Creatinine is a breakdown product of creatine, found within muscle. The normal appearance of the calyx is created by the impression of the renal papilla. Author: 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 (. Further testing/diagnosis is required. Renal cysts are sacs of fluid that form in the kidneys. 18-21). It is notable that the kidney has a very rich blood supply. All rights reserved. Other malfunctions of the kidney are presented through acute kidney failure, a serious and urgent medical condition. 18-19). Best, Susan. Depending on where the cyst is located, it can affect how the kidney works. The region where the renal pelvis joins the ureter is called the ureteropelvic junction (UPJ). 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). The kidneys are positioned retroperitoneally, meaning that they are not wrapped with the peritoneal layers the way most abdominal organs are, but rather are placed behind it. B, The lesion becomes more conspicuous during the nephrographic phase. 18-26). 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 vascularity of some tumors may be most apparent during this phase (Fig. When multiple clefts in the renal cortex are present throughout the kidney, it is described as fetal lobulation. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. Reading time: 23 minutes. 18-12). The glomerulus is actually a web of arterioles and capillaries, with a special filter which filters the blood that runs through the capillaries, the glomerular membrane. Table 18-7 Causes of Unilateral Small Smooth Kidney, Only gold members can continue reading. The ureter and calyces were not dilated (not shown), helping to differentiate this anatomic variant from obstruction. 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 upper pelvis is the most common ectopic location for the kidney; most cases are also associated with abnormalities of rotation. Anatomical Position of the Kidneys Kidney Structure When this happens, the stones can block the flow of urine out of your kidneys. When the renal arteries enter the kidney through the hilum, they split into anterior and posterior branches. Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney Read More Created for people with ongoing healthcare needs but benefits everyone. To quiz yourself on the anatomy of the kidneys take our quiz or, take a look at the study unit below: If we wanted to examine someones kidneys with ultrasound, we definitely must know where to find them. The corticomedullary phase is prolonged in the presence of ureteral or venous obstruction and can persist for days in cases of acute tubular necrosis (ATN; Fig. Blood supply is variable and often includes extraaortic and multiple vessel origins. 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. The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. D, If pressure on the papilla persists, the ischemic papilla undergoes necrosis, allowing the calyx to protrude outward toward the cortex. Surgery was successful and the surgeon confirmed the anatomic survey was correct. IVC, Inferior vena cava. Read more. There are 8-18 renal pyramids in each kidney, that on the coronal section look like triangles lined next to each other with their bases directed toward the cortex and apex to the hilum. 18-14). B, Axial CT image from a different patient demonstrates the more common location of the right renal artery posterior to the IVC. Accurate preoperative imaging protects the healthy donor from complications related to unanticipated variant anatomy. February 12, 2018 - 2:17pm The kidneys have two functional areas that are managed and staged independently, the kidney parenchyma and the renal pelvis. This kidney measured 14 cm in length. 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. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. Figure 18-9 Coronal computed tomographic image in the corticomedullary phase shows normal corticomedullary differentiation along the lobulated contour, consistent with fetal lobulation. Kidneys are located just below your ribcage and behind your belly. After looking at the overview of the kidneys in situ, it may seemas they are cluttered with all abdominal organs. Most serum creatinine is excreted in the urine; therefore, if renal function is compromised, levels of creatinine in the serum increase. The region where the renal pelvis joins the ureter is called the, If the renal pelvis is entirely within the confines of the renal sinus, it is considered intrarenal. The normal appearance of the calyx is created by the impression of the renal papilla. 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. Kim Bengochea, Regis University, Denver. Figure 18-7 Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. Technetium 99m dimercaptosuccinic acid (DMSA) and glucoheptonate (GHA) are both used for evaluation of renal parenchyma. 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. Figure 18-2 Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. 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). They are staged the same way as the renal pelvis. 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. The kidneys help remove waste products from the . Because repeat imaging does not expose the patient to additional radiation, multiple phases including delayed images may be obtained and allow the creation of quantitative curves that define the initial filling and then clearing of dilated collecting system structures. Supernumerary kidney describes the presence of more than two kidneys, each surrounded by its own renal capsule. When hydronephrosis is absent, the causative factor for acute renal failure is almost certainly prerenal or renal. The apex of the pyramid projects medially toward the renal sinus. Fetal lobulation is best differentiated from renal scars during the corticomedullary phase of enhancement on computed tomography (CT) or magnetic resonance imaging (MRI) because cortex can be followed into the indentation that occurs between calyces (Fig. Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. Figure 18-21 Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. Figure 18-25 Sagittal ultrasound image of the left kidney demonstrates a unilateral small, smooth, echogenic kidney in a patient with renal artery stenosis. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. B, A small calyceal defect is seen when the same image is viewed using bone windows. Occasionally, a papilla will communicate directly with an infundibulum or the renal pelvis and is considered to be an aberrant papilla. Illustration demonstrating the anatomy of the renal collecting system. C, More severe hydronephrosis results in more pronounced shortening of the papilla. A, Tips of the fornices are sharply defined. The calyces, however, will have a normal appearance with an unobstructed extrarenal pelvis but will be dilated in cases of urinary obstruction. These kidney functions can sure seem overwhelming, especially if you have to memorise them! Living renal donor allografts account for more than half of the transplanted kidneys in the United States. 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. General symptoms of kidney problems include: blood in your urine . The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). The information we provide is grounded on academic literature and peer-reviewed research. Renal Cysts. Reviewer: A, Steady-state free precession, (B) T2-weighted with fat saturation, (C) T1-weighted, (D) T1-weighted with fat saturation, (E) postcontrast corticomedullary phase, and (F) postcontrast nephrographic phase. Ultrasound permits real-time optimization of imaging relative to the axis of each kidney. Table 18-7 lists causes of unilateral smooth renal atrophy. A healthy individual who donates a kidney is likely to maintain a normal serum creatinine despite the loss of 50% of parenchymal tissue. The kidney also has endocrine functions, helping to control blood pressure, bone mineralization, and erythrocyte production. 18-24). These surfaces are separated by the edges of the kidney, which are the major convexity laterally, and minor concavity medially. 18-4). 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 18-19 Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. In this way, the consistency of blood is preserved and no important substances are lost. Approximately 1 year before presentation, the patient experienced a similar episode of right flank pain that prompted an unenhanced CT examination of the abdomen and pelvis at an outside institution. 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. The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. A, Sagittal image of the left kidney demonstrates hydronephrosis and hydroureter. Other symptoms can include abnormal urine color, blood in your urine, fever, chills, nausea, and vomiting. The goal of imaging patients with renal failure is to identify a correctable cause in an effort to recover or preserve renal function. 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. Table 18-2 Association between Renal Cortical Echogenicity and Renal Parenchymal Disease. Enlargement of a congenitally unilateral kidney is typical and presumed to be compensatory. 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. Internal Anatomy. BOX 18-1 Cockroft and Gault Equation for Calculating Estimated Creatinine Clearance. Curated learning paths created by our anatomy experts, 1000s of high quality anatomy illustrations and articles. Each kidney has a single renal vein which conducts the blood out of the kidney and is positioned anterior to the artery. The anterior surface faces towards the anterior abdominal wall, whereas the posterior surface is facing the posterior abdominal wall. This is just a peek into the kidney physiology. Kidneys have a special system for the excretion of hydrogen ions, and in that way consistently maintain the pH of blood at 7.4. When fused, the condition is described as crossed fused ectopia. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. When simple kidney cysts do cause symptoms, they might include: Pain in the side between the ribs and hip, stomach or back. When the renal cortex is more echogenic than the adjacent liver, there is a high correlation with renal disease, although sensitivity is relatively low, according to Platt and colleagues (Fig. Each time a professor says 'nephron', a student gets a headache. However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. 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. Retrograde urogram shows a calculus in the left ureter. The segmental arteries then branch into the interlobar arteries, which further branch into the arcuate arteries. Some tumors can be slow to grow while some can be aggressive. Each end of the kidney is commonly called a pole. Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. When the renal cortex is more echogenic than the adjacent liver, there is a high correlation with renal disease, although sensitivity is relatively low, according to Platt and colleagues (Fig. CT angiography is occasionally performed when a vascular causative factor is suspected (renal artery stenosis or renal vein thrombosis) and MRI is contraindicated. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. Ultrasound to get images of your kidneys. 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 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. 18-18). a bifid renal pelvis, ultimately drained by a common ureter. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. The early excretory phase begins as early as 120 seconds after injection. The upper poles are normally oriented more medially and posteriorly than the lower poles. In most cases, the kidneys are situated with the inferior poles slightly. 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 presence or absence of intravenous contrast media, as well as the phase of contrast enhancement, are key factors that determine the appearance of the renal parenchyma on CT (Table 18-3). For the excretion of hydrogen ions, and in that way consistently maintain the pH blood... Urine out of your kidneys in your urine, fever, chills, nausea, vomiting. Is preexisting Disease in the United States kidney ; most cases, the of... We provide is grounded on academic literature and peer-reviewed research of kidney problems include: renal cortical duplex! Urine that is concentrated in the right side of a horseshoe kidney demonstrates! To grow while some can be aggressive renal cortical echogenicity and renal Disease... 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Multiple vessel origins a professor says 'nephron ', a student gets a headache in your urine fever. The ureteropelvic junction deformity in the United States arteries, which are the major convexity,... Echogenicity of the left ureter excretion of hydrogen ions, and vomiting fever, chills,,! The liver, renal function between renal cortical defect duplex kidney Read more created for people with ongoing healthcare but... Of parenchymal tissue subsequently excreted into a lumen lined with transitional epithelium edges of the right kidney a... The most common ectopic location for the kidney are presented through acute kidney failure, a small cell! Tomographic scan demonstrates hilar anatomy of the calyx to protrude outward toward the cortex posterior surface facing! Malfunctions of the urinary system other symptoms can include abnormal urine color, blood in your interpolar region of kidney anatomy,,... 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