interpolar region of kidney anatomy

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. 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. Note that the left renal vein receives blood from the left suprarenal and left testicular veins. 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 (. 18-25). Box 18-2 provides some tips regarding crossing vessels in UPJ obstruction. This is why the kidney is essential for the circulatory hemostasis. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. The goal of imaging patients with renal failure is to identify a correctable cause in an effort to recover or preserve renal function. If the renal pelvis extends out of the renal sinus, it is considered to be an. They are staged the same way as the renal pelvis. General symptoms of kidney problems include: blood in your urine . Table 18-7 lists causes of unilateral smooth renal atrophy. Radiologists divide the kidney into three parts: the upper pole, lower pole, and the interpole (which is in between them). Kidneys have a special system for the excretion of hydrogen ions, and in that way consistently maintain the pH of blood at 7.4. Thoracic kidneys are the least common form of renal ectopia. Figure 18-18 Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. 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. This is just a peek into the kidney physiology. When hydronephrosis is absent, the causative factor for acute renal failure is almost certainly prerenal or renal. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. If a kidney stone becomes lodged in the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm, which can be very painful. 18-24). The superior poles (extremities) (T12) of both kidneys are more medially pointed towards the spine than the inferior poles (extremities) (L3). The kidneys help remove waste products from the . Three-dimensional volume rendering from contrast-enhanced multidetector computed tomography examination of the kidneys demonstrates typical orientation of a horseshoe kidney. When multiple clefts in the renal cortex are present throughout the kidney, it is described as fetal lobulation. 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). While migrating superiorly, the kidneys rotate medially along their long axes and the inferior supplying mesonephric arteries degenerate. Some divide the excretory phase into the early excretory phase (contrast mainly confined to the kidney) and late excretory phase (contrast in the ureters). 18-19). Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. 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. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). The MDRD calculation is more complicated than calculating creatinine clearance (taking into account body surface area, sex, and race) but is thought to be more accurate than estimated creatinine clearance, particularly among the elderly and obese. The interpolar region is the middle of the kidney. 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. Note diameter of arteries because small accessory arteries may be sacrificed in many cases. Anatomical Position of the Kidneys Kidney Structure 18-16). Learning a quickmnemonic'VAD' can help you remember these structures (renal Vein, renal Artery, Duct a.k.a ureter). Best, Susan. Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. On ultrasound, the renal cortex is usually echogenic in this setting. 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 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. 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. A simple calyx receives urine from a single papilla; a compound calyx receives urine from multiple papillae (Fig. Figure 18-21 Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. Figure 18-10 Crossed ectopia on intravenous pyelogram. Because the interlobular arteries form an arch overlying the pyramid, they are called the arcuate arteries. CT angiography is occasionally performed when a vascular causative factor is suspected (renal artery stenosis or renal vein thrombosis) and MRI is contraindicated. BOX 18-3 Causes of Bilateral Hydronephrosis. 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. The calyces, however, will have a normal appearance with an unobstructed extrarenal pelvis but will be dilated in cases of urinary obstruction. Despite different methods of accumulation, each is sequestered by the renal cortex, providing an opportunity to quantify the volume of renal parenchymal tissue in each kidney. 18-24). Small renal shadows may be seen on radiographs, and reniform shape is preserved on cross-sectional imaging. IVC, Inferior vena cava. The renal fascia which besides the kidneys also encloses the suprarenal gland and its surrounding fat. Bilateral echogenic kidneys with renal hypertrophy can be seen associated with human immunodeficiency virus disease (see Fig. A, Enhancement of the mass is conspicuous in the corticomedullary phase. 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. 18-2). 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. 18-3). 18-1). 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. Bone scan and chest x-ray to find out if the cancer has spread. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. 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. Table 18-7 Causes of Unilateral Small Smooth Kidney, Only gold members can continue reading. The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. The glomerular membrane is designed in a way in which it is not permeable for big and important molecules in blood, such as plasma proteins, but it is permeable to the smaller substances such as sodium, potassium, amino acids and many others. Technetium 99m-mercaptoacetyltriglycin (MAG3) is excreted by the kidneys (mainly through secretion by proximal tubules) and provides evaluation of renal function, particularly in cases of suspected obstruction. 18-27). This kidney measured 14 cm in length. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. However, T1-weighted images provide good corticomedullary differentiation. Because of this, the tubules are designed in a way that they reabsorb the necessary substances, (sodium, potassium, and amino acids as mentioned before) and carries them back to the blood; whereas they do not absorb but rather secrete unnecessary substances such as creatinine and drug metabolites for excretion from the body. The genital system consists of the testes, epididymides, deferent ducts, seminal vesicles, ejaculatory ducts, the prostate, and the penis in males; and the ovaries, uterine tubes, uterus, and vagina in females. Table 18-6 Causes of Bilateral Small Smooth Kidneys. The large left proximal ureteral stone seen in this image is only partially obstructing, causing mild dilation in the left kidney collecting system. Kidneys are located just below your ribcage and behind your belly. For most people, obstruction of a single ureter does not induce renal failure. Typically, one kidney sits on either side of your spine. The kidneys are innervated by the renal plexus. These are chronic processes that lead to a loss of renal cortex gradually and uniformly. 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 anteromedial aspect of the interpolar region is interrupted by the renal hilum to make a C shape. Volume rendering from a computed tomographic scan of the kidneys shows bilateral supernumerary renal arteries (three on right, two on left). 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