Because they rarely cause symptoms, renal cysts are most often found during . Besides blood volume and pressure regulation, kidneys also participate in the production of calcitriol (the active form of vitamin D). 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. Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. Duplication affects the axial appearance of the kidneys by dividing the renal sinus into superior and inferior components, separated by a circumferential band of cortex in the central region (. The urinary system comprises the upper urinary tracts (kidneys and ureters), the urinary bladder, and the urethra. This refers to the forming of the stones within the system of calyces because of too much calcium or uric acid into the filtrate. However, this individual is more likely to show a decline in renal function from an additional insult. Surgery was successful and the surgeon confirmed the anatomic survey was correct. Figure 18-18 Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. Renal function is better evaluated by measured creatinine clearance, which takes into account not only the amount of creatinine in the blood but also the amount of creatinine within a specified volume of urine over a given period. So the pyramids represent the functional tissue that creates urine, whereas the calyces are the beginning of the ureter and transport the urine to it. Renal Cysts. Aggressive tumors form, grow and spread very quickly. It is also permeable for the products of the metabolism, such are creatinine and drug metabolites. 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. Box 18-2 provides some tips regarding crossing vessels in UPJ obstruction. Because an extrarenal pelvis is not confined by the renal parenchyma, there is a tendency for it to expand. Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Creatinine is a breakdown product of creatine, found within muscle. Urine from the calyces flows to the renal sinus via tributaries called infundibula. This is why the kidney is essential for the circulatory hemostasis. 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. normal kidney size in adults normal kidney size in children Structure Prominent extrarenal pelves are typically positioned anteriorly (Fig. Note distance from origin to the first arterial division (Fig. A bean-like structure like the kidney has two borders: medial and lateral. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. The pyramids contain the functional units of the kidney, the nephrons, which filter blood in order to produce urine which then is transported through a system of the structures called calyces which then transport the urine to the ureter. B, A small calyceal defect is seen when the same image is viewed using bone windows. A furosemide challenge is often administered after initial excretion is observed to measure the impact of diuresis on the clearance of radiotracer from the renal pelvis. A, Axial image from contrast-enhanced computed tomography (CT) demonstrates an accessory right renal artery coursing anterior to the IVC. When fused, the condition is described as crossed fused ectopia. The presence of significant renal parenchyma may justify surgical repair to maximize the functional contribution of that kidney. Computed Tomographic Appearance of the Kidneys, Utility of Different Phases of Renal Contrast Enhancement. The region where the renal pelvis joins the ureter is called the ureteropelvic junction (UPJ). 18-8). Table 18-5 summarizes a checklist approach to the ultrasound examination. It protects your kidneys from injury, increases their stability and connects your kidneys to surrounding tissues. Duplication of the urinary tract is discussed in detail in Chapter 19. aware of such a vessel, the urologist may choose to perform an alternate procedure to avoid hemorrhagic complications. Although each kidney is about the size of a fist, the approximately one million nephrons per kidney require nearly 20% of the total cardiac output to perform this multitude of functions. Note that retroaortic components are usually near the inferior poles (Fig. Arterial stenosis was confirmed by magnetic resonance angiography. Note that the left renal vein receives blood from the left suprarenal and left testicular veins. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. Imaging must provide detailed images of the renal parenchyma and a survey of arterial, venous, and ureteral anatomy. Learning a quickmnemonic'VAD' can help you remember these structures (renal Vein, renal Artery, Duct a.k.a ureter). This layer sits posteriorly and posterolaterally to each kidney and separates it from the muscles of the abdominal wall. Copyright Each end of the kidney is commonly called a pole. Note origin of inferior accessories near inferior poles on each side. The defect proved to be blood clot from papillary necrosis. B, The lesion becomes more conspicuous during the nephrographic phase. BOX 18-2 Crossing Vessels in Ureteropelvic Junction Obstruction. Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. 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 (Table 18-2). Figure 25.1.2 Left Kidney. The kidneys serve important . 18-9). The dynamics of obstruction and quantification of relative renal function between the two kidneys may be important considerations in two general circumstances: (1) it is unclear whether obstruction is severe enough to warrant surgical intervention; or (2) significant parenchymal atrophy exists, and the relative merits of repair and nephrectomy are being compared. This kidney measured 14 cm in length. Learning anatomy is a massive undertaking, and we're here to help you pass with flying colours. However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. 18-3). These are chronic processes that lead to a loss of renal cortex gradually and uniformly. Overview. 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. Figure 18-2 Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. Causes. It's not clear what causes simple kidney cysts. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. 18-22). Figure 18-25 Sagittal ultrasound image of the left kidney demonstrates a unilateral small, smooth, echogenic kidney in a patient with renal artery stenosis. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. The small portion of the lumen surrounding the papilla is called the calyx. An increased amount of hydrogen ions can acidify the blood and cause a state called acidosis. Read More Created for people with ongoing healthcare needs but benefits everyone. The kidney is a very important organ in regards to body homeostasis. 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. 18-25). 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. This article will discuss the anatomy and major functions of the kidney. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. 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. Each kidney has a single renal vein which conducts the blood out of the kidney and is positioned anterior to the artery. The center of the minor concavity is marked as the hilum of the kidney where the renal artery enters the kidney, and the renal vein and ureter leave the kidney. Calcifications and renal calculi are notoriously poorly demonstrated with MRI. On ultrasound, the renal cortex is usually echogenic in this setting. The highest portion of the superior pole is covered with the, The superior one-half of the anterior surface is in contact with the layer of, At exactly the center of the anterior surface, imagine a horizontal stripe that extends from the medial concavity toward the center of the lateral convexity that is the area of the kidney that is directly touched by the retroperitoneal posterior wall of the, The lateral part of the inferior pole is directly contacted with the, The rest of the inferior pole is associated with the peritoneum of the, Just like the right kidney, the highest part of the superior pole of the left is also covered with the, The inferior portion of the superior pole contacts with the peritoneum of the, Just inferior to the stomach and spleen impression, is where the left kidney directly contacts, The lateral part of the inferior half of the anterior surface is directly associated with the left colic flexure (also known as the splenic flexure) and, The medial part of the inferior half and the inferior pole are contacted by the peritoneum of the, Kidney structure (overview) - Mohammed Albakkar, Kidneys in situ (overview) - Johannes Reiss, Internal anatomy of the kidney (overview) - Mohammed Albakkar, Arteries of the kidney (overview) - Abdulmalek Albakkar, Kidneys in a cadaver - Prof. Carlos Surez-Quian. Reading time: 23 minutes. The superior half of each kidney is covered by the diaphragm, which is why the kidneys move up and down during respiration. 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. Illustration demonstrating basic intrarenal arterial anatomy. Several formulas are available for this calculation, and calculators and on-line sites are available to simplify the calculations. I would honestly say that Kenhub cut my study time in half. For most of the students, the nephron is a mystical complexed structure that may be hard to understand. In most cases, the kidneys are situated with the inferior poles slightly more lateral and anterior than the superior poles. Clinical significance [ edit] Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. . The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). Table 18-1 Imaging the Living Renal Donor. Other common kidney conditions are acquired through life, and one of the most common is nephrolithiasis (kidney stones). Identify abnormal course of main or accessory right renal artery anterior rather than posterior to inferior vena cava (Fig. Illustration demonstrating the anatomy of the renal collecting system. The uniform high attenuation of the nephrographic phase provides an optimal background for detecting small, low-attenuation lesions in the renal parenchyma (Fig. 2023 They are usually characterized as "simple" cysts, meaning they have a thin wall and contain water-like fluid. BOX 18-1 Cockroft and Gault Equation for Calculating Estimated Creatinine Clearance. 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. The nephrons within the cortex comprise some of the most highly perfused parenchymal tissue in the body. 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. Renal cysts are sacs of fluid that form in the kidneys. Figure 18-10 Crossed ectopia on intravenous pyelogram. The upper poles are normally oriented more medially and posteriorly than the lower poles. chronic obstruction, or severe or repeated urinary infections. Radiologists divide the kidney into three parts: the upper pole, lower pole, and the interpole (whi. In other cases, each renal unit has its own ureter. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. Imaging must provide detailed images of interpolar region of kidney anatomy students, the renal cortex gradually uniformly... 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