Embolization in general. Ken U. Ekechukwu, MD, MPH, FACP.

What is embolization?
The word embolus comes from the Greek word embolus, which means a plug. It is a clot or other plugging material carried by blood from one site to another to obstruct the flow of blood.

Embolization is pathologic when blood clot from a vein in the lower limb or the pelvis is transported to the lungs to stop blood flow and cause acute shortness of breath or death – pulmonary thromboembolism. Pathologic embolization can also occur to any organ in the body, but evokes serious consequences when the organ is the brain, a kidneys, the intestines, the eye, or an extremity.

But embolization can be therapeutic or even life-saving, when a vessel is deliberately obstructed to avoid exsanguination from a hemorrhaging organ. Examples abound: Arteriovenous malformations (AVMs) are embolized to diminish the amount of blood flow through them and avoid heart failure; a vascular tumor destined for removal may be embolized to minimize blood loss during surgery; blood flow into a lacerated or hemorrhaging spleen, liver, pelvic artery or kidney is embolized to avoid shock and death; menstrual abnormalities caused by uterine fibroids are treated by deliberate embolization of the uterine arteries; stubborn nose bleeds, bleeding gut, hemoptysis (coughing up of blood), hemorrhage after child birth can all be embolized to save life.

This discussion is about therapeutic embolization, a practice that came into vogue in 1972 when the use of autologous blood clot (a person’s own blood clot) for embolization was first reported.

How do I prepare for embolization?
Learn about the procedure as much as you can and prepare yourself mentally for it. Most embolizations require hospitalization, conscious sedation (deep sedation with opiates and anxiolytics) and the injection of radiocontrast (dye) into the arteries. For these reasons you should refrain from eating 4 to 6 hours before the procedure. Drink a lot of water on the day before and after the treatment to minimize the adverse effects of the radiocontrast on your kidneys. Report all your medications to your physician before the procedure because there are some you should take and some that you must avoid before your procedure. Diabetics and hypertensives, the elderly, and those with poor kidney function deserve special care by the nature of their conditions and the risks they run in sustaining contrast-induced nephropathy (kidney damage from exposure to dye).

How is embolization done?
The technique of embolization varies with the kind of embolization planned for a patient. Nonetheless, some things are common to all embolizations. For many embolizations, a majority of interventionalists will administer systemic antibiotic to the patient to reduce their risk of infection after the treatment. Then after aseptic preparation of the access site and administration of conscious sedation, access is gained into an artery in your groin or your arm. A catheter is advanced through the access into the artery that feeds the organ or area to be embolized and an angiogram is performed to verify that the tip of the catheter is well-positioned. The embolic agent is injected into the artery under fluoroscopic watch. The choice of the embolization agent is informed by the nature of the disease, the size of the feeding artery, its location, and whether the occlusion of the vessel is temporary or permanent. A final angiogram is obtained to verify that the vessel is occluded and that no other vessel or organ was unintentionally embolized. Following the treatment, you will experience pain in the embolized area but it will be adequately treated with pain medicines. You may be nauseous or actually vomit and unable to hold food down. This is addressed with antiemetics (drugs that blunt or remove the urge to vomit), intravenous fluids, and by avoiding food or drinks until the urge to vomit passes. You may run a low-grade fever that may or may not require treating; it is  a response of your body to embolization. Sometimes there is diminished movement of the bowels, a response to the embolization or, more frequently, a side effect of the medications used to control pain. The use of stool softeners, ambulation, and cutting down on the pain medications usually resolve this problem. The duration of these symptoms, which collectively are called post embolization syndrome, varies from 3 days to 3 weeks.

Who needs embolization?
You will decide with your physician’s guidance whether embolization is what you need for your problem. Embolization may be used to treat the following conditions:
1. To stop rapid or heavy bleeding from an organ injured in trauma.
2. To stop rapid or heavy bleeding from the intestines, the nose, the lungs, the uterus, the urinary bladder, or other organs.
3. To control the growth of and symptoms caused by many tumors of the body.
4. To reduce the amount of blood loss during the surgical removal of certain tumors.
5. To close or isolate abnormal blood vessels from the rest of the circulation like arteriovenous malformations and pseudoaneurysms. This list is not exhaustive and your condition may not be on it.

What are the contraindications to embolization?
1. Unwilling patient: Do not offer embolization to a patient who does not wish to have it. 
2. Coagulopathy: Coagulopathy makes embolization ineffective.
3. Alternative treatment: If there is a better alternative to embolization for a condition, use it.
4. Infection: Treat infection in or around an organ before embolizing it.