Chromocystoscopy is an endoscopic method of assessing the patency of the upper urinary tract with a separate examination of the function of each kidney. The technique is based on intravenous administration of indigocarmine dye followed by separate fixation of its excretion from the mouths of the ureters. Chromocystoscopy is used to determine the functional state of each kidney, urodynamics and patency of the upper urinary tract, as well as differentiate renal colic and acute abdominal diseases. Chromocystoscopy is performed with a cystoscope, does not require special preparation, before the procedure (at least an hour) it is necessary to drink a glass of liquid to fill the bladder. The first thing observed during chromocystoscopy is the release of dye by a healthy kidney.
It is believed that the German doctors Friedrich Felker and Eugen Josef were the first to introduce this study into clinical practice in 1903, using indigocarmine as an intravenous dye to assess kidney function. Prior to that, methylene blue was used to study kidney function based on the work of German urologist R. Kutner. However, back in 1864, the Russian histologist and pathophysiologist, a graduate of Kazan University N.A. Hrzhonshchevsky developed a method for injecting indigocarmine into the vascular bed in order to study the pathohistology of various organs. Similar experiments were also carried out at the end of the XIX century by German physiologists and histologists R. Heydenhein and J. Nussbaum.
In 1896, the Russian pathologist, professor of the Kiev and Warsaw Universities V.K. Lindeman found that the indigo dye introduced into the vascular bed is excreted unchanged by the renal tubules. This discovery received its scientific recognition decades later thanks to the work of Scandinavian immunologist K. Oravisto, who proved the excretion of 92% of the dye by the tubules of the nephron, and only 12% by the glomeruli. At the end of the XIX century, the Austrian urologist M. Naitz developed the first surgical cystoscope, and in 1897, the French urologist of Cuban origin J. Albarran improved it by equipping it with a special lift. All these studies and developments formed the basis of modern chromocystoscopy.
Chromocystoscopy is a diagnostic procedure that allows you to quickly differentiate acute pathology of the abdominal cavity and upper urinary tract, one of the most informative and simple, and therefore widely used in urological practice manipulations that allow you to choose the right treatment tactics. It is more often used in urgent situations, but can also be carried out on a planned basis.
Urologists prescribe chromocystoscopy for a separate analysis of the excretory-secretory activity of the left and right kidneys, the tone of the urinary tract. Chromocystoscopy is also performed during the differential diagnosis of acute processes in the abdominal cavity and retroperitoneal space, united by pain syndrome (renal colic, blood impurities in urine of unclear etiology, appendicitis, intestinal colic, gynecological pathology, traumatic injury). In addition, chromocystoscopy is necessary for an adequate assessment of the patency of the urinary tract (stones, tumor, strictures).
Due to the impossibility of carrying out a cystoscope into the bladder, chromocystoscopy is not prescribed for adenoma, prostate cancer, strictures and shrinking of the bladder. Due to the risk of spreading infection and possible intensification of the inflammatory process, chromocystoscopy is contraindicated in acute cystitis, urethritis, epididymitis. Chromocystoscopy is not performed with a sharp violation of renal or general circulation (shock, collapse), end-stage renal and hepatic insufficiency, necrotic and febrile nephrosis.
Separately, it should be mentioned that the excretion of indigocarmine by the kidneys during chromocystoscopy depends on body temperature, hypoxia, pain syndrome and intoxication, which slow down the excretion of the dye, distorting the test results. In addition, there are special substances that are used for X-ray contrast studies, but at the same time reduce the excretion rate of indigo dye, so chromocystoscopy is not planned immediately after such diagnostic manipulations.
Preparation for chromocystoscopy
The study is carried out in a hospital or day hospital using a cystoscope. The essence of the procedure is the sequential execution of cystoscopy and intravenous administration of the dye. A urologist directs the patient to chromocystoscopy. Hospitalization in a hospital for performing invasive manipulation involves examination according to the clinical minimum: UAC, OAM, blood test for HIV, RW and hepatitis, clotting time and blood type. Chromocystoscopy does not require special preparation. Before it is performed (an hour or two in advance), the patient is offered to drink a glass of water to fill the bladder.
Methodology of conducting
Currently, chromocystoscopy is performed under local anesthesia (rarely without it), injecting about 20 ml of 1-2% solution of novocaine or its analog into the urethra. With increased pain sensitivity, anesthesia is repeated. Parenteral anesthesia before chromocystoscopy is contraindicated, since it disrupts the dynamics of the urinary tract. Chromocystoscopy is performed in stages. The patient is in a lying position on a special manipulation table with leg holders. At the initial stage of the procedure, an overview cystoscopy is performed and only then a study with a contrast agent is performed. This prevents untimely determination of the beginning of dye excretion. After a visual revision of the bladder, observation of the injected dye begins. 3-5 ml of 0.2-4% indigocarmine is administered intravenously, with normal kidney function, its release is recorded at 3-5 minutes in the form of a blue jet. Intramuscular administration of 15 ml of the solution is possible, while the discharge normally begins after 8-15 minutes.
A healthy kidney is evaluated first during chromocystoscopy, since the discharge begins earlier in it. The beak of the device should be located in close proximity to the mouth of the ureter, so as not to confuse the test release of the dye with the throwing of the colored urine stream from the opposite side. Testing with chromocystoscopy is carried out within 15-20 minutes. The intensity of excretion of colored urine, the period of appearance of the dye, the nature of the jet and the frequency of contractions of the ureter are evaluated. The result of chromocystoscopy is affected not only by the preservation of kidney function and urodynamics, but also by diuresis, renal blood flow, and the volume of the urinary tract. All results are recorded in the medical history in the form of a chromocystoscopy protocol. Complications are extremely rare, the risk of complications is determined by the doctor’s qualifications and compliance with the chromocystoscopy technique.
Interpretation of results
The assessment of the performed chromocystoscopy gives an idea of the preservation of the function of the nephron, the state of the upper urinary tract (tone, patency). The saturated blue color of urine corresponds to the content of dye in it in an amount of at least 0.5 mg. During chromocystoscopy, there is a normal release of indigocarmine, reduced and complete absence of it. If there is no dye intake from the ureter during observation, this indicates suppression of the excretory function of the kidney or obstruction of the ureter. With a slow, continuous discharge, a decrease in the saturation of urine color, they speak of a partial violation of kidney function, a decrease in the tone of the urinary tract. The release of indigocarmine by a “trickle of smoke” is indicative, indicating the recent departure of the stone and a decrease in the tone of the upper urinary tract. The same pattern is observed with hydronephrosis, pyelonephritis, ureter strictures.
However, functional testing with indigocarmine may give incorrect results. Thus, the timely release of dye during chromocystoscopy does not guarantee the normal function of the entire kidney parenchyma, even a small part of a well-functioning parenchyma provides normal sample parameters. Violation of the rate of dye release during chromocystoscopy may be caused by obstruction of the urinary tract with preserved kidney function. More valuable in chromocystoscopy is information about urine excretion for the differentiation of kidney diseases and acute pathology of the abdominal cavity. The conclusion on the performed chromocystoscopy is given to the patient in the form of an extract.