Interventional Radiology PDF

Interventional Radiology Interventional radiology is a medical specialization that involves performing a range of imaging procedures to obtain images of the inside of the body. The interventional radiologist carefully interprets these images to diagnose injury and disease, and to perform a range of...

Interventional Radiology Interventional radiology is a medical specialization that involves performing a range of imaging procedures to obtain images of the inside of the body. The interventional radiologist carefully interprets these images to diagnose injury and disease, and to perform a range of interventional medical procedures. -Interventional radiologist use imaging techniques such as X-rays, MRIs (magnetic resonance imaging) scans, fluoroscopy (an X-ray procedure that makes it possible to see internal organs in motion), CT (computed tomography) scans and ultrasounds. -Interventional radiologists perform a broad range of procedures such as treating tumours, taking organ biopsies or placing stents by inserting tiny instruments and thin plastic tubes (catheters) into the body via an artery or vein. -The images are used to guide the catheters and instruments to the exact area where the procedure or treatment is to be performed. This reduces the need for traditional (open) or keyhole (laparoscopic) surgery as treatment can be given via a small plastic tube about the size of a straw. -Continuing advances in technology mean the range of conditions that can be treated by interventional radiology is continuing to expand. 1 Image-guided procedures:  The most commonly used are US or CT. Less commonly is fluoroscopy.  US is most commonly used modality for two main reasons: 1. Relatively low cost (hence availability) 2. True real-time imaging: this means the ability to monitor the surgical instrument in real time (live). This allows easy re-adjustment of the position and direction of the instrument.  CT -when available- is very helpful in localizing the target. 1. Some organs, such as lungs and bones – a common sites of metastases- are particularly more suited to CT than US, which suffers many artifacts at air and bone. 2. On the other hand, CT is not a true real time modality. It requires the operator to insert the instrument, take CT cuts to revise the position and direction. Correction of the site or the direction of the instrument necessitates re-imaging until the instrument is precisely inserted into the target. This is time consuming.  Fluoroscopy can be used for some procedures, that do not requires precise targeting, e.g. the intervertebral discs. General knowledge of the anatomy will help avoiding critical areas, such the spinal canal and exit foramina.  MRI has been used for guidance, but its main problem is availability because of its high cost. Furthermore the need for specific non-magnetic instruments is another additional cost. 2 Interventional radiologists perform a wide range or procedures, including: 1. Angioplasty and Stent Insertion 2. Ascitic Tap 3. Bursal Injection 4. Carpal Tunnel Ultrasound and Injection 5. Image Guided Lumbar Epidural Corticosteroid Injection 6. Image Guided Liver Biopsy 1. Angioplasty and Stent Insertion Angioplasty and Stent Insertion Defination of angioplasty and stent insertion - Angioplasty and stent insertion is used to treat narrowing in an artery. - Angioplasty uses a small, sausage-shaped balloon to stretch the artery open and improve blood flow. - The stent is a small, metal cylinder that acts like a small scaffold to hold the artery permanently open. Angioplasty is the name of the procedure carried out with the assistance of an angiogram, a special kind of X-ray image or picture that shows the arteries live on a screen. - The procedure starts with an angiogram and is carried out through a skin puncture into the blood vessel that feeds the narrowed or diseased vessels. Most often, the skin puncture is in the groin, at the top of the leg. - Less commonly, you may need to have the skin puncture in your upper arm, if the blood vessel in the groin cannot be used. 3  - A liquid contrast agent (sometimes referred to as contrast medium or dye) is injected into the artery to show the blood vessels on an X-ray image. Without contrast injection, blood vessels are invisible on X-rays. Angioplasty and stent insertion is carried out using the live images that are displayed on a television screen to guide the procedure. - Cardiologists (doctors specialising in disorders of the heart) carry out stent insertions into the coronary (heart) arteries. Radiologists (specialist doctors) carry out angioplasty and stent insertion in all other arteries in the body. Preparation for an angioplasty and stent insertion - Depending on the hospital or radiology practice where you are having the procedure done, you may be required to fast before the procedure (that means to go without food and water) for 4 hours prior to the procedure. - The hospital or radiology practice will inform you if you need to fast. - Contrast medium is used to carry out angiograms, and if you have a history of kidney disease, this places some strain on the kidneys. - If you have abnormal kidney function or diabetes, one kidney rather than two, or other medical conditions that may increase the risk to your kidney function if you have contrast injection, then special precautions are required. - One of these precautions can be to give you extra fluid through an intravenous drip both before and after the procedure. Also, if you are on the blood thinning medication warfarin, an INR blood test will be needed to assess how ʻthinʼ the blood is before the procedure (see Iodine-containing contrast medium). - This should be discussed with your referring doctor or specialist and the radiologist who is carrying out the procedure. Procedure of an angioplasty and stent insertion - The procedure is usually not painful, but it is normal to be anxious before undergoing any procedure and you will normally be given a light sedation to help you relax. 4 1. Local anaesthetic is then injected into the skin and soft tissues, and around the artery that will be used to gain access to the blood vessels that require treatment. This artery is usually the one in front of the hip or groin region, called the femoral artery. 2. A needle is passed into the anaesthetised artery and then a soft and flexible guidewire is passed through the needle into the artery. A sheath is then passed over the wire and into the artery. The sheath is a plastic tube with a tap on one end. It usually measures 2–3 mm (1/8 inch) in diameter. Once the sheath is in place, the balloons and stents are all passed through this sheath. 3. A very thin tube is then passed through the sheath into the narrowed artery and an angiogram picture is taken. Using this picture, the correct sized balloon is chosen. Angioplasty is carried out by passing a thin tube into the artery. The tube is called a balloon angioplasty catheter and has an inflatable balloon on the end of it. The balloon is shaped like a long sausage when it is inflated. The correct balloon size is selected for the artery being treated. 4. The balloon is inflated where the artery is narrow and stretches the artery up to normal size. This procedure can be carried out for arteries almost anywhere in the body. After the balloon has been inflated for up to 3 minutes, it is deflated and removed. Another tube is passed into the artery to inject contrast medium. The contrast medium is injected while X-rays are being taken to provide an angiogram showing images of the new shape of the artery. 5. Sometimes, the angioplasty is enough to keep the artery open, but on many occasions a stent is required to hold the artery open. A stent is a metal tube that is inserted into the artery through the same sheath in the groin region. It acts as a scaffold to prevent the narrow section of artery collapsing back. A stent stays in the artery permanently. 6. The sheath is removed from the groin and an arterial closure device is sometimes inserted to close the artery and stop the bleeding. Alternatively, pressure (either with the doctorʼs or nurseʼs finger over the puncture site or with a clamp) is applied to the puncture site to stop the artery from 5  bleeding. You must lie flat for between 1 and 4 hours after this. Postoperative effects of an angioplasty and stent insertion You might experience some discomfort in the groin (at the site of the puncture), like a bruise. You may develop a bruise in the groin. This only matters if it is associated with a hard lump that can be felt with your finger or significant/increasing pain. This is called a pseudoaneurysm. If this happens, you should immediately contact the practice where you had your procedure carried out to report this to the radiologist, because it may represent a localised injury to the vessel wall that needs special treatment. There may also be some discomfort at the site of the stent, as the artery becomes accustomed to having a stent within it. This is usually mild (and often non-existent), but if it does occur, it usually subsides over a week. It is most strongly felt when long stents are used in leg arteries. Duration of an angioplasty and stent insertion take The procedure varies, but in most cases it takes between 30 and 60 minutes to complete. The risks of an angioplasty and stent insertion The risks of the procedure depend on which artery is being treated. General risks include the following: Bleeding/bruising at the groin puncture (approximately 3-5% of cases). This can be a problem requiring further treatment to either stop the bleeding or, even less commonly, to repair an injury to the vessel wall (this injury is called a pseudoaneurysm). Pseudoaneurysm at the puncture site will feel and look like a local lump that stays there for days to weeks after the procedure is finished. It is rarer than simple persistence of bleeding from the puncture site, but does require further treatment by the radiologist. Blocking the treated artery, making your symptoms worse in the short- term. The artery may close completely in approximately 1% of cases. Allergic reaction to intravascular contrast medium. Most reactions are mild, but very rarely can be severe (see Iodine-containing contrast 6  medium). Kidney failure – this can occur if you have diabetes or chronic kidney dysfunction and especially if adequate preventative steps are not taken (see Contrast Medium: Using Gadolinium or Iodine in Patients with Kidney Problems). You will have your kidney function assessed by blood testing before the procedure to see if you need these preventative steps (which usually consist of ensuring that you are well hydrated, and this may mean having an intravenous drip inserted to give you extra fluids before and after the procedure). Allergic reaction to the sedation drugs or any other medications that are used. The benefits of an angioplasty and stent insertion - The procedure re-opens the artery to restore blood flow. The benefits provided by this restoration of blood flow depend on the artery being treated. - In the case of leg arteries, this may help you to walk without pain or allow a wound/ulcer on the leg or foot to heal. - In the kidney arteries, it might help reduce abnormally high blood pressure or preserve kidney function. When carried out on an artery supplying the bowel, it may stop abdominal pain if this pain is due to reduced blood supply to the bowel. When carried out on the carotid artery (supplying the brain), it may prevent stroke. Balloon Angioplasty Balloon angioplasty is done to restore the normal caliber of localized narrowing of arteries and veins, as in atherosclerosis or congenital narrowing , e.g. fibromuscular A B C D E 7  dysplasias. A: Right femoral angiogram showing short segment occlusion of the SFA at the adductor canal. A guidewire is passed gently through the occluded segment, followed by deflated balloon. B: Angioplasty balloon inflated with contrast at the occluded segment. C: Post-dilatation angiogram showing opened lumen with irregular outline. D: Metallic stent deployed within the dilated segment and left in place. E: Post-stenting angiogram showing smooth outline due to stent. ANEURYSMS -Aneurysms are caused by localized weakness of arterial wall, resulting in localized dilatation which may be saccular or fusiform. - Aneurysms are liable to rupture with subsequent significant bleeding. Another problem is their mass effect on their neighborhood. -Apart from surgical treatment, fusiform aneurysms can be treated with stenting, while saccular aneurysms can be treated with coiling (and/or stenting), based on the shape of aneurysm. Coiling Aneurysm coiling. Left: A microcatheter is introduced into the aneurysmal neck. Middle: Platinum coil(s) deployed and convoluted into the sac. Right: complete packing of aneurysm with coils, securing the aneurysm. 8 Stenting Stents are prosthetic tubes with or without holes, used to restore the normal caliber of a tubular organ. They can be metallic or plastic Aneurysm stenting. Left: stent introduced over a guidewire across the saccular aneurysm. Right: After deployment: the stent aligned to the arterial lumen, while the rest of the aneurysmal cavity is isolated from the blood stream, and eventually become thrombosed. Stenting may also be an ideal treatment to arterial dissection. VASCULAR MALFORMATIONS -Vascular malformations are mal-developed blood vessels, of arterial or venous origin, or mixture of both. - Based on their hemodynamics (high flow or low flow), size and location, various clinical problems may arise. - At the CNS, they may result in cerebral hemorrhage, ischemia due to shunt of blood directly to the veins (steal phenomena), epileptic fits, mass effect, etc. - Large body AVMs may result in hyperdynamic circulation and eventually heart failure, or -sometimes- left-to-right shunt (which may contirbute to pulmonary embolism). - Small malformations with low hemodynamics (such as venous ones) may be of little clinical significance and may be left untreated. 9 Embolization -Embolization is the injection of thrombosing or foreign material that will lead to thrombosis or blockage of the downstream vascular tree, with subsequent reduction/cessation of blood flow. -This will reduce the probability of future hemorrhage, improve blood flow to the neighbourhood, improve overall circulation as well as other symptoms. -Extreme care should be paid to limit embolization to the targeted malformation, and avoid other adjacent areas. -Purely venous malformation and low-flow vascular lesions may be directly punctured and sclerosing material (e.g. glue or 95% alcohol) injected to obliterate the lesion. Embolic material:  Solid Particles: Consist of small powder-like material with variable sizes (in microns), thus giving control over the size of blood vessel (i.e. how deep they can penetrate into the tissues before they are lodged in the arterioles or capillaries)  Liquid: These are liquid material that -when it comes in contact with blood- it polymerizes rapidly into more solid material and takes the shape of the blood vessel with subsequent complete and permanent occlusion. A typical use is in the treatment of AVMs  Coils: These are sizeable metallic filaments which are driven into a vessel or vascular malformation, where they act as a foreign material inducing thrombosis. Some embolic materials are permanent (like coils and liquids, as well as some kinds of solid particles), while others are temporary (i.e. recanalization of the occluded vessel may take place few days after the procedure (e.g. gel foam, or autologous blood clots). BLEEDING Embolization is the modality of choice for treatment of uncontrolled/persistent hemorrhage almost 10 anywhere in the body. Applications include -just as an examples- Epistaxis, GI bleeding, hematuria, obstetrical or gynecological causes, bleeding neoplasms or hemorrhage due to trauma. PUlMONARY EMBOLISM -Pulmonary embolism may take place with a variety of materials based on the cause (blood clots, fat, air). Blood clots are the most common cause, and may represent a serious life- threatening complication. -Pulmonary embolism is a potential complication to deep venous thrombosis, the commonest site is the lower limbs. - The fresh thrombus may dislodge and flow with blood stream to settle in the pulmonary arteries, with subsequent block of pulmonary circulation and hypo-oxygenation. -The risk of Pulmonary embolism was found to be less if the patient with deep venous thrombosis is kept on anticoagulant. However, in some clinical contexts, the patient may have bleeding elsewhere in the body particularly with anticoagulation (operative site, cerebral hemorrhage, ,, etc.). In such case, anticoagulants may need to be stopped, raising the likelihood of PE. IVC Filter  In such clinical situation, a metallic filter, which looks like an umbrella is applied into patent IVC (in a similar manner to stents). The limbs of the umbrella will help as strainer, where floating thrombi will be lodged into them, thus the pulmonary arteries are spared (at least partially). Filter deployed in IVC Varicose veins / Varicocele -Primay Varicose veins are dilated tortuous veins, commonly associated with pain and skin alteration 2ry to increased venous pressure within the superficial venous system of the lower limbs Treatment is to get rid of the diseased vein. Traditionally this was done surgically. -Varicocele means varicosity of the veins around the testicles which is due to stagnation of flow 11 in the unhealthy testicular veins, with subsequent increased pressure. -More recently, the vein may be ablated, either with chemical cautery, mechanical or thermal energy effect, with subsequent obliteration of the vein. -Radiofrequency ablation (RFA) is a relatively new method that can achieve destruction of venous mucosa, ending in fibrosis and obliteration of the vein. -Treatment of varicoele is done through embolization of testicular vein with liquid embolic material with subsequent occlusion. - This is done following catheterization of the testicular veins bilaterally (via IVC on the right, and renal vein on the left side). ONCOLOGY -Oncology might be the branch of medicine that got the most benefit from IR. From the very early days of IR, diagnostic Image-guided fine needle biopsies have been the most common practiced techniques. - This has saved the effort, time, cost and stress associated with admitting patients for surgical exploration, under general anaesthesia, and taking core biopsy from a tumour then releasing the patient until the result is obtained from pathology. -IR has opened the door for tumour management via a variety of strategies: Direct tumour attack Under US or CT guidance, a needle may be introduced inside the tumour mass. Such needle can have different functions:  Thermal ablation (by RFA , MWA or hot water) 12   Cryo-ablation  Chemical ablation (by alcohol) Stop Vascular supply Catheterization of the arterial supply to the tumour has been used to attack the tumour either through:  embolization and occlusion of its blood supply, thus inducing tumour ischemia. Uterine fibroids have shown excellent response to this therapy. Typical candidates c/o menorrhagia or dysmenorrhea who are not looking for further children (as there is the risk of infertility) OR  injection of chemotherapeutic agent selectively into the arterial feeder of the tumour. This would help reduce - markedly- the dose of chemotherapy, thus avoiding the side effects. One of the most famous technique is TACE (Trans-Arterial Chemo- Embolization). TACE Via femoral artery, a catheter is introduced and driven into the aorta > Celiac a. > Hepatic a. > tumour arterial feeder. - A mixture of chemotherapy and Lipiodol (oily dye), is prepared and injected into the artery. Lipiodol helps bind the chemotherapy to tumour cells, thus prolonging the therapeutic effect. 2- Ascitic Tap Defination of an ascitic tap -An ascitic tap is a medical procedure where a needle is used to drain fluid that is trapped in an internal body cavity, most commonly the abdomen (belly). 13 - Fluid may have to be drained from the abdomen for different reasons, such as if the fluid is stretching the abdomen and causing pain; if the fluid is infected; or if a doctor needs to analyse the fluid in a laboratory for the presence of any disease. -A radiologist (specialist doctor) uses ultrasound to show images or pictures of the inside of the abdomen on a screen to guide the needle to where the fluid is situated. -Other names for an ascitic tap are ʻabdominocentesisʼ, ʻparacentesis of the abdomenʼ or ʻascitic drainʼ Preparation for an ascitic tap -You may be asked to fast (not to eat or drink for a period of time) before having the procedure. This is very important as your intestines (or bowel) move involuntarily after you eat, which can make the ascitic tap more difficult to carry out. -If you are taking warfarin or other blood thinning medications, you will need to stop taking it for several days before having the ascitic tap. -Alternate blood thinning medications may be necessary. If you are taking warfarin, an INR (this is the blood test you have regularly to check that your warfarin dose is appropriate) is required before the procedure, preferably on the same day. - Aspirin does not need to be stopped before you have the procedure. -Special blood tests are recommended for all patients with liver disease. Your referring doctor will arrange this before you have the ascitic tap. Procedure of an ascitic tap -You will be asked to lie on your back on a bed and your abdomen will be wiped clean with antiseptic liquid. -The doctor will locate the fluid in your abdomen and determine the easiest way to reach the fluid by using ultrasound images that show the inside of your abdomen on a screen. -You will be fully awake during the whole procedure, but the doctor will numb a small area of skin with local anaesthetic for your comfort. - Through the numb patch of skin, a needle is used to insert a thin plastic drain tube into the 14 area of fluid. This allows the fluid to drain out of the body into a sealed plastic bag. - Once enough fluid has been removed, the tube is carefully removed by a nurse or doctor. This only takes a couple of seconds and no stitches are required. You will then be allowed to go home. Post operative effects of an ascitic tap -Usually, you will feel as you did before the ascitic tap, with no after effects. If there has been a lot of fluid in your abdomen and this has been removed, you may feel much more comfortable than before. -If you have had a lot of fluid drained, it can lower your blood pressure and make you feel dizzy or lightheaded. Occasionally, the doctor may give replacement fluids into your veins to reduce this side-effect. -Once most of the fluid drains out from your abdomen, the tubing can be uncomfortable or even painful. This is usually relieved once the drain tube is removed. -Most patients will have a very tiny (3mm) scar on the skin at the site where the drain tube was inserted. After the procedure is finished, the entry site will be covered with a waterproof dressing so you may have a shower. - You should avoid swimming or any strenuous activities for at least 5 days while the wound fully heals. -Occasionally, fluid may continue leaking out of the wound under the dressing. It is important to keep the wound clean and covered with a dressing until it is dry and is no longer oozing any fluid. Duration of an ascitic tap -The whole procedure, including ultrasound scanning to locate the fluid, setting up the instruments and placing the tube into position, can take between 15 to 30 minutes. -Once the drain tube is in place, you will have to wait for the fluid to drain. This may take from 5 minutes to several hours, depending on the amount of fluid and how fast it drains. -You will be allowed to go home once the fluid has drained out and the drain tube has been removed. 15  The risks of an ascitic tap  This procedure is low risk. 1. The risk of introducing infection into your abdomen or the skin wound is also very low. Many measures are taken by the doctor to minimise this risk. 2. There is a small risk that you will continue to drain fluid from the puncture site for many days after the procedure. 3. Bleeding is a rare complication 4. Damage to adjacent organs is very rare due to the use of an ultrasound machine to guide the procedure. 5. If a lot of fluid is removed, you may be dizzy due to low blood pressure. Sometimes this might require intravenous fluids. Inform your doctor immediately if you develop a fever, severe pain, redness at the wound site, blood in your urine or bleeding from the site. The benefits of an ascitic tap 1- An ascitic tap allows fluid in the abdomen to be removed if it is infected, causing pain or if it requires laboratory analysis to diagnose a disease. 2- An ascitic tap is quicker, easier and safer than other methods that can be used to remove fluid from the abdomen. It also leaves a smaller scar and allows for quicker recovery afterwards. Occasionally, if the fluid is too deep to reach through the skin or if there are too many separate pockets of fluid, it may be decided an ascitic tap should not be used. This can only be determined at the time of the procedure, when the doctor uses ultrasound images to locate the fluid and is able to assess the best method to use for drainage. 3- Bursal Injection Defintion of a bursal injection A bursa is a soft tissue space between two 16  structures, such as bone, muscle, tendon and skin, which allows the structures to slide over one another. Soft tissue, such as muscle, fat and skin, connects and surrounds the bones and internal organs of the body. The most commonly injected bursas are around the shoulder (subacromial bursa) and hip (trochanteric (submaximus) bursa), but a bursal injection might also be helpful in many other areas of the body. These include the elbow (olecranon bursa) and the knee (prepatellar bursa). Ultrasound is most often used to guide the placement of a needle directly into the bursa, with an injection of corticosteroid (ʻcortisoneʼ or ʻsteroidʼ) and local anaesthetic medication. Indications for a bursal injection -Your doctor would refer you for this procedure if bursitis was thought to be the cause of your symptoms. - Bursitis (inflammation of a bursa) is a common cause of soft tissue pain. -Movement of the affected area might be painful and you might also have reduced movement. Injection of a small dose of corticosteroid and local anaesthetic into the bursa might relieve these symptoms by reducing inflammation in or around the 17  bursa. -Bursitis in the shoulder might also be felt as pain in the upper arm. - Bursitis around the hip is usually over the lateral aspect (outside) of the hip, where the gluteal muscles are located. - These muscles lie within your buttock, and extend to the top and outside of the upper femur (leg bone). - You are more likely to feel focal tenderness (pain when pressing) over the bone on the outside of the hip, and pain can sometimes go down the outside of your thigh. - Both shoulder and lateral hip bursitis can give you pain at night and disturb your sleep. Preparation for a bursal injection? - No specific preparation is needed. You should take any previous X-rays, ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) scans to the appointment. - When you make your appointment for the bursal injection, you need to let the radiology facility know if you are taking any blood thinning medication, particularly warfarin. - Blood thinning medications might need to be stopped for a period of days, or your normal dose reduced, before this procedure is carried out. The radiology facility or your own doctor will give you specific instructions about whether you need to stop or reduce the medication and when to restart the medication. - These medications are usually prescribed to prevent stroke or heart attack, so it is 18  very important that you do not stop taking them without being instructed to do so by your doctor or the radiology practice, or both. - A blood test might be required to check your blood clotting on the day of the procedure. Continue with pain medication and other medications as usual. Procedure of a bursal injection -You will most likely be asked to change into a gown. This will depend on the area that is being injected. - You will lie on a scanning bed or sit in a chair in a comfortable position, usually in an ultrasound room. - A radiologist (specialist doctor) and/or the sonographer (ultrasound technician) will explain the procedure to you. You will be able to ask any questions. - The area to be injected is imaged to locate the bursa. Sometimes a mark is placed on the skin by the doctor to help guide the needle into the correct place. - The skin is then cleaned with antiseptic liquid. A fine needle is passed directly into the bursa using ultrasound images to guide the placement of the needle. - Occasionally, the needle is inserted at the point of maximum tenderness for a lateral hip injection, without using ultrasound guidance. - A small amount of corticosteroid and local anaesthetic (usually just a few millilitres) is injected and the needle is removed. - The needle is generally in and out again within a minute. Most people are surprised by how quick the procedure is. - The doctor will then give you instructions for after the injection. This will generally include completely resting the limb or the part of the body injected for 6 hours, and then limiting its use for between 1 and 3 days, sometimes longer. Postoperative effects of a bursal injection? - As with any injection, there is sometimes a dull ache for a few hours after the procedure. There might be an area of numbness around the injection site, for 1 or 2 hours, due to 19  the local anaesthetic. Some bruising and a few spots of blood at the site of the injection might occur. - The corticosteroid does not usually start working for 24 hours, and sometimes this takes up to 3 days. - During this time, the normal symptoms might continue or occasionally worsen. If symptoms are much worse, it generally indicates a reaction to part of the injected medication or to the injection itself. - If you find this worrying or distressing, you should see your own doctor or contact the radiology facility where the procedure was carried out. - Sometimes people can experience general reactions, such as flushing and redness of the body and face, related to the absorption of the corticosteroid into the body. These occur over the first few days. - In diabetics, the absorption of the corticosteroid can increase the blood sugar levels (BSL) for a few days and the BSL should generally be checked several hours after the procedure. Duration of a bursal injection - The procedure itself rarely takes more than 5 minutes, and with the preparation (scanning, marking, explaining the procedure etc.) it will take approximately 15 minutes. - If your own doctor has requested an ultrasound to assess the area as well as an injection, this can take up to 30 minutes. The risks of a bursal injection - This is a very safe procedure with few significant risks. Few people complain of side- effects, but occasionally problems are experiencedsuch as: 1. The commonest complaint is a temporary worsening of the symptoms over 1, 2 or even 3 days. 2. Very rarely, an injection of corticosteroid and anaesthetic can cause an allergic reaction. The exact risk of this is not known. People are sometimes 20  allergic to the antiseptic solution and dressings/bandaids. 3. There is a very small risk of infection, which is minimised by the doctor carrying out the procedure in clean conditions. The injection will not be carried out if there is broken skin or infection in the skin over the bursal area, or if the bursa might already be infected. If symptoms do not settle orget worse, particularly if you feel unwell or have a temperature, you should see your own doctor. 4. There is a very small risk of damage to the soft tissues at the injection site. This is called tissue atrophy, which is a thinning or scarring of the skin or subcutaneous fat (fat found just beneath the skin), and can occur when the injected medication is very close to the surface. Tissue atrophy can also affect deeper structures in the body. This is more likely with repeated injections at the same location. 5. Some people find that the injection gives them pain relief for a few months, but then the pain comes back and they wonder about the safety of having another injection. Although the exact risk of multiple injections is not known, most doctors would advise against having a bursal injection more than three to four times a year to avoid tissue atrophy. This is more important when the injection is carried out in areas where there is already significant wear or tear (partly torn tendons or ligaments). The benefits of a bursal injection - The aim of a bursal injection is primarily to reduce any inflammation in or around the bursa by injecting a small dose of corticosteroid and local anaesthetic. This should result in pain relief and swelling reduction. - Sometimes the injection is carried out to assess if the bursa is the cause of your pain. A good response to the injection confirms that the source of pain is the bursa that was injected. If there is no improvement in your pain, it is unlikely to be arising from the bursa or the adjacent structures. This can be helpful information for your own doctor, as it means that other causes need to be investigated. 4. Carpal Tunnel Ultrasound and Injection 21