Intravenous pyelography (IVP), or intravenous urography, is a diagnostic test that involves the administration of intravenous contrast and X-ray imaging of the urinary tract. The iodinated contrast flows through the renal vasculature and filtered into the collecting system highlighting the anatomic structures on the X-ray image. It is often useful for the evaluation of hematuria, and renal stone disease, and as a follow-up after the intervention. The urographic imaging sequence is designed to depict specific parts of the urinary tract optimally. Portions of the urinary system appear opaque when filled with contrast material.[1] Accurate conclusions from the IVP are feasible only when the technique, limitations, and basic rules of interpretation are known.
Fritz Voelcker and Alexander von Lichtenberg introduced retrograde ureteral catheterization in 1906 for visualization of the urinary tract. This technique produced variable results and was seldom successful. In 1923, Osborne and colleagues devised intravenous pyelography for visualizing the kidneys, ureters, and bladder.[2] This procedure was more practical, simpler, and safer. An intravenous method for visualizing the upper urinary tract was a substantial contribution to the field of medicine.
In modern times, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) are commonly used for the evaluation of urinary tract diseases owing to the limitations of intravenous pyelography.[3]
Contrast material, radiologic table, X-ray tubes, monitor, fluoroscope, and detector are required to perform the test.
The patient must empty the bladder before the procedure. Images should systematically be obtained to improve the visualization of stones and increase the soft-tissue contrast.[4] Imaging shall include the area from the suprarenal region to below the pubic symphysis. Before the injection of contrast, the fields of calcification must undergo evaluation. Otherwise, the contrast may conceal the calcification, potentially missing the findings.
Oblique radiographs help confirm the position and nature of calcifications. This view is vital in cases where the patient may have signs of urinary tract calculus, but none is otherwise observable on the AP view.
Although unenhanced computed tomography has replaced intravenous pyelography (IVP) in the evaluation of flank pain, IVP might play a role in the follow-ups of these patients. Adjustments after contrast administration can be made based on preliminary images. The initial images play a vital role as they indicate urinary causes for the patient’s discomfort and also indirectly help detect other abdominal pathologies.
The standard procedure for pyelography consists of the following steps[1][5]:
IVP is a tool in the assessment of flank and lower back pain and hematuria. It is useful in diagnosing congenital anomalies of the urinary tract, urinary calculi, enlarged prostate, neoplasms of kidney, ureter, bladder, and scars and strictures of the urinary tract.
Imaging during early bladder filling is important in patients suspected of having a pathology of the urinary bladder. Minimal osmotic diuresis due to the use of low osmolar contrast material can cause delayed filling of the bladder. The presence of contrast can lead to excessive opacification of the bladder, which makes its assessment rather difficult. The release of compression of the abdomen allows the contrast to move into the ureters.[6][7] A KUB radiograph should be obtained just after the release of abdominal compression. This image should be supplemented with fluoroscopic spot images to view the whole luminal surface of the ureter. If fluoroscopic images are unobtainable, an oblique KUB should be ordered.[8]
In cases of obstruction, prone or oblique positions can help facilitate the flow of contrast material. In the prone position, the sacral ureter is dependent. The iodinated contrast, which is of higher specific gravity than the ureteral urine gravitates to this region and allows better visualization.[9] Delayed images in such cases should be obtained until the level of obstruction is pinpointed.
The results of the IVP should systematically be assessed to minimize the chances of error.
Assessment of both kidneys
Assessment of the ureters
Assessment of the urinary bladder
Interpretations of the results[4]:
Adverse reaction to the contrast material can present as hives, skin rash, and sometimes may even produce anaphylactic shock.
Preparing the patient
This examination is usually performed on an outpatient basis.
The clinical significance of IVP is highlighted by its extensive use in the early 20th century, to study the diseases of the urinary tract. It was a routine imaging modality of choice for the evaluation of neoplasms, ureteral obstruction, anatomical anomalies, and tuberculosis of the urinary system until the advent of ultrasonography and computer tomography, which has now largely replaced its place in renal imaging.
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