interpolar region of kidney anatomy
Figure 18-8 Junctional cortical line seen on a long-axis ultrasound image of the right kidney. In most cases, the kidneys are situated with the inferior poles slightly more lateral and anterior than the superior poles. Radiologists divide the kidney into three parts: the upper pole, lower pole, and the interpole (whi. Parasympathetic innervation enhances the peristalsis while sympathetic innervation inhibits it. This refers to the forming of the stones within the system of calyces because of too much calcium or uric acid into the filtrate. 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. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. Note number of veins by inspecting inferior vena cava along entire length of kidney. Kidney cysts can occur with disorders that may impair kidney function. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Entities for which sonography is most useful. It is also permeable for the products of the metabolism, such are creatinine and drug metabolites. RENAL ANATOMY Renal Parenchyma The kidneys can be divided into three main regions from cranial to caudal. Increasing pressure within the lumen initially distends the fornices (acutely angled portions of the calyx along the sides of the papillae), whereas the central portion of the papillary impression is preserved. When this happens, the stones can block the flow of urine out of your kidneys. Right-sided pain was related to crossed renal ectopia. A bean-like structure like the kidney has two borders: medial and lateral. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. February 12, 2018 - 2:17pm The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption. 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. Overview. (Courtesy of Karl T. Rew, MD) Introduction Synonyms Epidemiology More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. 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. The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. 18-14). urinary system quizzes and labeled diagrams. This can cause varicocele of the left testicle because gravity works against the column of the blood in the left testicular vein. Each nephron contains a renal corpuscle, which is the initial component that filters the blood, and a renal tubule that processes and carries the filtered fluid to the system of calyces. Radiologists divide the kidney into three parts: the upper pole, lower pole, and the interpole (which is in between them). The shape of the calyx is formed by the impression of the renal papilla. Supernumerary kidneys are quite rare and have been associated with aortic coarctation, vaginal atresia, and urethral duplications. Living renal donor allografts account for more than half of the transplanted kidneys in the United States. The region where the renal pelvis joins the ureter is called the ureteropelvic junction (UPJ). * Entities for which sonography is most useful. Renal scintigraphy can be performed with a variety of agents to provide assessment of either function or structure of the kidneys. 18-19). Anatomy of the Kidney and Ureter Parenchyma Cortex Medulla Perirenal fat Capsule Ureter Because the interlobular arteries form an arch overlying the pyramid, they are called the. Maintaining kidney health. The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. The left kidney measured 7.8 cm, and the right kidney measured 10.9 cm. 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. Figure 18-27 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). Hypotension is a stimulus for the kidneys to increase the retention of fluid and thus increase blood pressure. Each pyramid creates urine and terminates into a renal papilla. AMLs can bleed and while not cancerous are still taken very seriously. The medial border of the kidney contains a very important landmark called the hilum of the kidney, which is the entry and exit point for the kidney vessels and ureter. The information we provide is grounded on academic literature and peer-reviewed research. The renal veins empty to the inferior vena cava, so the right vein is shorter because the inferior vena cava runs closer to the right kidney. The left kidney (not shown) had a similar appearance. In other cases, each renal unit has its own ureter. 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. The right kidney has a normal appearance (not shown). Hydronephrosis is important to detect, because obstructive uropathy is often reversible if identified early. 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 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. The interpolar region is the middle of the kidney. The most common indication for cortical scintigraphy is to evaluate kidneys that have been injured by vesicoureteral reflux, chronic obstruction, or severe or repeated urinary infections. 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. On the other hand, babies with bilateral agenesis cannot survive without an immediate kidney transplant. 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. 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. Figure 18-9 Coronal computed tomographic image in the corticomedullary phase shows normal corticomedullary differentiation along the lobulated contour, consistent with fetal lobulation. 18-7). B, The lesion becomes more conspicuous during the nephrographic phase. The renal corpuscle has two components: the glomerular (Bowmans) capsule in which sits the glomerulus. Ultrasound is usually used in the initial evaluation of the patient with newly diagnosed renal failure. Made aware of such a vessel, the urologist may choose to perform an alternate procedure to avoid hemorrhagic complications. The small portion of the lumen surrounding the papilla is called the. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. Reading time: 23 minutes. Box 18-2 provides some tips regarding crossing vessels in UPJ obstruction. Renal size can be measured in several ways. 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. Renal size and cortical thickness can be assessed in a manner similar to ultrasound. Illustration demonstrating the anatomy of the renal collecting system. They extend from lumbar vertebra T12-L3. In cases of unilateral obstruction with acute renal failure, sonographic evaluation may show evidence of chronic renal parenchymal disease in the unobstructed kidney. These are chronic processes that lead to a loss of renal cortex gradually and uniformly. The uniform high attenuation of the nephrographic phase provides an optimal background for detecting small, low-attenuation lesions in the renal parenchyma (Fig. Kidney stones are most often treated by ultrasound shock therapy, during which high-frequency radio waves break the stone into smaller pieces that can be passed naturally into the urine. Relation between the right renal artery and the inferior vena cava (IVC). 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. More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. It participates in vital processes such as regulation of blood osmolarity and pH, regulation of blood volume and blood pressure, production of hormones, and filtration of foreign substances. Further testing/diagnosis is required. Learn more about the nephron in the following study unit or take our custom quiz to see what you know already: Each kidney is supplied by a single renal artery, which is a direct lateral branch of the abdominal aorta. Kim Bengochea, Regis University, Denver. 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. Renal scintigraphy can be performed with a variety of agents to provide assessment of either function or structure of the kidneys. Advantages of scintigraphy include accurate quantitative measurement of function and parenchymal mass without the risks for nephrotoxicity associated with iodinated contrast media or nephrogenic systemic fibrosis associated with gadolinium contrast agents. This is why the kidney is essential for the circulatory hemostasis. Figure 18-5 Illustration demonstrating the anatomy of the renal collecting system. and parenchymal mass without the risks for nephrotoxicity associated with iodinated contrast media or nephrogenic systemic fibrosis associated with gadolinium contrast agents. A, A low-attenuation lesion is difficult to identify during the corticomedullary phase. 18-23). Calcifications and renal calculi are notoriously poorly demonstrated with MRI. The superior poles (extremities) (T12) of both kidneys are more medially pointed towards the spine than the inferior poles (extremities) (L3). Checklist Approach to Ultrasound for Renal Failure, Absence of hydronephrosis makes postrenal causes unlikely, Cortical atrophy in one or both kidneys: suspect chronic or acute-on-chronic renal failure, Increased cortical echogenicity is associated with many forms of chronic renal parenchymal disease and indicates a renal cause for renal failure. B, Transverse image of the bladder demonstrates a large bladder tumor in the region of the trigone. Now lets pay attention to the borders of the kidneys. Just remember ' A WET BED', which stands for: The kidneys have their anterior and posterior surfaces. 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. D, If pressure on the papilla persists, the ischemic papilla undergoes necrosis, allowing the calyx to protrude outward toward the cortex. Of course, if the situation is the other way around (less than 5 liters of blood), blood pressure is too low (hypotension). 18-11). This causes them to fire impulses which stimulate rhythmical contraction and relaxation, called peristalsis. These terminal branches have no collateral circulation. The fused kidneys can have a variety of orientations, including side by side, in-line, or perpendicular. Creatinine is a breakdown product of creatine, found within muscle. It protects your kidneys from injury, increases their stability and connects your kidneys to surrounding tissues. Because the interlobular arteries form an arch overlying the pyramid, they are called the arcuate arteries. Table 18-7 lists causes of unilateral smooth renal atrophy. 18-24). When the fine, weblike complex of ureteral arteries is recruited to contribute to collateral circulation, enlarged vessels are seen surrounding the proximal ureter, causing the classic ureteral notching seen on intravenous urogram (IVU). I would honestly say that Kenhub cut my study time in half. Figure 18-4 Illustration demonstrating the relation between the renal papilla and calyx. IVC, Inferior vena cava. The isthmus connecting the kidneys is variable, ranging from normal renal cortex to a thin fibrous band. The relation between the UPJ and vascular anatomy can be quite complex. Increased cortical echogenicity is associated with many forms of chronic renal parenchymal disease and indicates a renal cause for 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. Kidneys have a special system for the excretion of hydrogen ions, and in that way consistently maintain the pH of blood at 7.4. But more often, kidney cysts are a type called simple kidney cysts. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. 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. CT and MR findings of renal artery stenosis parallel classic findings described on intravenous pyelogram, including one atrophic kidney with delayed nephrogram and excretion that can progress to a persistent nephrogram with hyperconcentrated excreted contrast media (Fig. B, A small calyceal defect is seen when the same image is viewed using bone windows. 18-6). 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. Technetium 99m dimercaptosuccinic acid (DMSA) and glucoheptonate (GHA) are both used for evaluation of renal parenchyma. Eliminating toxic metabolites through urine, regulation of blood homeostasis and blood pressure, production of some hormones, Positioned retroperitoneally, consists of the cortex and medulla, empties urine into the ureter (which carries urine to the urinary bladder), Renal artery (branch of the abdominal aorta), Renal vein (drains to the inferior vena cava), Third kidney, horseshoe kidney, kidney agenesis, kidney stones, acute kidney failure, Regulates the amount of fluid in the body by increasing or decreasing the urine production, Maintain the pH of blood at 7.4 by decreasing or increasing the excretion of hydrogen ions, Medial part of the lower half of superior pole, Lateral part of the lower half of superior pole, Lateral part of inferior half of anterior surface, Medial part of inferior half of anterior surface, The perinephric fat (perirenal fat capsule). 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