Preparation for ultrasound of kidney and ureter
- Preparation of the patient. Preparation is not required. If a bladder is needed, the patient should drink water.
- Position of the patient. Start the examination in the patient's position on the back. Apply the gel arbitrarily to the upper right abdomen.
- Select the sensor. Use a 3.5 MHz sensor for adults, a 5 MHz sensor for children and thin adults.
- Set the level of the required sensitivity. Start the study by placing the sensor in the right upper abdomen. Tilt the sensor and adjust the sensitivity so that the optimal image of the renal parenchyma is obtained.
Preparation for ultrasound of kidney and ureter
The ultrasound of any organ should be polypositional, i.e. Scanning should be performed from all surfaces available for ultrasound imaging.
Investigation of the kidney begins with the lumbar region, scanning them from behind in the longitudinal direction. The sensor is then moved to the lateral and anterior surface of the abdominal wall. After this, a series of transverse and oblique sections are performed in these same sections, determining the topography, size, condition of the parenchyma, the sinus of the kidneys and the calyx-pelvis system.
In this case, attention is drawn to the contour of the renal parenchyma, its thickness, uniformity, the presence or absence of visualization of the bowl-pelvic system and pathological formations, the size of the renal sinus, and also the mobility of the kidney during respiration.
The right kidney is visualized in the position of the patient on the back, while the liver is used as an acoustic window.
Scanning is always carried out while breathing is held in deep inspiration: ask the patient to take a deep breath and hold his breath. Do not forget to tell the patient to relax and breathe normally after that.
Methods of ultrasound of the kidneys and ureters
Normal kidney on longitudinal sections - the formation of a bean-shaped form with a clear, even outward contour created by the fibrous capsule, in the form of a thin (up to 1.5 mm) hyperechoic tissue layer between paranephrium and parenchyma. The kidney parenchyma is a tissue of a homogeneous echostructure and usually a low echo density (hypoechoic). Normally its thickness is about 1.5-2.0 cm. Its inner part is bordered by the sinus of the kidney and has a somewhat uneven contour due to the papillae protruding into the sine. Sometimes, especially in young people, in the renal parenchyma pyramids of triangular shape are seen, turned with a base toward the outer contour of the kidney, and the tip in a sinus, forming papillae. Pyramids have an even lower echo density than the parenchyma. The echogenicity of the renal sinus is similar to that of paranephric fiber. It is located in the center of the kidney and with longitudinal echoscanization is surrounded by parenchyma. With the normal kidney echography, only a few vascular bundles can be visualized in it. The cup-and-pelvic system is not normally defined. In the study of patients with a water load or with a filled bladder, the pelvis is visualized as an anechogenous formation. Its anteroposterior size should not exceed 1.0-1.5 cm. Vessels of the kidney, as a rule, are visible with transverse or oblique scanning from the front abdominal wall.
In normal breathing, the mobility of the kidney is 2-3 cm. Parainal fiber has a uniform ehostruktura. Increased echogenicity compared with renal tissue; has no pathological formations.
Ultrasound is important in the differential diagnosis of volumetric kidney formation. In this case, the tumor originating from the kidney parenchyma is defined as a round or oval formation, different in echomolarity. On this basis, all tumors can be divided into two large groups: solid (dense) and liquid. The ehostruktura can be homogeneous and heterogeneous. Depending on the form of growth and localization, the tumor can be extrarenal (changes the size and contour of the kidney), intralenal (located in the sinus, deforms it) or mixed. When a tumor is large. Occupying the entire kidney, the renal sinus can not be determined. With the displacement and compression of the cup-and-pelvis system, its dilatation is possible.
The diagnostic reliability of ultrasound for neoplasm of the kidney reaches 97.3%.
When a volumetric education in the kidney is detected during the study, it is first of all determined by its character (dense or liquid).
The measurements carried out during the ultrasound study are generally of lower values than the same parameters obtained by X-ray diffraction: they are more accurate.
Both kidneys should have approximately the same size in adults, the difference in the length of the kidneys by more than 2 cm is pathological.
Ultrasound signs of normal kidney and ureter
If any kidney is not visualized, then repeat the test. Adjust the sensitivity for clear visualization of the liver and spleen parenchyma and scan in different projections. Determine the size of the kidney to be visualized. Hypertrophy of the kidney takes place (at any age) a few months after the removal of another kidney or the cessation of its functioning. If there is only one large kidney, and the second is not detected even with the most careful search, it is possible that the patient has only one kidney.
Of all the dense (echospositive) neoplasms, the kidney is the most common kidney cancer (according to different authors, from 85 to 96%). From 5 to 9% are benign tumors (oncocytoma, angiomyolipoma, adenoma, leiomyoma, etc.).
It should be emphasized that one can not judge the morphological structure of the tumor on the basis of non-morphological methods of investigation, which include ultrasound.
If a solid (solid) kidney formation is found, the echogenicity of which may be lower, higher or closer to the latter, pay attention to its contours and uniformity. So. In kidney cancer, the formation of an inhomogeneous echostructure with alternating areas of low and high echolocation is observed. Often, such formations contain echo-negative (fluid) inclusions due to hemorrhages and necrosis. Echograms determine the absence of the effect of amplification of reflected ultrasonic waves (in contrast to liquid formations) or their weakening at the distal boundary of the tumor and underlying tissues. The outer contour of the multinodular formation is usually uneven, and when it invades adjacent tissues it is fuzzy. However, it should be borne in mind that an analogous echostructure is determined with xanthogranulomatous pyelonephritis, benign kidney tumors and fibrous-cavernous tuberculosis.
Of all solid benign tumors of the kidney, angiomyolipoma and lipoma are the most characteristic ultrasound picture, which on echograms look like increased echogenicity of homogeneous formations similar in this respect to paranephric (fatty) fiber. However, more accurate methods used for differential diagnosis of solid kidney formations detected by ultrasound are computed tomography (CT) and MRI.
When an anechoic formation is found in the kidney, attention is also paid to the uniformity of its echostructure. Cysts are characterized by homogeneous anechogenous contents, smooth contours, absence of internal structures, amplification of reflected ultrasonic waves at the distal boundary. Internal structures in a liquid formation medium may indicate a malignant process (sarcoma, cystic kidney cancer, a tumor in the cyst) or to pathological conditions such as hematoma, echinococcosis, kidney abscess, tuberculous cavern.
In case of doubt in the dense or liquid nature of the formation, CT with contrast, MRI or puncture under ultrasound control with subsequent cytological examination of the obtained fluid and cystography is performed to clarify the diagnosis. If no fluid is obtained during puncture, then one can assume a solid structure of the formation and perform its biopsy.
Quite often, especially with a small size, the neoplasm by its acoustic properties practically does not differ from the normal parenchyma. That is why the closest attention with ultrasound should be given to irregularities of the kidney contour, deformations of the renal sinus, thickening of the parenchyma. The minimal size of the tumor of the renal parenchyma, which can be reliably detected by echography 2 cm. When formations of small size, differential diagnosis with an additional lobule of the renal parenchyma (especially in the "humped" kidney) is often required. If ultrasound is suspected of such a formation, then to clarify the diagnosis used multispiral CT (MSCT) with contrast, the informativeness of which is much higher (especially with small formations) and is close to 100%.
Along with the detection of the tumor, the echography provides valuable information on the prevalence of the process. In addition to signs of germination in neighboring organs, it is possible to diagnose tumor thrombosis of the renal and inferior vena cava, enlarged regional lymph nodes located paraaortally, paracavally and in the arthroscopic space, but CT and MRI are considered more informative methods for determining the stage of the disease.
With the introduction of ultrasound in medicine, the frequency of detection of Kidney Cancer (especially asymptomatic forms) has increased significantly. This is due to the use of this method as a screening test for preventive examinations of the population. The asymptomatic course of kidney cancer and its occasional detection with ultrasound is noted in more than 54% of patients.
Ultrasound diagnosis of papillary tumors of the VMP is extremely difficult. With a small amount of papillary tumor of the pelvis that does not disturb the outflow of urine from the cup-and-pelvis system, the echographic picture of the kidney may not differ from normal. Tumors of the cup-and-pelvis system look basically like hypoechoic formations of irregular shape in the sinus of the kidney. They can easily be taken for an enlarged calyx or cyst of the renal sinus.
It is sometimes possible to detect and differentiate such a tumor only against the background of the expansion of the cup-and-pelvic system (in case of a violation of the outflow of urine) or with the help of artificially created polyuria.
If the swelling of the cup-and-pelvis system infiltrates the renal pedicle or sprouts into the tissue of the organ, its detection in normal ultrasound is simplified, but in this situation it is necessary to differentiate it from the tumor of the renal parenchyma.
Ureter with normal ultrasound is not determined. Only with significant expansion is possible its partial visualization in the upper and lower third. Consequently, the diagnosis with the help of the usual non-invasive ultrasound of the papillary ureter is impossible. Developed in recent years, a new invasive method - endoluminal echography - allows you to obtain a high-quality image of the VMP throughout the entire length and to diagnose any irregularities in their structure (including tumors) with great accuracy. The essence of the method consists in carrying out a miniature ultrasonic sensor, mounted in a flexible probe, retrograde along the urinary tract. In addition to detecting the tumor and determining the nature of its growth, this method allows to determine the prevalence and extent of tumor invasion into the urinary tract wall and surrounding tissues, which is of great importance in determining the stage of the disease.
Ultrasound plays an important role in the complex diagnosis of inflammatory processes of the urinary tract. So, for acute pyelonephritis, the presence or absence of visualization of the cup-and-pelvis system is determined by the nature of pyelonephritis (obstructive or non-obstructive). Ultrasound also makes it possible to detect edema of paranephric fiber, which manifests not only by limiting the respiratory mobility of the affected kidney, but also by the peculiar halo of dilution around it. Carbuncle of the kidney - the formation of low echomolarity with clear and not always even contours. Its internal structure may be heterogeneous, sometimes with small echopositive inclusions. With purulent content, education will be almost anechogenous. At the location of the carbuncle, the kidney contour may be uneven and bulge. Its echographic pattern should be differentiated from that of tubercular cavern. The latter has a dense echopositive capsule and denser internal inclusions - calcifications (up to petrification), which look like hyperechoic formations with a clear acoustic path.
In the initial stages of chronic pyelonephritis, ultrasound does not detect any reliable signs of the disease. With a far-gone inflammatory process with an outcome in the wrinkling of the kidney, a significant decrease in its size is noted with a relative increase in the area of the renal sinus structures relative to the parenchyma. The latter acquires a heterogeneous structure, uneven contours and a thickened capsule.
In the final stages of inflammation (pionephrosis), it is possible to detect an increase in the kidney, a thickening of its capsule, a thickening of the surrounding paranephric fiber, often a restriction of the mobility of the affected kidney, a decrease in the thickness of the parenchyma with enlargement and uneven contours of calyxes and pelvis whose walls, due to cicatricial changes, Echogenicity. In their lumen, an inhomogeneous suspension (pus and necrotic tissues) and echopositive formations with acoustic shade (concretions) can be visualized.
Ultrasound provides significant assistance in the diagnosis of paraneural abscess and suppurative changes in the cellulose of the retroperitoneal space. Usually, the abscess is located in the immediate vicinity of the kidney and looks like an echonegative oval formation, almost completely devoid of internal structures. It usually has a clear outer and inner contour. Purulent changes in the cellulose of the retroperitoneal space are less often imprints and are more often reminiscent of phlegmon. In this ultrasound allows you to see fuzzy contours of muscles and heterogeneous hypoechogenic contents between them and in the retroperitoneal space.
With ultrasound, visualization of a calculus in a kidney larger than 0.5 cm does not present significant difficulties. A single stone on the echogram is defined as a clearly defined, echopositive (hyperechoic) formation in the sinus with an acoustic path (shadow) distal to the calculus. Its presence is associated with the complete reflection of ultrasonic rays from dense stone structures at the media interface. Certain difficulties arise when surrounded by small and flat stones. Under the experimental conditions, the minimum thickness of the stone located in the kidney and detected during echography is about 1.5 mm. The most clearly concrements are visualized by dilating the cup-and-pelvis system. Small hyperechoic areas of the sinus of the kidney without acoustic effect can be mistakenly interpreted as stones (the cause of overdiagnosis).
With the help of ultrasound, you can detect any concrements, regardless of their chemical composition. That is why metol is used for differential diagnosis of urate lithiasis and papillary neoplasms when it is necessary to exclude the presence of an X-ray negative carotene in the kidney if a filling defect in the cup-pelvis system is detected on urograms.
Non-invasive methods of ultrasound can determine the calculi in the calyx. Lohanka, the upper third (with its dilatation) and the intramural part of the ureter with a sufficiently filled bladder. Stones in the middle and lower third of the ureter can not be detected by a noninvasive method of echography. This is due to the presence of gas in the intestine, which prevents the passage of ultrasonic waves. Only in rare cases in the absence of gas in the intestine and a significantly expanded ureter, one can visualize it fragmentarily in all departments. Detection of the calculus in any part of the urinary tract is possible with the help of endoluminal echography, if there is a method of carrying an ultrasound probe between the stone and the ureter wall.
Ultrasound signs of kidney and ureter pathology
The use of ultrasound has greatly simplified the task of differential diagnosis of renal colic and acute processes in the abdominal cavity, as well as gynecological and neurological diseases. So, before the introduction of ultrasound diagnostic methods in the admissions department of hospitals, the examination was carried out according to the following scheme: overview radiography and excretory urography, chromoscystoscopy, often blockage of the round ligament of the uterus or spermatic cord. At present, ultrasound is used to detect impaired urine outflow from the kidneys. If, during the study of the kidneys, dilatation of the cup-and-pelvis system was not detected, the pain in the lumbar region in the patient is not associated with a violation of the outflow of urine from the VMP. However, it should not be forgotten that in the absence of dilation, the renal genesis of pain and the presence of a urological disease can not be completely ruled out. Pain similar to renal colic is observed with thrombosis of kidney vessels, acute non-obstructive inflammatory diseases of the kidneys and urinary tracts, etc.
Modern ultrasonic diagnostics has a functional focus. The method, which allows to assess the functional state of the VMP, is considered pharmacoehography. To perform it after initial examination of the kidneys and determine the initial size of the calyx and pelvis, 10 mg of furosemide is intravenously administered. Then every 5 minutes, repeat the examination and measurement of calyxes and pelvis. Polyuria can lead to dilatation of the cup-and-pelvis system. The degree of which is estimated by means of measurements. The study is repeated until its dimensions return to the original. Under normal conditions, the dilatation is not pronounced sharply and is present no more than 10 min. Longer its preservation (after the introduction of a saluretic during pharmacoehography) indicates the presence of an obstacle to urinary outflow and / or functional incompetence of the proximal urinary tract.