Interventional Radiology (Embolization)

Embolization is a minimally invasive procedure in which a radiologist deliberately blocks a blood vessel to cut off blood supply to a problem area, such as a tumour or a bleeding site, without open surgery.

A thin, flexible tube called a catheter is guided through an artery — usually one in the wrist or groin — and steered under live X-ray guidance to the target vessel. Once in position, the doctor releases blocking agents (tiny particles, coils, or a special glue) directly into that vessel. Without a blood supply, the target tissue shrinks, bleeds less, or stops functioning. The rest of the body is largely unaffected because only the specific vessel is blocked.

Embolization is used whenever a doctor needs to reduce or stop blood flow to a specific area of the body without removing tissue surgically. It covers a wide range of conditions across many organ systems.

• Uterine fibroids (non-cancerous growths in the womb) — to shrink them and reduce heavy bleeding
• Liver tumours, both primary liver cancer and metastases (cancer that has spread from another organ), when surgery is not possible
• Haemoptysis (coughing up blood) caused by damaged blood vessels in the lungs
• Gastrointestinal bleeding (bleeding inside the stomach or intestines) that cannot be controlled by endoscopy
• Trauma-related internal bleeding, such as bleeding in the pelvis, spleen, or liver after an accident
• Aneurysm (a dangerous bulge in a blood vessel) in the brain or body
• Arteriovenous malformation or AVM (an abnormal tangle of arteries and veins) in the brain or spine
• Enlarged prostate (benign prostatic hyperplasia or BPH) — treated by prostatic artery embolization (PAE) to improve urinary symptoms
• Varicocele (enlarged veins in the scrotum) causing male infertility or pain
• Hypersplenism (an overactive spleen) in patients who cannot tolerate surgery

Embolization is not suitable for every patient or every condition. A specialist will review the patient's individual situation carefully before recommending it.

• Severe kidney impairment, because the contrast dye (a liquid that makes blood vessels visible on X-ray) used during the procedure can stress the kidneys
• Known allergy to contrast dye that cannot be managed with pre-medication
• Blood clotting disorders that cannot be corrected before the procedure
• Pregnancy, in most cases, because of radiation exposure to the foetus
• Poor overall health that makes even a minimally invasive procedure too risky
• Situations where the target vessel cannot be safely reached with a catheter

Embolization is generally considered safer than open surgery for the same conditions, but like any procedure that enters the body, it carries recognised risks.

• Post-embolization syndrome — fever, fatigue, nausea, and pain in the days after the procedure, caused by the body reacting to blocked or dying tissue; this is common and expected rather than a sign of a serious problem
• Pain or cramping at the treated site, which can range from mild to severe
• Bruising, swelling, or bleeding at the catheter entry point (usually the groin or wrist)
• Accidental embolization — the blocking agents travel to a vessel that was not intended to be blocked, potentially affecting nearby healthy tissue
• Infection at the entry site or, less commonly, inside the treated area
• Contrast dye reaction — ranging from a mild rash to, rarely, a serious allergic response
• Kidney stress or injury from the contrast dye, especially in patients who already have reduced kidney function
• Incomplete treatment — not all of the target tissue may be fully blocked in one session, and a repeat procedure may be needed
• Damage to the artery through which the catheter travels
• In rare cases, unintended tissue damage in organs near the treated area

Preparation usually begins several days before the procedure. The medical team will give specific instructions based on the patient's condition, the organ being treated, and the hospital's own protocols — what follows is a general guide.

Before arriving at the hospital, patients are usually asked to fast (eat and drink nothing, or only clear fluids) for a number of hours — the team will state exactly how long. Blood thinners such as aspirin or warfarin are often paused for several days beforehand; the prescribing doctor decides whether and when to stop them. Smoking and alcohol are typically discouraged in the days leading up to the procedure because both affect how the blood vessels respond and how the body heals. If the patient takes regular medications for other conditions, they should discuss each one with the team — most can continue, but some may need to be adjusted.

Standard pre-procedure tests usually include:

• Blood tests to check kidney function, blood clotting (coagulation screen), and blood cell counts
• Imaging already done (CT, MRI, or ultrasound) to plan the exact route for the catheter
• An ECG (electrocardiogram — a recording of the heart's electrical activity) if the patient is older or has a heart condition
• A pregnancy test for women of childbearing age, because radiation is used during the procedure

On the day of the procedure, the typical sequence of steps is as follows, though the order and exact details can vary:

• 1. The patient changes into a hospital gown and an intravenous (IV) line is placed in the arm to give fluids and medication.
• 2. The skin at the catheter entry site (groin or wrist) is cleaned and numbed with a local anaesthetic (a numbing injection) so the patient feels pressure but not sharp pain.
• 3. Sedation (medication to relax the patient) is given through the IV line; general anaesthesia (being put fully to sleep) is used only in certain cases.
• 4. The radiologist makes a very small puncture in the skin and inserts a short hollow tube called a sheath.
• 5. The catheter is threaded through the sheath and guided through the arteries towards the target vessel, using live fluoroscopy (real-time moving X-ray) on a screen.
• 6. Contrast dye is injected through the catheter so the blood vessels show up clearly — the patient may feel a brief warm or flushing sensation.
• 7. Once the correct position is confirmed, the blocking agent (particles, coil, or glue) is released into the target vessel.
• 8. A final dye injection checks that blood flow to the target has been successfully reduced or stopped.
• 9. The catheter and sheath are removed, and firm pressure or a small closure device is applied to the entry site to prevent bleeding.
• 10. The patient is moved to a recovery area to be monitored.

Recovery after embolization is generally faster than after open surgery for the same condition, but the level of monitoring and the length of hospital stay depend on what was treated, which organ was involved, and how the patient responds in the first few hours.

• Monitoring: Most patients spend at least several hours — and often one or more nights — in hospital so that the team can watch for post-embolization syndrome, bleeding at the entry site, and signs that the target area is responding as expected.
• Pain management: Pain and cramping at the treated site are common for the first few days; the medical team will typically provide appropriate pain relief in hospital and advise on what to take at home.
• Entry-site care: The catheter entry point (usually groin or wrist) should be kept clean and dry as directed. The patient is usually told to watch for signs of infection such as redness, swelling, warmth, or discharge.
• Activity restrictions: Patients are generally advised to avoid heavy lifting, strenuous exercise, and long periods of standing for a period set by their doctor — this varies depending on the site treated.
• Driving: Driving is usually not permitted for at least 24 hours after sedation, and sometimes longer if the groin was used as the entry site.
• Diet and fluids: Drinking plenty of water in the days following the procedure is often encouraged to help the kidneys clear the contrast dye from the body.
• Medications: Blood thinners or antibiotics may be prescribed for a defined period after the procedure; the treating team will explain what is needed.
• Follow-up imaging: A repeat CT, MRI, or ultrasound is usually scheduled weeks to months later to check whether the target tissue has shrunk or the bleeding has resolved as expected.
• Outpatient follow-up: A clinic appointment with the interventional radiologist is usually arranged to review recovery, discuss imaging results, and decide whether any further treatment is needed.
• When to seek urgent help: Patients are instructed to go back to hospital immediately if they develop a high fever, heavy bleeding from the entry site, sudden severe pain, difficulty breathing, or any other symptom that feels serious.