Intravenous urography

Intravenous urography is one of the main X-ray examinations performed on patients with urinary tract disorders. Intravenous urography is based on the physiological ability of the kidneys to capture iodinated organic compounds from the blood, concentrate them and excrete them with urine. During conventional urography, the patient is given 20-60 ml of one of the urotropic contrast agents - ionic or, more preferably, non-ionic - intravenously on an empty stomach after preliminary bowel cleansing and bladder emptying. During the first minute after the intravenous injection, 1-2 images are taken, which display the nephrographic phase of drug excretion. To improve visualization of the renal parenchyma, it is recommended to perform linear tomography at this time, i.e., obtain a nephrotomogram. In the absence of contraindications (for example, aortic aneurysm or extensive abdominal tumor), the patient undergoes abdominal compression. This leads to retention of urine and contrast agent in the renal pelvis and ureter. The urograms taken 4-5 minutes later show a clear image of the renal pelvis and ureters. The compression is then removed and several delayed images are taken - after 10-15 minutes, sometimes after 1-2 hours. At the same time, tomograms and targeted radiographs are taken, including of the urinary bladder, as indicated. If nephroptosis (prolapse of the kidney) is suspected, radiographs are taken both in the horizontal and vertical positions of the patient.

In cases of decreased excretory function of the kidneys, which is observed, for example, in patients with pyelonephritis or nephrosclerosis, infusion urography is used. In this case, a large amount of contrast agent (up to 100 ml) in a 5% glucose solution is slowly administered intravenously to the patient using a drip infusion system. Pictures are taken as the contrast agent is administered. It should be emphasized that urography is mainly a method of morphological examination. It allows one to obtain only the most general idea of kidney function and in this respect is significantly inferior to radionuclide methods.

The kidneys on urograms look the same as on the general image, but their shadow is somewhat more intense. The size and especially the shape of the calyces and pelvises are quite varied. Usually, three large calyces are distinguished: upper, middle and lower. Small calyces extend from the top of each of them. One or more renal papillae protrude into each small calyx, so its outer contour is concave. Large calyces merge into the pelvis. As indicated above, the size and shape of the pelvis are normally different: from an ampullar pelvis with poorly developed calyces to a narrow pelvis with elongated calyces (branched type of pelvis). However, in any case, the outlines of the normal pelvis are smooth and sharp. Its contours smoothly pass into the outlines of the ureter, which forms an obtuse angle with the axis of the pelvis.

The ureter causes a shadow in the form of a narrow strip. Normally, due to contractions and relaxations of the cystoids, this strip is interrupted in places. The abdominal part of the ureter is projected almost parallel to the spine, the pelvic part is superimposed on the shadow of the iliac-sacral joint, then describes an arc convex outward and passes into a short intramural section.

The urinary bladder produces a shadow in the form of a transverse oval, the lower contour of which lies at the level of the upper edge of the pubic bones. During urography, the bladder shadow reaches medium intensity, its contours are smooth. A contrast agent can be introduced into the urinary bladder through the urethra (this technique is called cystography). Then the bladder shadow becomes very intense. In the absence of pathological formations in the bladder (stones, tumors), its shadow is completely uniform. Indications for cystography are traumatic or postoperative urinary extravasation, suspected bladder diverticulum and vesicoureteral reflux.

During urination, the contrast agent flows from the bladder into the urethra. Filming during urination is called "micturition cystoerraphy." It allows you to get an image of the urethra (urethrography). However, a clearer image of the urethra is obtained by introducing the contrast agent retrogradely, through its external opening. In this case, the internal opening of the urethra is blocked by a catheter with a balloon inserted into it (retrograde urethrography). With the help of urethrography, it is possible to diagnose urethral strictures, tumors, diverticula, and traumatic injuries to the urethra.

The main advantages of intravenous urography are availability, low cost, non-invasiveness, the ability to study the structure of the renal pelvis and calyces and to detect calcifications of various types. It can also be used to some extent to judge the excretory function of the kidneys. The disadvantages of urography are limited information on the structure of the renal parenchyma and perirenal spaces, the lack of data on the functional parameters of urination, the impossibility of performing the procedure in case of renal insufficiency and, finally, the use of iodine preparations and ionizing radiation in this study. Urography is contraindicated in cases of severe insufficiency of the heart, liver, kidneys and intolerance to iodine preparations.

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