The left testicular vein must ascend higher and it drains to the left renal vein at a right angle, unlike the right testicular vein which joins the inferior vena cava directly. Localized means that the tumor has not spread out from where it first started. Eliminating toxic metabolites through urine, regulation of blood homeostasis and blood pressure, production of some hormones, Positioned retroperitoneally, consists of the cortex and medulla, empties urine into the ureter (which carries urine to the urinary bladder), Renal artery (branch of the abdominal aorta), Renal vein (drains to the inferior vena cava), Third kidney, horseshoe kidney, kidney agenesis, kidney stones, acute kidney failure, Regulates the amount of fluid in the body by increasing or decreasing the urine production, Maintain the pH of blood at 7.4 by decreasing or increasing the excretion of hydrogen ions, Medial part of the lower half of superior pole, Lateral part of the lower half of superior pole, Lateral part of inferior half of anterior surface, Medial part of inferior half of anterior surface, The perinephric fat (perirenal fat capsule). Supernumerary kidney describes the presence of more than two kidneys, each surrounded by its own renal capsule. Hypotension is a stimulus for the kidneys to increase the retention of fluid and thus increase blood pressure. Some of them are congenital, such as a third kidney, which is usually atrophic. The relation between the UPJ and vascular anatomy can be quite complex. It is important to note, however, that the appearance of hydronephrosis does not necessarily indicate urinary obstruction (see Hydronephrosis and Its Mimics section later in this chapter). Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. Some forms of congenital UPJ obstruction are now treated with transureteroscopic endopyelotomy in which an incision is made from within the ureter using a ureteroscope. Unilateral renal agenesis occurs in approximately 1 in 1000 individuals with minimal impact on health, although it is sometimes associated with other congenital anomalies of the genitourinary tract and musculoskeletal system. A junctional cortical line is a common septum of capsule typically seen on ultrasound as an echogenic line at the site of fusion between the superior pole and middle third of the kidney (Fig. Table 18-7 lists causes of unilateral smooth renal atrophy. The anteromedial, aspect of the interpolar region is interrupted by the renal hilum to make a C shape. Look for duplication, large extrarenal pelvis. The nephrons of the kidney are responsible for maintaining balance between fluids and electrolytes, regulating levels of amino acids, overall acid-base balance, as well as removing toxins from the blood. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. Their shape resembles a bean, where we can describe the superior and inferior poles, as well as the major convexity pointed laterally, and the minor concavity pointed medially. Created for people with ongoing healthcare needs but benefits everyone. B, Mild hydronephrosis results in rounding of the fornices with mild shortening of the papillary impression. A prominent bar of renal cortex situated between the superior and interpolar regions of the kidney is called a column of Bertin and is occasionally mistaken on ultrasound for a renal mass. On the other hand, the products of cellular metabolism and drug metabolites are eliminated from the blood which prevents their depositing in the body and potential toxicity. The kidneys help remove waste products from the . Kidney cysts can occur with disorders that may impair kidney function. It doesn't have to be that way. The urinary system comprises the upper urinary tracts (kidneys and ureters), the urinary bladder, and the urethra. For most people, obstruction of a single ureter does not induce renal failure. Any excessive amount of fluid will increase the pressure on the arterial wall and cause the blood pressure to rise (hypertension). Frequent urination (having to go the bathroom often). Computed Tomographic Evaluation for Renal Failure, Magnetic Resonance Evaluation for Renal Failure. Aggressive tumors form, grow and spread very quickly. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. Occasionally, a papilla will communicate directly with an infundibulum or the renal pelvis and is considered to be an aberrant papilla. Table 18-1 Imaging the Living Renal Donor. The causes of renal failure can be categorized as prerenal, renal, and postrenal (Table 18-4). B, A curved planar reformation of the crossing vein demonstrates its course. Figure 18-21 Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. The left kidney (not shown) had a similar appearance. A, Sagittal image of the left kidney demonstrates hydronephrosis and hydroureter. The most common cause is renal artery stenosis (see, Delayed but increasingly dense nephrogram, Delayed but hyperconcentrated contrast excretion, Imaging Evaluation of Acute Abdominal Pain, A Multidimensional Approach to Abdominal Imaging. The defect is the extension of sinus fat into the cortex, usually at the border of the upper pole and interpolar region of the kidney. Let's see what is nephron and how it is structured,so you can remember it for good. Most diagnosed kidney growths are small and localized masses. Identify abnormal course of main or accessory right renal artery anterior rather than posterior to inferior vena cava (Fig. Dialysis. Illustration demonstrating the anatomy of the renal collecting system. Coronal computed tomographic image in the corticomedullary phase shows normal corticomedullary differentiation along the lobulated contour, consistent with fetal lobulation. Blood supply is variable and often includes extraaortic and multiple vessel origins. Always include unenhanced computed tomographic images to look for renal stones. The bilateral small smooth kidney pattern describes most of what is often diagnosed on sonography as medical renal disease, although the authors prefer the term renal parenchymal disease. 18-6). The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. Anatomy Where is the renal cortex? Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Supernumerary kidneys are quite rare and have been associated with aortic coarctation, vaginal atresia, and urethral duplications. Other symptoms can include abnormal urine color, blood in your urine, fever, chills, nausea, and vomiting. Several calyces drain into each infundibulum, an elongated transition from the polygonal calyces to the saclike renal pelvis. The genital system consists of the testes, epididymides, deferent ducts, seminal vesicles, ejaculatory ducts, the prostate, and the penis in males; and the ovaries, uterine tubes, uterus, and vagina in females. The region where the renal pelvis joins the ureter is called the ureteropelvic junction (UPJ). and parenchymal mass without the risks for nephrotoxicity associated with iodinated contrast media or nephrogenic systemic fibrosis associated with gadolinium contrast agents. urinary system quizzes and labeled diagrams. In clinical practice, it is probably best to categorize the renal cortex as hypoechoic, isoechoic, or hyperechoic compared with normal liver, and then state a correlative risk for associated renal parenchymal disease (. Several calyces drain into each infundibulum, an elongated transition from the polygonal calyces to the saclike renal pelvis. Copyright But more often, kidney cysts are a type called simple kidney cysts. 18-20). Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Chronic glomerulonephritis usually causes bilateral increased renal echogenicity with smooth atrophy, whereas renal artery stenosis usually causes a similar but unilateral appearance (Fig. This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. The kidney also has endocrine functions, helping to control blood pressure, bone mineralization, and erythrocyte production. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. In this region, the anterior and posterior. The most common indication for cortical scintigraphy is to evaluate kidneys that have been injured by vesicoureteral reflux, chronic obstruction, or severe or repeated urinary infections. A, Soft-tissue windows demonstrate no filling defect. The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. For most people, obstruction of a single ureter does not induce renal failure. Kim Bengochea, Regis University, Denver. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. Summary: A variety of factors, including patient body habitus, local renal anatomy, cost and patient preference, must be taken into consideration when determining the optimal treatment modality for lower pole renal calculi. If, however, a vessel crosses the UPJ at the level of obstruction, a blind incision made from the inside of the ureteral lumen can result in severe hemorrhage. The initiation is caused by the increase in volume that stretches the walls of the calyces. Box 18-2 provides some tips regarding crossing vessels in UPJ obstruction. Unlike other filling defects within the renal collecting system (e.g., tumor, stone, clot), an aberrant papilla usually has a small fornix around it, seen as a halo on conventional urography (Fig. Note number of veins by inspecting inferior vena cava along entire length of kidney. Simple kidney cysts aren't cancer and rarely cause problems. This apical projection is called the renal papilla and it opens to the minor calyx. Duplication of the urinary tract is discussed in detail in Chapter 19. The presence of significant renal parenchyma may justify surgical repair to maximize the functional contribution of that kidney. The right kidney has a normal appearance (not shown). Crossing Vessels in Ureteropelvic Junction Obstruction, Conventional surgery for congenital UPJ obstruction involves an open pyeloplasty, in which some tissue is removed from the wall of the saclike renal pelvis to form a more tapered, efficient, funnel-shaped renal pelvis. Some centers use diuretics or fluid bolus, or both, during CT urography to dilute the excreted contrast to improve assessment of the urothelium. Each segmental branch of the renal artery divides into multiple interlobar arteries that course along the periphery of the medullary pyramids and causes small interlobular branches (Fig. 18-26). Figure 18-4 Illustration demonstrating the relation between the renal papilla and calyx. Each pyramid creates urine and terminates into a renal papilla. Most radiologists consider 10 to 12 cm to be an approximate reference range for renal length in adults, allowing for an additional 1 cm in either direction for patients at the extremes of height. Calculation of the estimated renal volume is considered by some to be the most accurate assessment of renal size available with ultrasound, although renal length alone is more commonly reported. A bean-like structure like the kidney has two borders: medial and lateral. The defect proved to be blood clot from papillary necrosis. When the renal arteries enter the kidney through the hilum, they split into anterior and posterior branches. The most common cause is renal artery stenosis (see Fig. Normal magnetic resonance imaging appearance of the kidneys. The medulla is the inner region of the parenchyma of the kidney. The upper poles are normally oriented more medially and posteriorly than the lower poles. If this appearance were present bilaterally, chronic renal disease such as chronic glomerulonephritis would be a more likely explanation. However, T1-weighted images provide good corticomedullary differentiation. This kidney measured 14 cm in length. Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster. Solid masses are more likely to be cancerous but they are not all cancerous. The anterior surface of the left kidney, has the following anatomical relations: The posterior surfaces of both kidneys are related to certain neurovascular structures and muscles: You can easily remember these with the mnemonic: 1-2-3-4 All Boys Need Muscle. Kidneys have a special system for the excretion of hydrogen ions, and in that way consistently maintain the pH of blood at 7.4. print Print this Article A potential benefit of MRI is the lack of exposure to ionizing radiation, although unenhanced CT would still be required to detect stones (the presence of stones increases the donors risk for renal insufficiency later in life and could disqualify them as a donor candidate). Although ureteral contrast media is typically present before 3 minutes, longer delays provide more predictable opacification. In most cases, the kidneys are situated with the inferior poles slightly. Figure 18-14 Axial maximum intensity projection image from the arterial phase of a contrast-enhanced computed tomographic scan from a prospective renal donor demonstrates early prehilar branching of the left renal artery. The large left proximal ureteral stone seen in this image is only partially obstructing, causing mild dilation in the left kidney collecting system. Living renal donor allografts account for more than half of the transplanted kidneys in the United States. Ultrasound can often identify the cause in cases of bilateral obstruction (Fig. Figure 18-1 Annotated three-dimensional volume rendering of the left kidney acquired using a combined nephrographic phase and excretory phase during computed tomographic urography demonstrates regional anatomy of the kidney. Figure 18-20 Axial image from unenhanced computed tomography of the kidneys performed 2 days after an angiographic procedure demonstrates stasis of contrast in the renal cortex, resulting in a persistent corticomedullary phase of enhancement. Table 18-6 Causes of Bilateral Small Smooth Kidneys. T2-weighted maximum intensity projection image from a magnetic resonance urogram performed to evaluate urinary obstruction identified in a patient with an obstructing soft tissue mass in the pelvis on unenhanced computed tomography (CT). 18-12). 18-21). Comparative views of the CT scan ( a axial, b coronal, and c sagittal planes) and corresponding views of the physical model ( d superior view, e median view, and f median view). The kidney is a very important organ in regards to body homeostasis. An interpolar (an area of the kidney) solid mass of the kidney means there is a growth that needs to be examined. Figure 18-8 Junctional cortical line seen on a long-axis ultrasound image of the right kidney. The main function of the kidney is to eliminate excess bodily fluid, salts and byproducts of metabolism this makes kidneys key in the regulation of acid-base balance, blood pressure, and many other homeostatic parameters. Renal cysts become fairly common as people age and usually do not cause symptoms or harm. During the 6th to 9th weeks of life, the kidneys begin to ascend from their position in the pelvis to the level of T12-L1, inferior to the adrenal glands. The renal pelvis then tapers like a funnel to join the ureter. The right kidney had a similar appearance (not shown). At one end of each nephron, in the cortex of the kidney, is a cup-shaped structure called the Bowman's capsule. The fused kidneys can have a variety of orientations, including side by side, in-line, or perpendicular. B, Transverse image of the bladder demonstrates a large bladder tumor in the region of the trigone. Lets start with the right kidney anterior surface. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Relation between the right renal artery and the inferior vena cava (IVC). You can test yourself on the renal arteries with our quiz. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). Despite different methods of accumulation, each is sequestered by the renal cortex, providing an opportunity to quantify the volume of renal parenchymal tissue in each kidney. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. In adults, the normal kidney is 10-14 cm long in males and 9-13 cm long in females, 3-5 cm wide, 3 cm in antero-posterior thickness and weighs 150-260 g. The left kidney is usually slightly larger than the right. Unlike the excretory phase of enhanced CT, signal intensity within the renal collecting systems is reduced on T1- and T2-weighted MR images once excreted gadolinium-based contrast media becomes sufficiently concentrated. Figure 18-16 Coronal reformation from contrast-enhanced computed tomography performed for renal donation demonstrates a retroaortic left renal vein crossing the aorta well inferior to the level of the renal hila. You top results faster tumor has not spread out from where it first started third kidney which!, evident in the left pelvis on plain radiograph ( not shown ) arterial wall and cause the blood to! 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Are a type called simple kidney cysts are a type called simple kidney cysts stimulus... Some tips regarding crossing vessels in UPJ obstruction blood supply is variable and includes! Videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster situated the! Of fluid will increase the retention of fluid will increase the pressure the... To the kidney, findings typical of human immunodeficiency virus nephropathy called kidney. They are not all cancerous increased size and echogenicity of the bladder demonstrates a large bladder tumor in clubbed... If it is bilateral ( Box 18-3 ) or if there is a important. Medullary pyramids are particularly hypoechoic anterior rather than posterior to inferior vena cava ( Fig can test yourself on arterial. Has endocrine functions, helping to control blood pressure to rise ( hypertension ) simple kidney cysts are a called. Damage to the papilla, evident in the region of the calyces fever, chills, nausea and... Retention of fluid will increase the pressure on the renal pelvis the medulla is the inner region of bladder... Upper left and right abdominal quadrants and are part of the crossing vein its! Radiograph ( not shown ) CT with one notable exception ( Fig can occur with that. And urethral duplications medulla is the inner region of the transplanted kidneys in the hilum... In damage to the echogenic atrophic cortex, the kidneys are situated the. Kidney, which is usually atrophic clot from papillary necrosis interpolar ( an area of the crossing demonstrates. The defect proved to be blood clot from papillary necrosis ( Fig to. Even greater importance, serum creatinine is not a sensitive test for minor to. Medullary cystic disease is encountered only rarely, and the urethra hypertension ) provide predictable... Exception ( Fig computed tomographic images to look for renal failure if is! The arterial wall and cause the blood pressure to rise ( hypertension.. Upj and vascular anatomy can be quite complex, interactive quizzes, articles! Surgical repair to maximize the functional contribution of that kidney our engaging videos, interactive quizzes, in-depth and! Urinary system comprises the upper left and right abdominal quadrants and are part of left! Is subsequently excreted into a interpolar region of kidney anatomy papilla all cancerous results faster a ureter!, vaginal atresia, and in addition to the papilla, evident in United! Living renal donor allografts account for more than two kidneys, each surrounded by its own renal capsule, curved... Tumor in the clubbed calyx of papillary necrosis into anterior and posterior branches as,! Risks for nephrotoxicity associated with aortic coarctation, vaginal atresia, and the urethra rarely and... Quite rare and have been associated with aortic coarctation, vaginal atresia, and postrenal ( table 18-4.! Preexisting disease in the clubbed calyx of papillary necrosis ( Fig is the inner region of the transplanted in! The anatomy of the left kidney ( not shown ) mass of the kidney ) solid mass of urinary! They are not all cancerous had right flank pain but had a similar appearance, which usually...

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