This plexus provides input from: The sensory nerves from the kidney travel to the spinal cord at the levels T10-T11, which is why the pain in the flank region always rises suspicions that something is wrong with the corresponding kidney. Look for duplication, large extrarenal pelvis. Most serum creatinine is excreted in the urine; therefore, if renal function is compromised, levels of creatinine in the serum increase. D, If pressure on the papilla persists, the ischemic papilla undergoes necrosis, allowing the calyx to protrude outward toward the cortex. Anatomical Position of the Kidneys Kidney Structure Read more. BOX 18-2 Crossing Vessels in Ureteropelvic Junction Obstruction. The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. Overview. Internal Anatomy. 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. 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). The small portion of the lumen surrounding the papilla is called the. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. The segmental arteries then branch into the interlobar arteries, which further branch into the arcuate arteries. 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. A frontal section through the kidney reveals an outer region called the renal cortex and an inner region called the renal medulla (Figure 25.1.2). Weve mentioned that the most important functions of the kidney are the regulation of the blood homeostasis and blood pressure, so acute kidney failure can lead to a quick fall of blood pressure which presents as a state of shock. This method is the standard in evaluation of UPJ obstruction and often is used for other types of chronic obstruction. 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. The initiation is caused by the increase in volume that stretches the walls of the calyces. In this case, the right kidney had more favorable anatomy for laparoscopic donor nephrectomy. Diagnostic ultrasound uses sound wave technology to look at parts of your body, including: Brain Heart and blood vessels Breast Abdominal Organs Eyes Thyroid Skin and muscles Types of Ultrasound. "Angio" indicates blood vessels, "myo" indicates muscle, and "lipoma" indicates fat. Table 18-3 Utility of Different Phases of Renal Contrast Enhancement. The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption. This apical projection is called the renal papilla and it opens to the minor calyx. 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). Some of them are congenital, such as a third kidney, which is usually atrophic. Ultrasound It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. Read more. 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. 18-8). Jana Vaskovi MD 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 apex of the pyramid projects medially toward the renal sinus. Kenhub. 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 interpolar region is the middle of the kidney. 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. 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). Sometimes, one or both kidneys fail to develop, which causes unilateral or bilateral renal agenesis. The kidneys are innervated by the renal plexus. If the renal pelvis extends out of the renal sinus, it is considered to be an extrarenal pelvis (Fig. This kidney measured 14 cm in length. Since they are located deep retroperitoneally, the easiest way to examine them is from the patients back. 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). Finally, the arcuate arteries branch into the interlobular arteries which branch off even further by giving afferent arterioles to run blood past the glomerulus for blood filtration. 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 (Fig. Several calyces drain into each infundibulum, an elongated transition from the polygonal calyces to the saclike renal pelvis. Dialysis. 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. 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. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. 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). Illustration demonstrating the anatomy of the renal collecting system. It is also permeable for the products of the metabolism, such are creatinine and drug metabolites. 18-12). The left kidney (not shown) had a similar appearance. 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. 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. Parasympathetic innervation enhances the peristalsis while sympathetic innervation inhibits it. Retrograde urogram shows a calculus in the left ureter. Table 18-2 Association between Renal Cortical Echogenicity and Renal Parenchymal Disease. The information we provide is grounded on academic literature and peer-reviewed research. The vascularity of some tumors may be most apparent during this phase (Fig. Always include unenhanced computed tomographic images to look for renal stones. Use of MR contrast agents in renal failure poses a lower risk than iodinated contrast material for exacerbating renal failure, but there is evidence that gadolinium-based MR contrast media pose some risk for systemic complications (nephrogenic systemic fibrosis) and should be used with caution in patients with severe or acute renal insufficiency. Let's see what is nephron and how it is structured,so you can remember it for good. Radiologists divide the kidney into three parts: the upper pole, lower pole, and the interpole (which is in between them). Cells in our body constantly produce hydrogen ions. Small renal shadows may be seen on radiographs, and reniform shape is preserved on cross-sectional imaging. Figure 18-18 Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. 18-25). 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. 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. 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. It protects your kidneys from injury, increases their stability and connects your kidneys to surrounding tissues. Causes. The kidneys play a central role in homeostasis. Made. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. 18-14). 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. However, T1-weighted images provide good corticomedullary differentiation. Duplication of the urinary tract is discussed in detail in Chapter 19. 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. In this region, the anterior and posterior. Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Because they rarely cause symptoms, renal cysts are most often found during . 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. Several small stones are visible in the left kidney, and the left kidney is somewhat atrophied from chronic obstruction. Curated learning paths created by our anatomy experts, 1000s of high quality anatomy illustrations and articles. 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 most superior vessel is the renal vein which exits the kidney, just under it is the renal artery that enters in, and under the artery is the exiting ureter. Table 18-5 summarizes a checklist approach to the ultrasound examination. Renal size can be measured in several ways. The shape of the calyx is formed by the impression of the renal papilla. The superior poles (extremities) (T12) of both kidneys are more medially pointed towards the spine than the inferior poles (extremities) (L3). Due to the segmental vascular supply of the kidney it is often feasible to ligate the relative arteries and veins and remove the tumour with a safe zone of healthy surrounding parenchyma ( partial nephrectomy) without removing the entire kidney or compromising its total vascular supply by ischaemia. Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (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. When fused, the condition is described as crossed fused ectopia. There is no specific treatment for fused kidneys and the only option is to treat the pathologies that affect them during life. 2023 The normal appearance of the calyx is created by the impression of the renal papilla. 18-25). General symptoms of kidney problems include: blood in your urine . 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. B, A small calyceal defect is seen when the same image is viewed using bone windows. The right kidney has a normal appearance (not shown). The interpolar region is the middle of the kidney. 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. Because the interlobular arteries form an arch overlying the pyramid, they are called the. Figure 18-26 Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. Other malfunctions of the kidney are presented through acute kidney failure, a serious and urgent medical condition. 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. 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. For most of the students, the nephron is a mystical complexed structure that may be hard to understand. Publication types Review MeSH terms Humans 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. Association between Renal Cortical Echogenicity and Renal Parenchymal Disease. The presence of significant renal parenchyma may justify surgical repair to maximize the functional contribution of that kidney. The lateral border is directed towards the periphery, while the medial border is the one directed towards the midline. Figure 25.1.2 Left Kidney. Coronal maximum intensity projection image from a contrast-enhanced computed tomographic scan demonstrates a dilated and tortuous lumbar veins joining the left renal vein. Table 18-7 Causes of Unilateral Small Smooth Kidney, Only gold members can continue reading. Serum creatinine, however, is dependent not only on its disposal but also its production. 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. In some cases, two separate kidneys drain into a bifid renal pelvis, ultimately drained by a common ureter. When hydronephrosis is absent, the causative factor for acute renal failure is almost certainly prerenal or renal. In order to understand the functions of the kidney, we must first learn its anatomy. Just remember ' A WET BED', which stands for: The kidneys have their anterior and posterior surfaces. 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. Most diagnosed kidney growths are small and localized masses. Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. Concerning lymphatic drainage, each kidney drains into the lateral aortic (lumbar) lymph nodes, which are placed around the origin of the renal artery. MR angiography can be useful for the diagnosis of renal vascular abnormalities. impression is preserved. Each kidney should always be evaluated in long axis (coronal, sagittal, or both, depending on sonographic window) and axial to the kidney. This causes them to fire impulses which stimulate rhythmical contraction and relaxation, called peristalsis. 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. Note number of veins by inspecting inferior vena cava along entire length of kidney. Table 18-6 lists the most common causes of bilateral smooth renal atrophy. Three-dimensional volume rendering from contrast-enhanced multidetector computed tomography examination of the kidneys demonstrates typical orientation of a horseshoe kidney. This can cause varicocele of the left testicle because gravity works against the column of the blood in the left testicular vein. Ultrasound can often identify the cause in cases of bilateral obstruction (Fig. 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. Renal scintigraphy can be performed with a variety of agents to provide assessment of either function or structure of the kidneys. The isthmus connecting the kidneys is variable, ranging from normal renal cortex to a thin fibrous band. 3D printed model for a 53-year-old female presenting a 21 15 15 mm renal tumor located in the interpolar region of left kidney, treated by left partial nephrectomy. and grab your free ultimate anatomy study guide! B, Mild hydronephrosis results in rounding of the fornices with mild shortening of the papillary impression. The small portion of the lumen surrounding the papilla is called the calyx. This is why the kidney is essential for the circulatory hemostasis. Supernumerary kidney describes the presence of more than two kidneys, each surrounded by its own renal capsule. The uniform high attenuation of the nephrographic phase provides an optimal background for detecting small, low-attenuation lesions in the renal parenchyma (Fig. 18-1). Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. 18-13). Note that there is no contrast in the aorta. Figure 18-2 Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. 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. Several calyces drain into a bifid renal pelvis while the medial border is directed towards the midline isthmus... 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