In Whitaker test, a contrast dye is injected directly into one of the kidneys, and a series of x-ray films is taken as the material flows through the kidney and ureter. The dye delineates these structures on the x-ray images and reveals any abnormalities.
Pressures are also measured in the kidneys and bladder. Correlation of the pressure measurements with the x-ray findings can provide information about the flow of urine through the kidney and the presence of any obstructions.
Purpose of the Whitaker Test
- To identify and evaluate kidney obstructions (such as narrowing or stones)
- To help determine whether surgery is needed to remove a kidney obstruction
Who Performs the Whitaker Test
- A physician, usually an interventional radiologist
Special Concerns about the Whitaker Test
- People who have an allergy to shellfish or iodine may experience an allergic reaction to the contrast dye.
- Pregnant women should not undergo this test because exposure to ionizing radiation may harm the fetus.
- This test may not be safe for people who have a bleeding disorder or a severe infection.
- The presence of feces, gas or residual barium in the abdomen from recent contrast x-rays may hinder accurate needle placement and interfere with visualization of the upper urinary tract.
Before the Whitaker Test
- Tell your doctor if you regularly take anticoagulant drugs. You may be instructed to discontinue them for some time before the test.
- Be sure to tell your doctor if you have a known shellfish or iodine allergy or have ever had an adverse reaction to x-ray contrast dyes.
- Do not eat or drink anything for at least 4 hours before the test.
- You will be asked to disrobe and put on a hospital gown.
- You may be given a mild sedative.
- You may be asked to empty your bladder just before the procedure.
What You Experience During the Whitaker Test
- You will lie on your back on an examination table.
- A thin tube, or catheter, equipped with a special pressure sensor is gently inserted through the urethra into the bladder.
- The doctor takes a plain x-ray film of the urinary tract to locate the position of the kidney and ureter.
- A contrast dye is administered through an intravenous (IV) catheter inserted into a vein in your arm. (Upon injection of the dye, you may experience a brief flushing sensation and a metallic taste in your mouth.)
- When x-rays show that the contrast dye has entered the kidney, the skin over the kidney is cleansed with an antiseptic solution and draped. A local anesthetic is then injected to numb the area.
- You will be asked to hold your breath as the doctor inserts a hollow needle into your kidney, using fluoroscopy or ultrasound imaging as a guide. A pressure sensor is connected to this needle.
- Contrast dye is infused through the needle into your kidney, and serial x-ray films are obtained to visualize the kidney and ureter. You should remain still as each x-ray is taken.
- Pressures within the kidney and bladder are measured.
- The needle and catheter are then removed, and a small bandage is applied over the needle insertion site.
- The test takes about 60 to 90 minutes.
Risks and Complications of the Whitaker Test
- X-rays involve minimal exposure to radiation.
- Possible complications include bleeding at the site of needle insertion.
- Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.
After the Whitaker Test
- A pressure dressing is applied to the site of needle insertion.
- You will rest in a recovery room for 15 to 30 minutes. Your vital signs will be monitored, and pain medication will be provided if necessary.
- If no complications develop, you are usually free to leave the testing facility. You will be advised to remain on your back for 12 hours after the test.
- You will be instructed to keep track of your urine output and report any urinary retention (inability to urinate due to swelling). At first, the urine may contain blood, causing a slight pink tinge; this should resolve after voiding a few times. If blood persists or you see bright red blood or blood clots, notify your physician.
- You may resume your normal diet and any medications withheld before the test.
- Delayed allergic reactions to the contrast dye, such as hives, rash, or itching, may appear 2 to 6 hours after the procedure. If this occurs, your doctor will prescribe antihistamines or steroids to ease your discomfort.
- You may be given prophylactic antibiotic drugs for several days to prevent infection.
- Report to your doctor any signs of infection, such as chills, fever rapid breathing, or a feeling of faintness.
Results of the Whitaker Test
- The doctor will examine the x-rays and pressure measurements to determine whether a kidney obstruction is present.
- A definitive diagnosis can usually be made after this test. Appropriate treatment will be initiated, depending on the specific problem.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media