“Upper tract studies” are evaluations that your doctor does of your kidneys and ureters. The lining of the bladder is the urothelium. The same urothelium also lines the ureters and the inside of the kidneys. The kidneys and the ureters are then also potential locations of transitional cell cancer. The study that your doctor chooses depends on his or her personal opinion as well as the availability of each test at your hospital. Even if the upper tract study is negative, you will likely need to repeat the studies periodically. Patients with low-grade tumors have a low risk (approximately 2%) of developing upper tract tumors. The presence of a high-grade tumor or of diffuse carcinoma in situ, how-ever, carries up to a 40% lifetime risk of developing an upper tract tumor.
1. An ultrasound is often the easiest test to obtain and is therefore popular as a first study. Ultrasound technology generates sound waves and then measures their reflections off of internal structures to produce an image. The same imaging is used for obstetric ultrasounds to produce an image of the fetus. There is no radiation with an ultrasound. An ultrasound is very good for showing tumors and stones in the kidneys and for showing obstruction of the ureter causing hydronephrosis. It is not as good for showing small tumors inside the ureter or renal pelvis, and thus a second kind of study is usually needed in addition to the ultrasound.
2. An intravenous pyelogram (IVP) is an X-ray study that shows the general outline of the kidneys and better detail of the collecting system than an ultra-sound. X-ray contrast is given to the patient intravenously. The kidneys then filter and concentrate the contrast, creating an image on an X-ray taken a few minutes after the injection is given. A small tumor or stone inside the collecting system can be seen as a dark spot inside the collecting system. Historically, the IVP was a common test to evaluate upper tracts. However, due to the decreased cost of CT scans and the increased availability, it has largely been replaced by CT scanning.
3. CT scanners use X-rays to create a detailed image of the internal organs. The scanner takes many X-rays at once and uses a computer to combine all of the images into the one picture that you see. When getting a CT scan of the kidneys, the patient is usually scanned three times. The first scan is per-formed without contrast and will reveal any kidney stones. The second scan is performed with contrast, which helps to show tumors in the kidneys. The third scan is obtained a few minutes later, after the kidney has had time to process the contrast. The contrast fills the collecting system similar to the IVP but with greater detail. A CT scan is very good for seeing tumors in both the kidneys and the collecting system. In addition to the ability to see the kidneys and ureters better, the CT scan allows for visualization of the entire abdomen and lymph nodes, helping to identify metastases or unrelated diseases. Over the last several years, the cost of CT scans has come down, and the availability of scanners to patients has increased, making the CT scan the most common upper tract study. As with the IVP test, CT scans meant to examine the kidneys and ureters require intravenous contrast. Patients with poorly functioning kidneys will usually require an ultrasound of the kidney as well as a retrograde pyelogram in the operating room (see below).
4. Magnetic resonance imaging (MRI) of the kidneys is still a relatively new technology. MRI technology uses magnets to align the molecules in the body. When the magnet is turned off, the molecules revert to their usual state of random directions. As they turn back, they generate a tiny electrical signal that the MRI machine can detect. These signals are then processed to create a very detailed image. An MRI provides more information about small kidney masses, which can be helpful to determine if they are benign or malignant. In general, an MRI is not a more useful test than a CT scan to evaluate hematuria. It is, how-ever, far more costly and often unavailable; thus, it is an uncommon choice for routine upper tract studies. People who have certain surgical implants, such as brain aneurysm clips, cochlear implants, insulin pumps, or other metal devices, may not be able to have an MRI scan. Also, patients with bullet fragments or shrapnel in their bodies should not have an MRI. The machine itself is similar to a CT scanner but can be quite noisy, making it difficult for some people who are claustrophobic.
5. Retrograde pyelograms are performed by a urologist in the operating room or well-equipped office. While performing cystoscopy, the urologist feeds a catheter into the opening of the ureteral orifice. He or she then injects dye through the catheter, filling the ureter and renal pelvis. An X-ray is obtained that will now show the entire upper tract in good detail. It does not require any intravenous contrast and thus is very useful for patients who are allergic to the contrast or have kidney disease preventing them from receiving contrast. The retrograde pyelogram probably gives the best image of the upper tracts of all of the studies except ureteroscopy. Although the quality of the image is excellent, it does usually require anesthesia and instrumentation that the other studies do not. Therefore, it is most often used in those individuals who are unable to have one of the previously mentioned X-ray studies or for those patients who have had an abnormality seen on one of those studies.
6. Although ureteroscopy is not technically an “upper tract study,” it gives us the most definitive examination. It is similar to cystoscopy but uses a smaller scope. In the operating room or well-equipped office, the ureteroscope is carefully passed into the ureter as it opens into the bladder. This allows the urologist to see the inside of the ureter. It is gently passed all of the way up the ureter into the kidney. Like cy-toscopy, there are both rigid and flexible ureteroscopes. The flexible scope allows doctors to see all or most of the deep corners of the collecting system within the kidney. Biopsies of any suspicious areas can be taken and sent to pathology for analysis. Although ureteroscopy provides the best view of the collecting system, it usually requires anesthesia, and there is some small risk of damage to the kidney or ureter; thus, it is usually reserved for those patients who have had an abnormal upper tract study.