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What is the renal artery blood flow rate? Ultrasound of the arteries and vessels of the kidneys with Doppler

Ultrasound of the renal vessels is a method of examining the location of arteries and veins, their diameter and the speed of blood flow in them. The method of Doppler ultrasound (USDG of renal vessels) is based on the Doppler effect.

Why is this procedure needed?

Ultrasound scanning of renal vessels is based on the fact that ultrasonic waves are reflected from red blood cells contained in the blood. The ultrasound sensor detects the reflected waves, after which they are converted into electrical impulses.

The result is a graphical display on the monitor with color photographs representing the flow of blood in the blood vessels. Ultrasound scanning of the renal arteries allows you to view the arteries “from the inside” in real time, thanks to which you can notice changes in blood flow in them. This occurs due to spasm, narrowing or thrombosis.

Dopplerography of renal vessels helps to identify:

impaired blood supply to the organ
blood flow speed in arteries
early vascular disorders that caused atherosclerotic plaques
the presence of arterial stenosis.

The study of renal vessels is used not only to identify pathological processes, but also to evaluate the effectiveness of treatment.

Diseases for which the method is prescribed

pain in the lumbar region
renal colic
edema and cardiovascular disease
late toxicosis during pregnancy
endocrine disorders
acute or chronic diseases of the kidneys or genitourinary system (in this case, an ultrasound scan of the bladder may be recommended)
hypertension (high blood pressure)
clarification of the diagnosis if there are any deviations from the norm in the urine test
severe lumbar bruise or injury
analysis of the condition after transplantation of the organ under study
diagnosis of vascular pathology of an organ or tumor.

Ultrasound of the kidneys in children helps to determine vesicoureteral reflux, as well as to exclude congenital anomalies of the renal vessels.

Preparation for the procedure

It is necessary to carefully prepare for the procedure, since gases accumulated in the intestines make visualization difficult. If it is carried out efficiently, it will have a positive effect on the accuracy of the examination results.

How is the examination carried out?

The examination is carried out in a sitting or lateral lying position. The sonologist will apply a special gel to the skin in the lumbar region, ensuring close contact between the skin and the sensor of the device. The doctor will then move an ultrasound probe over the area being examined while viewing constantly changing images (“slices”) on a monitor.

The procedure is painless and does not take more than 30 minutes. After the examination, you can immediately begin your business.

Interpretation of results and normal indicators

After the procedure, the sonologist must issue a conclusion containing a transcript of the study:

the organ must be bean-shaped
the outer contour has smooth and clear edges
hyperechoic capsule (thickness up to 1.5 mm)
the system of calyces and pelvis is not visualized; with a full bladder, it becomes anechoic
the right kidney is slightly lower than the left
the echo density of the pyramids is lower than that of the parenchyma
the buds must be the same size or differ by no more than 2 cm
echodensity coincides with the renal sinus and perinephric tissue
the kidneys have the same echogenicity as the liver or it is slightly reduced
the concepts of “partial hypertrophy” of the renal cortex and “Bertin’s columns” are variants of the norm
indicators of the anterior-posterior dimensions of the organ - no more than 15 mm
kidney mobility during breathing – 2.5-3 cm
decoding of the resistance index of the main artery - approximately 0.7 in the hilum area, in the interlobar arteries - from 0.36 to 0.74.

Classmates

CDS of the aorta and renal arteries makes it possible to determine the cause of arterial hypertension detected for the first time or that has become severe and uncontrolled in terms of blood pressure despite intensive antihypertensive therapy. The study of the renal arteries and veins is carried out in parallel to determine venous disorders in the existing clinical manifestations of the disease.
CDS of the aorta and renal arteries with sufficient visualization allows you to objectively assess the condition of the vascular wall and the internal lumen of the renal arteries, determine the presence of additional (aberrant) renal arteries, and torsion of the vascular bundle of the kidney during its descent. This technique reveals the presence and localization of hemodynamically significant stenoses of the renal arteries in atherosclerosis, fibromuscular dysplasia or aortoarteritis, quantitatively assesses their extent and the degree of narrowing of the artery lumen. This study allows you to prepare materials for consultation with a vascular surgeon in order to determine the degree of need for surgical treatment (stenting, prosthetics of renal arteries).

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Doctor Ginzburg L.Z. about preparation: to obtain highly informative data by ultrasound, it is still better to prepare - 3 days of a slag-free diet and use sorbents to reduce intestinal carbonation. Gases significantly reduce visualization during renal ultrasound.

Doppler ultrasound of the renal vessels (USDG) is a diagnostic method that can detect changes in blood flow. It is based on the Doppler effect. The meaning of this effect is the reflection of ultrasonic waves from red blood cells, which helps to visualize the condition of the vessels from the inside and evaluate their work. Ultrasound of the renal arteries with Doppler allows specialists to diagnose the state of blood flow in the renal vessels .

This is important because the most important function of the kidneys, excretory, directly depends on the state of blood flow.. Doppler ultrasound helps evaluate:

the degree of damage to the vascular walls due to atherosclerosis, thrombosis;
(atherosclerotic plaques, thrombosis);
blood flow parameters (speed, volume);
lumen of blood vessels (stenosis, spasms);
the effectiveness of the prescribed treatment.

Ultrasound scanning of renal vessels is prescribed by a nephrologist for many kidney disorders. There are certain symptoms and conditions that indicate the possible presence of kidney disease, which are indications for this ultrasound examination:

Lower back pain.
Swelling of the legs, face.
Difficulty urinating.
Increased blood pressure.
Changes in general urinalysis (UCA): presence of blood (red blood cells), protein, increase in the number of leukocytes, change in density.
Attacks of renal colic.
Late toxicosis during pregnancy.
Bruises in the lumbar region.
Acute and chronic kidney diseases.
Systemic diseases (diabetes mellitus, vasculitis).
In preparation for kidney surgery.
If a tumor is suspected.

It is worth noting that ultrasound of the kidney vessels has no contraindications or harmful effects on humans.

The only drawback of this method is the difficulty in assessing and examining the small vessels of the kidneys.

Therefore, to clarify the diagnosis, angiography (CT, MRI) is additionally performed. Obstacles may also arise in the presence of areas of calcification that occur in vessels due to atherosclerosis.

How to prepare for the echographic method with Doppler

In order for the ultrasound to be as informative as possible, it is necessary to take a responsible approach to preparation. The most important condition for Doppler ultrasound is to reduce gas formation in the intestines. This allows for better visualization of the kidneys.

The following activities are carried out:

A few days before the ultrasound, the patient needs to follow a diet. Products that contribute to increased gas formation are excluded from the diet: baked goods, cabbage in any form, legumes, raw fruits and vegetables, carbonated drinks, confectionery.
These days, the doctor prescribes enterosorbents (activated carbon, espumizan, enterosgel, sorbex) 2 capsules 1-3 times a day as preparation.
Ultrasound must be performed on an empty stomach. You should not drink or take medications before the test. If the procedure is scheduled after lunch, then the interval between the last meal and the ultrasound should be at least 6 hours. In exceptional cases, the interval can be reduced to 3 hours (seriously ill patients).

It is impossible to perform an ultrasound scan of the vessels of the kidneys and their arteries after the following procedures: fibrogastroscopy, colonoscopy. After them, air enters the intestines, which makes it difficult to examine blood vessels and diagnose internal organs.

Survey methodology

Dopplerography of the kidneys is a gentle and comfortable procedure for the patient. It does not cause discomfort and is painless.

The patient undresses to the waist and takes a sitting or lying position on his side. The doctor applies a contact gel to the area being examined so that there is no layer of air between the sensor and the skin, this ensures maximum contact of the sensor with its surface. Then the doctor moves the sensor along the skin in the projection of the location of the kidneys and evaluates the resulting images. The results are recorded on paper and in photographs.

The whole procedure takes no more than 30 minutes.

At the end, the doctor issues a conclusion - a protocol, which contains the following information:

organ shape (normally bean-shaped);
outer contour (clear, even);
capsule structure (hyperechoic, thickness up to 1.5 mm);
relative position of organs (the right kidney is slightly lower than the left);
comparison of sizes (buds are the same size or the difference is no more than 2 cm);
mobility of the organ (during breathing up to 2-3cm);
anterior-posterior size (no more than 15mm);
resistance index of the main artery (in the hilum area about 0.7, in the interlobar arteries from 0.36 to 0.74);
developmental anomalies and vascular neoplasms are excluded;
the anatomical location of the vessels and the origin of additional branches;
condition of the vascular wall (thickening, thinning, aneurysms, ruptures);
the state of the lumen of the vessel (if narrowing occurs, the reasons are determined);
the resistance index is measured in the middle, terminal and proximal sections of the artery (a large difference in the indices in both kidneys indicates a violation of blood flow);
The size and structure of the adrenal glands and the structure of the perinephric fiber are assessed.

Indicators and norms of arterial trunks and their blood flow

Duplex and triplex mode of visualization of vessels and arteries (photo)

Here are some norms of renal vessels during ultrasound Dopplerography of the kidneys in conclusion:

Normal artery diameter:

main trunk – 3.3-5.6 mm;
segmental arteries – 1.9-2.3 mm;
interlobar arteries – 1.4-1.6 mm;
arcuate arteries – 0.9-1.2 mm.

Systolic blood flow velocity in the arteries of the kidney:

main trunk – 47-99 cm/sec;
interlobar arteries – 29-35 cm/sec.

Diastolic arterial blood flow velocity:

main trunk – 36-38 cm/sec;
interlobar arteries – 9-17 cm/sec.

Benefits of Sonography

All of the advantages of the Doppler ultrasound method listed below help the doctor quickly make decisions about the necessary treatment methods. This is especially important when there is a question of surgical intervention.

Non-invasive (no needle or injection).
Get results quickly.
Allows you to identify pathology at the time of examination.
Makes it possible to examine soft tissues.
No ionizing radiation is used during the procedure.
Availability.

To summarize, we can say that with the help of vascular ultrasound, an experienced ultrasound diagnostic doctor can quickly and easily diagnose most pathological conditions of the organ. The examination takes a minimum of time, has no contraindications, is absolutely painless and harmless.

Basics of preparation for ultrasound of the renal arteries with color circulation

Using ultrasound examination of renal vessels, it is possible to detect serious pathologies in real time. Using such a diagnostic measure, the position of these vessels is determined and their physiology is assessed. It is also important to consider their location relative to the kidney and determine the diameter, as well as identify possible obstacles to normal blood flow.

What methods are used to study the renal arteries?

The following common methods are used:

Ultrasound Doppler ultrasound. This method works based on the Doppler effect, in which ultrasound waves are able to reflect from movable objects, which are blood cells.
Duplex scanning. This method opens up the possibility of assessing not only the speed of blood flow, but also the chance to consider the anatomy of each vessel. This technique is advanced and will help determine the entire range of vascular pathologies, regardless of their level of development. This method makes it possible to find out the structure and caliber of the vessel, all its functional components.
Triplex scanning, also called color Doppler mapping or color doppler mapping. This method is similar to Doppler, but there is also an overlay of color blood flow on a two-dimensional image.

At the moment, a comprehensive examination of blood vessels using all methods is considered the most effective. This is the only way to obtain complete and reliable data with clear visualization. Pathologies can be identified at the initial stages of development, which will simplify their treatment. At first, it is often asymptomatic. The harmlessness of such a procedure allows you to monitor the condition of the arteries over time and track all changes.

The essence of the CDK procedure

Color Doppler mapping is a method that makes it possible to assess blood flow in vessels. The basis of the study is a combination of two-dimensional images and assessment of blood flow in accordance with Doppler indicators.

The diagnostician displays an image familiar to ultrasound, and in the place being studied, blood flows and, accordingly, their speeds are represented in color. The following colors will be visible on the monitor:

Red streams are blood that moves towards the sensor.
Blue streams are blood that follows from the sensor.

The speed can be judged by the intensity of the color; the less pronounced it is, the slower the flow moves. The color flow method not only displays a visual image, but also analyzes the direction, speed, and nature of the blood flow. The patency of the kidney vessels, their diameter, and resistance are also examined.

Using this method you can install:

Is there thickening of the vessel wall?
Are blood clots present?
The presence of atherosclerotic plaques.
Tortuosity.
Excessive expansion of the lumen of the vessel - aneurysm.

When is a renal artery study prescribed?

The main reason for prescribing a Doppler study of the renal vessels is the suspicion of a violation of the inflow and outflow of blood to the organ. During diagnosis, it is possible to clarify the reasons for this and the form of the anomaly. The patient is referred for additional examination of the kidneys if a pathology is detected during a routine ultrasound of the organ. Also, cases of appointment are associated with:

Impaired and/or painful urination.
The patient experiences swelling of the facial eyelids in the morning.
There are pain sensations in the lumbar region, but they are not related to diseases of the spine.
For persistent hypertension.
If there is suspicion of organ failure.
If tumors of the kidneys and adrenal glands are diagnosed.
If necessary, study the circulatory system that ensures the functioning of the tumor.
If it is necessary to track the dynamics of treatment.

As for contraindications, there are no absolute ones. The only thing is that if there is no need for urgent surgical intervention, then the study is carried out after FGDS and colonoscopy. Indeed, during these procedures, a large amount of air is released into the intestines, which becomes an obstacle to vascular diagnostics.

It is impossible to implement this method if there is a wound opening or burns at the site where the diagnostic sensor is installed.

Preparation measures and implementation plan

Lengthy and extensive preparation is not necessary, but several steps should still be taken to ensure that the results have high reliability and accuracy. Main stages:

3 days before the test you need to go on a diet. In this case, fatty foods, smoked meats, cabbage and legumes in any form, and carbonated drinks should be excluded from the menu.
You can eat porridge, vegetables, steamed meat and fish during the preparatory period.
During preparation, it is also worth taking sorbents in accordance with the instructions.
If there are problems with flatulence, then it is also necessary to include enzyme preparations in your intake.
Before the study in the evening, you need to have dinner no later than 18:00.
Also in the evening you need to do a cleansing enema and take activated carbon at the rate of 1 tablet per 10 kg of weight.
The procedure is carried out on an empty stomach, so you should not have breakfast in the morning.

If the patient has hunger pains or other severe pathological conditions, then it is allowed to eat no later than 3 hours before the procedure.

It is carried out according to the standard scheme. The patient removes clothing from the area being examined and lies on his side. A gel is applied to the skin and an examination is carried out.

Norms and pathologists

During the diagnosis, vascular pathologies can be identified. They are determined by comparing the norm with the obtained data. You need to go with the research protocol to your attending physician, he will be able to decipher the data and prescribe treatment as necessary.

Conclusion. The combination of several methods in the study of renal vessels is considered the most effective and efficient method, which makes it possible to identify pathologies at the very beginning of its development. Regular preventive examinations for risk groups are mandatory.

Some kidney diseases are directly related to impaired blood supply to the organs. The opposite situation consists of damage to the renal vascular bed, which occurs against the background of diseases of the excretory organs. In both situations, in order to adopt the most effective treatment tactics, a more thorough examination of the renal vessels is necessary in order to identify their pathological changes, which lead to disruption of the blood supply to the tissues of the paired organ. One of the most informative methods for studying renal vascular disorders is ultrasound of the kidneys with color circulation and other ultrasound methods in combination with Dopplerography and Doppler ultrasound.

The Doppler effect is the basis of modern vascular research

Ultrasound diagnostics is based on the partial reflection of ultra-high frequency sound by various tissues and their structural components. Stationary objects reflect a sound echo of the same frequency (wavelength) as the sent signal. If the object of study is in forward motion, the frequency of the reflected ultrasound changes in proportion to the speed of the object's movement. This is the Doppler effect, on which the study of the vascular bed and hemodynamic characteristics - the movement of blood through the vessels - is based.

Normally, blood is in constant motion, so the ultrasound reflected from red blood cells will have a changed frequency, which is detected by special sensors. The computer-converted data is displayed on the screen in the form of graphics, allowing one to draw conclusions about the following characteristics of blood vessels and hemodynamics:

shape of the vascular bed;
vascular wall thickness;
the presence of blood clots and atherosclerotic plaques in the lumen;
blood flow speed;
direction of blood flow.

These data are of great diagnostic value, making it possible to identify vascular pathologies even at the stage when the disease is latent and does not manifest itself in any way. Early diagnosis of vascular pathologies makes it possible to adopt adequate therapeutic or surgical treatment methods, preventing the development of more severe consequences.

Types of ultrasound diagnostics of renal vessels

The following ultrasound examinations based on the Doppler effect are currently used:

Color mapping;
renal vessel duplex or duplex ultrasound scanning (USDS);
Dopplerography or Doppleroscopy (ultrasound of renal vessels).

The method of ultrasound diagnostics of renal vessels with color circulation makes it possible to visualize the architectonics of the vascular bed. The vascular network is visible on the monitor in color, which depends on the speed and direction of blood movement. The direction of blood flow is assessed relative to the sensor receiving the reflected signal. Blue tones mean that blood is moving away from the sensor, red colors - towards the device. The speed of blood flow is characterized by color saturation - the more intense the shade, the faster the blood flow in a given vessel. The Color Domain Mode is additional and is reflected against the background of the B-mode, that is, a conventional black-and-white ultrasound image. This makes it possible to determine the exact localization of the studied vascular network in the tissues of the organ.

Duplex scanning is considered a very informative method of ultrasound vascular diagnostics. Duplex means a double approach to studying the vessel of interest. The method allows you to simultaneously determine the architecture of the vessel (diameter, type, morphology) and the state of hemodynamics in it (resistance to blood flow and its speed).

The simplest method of Doppler measurement of renal vessels is to construct a graph on the monitor screen that displays the characteristics of blood flow or the vascular wall. Conclusions about hemodynamic disorders and the architectonics of the vascular bed are made based on the analysis of the obtained graphs.

Indications for Doppler examination of renal vessels

One of the types of Doppler diagnostics of vascular disorders in the excretory organs is prescribed for symptoms of renal pathologies and general manifestations indicating the likelihood of damage to the kidney vessels. Symptoms that may prompt ultrasound examinations include:

pain in the lumbar and lower abdominal region;
changes in the volume, mode and frequency of urination, pain during this physiological process;
the presence of persistent swelling of facial tissues, extensive swelling of other localizations;
stable hypertension at a young age, or resistant to the effects of antihypertensive drugs;
laboratory tests of urine or blood indicating the presence of nephrotic or uremic syndrome.

In addition, Doppler ultrasound can be used in the following pathological conditions:

signs of insufficiency of the function of excretory organs (azotemia, uremia);
suspicion of abnormally developed renal vascular structures;
assumptions about the presence of tumor-like growths in the tissues of the kidneys or adrenal glands;
suspicion of deterioration of renal hemodynamics due to the formation of blood clots, atherosclerotic plaques, stenoses and aneurysms in the renal vessels.

The advantage of the Doppler technique for studying the vascular network of excretory organs is the ability to assess the hemodynamics and architecture of blood vessels in the present time. In addition, Doppler sonography is completely harmless, and therefore has no contraindications for use at any age and for any general condition of the patient.

Important! Doppler of the vessels of the excretory organs is more informative and diagnostically valuable than tomographic angiography, although the study is much simpler and does not require complex and time-consuming preparation.

How do you prepare for CDC and other Doppler studies of the kidneys?

Another advantage of Doppler ultrasound examinations is the minimal preparation of patients for diagnostic procedures. When conducting examinations of the vessels of the head, legs, uterus, and external genitalia, no preparation is needed at all. Patients are prepared only for examination of objects located in the abdominal cavity, including the kidneys. This need is associated with the presence of gas bubbles in the intestines that interfere with ultrasonic waves, dissipating them. This leads to a fuzzy, blurry picture, which distorts the idea of the real state of things, so preparatory measures consist of minimizing the number of air inclusions in the intestines.

To minimize gas contamination of the intestines before Doppler of the renal vascular bed, it is necessary to adhere to certain dietary restrictions for several days before the study. Vegetable protein (especially legumes) and baked goods made from wholemeal rye and wheat flour should be excluded from food. The consumption of fresh vegetables and fruits, fruit juices, and dairy products is also reduced to a minimum. Patients suffering from a tendency to increased gas formation in the intestinal lumen (flatulence) are recommended to use carminative drugs (Espumizan, Disflotil) containing the substance simethicone. Also in such a situation, enterosorbents such as Enterosgel can be useful.

Renal vessels are examined using Doppler on an empty stomach, mainly in the morning. Abstinence from eating should be at least 8-12 hours for adults, about 6 hours for children. For patients with hunger pain, diabetes, and young children, the period of food refusal is reduced to 3-4 hours.

Carrying out an ultrasound diagnostic examination of the renal vessels

Only deep skin burns in the examined area are contraindications for ultrasound scanning or ultrasound scanning. In the absence of urgent indications for Doppler examination of the vessels of the excretory organs, studies are not carried out after colonoscopy and fibrogastroduadenoscopy (FGDS) - these diagnostic methods provoke the formation of bubbles in the intestine.

The examination procedure differs little from a regular ultrasound for the patient, with the difference that it takes more time (up to half an hour). Diagnostic measures are carried out with the patient in a supine position. A special gel is applied to the skin in the area being examined to improve the sliding of the sensor and the conduction of ultrasound. The conclusion made based on the analysis of the data obtained is given to the patient or his relatives for further transmission to the attending physician.

The normal functioning of the kidneys, which depends on the blood supply, largely determines the general condition of the human body. In this paired organ, cleansing of toxins, synthesis of hormones and substances that regulate blood pressure (renin) and the number of red blood cells (erythropoietin) occur. The renal arteries arise directly from the aorta, the largest vessel with high pressure and blood flow speed of up to 50 cm/s. Changes in this segment significantly affect kidney function. To diagnose impaired delivery of nutrients and oxygen in the blood, the duplex scanning method is used.

What is the diagnostic method?

Duplex scanning of the renal arteries is an ultrasound method for diagnosing hemodynamic disorders in the vessels that nourish the kidney tissue using the Doppler effect.

To study the anatomical structure of the kidneys, “B-mode” (from “brightness” - brightness) is used: in a two-dimensional image, different tissue densities are visualized in grayscale. The result of the study is high-frequency ultrasonic waves recorded by a special sensor, which are reflected from the organs.

Visualization of moving objects is based on the difference in frequency of reflected signals. Depending on the direction of movement of the object (in duplex scanning - these are erythrocytes, red blood cells), the image acquires a color. As the particles approach, the signal becomes more frequent and a red image appears on the cartogram. Waves with lower rates form blue.

In addition, there are different types of blood flow:

Laminar (“irrotational”) - the entire volume moves in one direction at the same speed. The image is presented in a uniform blue or red color.
Turbulent (“chaotic”) - a kind of mosaic of blue, red and sometimes violet colors, formed by the multidirectional movement of red blood cells, is visualized on the screen.
A mixed version is a combination of the previous types in one vessel, in different parts of it.

To carry out the examination, you only need an ultrasound machine and a specialist who will identify changes and analyze the results using a computer program.

Indications and contraindications for the study

Impaired blood supply to the kidneys can be caused by both local and generalized pathological processes in the body. However, all nephrological diseases have common symptoms, in the presence of which duplex scanning is indicated, described below.

Renal colic is an acute pain syndrome that occurs in the lower back and is transmitted to the external genitalia and inner thigh. It occurs due to increased fluid pressure inside the renal collecting system (most often with urolithiasis when the outflow of urine is impaired due to a stone in the ureter).
Hematuria (from “haem” - blood and “uro” - urine). A symptom for which patients often consult a doctor themselves. The presence of blood in the urine with a pink or bright red color. This condition can be caused by injury, taking toxic medications, or inflammatory kidney diseases.
Low back pain, which is accompanied by changes in urine analysis or when neurological pathology is excluded (for example, radicular syndrome).
Arterial hypertension is a persistent increase in blood pressure greater than 140/90 mmHg. Art. There is a renovascular mechanism for the development of the disease. When the blood supply to the kidneys is disrupted, they synthesize a large amount of biologically active substance - renin. This hormone triggers a cascade of reactions that stimulate an increase in systemic blood pressure.
Edema. The mechanism of their development is a violation of the filtration ability of the kidneys and the accumulation of fluid in the tissues.
Diabetes mellitus. With this pathology, vessels of all sizes are affected; impaired functioning of the renal arteries can lead to chronic failure, which requires regular hemodialysis.
Kidney pathologies: glomerulonephritis (inflammatory disease with damage to the glomerular system), nephroangiosclerosis (damage to small renal vessels), nephropathy (diseases of unknown origin that impair filtration and reabsorption in the tubular system).

In addition, the method is used to diagnose congenital kidney anomalies (for example, L- or S-shaped kidney), to assess the condition before and after surgery.

A contraindication to the study may be an acute mental illness of the patient or the inability to be in a horizontal position (for example, after a spinal injury). In the presence of multiple organ (cardiovascular, respiratory, hepatic) failure that requires hardware for life support, duplex scanning is postponed until the condition has stabilized.

How to prepare for the duplex scanning procedure

Ultrasound diagnostic methods do not require special preparation of the patient. However, if there is increased gas formation in the intestines, the image may be distorted. Therefore, doctors advise adhering to some simple rules:

2 days before the scan, it is not recommended to eat raw fruits, legumes, potatoes, cabbage, baked goods made from premium flour, sweets, cakes and other confectionery products.
On the day before the study, take enterosorbents: White Coal, Smecta, Polysorb.
If possible, have your scan done in the morning on an empty stomach.

Doctor's advice! If the test is scheduled for the afternoon, it is acceptable to have a light breakfast at least 6 hours before the test

How the research works

Duplex scanning of the renal arteries is performed in the ultrasound diagnostic room of a clinic or private medical center.

The patient should remove all clothing up to the waist, as well as accessories that may interfere with the movement of the sensor. Depending on the condition and features of the anatomical structure of the kidneys, the patient lies down on the couch or stands next to the ultrasound machine.

Before the study, a special gel is applied to the sensor, which prevents the formation of air space between it and the human skin.

Important! The presence of gas (air outside or inside the intestines) interferes with the passage of ultrasound waves, distorts the image and can cause false results

Switching modes, the doctor first examines the structure of the vessel, the evenness and clarity of the contour of the wall, the diameter and the presence of formations inside the lumen. When you select Dopplerography (D-mode), a moving color image appears on the screen, which may be accompanied by slight noise (the sound of blood moving through the vessels). During the study, linear and volumetric velocity and the presence of abnormal direction of blood flow are determined.

The duration of the procedure is from 15 to 30 minutes. After the doctor takes the sensor, the patient wipes off the remaining gel from the skin, gets dressed and can go home.

The results of the study, presented in the form of a conclusion, images on special thermal paper or on digital media, are issued immediately after the completion of the diagnostic procedure.

Advantages of the method and possible complications after the study

Diagnosis of disorders in the renal vascular system involves studying the cause, location and severity of the lesion. For this purpose, ultrasound (duplex scanning) and X-ray (angiography and excretory urography) methods are used.

Comparative characteristics of the studies are presented in the table.

Criterion	Duplex scanning	Angiography	Excretory urography
Image acquisition method	Registration of ultrasound waves reflected from blood cells and kidney tissue	X-ray of the renal arteries filled with contrast agent	X-ray of the kidneys and ureters during the passage of the contrast agent through the vessels, tubules, collecting system and ureters
Study of the anatomical structure of the kidneys	The thickness and uniformity of the layers of the renal parenchyma (tissue containing glomeruli and tubules), the size of the collecting system, and the presence of stones are examined.	Not studied	Only the outlines of the kidneys and the pyelocaliceal system are visualized in subsequent phases of urography
Diagnosis of circulatory disorders	Visualization of narrowings, blocking of the vessel lumen by a thrombus or plaque, the presence of anomalies	Clear visualization of renal vessels of all sizes	Small vessels of the kidneys are visualized, which reflect the uniformity of blood supply to the tissue
Safety	Absolutely safe procedure	X-ray exposure.	X-ray exposure. Toxic effect of contrast agent
Contraindications	The patient's serious condition. Mental illness	Kidney and liver failure. Tuberculosis. Severe cardiovascular failure. Thyrotoxicosis (increased secretion of thyroid hormones). Pregnancy. Allergic reactions to iodine preparations	Decompensated renal failure. Allergic reaction to iodine preparations
Necessary preparation	Diet that prevents increased gas formation	Preliminary studies: electrocardiography (ECG), fluorography, blood test, coagulogram	Diet to prevent increased gas formation. Cleansing enema on the day of the study
Duration	15-30 minutes	30-60 minutes

Important! For all studies that require the introduction of a contrast agent, a preliminary allergy test is required.

Duplex scanning, like all ultrasound diagnostic methods, is the safest examination of the circulatory system, which does not cause undesirable consequences.

How to decipher the results

The duplex scanning method combines the study of the morphological structure of the kidney and the characteristics of blood supply. An ultrasound diagnostic specialist evaluates the following indicators:

Location, shape and size of the organ.
The thickness and homogeneity of the cortex and medulla.
Deformations of the collecting system.
Presence of neoplasms.
The structure of the “renal gate”: features of the location of the renal artery, vein and ureter.
Length and diameter of vessels. Normally, the length of the renal artery ranges from 2.5 to 6 cm with a lumen diameter of 0.2 to 0.7.
The presence of intravascular formations: blood clots, atherosclerotic plaques.
Blood flow velocity (cm/s) and resistance index, which indicates the resistance created by the vessels.

With congenital anomalies, variable placement of blood vessels is observed depending on the shape and location of the organ: horseshoe-shaped, L- or S-shaped kidney.

The presence of obstacles to the free movement of blood on the scanogram is reflected by an increase in the resistance index, an increase in linear and a decrease in volumetric velocity, and a characteristic turbulent blood flow.

This method is widely used to clarify the location, length and shape of blood vessels before surgery, as well as to assess the effectiveness of the latter. The absence of undesirable consequences and contraindications allows duplex scanning of the renal arteries to be considered the method of choice for children and pregnant women.

The anatomical structure and movement of blood in the renal artery system during duplex scanning are presented in the video below.