Ultrasound signs of kidney and ureter pathology

Nonvisualizable kidney

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.

If one kidney is not detected, then keep in mind the following:

1. The kidney could be removed. Check the medical history and look for scars on the patient's skin.
2. The kidney can be dystopic. Examine the area of the kidneys, as well as the entire abdomen, including the small pelvis. If the kidney is not found, then take a chest radiograph. You may also need intravenous urography.
3. If one large but normal kidney is detected, if there was no previous surgical intervention, then it is likely congenital agenesis of another kidney. If one kidney is visualized, but it is not enlarged, the lack of visualization of the second kidney suggests a chronic disease.
4. If there is one large, but displaced kidney, then this may be an anomaly of development.
5. The lack of visualization of both kidneys can be a consequence of a change in the echogenicity of the kidneys as a result of a chronic disease of the renal parenchyma.
6. The kidney, having a thickness of less than 2 cm and a length of less than 4 cm, is poorly visualized. Locate the kidney vessels and ureter, it can be useful for determining the location of the kidney, especially if the ureter is dilated.

Pelvic kidney may be mistaken for echography for a tubo-thoracic formation or a tumor of the gastrointestinal tract. Use intravenous urography to clarify the location of the kidney.

Large bud

Two-sided increase

1. If both kidneys are enlarged, but have a normal shape, normal, increased or decreased echogenicity. Homogeneous ehostrukturu, it is necessary to keep in mind the following possible reasons:
   • Acute or subacute glomerulonephritis or severe pyelonephritis.
   • Amyloidosis (more often with increased echogenicity).
   • Nephrotic syndrome.
2. If the kidneys have an even contour and are diffusely enlarged, a heterogeneous structure, increased echogenicity, then the following possible reasons should be borne in mind:
   • Lymphoma. Can give multiple sites of low echogenicity, especially Burkitt's lymphoma in children and adolescents.
   • Metastases.
   • Polycystic kidney disease.

One-sided increase

If the kidney is enlarged, but has normal echogenicity, and the other kidney is small or nonexistent, the increase can be the result of compensatory hypertrophy. If one kidney is not visualized, cross dystopy and other developmental anomalies should be excluded.

The kidneys can be slightly enlarged as a result of congenital lobulation (doubling) with two or three ureters. Examine the kidneys: two or more vascular legs and ureters should be visualized there. It may be necessary to perform intravenous urography.

One kidney is enlarged or has a more lobed structure than normal

The most common cause of kidney enlargement is hydronephrosis, which is represented on echograms in the form of multiple rounded cystic zones (calyx) with a wide central cystic structure (the width of the renal pelvis is normally less than 1 cm). Sections in the frontal band demonstrate the connection between the calyx and the pelvis. With multicystosis of the kidneys, this connection is not detected.

Always compare two kidneys when measuring the size of the renal pelvis. When most of the renal pelvis is located outside the renal parenchyma, then this may be the norm option. If the renal pelvis is enlarged, the normal echostructure is broken due to the tight filling of the pelvis with liquid.

Enlargement of the renal pelvis may occur with hyperhydration with an increase in diuresis or with overflow of the bladder. The kidney cups will be normal. Ask the patient to urinate and repeat the test.

An enlargement of the pelvis can take place during normal pregnancy and does not necessarily mean the presence of inflammatory changes. Check the urine test for infection and the uterus for pregnancy.

Enlarged renal pelvis

An enlarged renal pelvis is an indication for the examination of the ureters and the bladder, as well as another kidney to identify the causes of obstruction. If the cause of dilatation is not detected, then excretory urography is necessary. The normal, concave forms of the calyx may acquire a convex or rounded shape with an increase in the degree of obstruction. Accordingly, the renal parenchyma becomes thinner.

To determine the degree of hydronephrosis, measure the size of the renal pelvis with an empty bladder. If the pelvis is thicker than 1 cm, then the expansion of the calyx is not determined, there are initial signs of hydronephrosis. If there is a dilatation of the calyx, then there is a moderately pronounced hydronephrosis; if there is a decrease in the thickness of the parenchyma, then hydronephrosis is pronounced.

Hydronephrosis can be caused by congenital stenosis of the ureteropelvic segment, stenosis of the ureter, for example, in schistosomiasis, or in the presence of stones, or with external compression of the ureter by retroperitoneal formations, or formations in the abdominal cavity.

Kidney cysts

With ultrasound detection of multiple, anehogennye, well-delimited zones throughout the kidney can be suspected multicystosis kidney. Multicystosis is usually one-sided, while congenital polycystosis is almost always bilateral (although cysts may be asymmetric).

1. Simple cysts can be single or multiple. With ultrasound, cysts have a rounded shape and a flat contour without an internal echostructure, but with a distinct increase in the posterior wall. Such cysts are usually single-chambered, and in the presence of multiple cysts the size of the cysts differ. Occasionally these cysts become infected or a hemorrhage occurs in their cavity, and an internal echostructure appears. In this case, or if there is an uneven contour of the cyst, additional investigation is required.
2. Parasitic cysts usually contain sediment and are often multi-chambered or have septa. When the cyst is calcified, the wall looks like a bright echogenic convex line with an acoustic shadow. Parasitic cysts can be multiple and bilateral. Scan also the liver to identify other cysts, perform chest radiography.
3. If the kidney determines a number of cysts, then it is usually enlarged. In this case, alveolar echinococcus can be detected. If the patient is less than 50 years old and there are no clinical manifestations, then examine the second kidney for the detection of polycystic disease: congenital cysts are anechogenous and do not have near-wall calcification. Both kidneys are always enlarged.

More than 70% of all kidney cysts are a manifestation of benign cystic disease. These cysts are widespread in people over 50 years old and can be bilateral. They rarely give clinical symptoms.

Renal Tumors

Ultrasound can not reliably differentiate benign renal tumors (other than renal cysts) and malignant tumors of the kidneys and does not always exactly differentiate malignant tumors and kidney abscesses.

There are two exceptions to this rule:

1. In the early stages of angiomyolipoma, the kidney has pathognomonic echographic features that allow you to make an accurate diagnosis. These tumors can occur at any age and can be bilateral. Echographically angiomyolipoma is presented clearly defined, hyperechoic and homogeneous structure, and as the tumor grows, dorsal weakening occurs. Nevertheless, in tumors with central necrosis there is a pronounced dorsal enhancement. At this stage, a differential diagnosis with ultrasound is not possible, but an abdominal radiography can reveal fat within the tumor, which practically does not occur in any other type of tumor.
2. If a kidney tumor invades an inferior vena cava or parainal tissue, then it is undoubtedly malignant.

Solid kidney tumors

Kidney tumors can be well delineated, and can have fuzzy boundaries and deform the kidney. Echogenicity can be increased or decreased. In the early stages, most tumors are uniform, with central necrosis they become heterogeneous.

It is important to be able to differentiate the normal or hypertrophied pillars of Bertin and the kidney tumor. The echostructure of the cortex will be the same as that of the rest of the kidney; nevertheless, in some patients, differentiation may be difficult.

The formation of mixed echogenicity with a heterogeneous ehostruktura

Differential diagnosis in the presence of heterogeneous formations can be very difficult, but if there is a spread of the tumor outside the kidney, then there is no doubt that it is malignant. Malignant tumors can not go beyond the kidneys. Both tumors and hematomas can give an acoustic shadow as a result of calcification.

As the tumor grows, its center is necrotic, and a mixed echogenicity structure appears with an uneven contour and a large amount of internal suspensions. Differentiating the tumor in such a stage from an abscess or a hematoma can be difficult. To make the correct diagnosis in this case, you need to compare the zoographic picture and clinical data. Tumors can spread to the renal vein or inferior vena cava and cause thrombosis.

Always examine both kidneys if you suspect a malignant kidney tumor (at any age), scan the liver and lower vena cava. Also perform a chest x-ray to exclude metastases.

Echogenic formation with uneven, undercut contour, containing a suspension against the background of an enlarged kidney, can be a malignant tumor or a pyogenic or tuberculous abscess. Clinical data will help differentiate these conditions.

In children, malignant tumors, such as, for example, nephroblastoma (Wilms' tumor), are well encapsulated, but may be non-uniform. Some have calcification, but not a capsule. Changing the echogenicity can be hemorrhages or necrotic changes. Some tumors are bilaterally.

Small kidney

1. A small kidney with normal echogenicity can occur as a result of stenosis or occlusion of the renal artery or congenital hypoplasia.
2. A small normal kidney, a hyperechoic kidney can indicate chronic kidney failure. With chronic insufficiency, both kidneys are probably affected.
3. A small hyperechogenic kidney with an uneven, scalloped contour, with uneven parenchyma thickness (usually changes are bilateral, but always asymmetric), often occurs as a result of chronic pyelonephritis or an infectious lesion, such as tuberculosis. In abscesses, calcifications may occur, which are defined as hyperechoic structures.
4. A small, normal form, a hyperechoic kidney may occur in the late stages of a vein thrombosis. Acute thrombosis of the renal vein usually causes an increase in the kidney followed by wrinkling. Chronic obstructive nephropathy can also give similar changes in one kidney, but changes in chronic glomerulonephritis are usually bilateral.

Kidney stones (concrements)

Not all stones are visible in the survey of the radiography of the urinary system, but not all stones are detected by ultrasound. If clinical symptoms suggest concrement, all patients with a negative ultrasound result should undergo intravenous urography.

Assumption of urinary stones, pathology in urinalysis, but negative results of ultrasound investigation - intravenous urography.

The stones are most clearly visible in the collecting system of the kidneys. The minimum size of the stone, which is visualized using general-purpose ultrasonic equipment using a 3.5 MHz sensor, is 3-4 mm in diameter. Smaller stones (2-3 mm) can be detected using a 5 MHz sensor. The stones are defined as hyperechoic structures with an acoustic shadow. The stones should be visualized in two different projections, in longitudinal and transverse, to determine the exact location and measurement. This will help to avoid false positive diagnosis in the presence of calcifications in the renal parenchyma and other tissues, for example in the neck of calyxes, which can simulate stones, creating a similar hyperechoic structure with a shadow.

Stones of the ureter are always very difficult to identify using ultrasound. Impossibility of visualization of the ureteral stone does not mean that it does not exist.

Injury

1. In an acute stage, the echography can reveal intracellular or pararenal anechogenous areas as a result of the presence of blood (hematoma) or extravasation of urine.
2. With the organization of blood clots and the formation of blood clots there are hyperechoic or mixed zhogennosti with anzohogennymi inclusions of the structure (mixed ehogennosti education or education). In all cases of injury, examine the opposite kidney, but remember that ultrasound can not determine the kidney function.

The possibility of kidney imaging does not mean that this kidney is functioning. To determine the renal function, use intravenous urography, radioisotope studies or laboratory tests. Remember that a kidney injury can lead to a temporary loss of function.

Paranephalic fluid accumulation

Blood, pus and urine near the kidney during echography can not be differentiated. All this looks like anechogenic zones.

Retroperitoneal formations

Lymphomas are usually represented by para-aortic and aortocaval formations. If the sensitivity level is low enough, they may look liquid. Any such formation can shift the kidney.

An abscess of the lumbar muscle or a hematoma can be anechogenic or have a mixed echogenicity: blood clots are hyperechoic. In the presence of gas, some areas can be hyperechoic and give an acoustic shadow.

Adrenal formations

Scan both adrenal glands. Adrenal formations can be represented by primary or metastatic tumors, abscesses or hematoma. Most of them have a clear boundary, but some differentiate badly. In newborns the most common are hematomas.

Impossibility of visualization of the adrenal gland does not exclude the presence of pathology in it.

Urolitters

Because of the deep location of the ureters behind the intestine, it is very difficult to visualize the normal ureters by ultrasound. In the presence of dilatation (for example, with obstruction due to enlargement of the prostate or urethral stricture or due to vesicoureteral reflux), the ureters are better visualized, especially near the kidney or bladder. The middle third of the ureter is always visualized with difficulty, while intravenous urography is much more informative. However, in the presence of wall thickening, for example in schistosomiasis (in some cases with calcification), the ureters are easily visualized by echography.

The lower third of the ureters can be visualized when scanning through a filled bladder, which creates a sufficient acoustic window.

Ultrasound is not a reliable method of recognizing both ureteral stones and stenosis.

Differential diagnosis of kidney disease

Single large cyst

• Exclude giant hydronephrosis.

Unevenness of the contour of the kidney (except lobulation)

• Keep in mind the possibility of chronic pyelonephritis or multiple renal infarcts.

Unevenness of the contour of the kidney (smoothed nature)

• Normal lobulation or cystic disease (congenital or parasitic).

Nonvisualizable kidney

• Extraction or displacement.
• Surgical intervention.
• Too small for echographic imaging.
• Displacement of the tumor.

Large bud (normal form)

• Hydronephrosis.
• Cystic disease.
• Acute venous renal thrombosis.
• Compensatory hypertrophy (other kidney absent or wrinkled).

Large bud (asymmetric shape)

• Tumor.
• Abscess.
• Parasitic cyst.
• Polycystic in adults.

Small kidney

• Glomerulonephritis.
• Chronic pyelonephritis.
• An infarction or chronic renal venous thrombosis.
• Congenital hypoplasia.

Paranephalus fluid *

• Blood.
• Pus.
• Urine.

Ultrasonics can not distinguish between these types of fluid.

Nonvisualizable kidney? Always check the contralateral kidney and look for the kidney in the small pelvis.