(Venogram-Renal, Renal Venography, Venogram of the Kidneys)
What is a renal venogram?
A renal venogram is a diagnostic procedure that provides information about the circulatory health of the kidneys. A renal venogram uses X-rays and intravenous (IV) contrast dye to visualize the veins within the kidneys and the veins carrying blood away from the kidneys. Contrast dye causes the blood vessels to appear opaque on the X-ray image, allowing the doctor to visualize the blood vessels being evaluated.
Fluoroscopy is often used during a renal venogram. Fluoroscopy is a study of moving body structures similar to an X-ray movie. A continuous X-ray beam is passed through the body part being examined, and is transmitted to a TV-like monitor so that the body part and its motion can be seen in detail.
In addition to evaluating the renal veins, hypertension (high blood pressure) may be assessed during a renal venogram. A blood sample (renin assay) is obtained from each renal vein. The level of renin in the blood may help the doctor determine the cause of hypertension.
What is an X-ray?
X-rays use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film. X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body structures onto specially-treated plates (similar to camera film) and a "negative" type picture is made (the more solid a structure is, the whiter it appears on the film).
Other related procedures that may be used to diagnose problems of the kidney's blood flow include computed tomography (CT scan) of the kidneys, renal ultrasound, renal angiogram, and pyelogram (intravenous, antegrade, and retrograde). Please see these procedures for additional information.
How do the kidneys work?
The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.
The kidneys and urinary system keep chemicals, such as potassium and sodium, and water in balance, and remove a type of waste, called urea, from the blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.
Two kidneys, a pair of purplish-brown organs, are located below the ribs toward the middle of the back. Their function is to:
Remove liquid waste from the blood in the form of urine
Keep a stable balance of salts and other substances in the blood
Produce erythropoietin, a hormone that aids the formation of red blood cells
Regulate blood pressure
The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.
Reasons for the procedure
The veins in a healthy kidney are free from obstruction, clots, or high blood pressure (hypertension). Some medical conditions may impede blood flow through the kidneys or cause increased blood pressure to the kidneys. If a problem with the veins of the kidney is suspected, your doctor may request a renal venogram to determine the cause of the problem.
A venogram can detect conditions stemming from the renal vein itself, as well as other problems that result from influences on the renal vein from other organs, such as the kidneys. Problems involving renal circulation include structural problems that can lead to a blockage of blood flow to or from the kidneys.
Problems involving the renal circulatory system may include, but are not limited to, the following:
Renal vein thrombosis. An acute or chronic problem in which a blood clot forms in the renal vein. It can occur for various reasons including, but not limited to: postoperative complication after abdominal surgery, dehydration, congestive heart failure, kidney disease, pregnancy, and morbid obesity.
Retroperitoneal fibrosis. A mass of fibrous tissue located towards the back of the abdomen near the kidneys. This mass may cause compression of the renal veins impeding normal blood flow.
Renal tumors. Benign (noncancerous) or malignant (cancerous) tumors on or inside the kidneys
Renal agenesis. Absence of one kidney
Renovascular hypertension. High blood pressure in the kidneys resulting from abnormal hormone levels that are produced or regulated in the kidneys
There may be other reasons for your doctor to recommend a renal venogram.
Risks of the procedure
You may want to ask your doctor about the amount of radiation used during the procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous scans and other types of X-rays, so that you can inform your doctor. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.
If you are pregnant or suspect that you may be pregnant, you should notify your health care provider. Radiation exposure during pregnancy may lead to birth defects.
Because contrast dye is used, there is a risk for allergic reaction to the dye. Patients who are allergic to or sensitive to medications, contrast dye, or iodine should notify their doctor.
Patients with kidney failure or other kidney problems should notify their doctor In some cases, the contrast dye can cause kidney failure, especially if the person is taking Glucophage (a diabetic medication).
Because the procedure involves the blood vessels and blood flow of the kidneys, there is a small risk for complications involving the kidneys. These complications may include, but are not limited to, the following:
Hemorrhage due to puncture of a blood vessel
Injury to nerves
Embolus. This is a clot in the blood vessel.
Hematoma. An area of swelling caused by a collection of blood.
Transient kidney failure
Renal venography is contraindicated for patients with severe thrombosis of the inferior vena cava (the large vein that brings unoxygenated blood from the lower body to the heart) or the renal vein.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Certain factors or conditions may interfere with the accuracy of a renal venogram. These factors include, but are not limited to, the following:
Remaining contrast substances from recent contrast studies, such as a barium enema
Gas or stool in the intestines
Certain medications, such as blood pressure medications, diuretics (water pills), estrogen (hormone), and oral contraceptives (birth control pills), as well as failure to restrict salt intake may interfere with a renin assay blood test if performed during the procedure
Before the procedure
Your doctor will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
You will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if something is not clear.
Notify your doctor if you have ever had a reaction to any contrast dye, or if you are allergic to iodine.
Notify your doctor if you are sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general).
You will be asked to fast for several hours prior to the procedure. Your doctor will give you specific instructions as to how long to fast. If a renin assay is to be done during the procedure, you will be instructed to restrict your salt intake for a certain period of time.
Notify your health care provider if you are pregnant or suspect you may be pregnant.
Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
Notify your doctor if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop these medications prior to the procedure.
If a sedative is given before or during the procedure, you may need to have someone drive you home afterwards.
Based on your medical condition, your doctor may request other specific preparation.
During the procedure
A renal venogram may be performed on an outpatient basis or as part of your stay in the hospital. Procedures may vary depending on your condition and your and your doctor’s practices.
Generally, a renal venogram follows this process:
You will be asked to remove your clothing, jewelry or other objects that may interfere with the procedure
If you are asked to remove clothing, you will be given a gown to wear.
An intravenous (IV) line will be inserted in your arm or hand.
You will be positioned on the X-ray table.
An intravenous line will be inserted into a vein in your groin after the skin is cleansed and a local anesthetic is injected. The site will be shaved prior to insertion of the IV.
The radiologist will check your pulses below the injection site for the contrast dye and mark them with a marker so that the circulation to the limb below the site can be checked after the procedure.
Once the IV needle has been placed, a catheter (a long, thin tube) will be inserted into the vein and advanced until it reaches the renal vein. Fluoroscopy may be used to verify the location of the catheter inside the body.
An injection of contrast dye will be given. You may feel some effects when the dye is injected into the catheter. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.
You should notify the radiologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.
After the contrast dye is injected, a series of X-rays will be taken. Your doctor will be able to view these X-rays on a separate TV monitor.
You may be asked to move into the prone position (lying face down) for additional X-rays.
A blood sample (renin assay) may be obtained from the IV.
Once sufficient information has been obtained, the IV catheter will be removed and pressure will be applied over the area to keep the vein from bleeding.
After the IV site stops bleeding, a dressing will be applied to the site. A tight pressure dressing may be placed over the site for a period of time to prevent further bleeding or the formation of a large bruise under the skin.
After the procedure
After the procedure, you will be taken to the recovery room for observation. You will remain flat in bed for two hours or longer. The circulation and sensation of the affected leg will be monitored. The dressing on your groin will be checked for bleeding. Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room or discharged to your home.
You may be given pain medication for pain or discomfort related to the injection site or to having to lie flat and still for a prolonged period.
Once you are home, monitor the groin site for bleeding or other discharge, unusual pain, swelling, and abnormal discoloration or temperature change at or near the site. A small bruise is normal, as is an occasional drop of blood at the site. If you notice a constant or large amount of blood at the site that cannot be contained with a small dressing, notify your doctor.
Monitor the leg for changes in temperature or color, pain, numbness, tingling, or loss of function of the limb.
Drink plenty of fluids to prevent dehydration and to help pass the contrast dye.
You may be advised not to do any strenuous activities or take a hot bath or shower for a period of time after the procedure.
Notify your doctor to report any of the following:
Fever and/or chills
Increased pain, redness, swelling, bleeding, or other drainage from the groin injection site
Coolness, numbness and/or tingling, or other changes in the affected extremity
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.