor compression, external compression, scar tissue, edema, inflammation, or kinking of a conduit such as a graft or stent. Assessments use imaging and functional tests, including Doppler ultrasound, CT or MR angiography, conventional angiography, endoscopy, and intraluminal measurements of flow or pressure.

In vascular interventions, patency concepts include primary patency (time from treatment to first occlusion), assisted primary patency (reinterventions to maintain patency before occlusion), and secondary patency (patency restored after occlusion). Restoring patency may involve thrombolysis or thrombectomy, angioplasty, stent placement, bypass surgery, or surgical revision. Similar strategies apply in nonvascular ducts and airways, such as dilation, stenting, or removal of obstructive material.

Patency is a dynamic condition influenced by patient factors, device choice, and mechanical forces, and it is often reported as patency rates in clinical studies.