Embolization (or embolisation) refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin (pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially induced (therapeutic), as a hemostatic treatment for bleeding or as a treatment for some types of cancer by deliberately blocking blood vessels to starve the tumor cells.
In the cancer management application, the embolus, besides blocking the blood supply to the tumor, also often includes an ingredient to attack the tumor chemically or with irradiation. When it bears a chemotherapy drug, the process is called chemoembolization. Transcatheter arterial chemoembolization (TACE) is the usual form. When the embolus bears a radiopharmaceutical for unsealed source radiotherapy, the process is called radioembolization or selective internal radiation therapy (SIRT).
Embolization involves the selective occlusion of blood vessels by purposely introducing emboli, in other words deliberately blocking a blood vessel.
Embolization is used to treat a wide variety of conditions affecting different organs of the human body.

Bleeding

The treatment is used to occlude:

Recurrent coughing up of blood

Cerebral aneurysm

Gastrointestinal bleeding

Nosebleed

Varicocele

Primary post-partum bleeding

Surgical bleeding

Traumatic bleeding such as splenic rupture or pelvic fracture

Growths

The treatment is used to slow or stop blood supply thus reducing the size of the tumour:

Kidney lesions

Liver lesions, typically hepatocellular carcinoma (HCC). Treated either by particle infarction or transcatheter arterial chemoembolization (TACE).

Uterine fibroids

Arteriovenous malformations (AVMs)

Juvenile Nasopharyngeal Angiofibroma

The procedure is carried out as an endovascular procedure by an interventional cardiologist in an interventional suite. It is common for most patients to have the treatment carried out with little or no sedation, although this depends largely on the organ to be embolized. Patients who undergo cerebral embolization or portal vein embolization are usually given a general anesthetic.
Access to the organ in question is acquired by means of a guidewire and catheter(s). Depending on the organ this can be very difficult and time-consuming. The position of the correct artery or vein supplying the pathology in question is located by digital subtraction angiography (DSA). These images are then used as a map for the radiologist to gain access to the correct vessel by selecting an appropriate catheter and or wire, depending on the 'shape' of the surrounding anatomy.
Once in place, the treatment can begin. The artificial embolus used is usually one of the following:

Coils: Guglielmi Detachable Coil or Hydrocoil

Particles

Foam

Plug

Microspheres or Beads

Once the artificial emboli have been successfully introduced, another set of DSA images are taken to confirm a successful deployment.