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When the pediatrician refers a patient for radiographic or other diagnostic imaging studies, he should relate the individual needs of that patient to the information obtained from the procedures requested. Thorough knowledge of such new modalities as ultrasound and computed tomography, as well as the traditional procedures of excretory urography, cystography, and radioisotope scintigraphy, is essential.
Although excretory urography has been the main method for evaluating the urinary tract, it may no longer be necessary in the evaluation of all abdominal masses. The role of ultrasound and computed tomography in abdominal masses will be discussed. Because techniques have become more complicated and expensive, closer consultation with the radiologist is critical in order to gain the maximum information for patient evaluation from the imaging study at the least cost, trauma, and radiation exposure.
EXCRETORY UROGRAPHY
Detailed demonstration of the urinary-tract anatomy is essential for diagnosis of diseases affecting the kidneys and for subsequent evaluation of treatment. Excretory urography provides good anatomic information of these structures (Figure 1). Proper evaluation is not possible unless the features of the kidneys are sharply defined. For this reason, the excretory urogram should be done with radiographic equipment that has the capability of performing tomography. If poor visualization of the urinary system occurs, nephrotomography1 may aid in distinguishing the anatomy of the kidney.
If bowel preparation is inadequate, the kidney may be obscured by overlying gas and feces in the intestinal tract. To avoid the need for a second test, the gas and feces can be displaced by placing the patient in the prone position and positioning a paddle with an inflated balloon under the kidney (Figure 2).2 Carbon dioxide or carbonated drinks may also be utilized to produce a stomach bubble through which the kidneys may be visualized.
Application of compression to the lower abdomen causes mild stasis of the ureters and increases filling of the intrarenal structures (Figure 3). This simple maneuver can eliminate the need for retrograde pyelography.
NEPHROTOMOGRAPHY
Nephrotomography1 can demonstrate renal outlines, the calyceal system, and functioning renal parenchyma and is helpful in detecting a rim of compressed renal tissue due to severe hydronephrosis.
EXAMINATION OF THE BLADDER AND URETHRA
The main purpose of cystourethrography is to determine whether reflux occurs. Contrast material is usually introduced...