Luckily, the kidneys also feel this increase of pressure, and in cases when this happens, they increase the filtration rate of blood and production of urine, which subsequently leads to the increase fluid excretion and decrease of blood pressure. These terminal branches have no collateral circulation. Bone scan and chest x-ray to find out if the cancer has spread. Publication types Review MeSH terms Humans On the other hand, babies with bilateral agenesis cannot survive without an immediate kidney transplant. Best, Susan. However, T1-weighted images provide good corticomedullary differentiation. Because the fascia of the retroperitoneum prevents significant extravasation, the incision usually heals to form a larger lumen. Although this dilatation of the renal pelvis may occasionally mimic hydronephrosis, delicate and sharply defined calyces and thin infundibula can be used to differentiate an extrarenal pelvis from obstruction. The left kidney appeared unremarkable. Created for people with ongoing healthcare needs but benefits everyone. Sometimes, one or both kidneys fail to develop, which causes unilateral or bilateral renal agenesis. Note distance from origin to the first arterial division (Fig. Log In or, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), Estimated Creatinine Clearance and Glomerular Filtration Rate, Cockroft and Gault Equation for Calculating Estimated Creatinine Clearance, The Modification of Diet in Renal Disease (MDRD) is another method for estimating renal function that yields a value often called, The kidneys can be divided into three main regions from cranial to caudal. The upper pelvis is the most common ectopic location for the kidney; most cases are also associated with abnormalities of rotation. Figure 18-15 Relation between the right renal artery and the inferior vena cava (IVC). These surfaces are separated by the edges of the kidney, which are the major convexity laterally, and minor concavity medially. The normal appearance of the calyx is created by the impression of the renal papilla. Several formulas are available for this calculation, and calculators and on-line sites are available to simplify the calculations. The right kidney has a normal appearance (not shown). 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). Now lets pay attention to the borders of the kidneys. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Because production of creatinine is affected by sex, age, muscle mass, protein intake, and liver function, the serum creatinine can be an inaccurate predictor of renal function, particularly in those at the extremes of age and body weight. The defect proved to be blood clot from papillary necrosis. Other methods include classical surgical removal of the stone, either through the ureter or by open surgery. Reviewer: Figure 18-24 Normal magnetic resonance imaging appearance of the kidneys. However, this individual is more likely to show a decline in renal function from an additional insult. It is important to remember this order of vessels and ducts since this is the only thing that will make you able to orient the kidney and differentiate the left one from the right when they are outside of the cadaver. 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. The posterior branch supplies the posterior part of the kidney, whereas the anterior branch arborizes into five segmental arteries, each supplying a different renal segment. This causes them to fire impulses which stimulate rhythmical contraction and relaxation, called peristalsis. The apex of the pyramid projects medially toward the renal sinus. The superior poles (extremities) (T12) of both kidneys are more medially pointed towards the spine than the inferior poles (extremities) (L3). The renal pelvis then tapers like a funnel to join the ureter. Some of them are congenital, such as a third kidney, which is usually atrophic. 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. 18-10). Hypotension is a stimulus for the kidneys to increase the retention of fluid and thus increase blood pressure. In this way, the consistency of blood is preserved and no important substances are lost. The most common cause is renal artery stenosis (see Fig. The kidney tissue is protected by three layers that entirely surround the kidney: Outside the fascia is the most superficial layer a layer of fat tissue called the paranephric fat. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). 18-5). AMLs can bleed and while not cancerous are still taken very seriously. 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. 18-19). 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. Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. Figure 18-12 Axial sections of the right kidney from contrast-enhanced computed tomography demonstrate a bar of renal parenchyma separating renal hila in the superior and inferior poles, consistent with duplication. The vessel which brings blood into the glomerulus is the afferent arteriole, whereas the vessel that carries the rest of the blood out that hasnt been filtered out of the glomerulus is called the efferent arteriole. Some divide the excretory phase into the early excretory phase (contrast mainly confined to the kidney) and late excretory phase (contrast in the ureters). Figure 18-5 Illustration demonstrating the anatomy of the renal collecting system. Read more. A, Axial image from contrast-enhanced computed tomography (CT) demonstrates an accessory right renal artery coursing anterior to the IVC. 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. The renal cortex and medulla both have high signal intensity on T2-weighted images resulting in poor corticomedullary differentiation. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. The Modification of Diet in Renal Disease (MDRD) is another method for estimating renal function that yields a value often called estimated glomerular filtration rate (eGFR). 18-21). Arterial stenosis was confirmed by magnetic resonance angiography. The axes of the renal moeities are abnormal with the inferior poles angled medially. They are usually characterized as "simple" cysts, meaning they have a thin wall and contain water-like fluid. This is called the nutcracker phenomenon. The interpolar region is the middle of the kidney. 18-11). . In most kidneys, the renal hilum faces more anteromedial in the upper half of the kidney and more directly medial in the lower half. Kim Bengochea, Regis University, Denver. Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. Axial images of the left kidney from a three-phase renal computed tomographic scan demonstrate improved conspicuity of low-attenuation lesions of the renal medulla during the nephrographic phase. One of the most commonly used (and least complicated) equations is shown in Box 18-1. Thoracic kidneys are the least common form of renal ectopia. Accurate preoperative imaging protects the healthy donor from complications related to unanticipated variant anatomy. Each kidney should always be evaluated in long axis (coronal, sagittal, or both, depending on sonographic window) and axial to the kidney. For most people, obstruction of a single ureter does not induce renal failure. The medulla consists of multiple pyramidal tissue masses, called the renal pyramids, which are triangle structures that contain a dense network of nephrons. Normal parenchymal enhancement on CT or MRI allows definitive characterization. More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. Crossed ectopia can be either fused or unfused. This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. Identify abnormal course of main or accessory right renal artery anterior rather than posterior to inferior vena cava (Fig. 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. However, you may have symptoms related to the condition that's causing it. Poorly functioning kidneys with little residual parenchymal volume may be removed because preservation offers opportunities for future complications (infection, hypertension) without contributing significantly to renal function. Look for retroaortic or circumaortic left renal vein. Literature supports the use of either multidetector computed tomography (MDCT) or MRI in donor evaluation. 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 (. Illustration demonstrating the relation between the renal papilla and calyx. Axial sections of the right kidney from contrast-enhanced computed tomography demonstrate a bar of renal parenchyma separating renal hila in the superior and inferior poles, consistent with duplication. 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. Because the interlobular arteries form an arch overlying the pyramid, they are called the arcuate arteries. Bilateral echogenic kidneys with renal hypertrophy can be seen associated with human immunodeficiency virus disease (see. The kidneys help remove waste products from the . Reading time: 23 minutes. The anterior surface faces towards the anterior abdominal wall, whereas the posterior surface is facing the posterior abdominal wall. The renal fascia which besides the kidneys also encloses the suprarenal gland and its surrounding fat. If the renal pelvis extends out of the renal sinus, it is considered to be an extrarenal pelvis (Fig. When both kidneys are on the same side crossed ectopia is present, because the ureter from one kidney must cross the midline to insert into the bladder (Fig. Pancake kidney describes a more severe fusion anomaly with a single, flat kidney positioned low in the pelvis with an anterior collecting system drained by either one or two ureters. Renal size and cortical thickness can be assessed in a manner similar to ultrasound. The initiation is caused by the increase in volume that stretches the walls of the calyces. Because the fascia of the retroperitoneum prevents significant extravasation, the incision usually heals to form a larger lumen. Extraaortic origin of the renal arteries and accessory renal arteries are common. Figure 18-17 Coronal maximum intensity projection image from a contrast-enhanced computed tomographic scan demonstrates a dilated and tortuous lumbar veins joining the left renal vein. The portion of the kidney between the poles is called the interpolar region and contains the renal hilum (Fig. Copyright The large left proximal ureteral stone seen in this image is only partially obstructing, causing mild dilation in the left kidney collecting system. The pyramids are separated by extensions of the cortex called the renal columns. All content published on Kenhub is reviewed by medical and anatomy experts. Table 18-5 Checklist Approach to Ultrasound for Renal Failure. 18-4). 18-27). Figure 18-21 Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. The kidneys are highly vascular (contain a lot of blood vessels) and are divided into three main regions: the renal cortex (outer region which contains about 1.25 million renal tubules), renal medulla (middle region which acts as a collecting chamber), and renal pelvis (inner region which receives urine through the major calyces). A, Axial image demonstrates the dilated renal pelvis and crossing vessel. 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 left renal vein passes anteriorly to the aorta just below the trunk of the superior mesenteric artery, which is risky because it can be compressed by one of those two. This kidney measured 14 cm in length. The kidneys are located between the transverse processes of T12-L3 vertebrae, with the left kidney typically positioned slightly more superiorly than the right. Table 18-1 provides a quick guide itemizing key imaging findings in the potential renal donor. The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. They are branches of the abdominal aorta and all together are called the extrahilar renal arteries. Extraaortic origin of the renal arteries and accessory renal arteries are common. They extend from lumbar vertebra T12-L3. More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. Bilateral echogenic kidneys with renal hypertrophy can be seen associated with human immunodeficiency virus disease (see Fig. aware of such a vessel, the urologist may choose to perform an alternate procedure to avoid hemorrhagic complications. Many clinical laboratories now provide computer-generated calculations of estimated creatinine clearance or eGFR using patient data in the medical information system. The right kidney has a normal appearance (not shown). It's not clear what causes simple kidney cysts. Axial image of the left kidney obtained in the excretory phase of a computed tomographic urogram demonstrates the effects of window settings on visualizing structures near excreted contrast. RENAL ANATOMY Renal Parenchyma The kidneys can be divided into three main regions from cranial to caudal. B, A curved planar reformation of the crossing vein demonstrates its course. At the Brady Urological Institute, we believe in the adage, "An ounce of prevention is worth a pound of cure," so we place great emphasis on a thorough metabolic evaluation, so that therapies can be appropriately directed towards reducing the risk of recurrent stone disease. Usually, there are two to three major calyces in the kidney (superior, middle, and inferior), which again unite to form the renal pelvis from which the ureter emerges and leaves the kidney through the hilum. Cells in our body constantly produce hydrogen ions. Always include unenhanced computed tomographic images to look for renal stones. B, A small calyceal defect is seen when the same image is viewed using bone windows. Right-sided pain was related to crossed renal ectopia. urinary system quizzes and labeled diagrams. The vascularity of some tumors may be most apparent during this phase (Fig. Made aware of such a vessel, the urologist may choose to perform an alternate procedure to avoid hemorrhagic complications. Table 18-7 lists causes of unilateral smooth renal atrophy. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. This significantly affects the testicle, since an obstruction of drainage causes an obstruction of fresh arterial blood inflow, which can result in the infarction of testicular tissue. The anteromedial aspect of the interpolar region is interrupted by the renal hilum to make a C shape. The visible contrast seen in the excretory phase has been concentrated many-fold. If the renal pelvis is entirely within the confines of the renal sinus, it is considered intrarenal. Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Note that the left renal vein receives blood from the left suprarenal and left testicular veins. 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. 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