Urography is indicated for diagnosing disorders affecting the urinary system, such as stones , trauma, obstructions, congenital defects or tumors .
Urography uses a contrast medium (generally an iodine solution) which allows the structures of the urinary system to be precisely assessed. On x-ray images, after intravenous injection , this “dye” becomes visible almost immediately (appears bright white). The contrast agent is then removed from the bloodstream through the kidneys and the urine they produce. The radiograms, obtained during intravenous urography, allow you to clearly visualize the structures through which the contrast medium passes, allowing you to examine the anatomy of the affected parts and determine whether they are performing their physiological function correctly.
The doctor may recommend intravenous urography if the patient experiences signs and symptoms that may be related to a urinary tract disorder (such as, for example, blood in the urine , back and side pain, etc.). In fact, intravenous urography can be used to diagnose a number of conditions that affect the urinary tract , such as:
- Kidney and bladder stones ;
- Kidney cysts ;
- Inflammations and infections of the bladder and kidney ;
- Urinary tract tumors (example: renal cell carcinoma , transitional cell carcinoma, etc.);
- Obstruction (for example, at the vesicoureteric junction);
- Anatomical anomalies of the urinary tract;
- Enlarged prostate .
An intravenous urography can be performed in both emergency and routine situations:
- Emergency . This procedure is performed on patients who present to the emergency room with symptoms suggestive of a serious obstructive urological condition, such as severe renal colic accompanied by hematuria . In this circumstance, the doctor may suspect a kidney stone, which is causing blockage of the urinary system. Patients are usually monitored for follow-up and further treatment. Radiographic images, obtained at a “double time” interval (at 30 minutes after injection, 1 hour, 2 hours, 4 hours etc.), provide important information for the urologist on the location and severity of the obstruction .
- Routine. This procedure is most common for patients who have unexplained microscopic or macroscopic hematuria. Urography is used to ascertain the presence of a tumor or similar disorder that alters the anatomy of the urinary tract.
- Before the procedure, a blood test may be necessary to check correct kidney function ( creatinine , urea nitrogen , etc.). The kidneys must in fact be able to filter the contrast medium; therefore, intravenous urography is rarely performed if you have kidney failure .
- The patient should inform the doctor if he suffers from allergies , particularly to contrast agents . Urography is also contraindicated in cases of iodine intolerance , severe heart disease , multiple myeloma and ongoing pregnancy .
- Before the procedure, the patient may be asked not to eat for several hours and to take some laxatives for a day or two. This measure helps ensure that the intestine is free of large amounts of feces , which can make interpretation of x-ray images more difficult.
- In case of diabetes and metformin therapy it may be necessary to stop taking the drug 48 hours before and after the procedure, as an interaction with the contrast agent may occur (the appropriate management can be discussed with your doctor of diabetes during this period).
The sequence of images is approximately collected as follows:
- The patient lies in a supine position on an examination table. An initial frontal x-ray of the abdomen is performed . The contrast medium is then injected into a vein in the arm or hand. The dye begins to be excreted through the kidneys, ureters and bladder.
- During the following 30-60 minutes, at certain time intervals (approximately every 5 minutes), x-rays of the renal area are collected. Every time an x-ray is to be taken, the patient is asked to hold his breath. Radiographic images show the contrast medium as it travels, during various stages, through the urinary system. Immediately after administration of the contrast medium, it is filtered through the renal cortex. At an interval of 3 minutes, the calyces and renal pelvis are visible. At 9-13 minutes, the contrast begins to empty into the ureters and travel to the bladder, which begins to fill. About 10 minutes after injecting the contrast medium, the doctor may apply compression if necessarylower abdominal area , to cause distension of the upper urinary tract and evaluate certain conditions (the maneuver is contraindicated in cases of obstruction). To visualize the bladder correctly, the patient is asked to empty the bladder before collecting the last x-ray image. The contrast medium collected in the organ, in fact, could mask a pathology.
Intravenous urography is usually completed in 30 to 60 minutes. The patient should be able to return to normal activities as soon as the procedure is finished. It is advisable to drink plenty of fluids to help remove all the contrast medium from your body.
During the urography the following are evaluated:
- Kidneys : regular appearance, smooth contours, size, location, filtration and flow;
- Ureters : size, regular appearance and symmetry;
- Bladder : complete emptying, smooth and regular appearance.
A radiologist examines and interprets the radiographic images obtained during intravenous urography and sends a report to the doctor, with whom the patient can discuss the results.
Side Effects And Contraindications
An intravenous urography is generally a safe diagnostic investigation and complications are rare.
- After the injection of the contrast medium you may experience a metallic taste in your mouth and a tingling or warm sensation (similar to hot flashes ). Some people experience general malaise, headache , nausea or vomiting . These side effects are almost always temporary.
- In a small number of cases, an allergic reaction to the contrast medium used in the test may occur. Symptoms may be mild (for example , itchy skin rash and mild swelling of the lips ). More serious manifestations include: cardiac arrest and collapse due to extremely low blood pressure, difficulty breathing , and other symptoms of anaphylactic shock . It must be emphasized that serious reactions are rare and, should it be necessary, the hospital department has access to full resuscitation equipment during the procedure.
- During intravenous urography, the patient is exposed to a very limited amount of radiation , so he is not susceptible to any harm. However, the investigation is contraindicated during pregnancy, since the fetus is more sensitive to the associated risks (malformations).
- Acute renal failure is a rare complication of intravenous urography. The contrast medium used during the procedure can cause harm in people with poor kidney function.
Since some investigations, such as computed tomography and magnetic resonance imaging, take less time and provide more detail about the anatomy and function of the structures evaluated, the clinical application of intravenous urography has become less common.
However, this can still be a valid diagnostic tool, particularly for:
- Identification of some structural disorders of the urinary tract;
- Detection of kidney stones;
- Provide information on urinary tract obstruction.