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). 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. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. The medulla is the inner region of the parenchyma of the kidney. Renal artery I hope this helps. Renal size can be measured in several ways. CT is occasionally used to evaluate patients with renal failure. Unenhanced MRI can also be used to diagnose obstruction and identify the source (Fig. The left artery has a short way to the left kidney, whereas the right has to go behind the inferior vena cava in order to reach the right kidney. Although ureteral contrast media is typically present before 3 minutes, longer delays provide more predictable opacification. Occasionally, a papilla will communicate directly with an infundibulum or the renal pelvis and is considered to be an aberrant papilla. The main parts of your kidney anatomy include: Kidney capsule (renal capsule) The renal capsule consists of three layers of connective tissue or fat that cover your kidneys. When fused, the condition is described as crossed fused ectopia. 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. Now that weve mastered the borders, it will be easier to take a closer look at the anatomical relations that the kidneys share with other abdominal structures. People with unilateral agenesis often are unaware that they lack one kidney until an accidental discovery, since the one kidney that they have is able to functionally compensate for the other. 18-19). But more often, kidney cysts are a type called simple kidney cysts. When. Reviewer: The presence of significant renal parenchyma may justify surgical repair to maximize the functional contribution of that kidney. A, Sagittal image of the left kidney demonstrates hydronephrosis and hydroureter. chronic obstruction, or severe or repeated urinary infections. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. Maintaining kidney health. On the other hand, kidneys do have relations with peritoneum, or precisely with the specific organs that are covered with peritoneum which are placed directly adjacent to the kidneys. Kenhub. 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 (. 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. The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. Table 18-6 Causes of Bilateral Small Smooth Kidneys. Table 18-5 Checklist Approach to Ultrasound for Renal Failure. 18-2). If the renal pelvis is entirely within the confines of the renal sinus, it is considered intrarenal. However, T1-weighted images provide good corticomedullary differentiation. Figure 18-10 Crossed ectopia on intravenous pyelogram. On axial sections, the polar regions of the kidney typically form a closed circle or donut shape, with the hole formed by renal sinus fat. Normal magnetic resonance imaging appearance of the kidneys. This layer sits posteriorly and posterolaterally to each kidney and separates it from the muscles of the abdominal wall. The initiation is caused by the increase in volume that stretches the walls of the calyces. In fact, evaluation of the renal collecting system during the excretory phase often requires window and level settings approaching those used for evaluating the osseous structures (Fig. Best, Susan. 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. Publication types Review MeSH terms Humans Ultrasound It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. 18-4). Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. They are staged the same way as the renal pelvis. 18-24). The main symptom is severe sharp pain that starts suddenly, usually in your belly or one side of your back, and it may go away just as quickly. Extraaortic origin of the renal arteries and accessory renal arteries are common. Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. 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. The upper pelvis is the most common ectopic location for the kidney; most cases are also associated with abnormalities of rotation. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). Renal Cysts. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. Supernumerary kidneys are quite rare and have been associated with aortic coarctation, vaginal atresia, and urethral duplications. Hydronephrosis is important to detect, because obstructive uropathy is often reversible if identified early. Diabetes, hypertension, acute tubular necrosis, Increased echogenicity has high association with parenchymal disease, Acute tubular necrosis usually results in an increased RI, whereas prerenal causes usually do not have an increased RI; postrenal causes often increase the RI, but hydronephrosis should be present in those cases, If present, suspect neurogenic bladder or outlet obstruction, Often severe aortic disease or fibromuscular dysplasia. Identify abnormal course of main or accessory right renal artery anterior rather than posterior to inferior vena cava (Fig. In this case, the right kidney had more favorable anatomy for laparoscopic donor nephrectomy. Because an extrarenal pelvis is not confined by the renal parenchyma, there is a tendency for it to expand. Thoracic kidneys are the least common form of renal ectopia. When this happens, the stones can block the flow of urine out of your kidneys. Table 18-3 Utility of Different Phases of Renal Contrast Enhancement. 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. In most cases, unenhanced CT is performed when the duration and cause of renal failure are unknown because exposure to iodinated contrast media could impair recovery of renal function. Several small stones are visible in the left kidney, and the left kidney is somewhat atrophied from chronic obstruction. Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. For most people, obstruction of a single ureter does not induce renal failure. Other methods include classical surgical removal of the stone, either through the ureter or by open surgery. Each time a professor says 'nephron', a student gets a headache. 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. Figure 18-25 Sagittal ultrasound image of the left kidney demonstrates a unilateral small, smooth, echogenic kidney in a patient with renal artery stenosis. This refers to the forming of the stones within the system of calyces because of too much calcium or uric acid into the filtrate. Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney 18-25). Normal parenchymal enhancement on CT or MRI allows definitive characterization. The relation between the UPJ and vascular anatomy can be quite complex. The kidneys play a central role in homeostasis. Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. Dialysis. 18-9). Literature supports the use of either multidetector computed tomography (MDCT) or MRI in donor evaluation. The kidneys help remove waste products from the . However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. Several formulas are available for this calculation, and calculators and on-line sites are available to simplify the calculations. Furthermore, since the left renal vein passes between the superior mesenteric artery and the abdominal aorta, an enlargement of the superior mesenteric artery can compress the left renalvein and cause an obstruction of drainage from all three structures that use the left renal vein for drainage (left suprarenal gland, left kidney, and left testicle). The right kidney had a similar appearance (not shown). Further testing/diagnosis is required. After looking at the overview of the kidneys in situ, it may seemas they are cluttered with all abdominal organs. The anteromedial, aspect of the interpolar region is interrupted by the renal hilum to make a C shape. print Print this Article The stones can move into the ureter and literally get stuck there because the lumen of the ureter is much smaller compared to the calyces, which is very painful for the patient. Retrograde urogram shows a calculus in the left ureter. 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. Technetium 99m dimercaptosuccinic acid (DMSA) and glucoheptonate (GHA) are both used for evaluation of renal parenchyma. Despite the complexity of renal physiology, many attempt to assess renal function with a simple quantitative measure, the serum creatinine. 18-15). Supernumerary kidneys are quite rare and have been associated with aortic coarctation, vaginal atresia, and urethral duplications. These kidney functions can sure seem overwhelming, especially if you have to memorise them! B, Low-attenuation lesion in the late nephrographic/early excretory phase is less suspicious in appearance. Figure 18-11 Three-dimensional volume rendering from contrast-enhanced multidetector computed tomography examination of the kidneys demonstrates typical orientation of a horseshoe kidney. Created for people with ongoing healthcare needs but benefits everyone. The ureter and calyces were not dilated (not shown), helping to differentiate this anatomic variant from obstruction. The kidneys are a pair of bean-shaped organs located below the rib cage, one on each side of the spine. This kidney measured 14 cm in length. Let's see what is nephron and how it is structured,so you can remember it for good. Around 40% of kidney cancers are localized renal masses. This is just a peek into the kidney physiology. 18-7). 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