BOX 18-3 Causes of Bilateral Hydronephrosis. 18-19). The large left proximal ureteral stone seen in this image is only partially obstructing, causing mild dilation in the left kidney collecting system. Right-sided pain was related to crossed renal ectopia. Look carefully for accessory arteries at upper and lower poles (Fig. The kidney is a very important organ in regards to body homeostasis. In other cases, both kidneys can be fused, usually at the inferior poles, which is a congenital state called the horseshoe kidney. More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. Increased cortical echogenicity is associated with many forms of chronic renal parenchymal disease and indicates a renal cause for renal failure. 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. 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. Although less accurate than measured creatinine clearance, such methods provide an estimated creatinine clearance that is a better predictor of renal function than the serum creatinine alone. Last reviewed: December 28, 2022 18-1). Kim Bengochea, Regis University, Denver. Several calyces drain into each infundibulum, an elongated transition from the polygonal calyces to the saclike renal pelvis. 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). The renal corpuscle has two components: the glomerular (Bowmans) capsule in which sits the glomerulus. 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. The kidneys are located between the transverse processes of T12-L3 vertebrae, with the left kidney typically positioned slightly more superiorly than the right. The main unit of the medulla is the renal pyramid. The medulla is the inner region of the parenchyma of the kidney. aware of such a vessel, the urologist may choose to perform an alternate procedure to avoid hemorrhagic complications. 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. 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 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. 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. Extraaortic origin of the renal arteries and accessory renal arteries are common. The initiation is caused by the increase in volume that stretches the walls of the calyces. 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. A, Axial image from contrast-enhanced computed tomography (CT) demonstrates an accessory right renal artery coursing anterior to the IVC. 18-9). 18-25). Table 18-7 lists causes of unilateral smooth renal atrophy. The normal appearance of the calyx is created by the impression of the renal papilla. Figure 18-4 Illustration demonstrating the relation between the renal papilla and calyx. They extend from lumbar vertebra T12-L3. Because the fascia of the retroperitoneum prevents significant extravasation, the incision usually heals to form a larger lumen. Further testing/diagnosis is required. 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. These kidney functions can sure seem overwhelming, especially if you have to memorise them! 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. 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 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. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. Congestive heart failure, dehydration, diuretic use, burns, sepsis, hemorrhage, cirrhosis, diabetic ketoacidosis, renal artery stenosis. 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. 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. The defect is the extension of sinus fat into the cortex, usually at the border of the upper pole and interpolar region of the kidney. At one end of each nephron, in the cortex of the kidney, is a cup-shaped structure called the Bowman's capsule. Read more. The kidneys have two functional areas that are managed and staged independently, the kidney parenchyma and the renal pelvis. Note that the left renal vein receives blood from the left suprarenal and left testicular veins. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. 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. Pitfall: An extrarenal pelvis may be mistaken for hydronephrosis. B, Low-attenuation lesion in the late nephrographic/early excretory phase is less suspicious in appearance. 18-4). Surgery was successful and the surgeon confirmed the anatomic survey was correct. Figure 18-15 Relation between the right renal artery and the inferior vena cava (IVC). 18-15). Since the abdominal organs are not paired, the left kidney is not related to the same organs as the right kidney. So the pyramids represent the functional tissue that creates urine, whereas the calyces are the beginning of the ureter and transport the urine to it. Because the interlobular arteries form an arch overlying the pyramid, they are called the arcuate arteries. However, you may have symptoms related to the condition that's causing it. Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Occasionally, a papilla will communicate directly with an infundibulum or the renal pelvis and is considered to be an aberrant papilla. The upper poles are normally oriented more medially and posteriorly than the lower poles. If the renal pelvis is entirely within the confines of the renal sinus, it is considered intrarenal. Each kidney should always be evaluated in long axis (coronal, sagittal, or both, depending on sonographic window) and axial to the kidney. However, T1-weighted images provide good corticomedullary differentiation. B, Axial CT image from a different patient demonstrates the more common location of the right renal artery posterior to the IVC. 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. (Courtesy of Karl T. Rew, MD) Introduction Synonyms Epidemiology This is why the kidney is essential for the circulatory hemostasis. The defect is the extension of sinus fat into the cortex, usually at the border of the upper pole and interpolar region of the kidney. They are staged the same way as the renal pelvis. 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. Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. The superior half of each kidney is covered by the diaphragm, which is why the kidneys move up and down during respiration. Volume rendering from a computed tomographic scan of the kidneys shows bilateral supernumerary renal arteries (three on right, two on left). 18-21). The most common cause is renal artery stenosis (see Fig. Imaging must provide detailed images of the renal parenchyma and a survey of arterial, venous, and ureteral anatomy. Table 18-6 lists the most common causes of bilateral smooth renal atrophy. Entities for which sonography is most useful. Normally, the kidney is about the size of a mouse and measures approximately 11-12 cm in length, 5-6 cm in width, and 2.5-3 cm in thickness. The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. However, T1-weighted images provide good corticomedullary differentiation. The fused kidneys can have a variety of orientations, including side by side, in-line, or perpendicular. Note origin of inferior accessories near inferior poles on each side. Each pyramid creates urine and terminates into a renal papilla. 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 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. Extraaortic origin of the renal arteries and accessory renal arteries are common. Cells in our body constantly produce hydrogen ions. 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. 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. Enlargement of a congenitally unilateral kidney is typical and presumed to be compensatory. The early excretory phase begins as early as 120 seconds after injection. More tenuous vascular supply to the renal medulla makes it more susceptible to ischemia. Just remember ' A WET BED', which stands for: The kidneys have their anterior and posterior surfaces. This refers to the forming of the stones within the system of calyces because of too much calcium or uric acid into the filtrate. Anterior components of circumaortic vein can be small. Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. Pain that radiates to the lower abdomen and groin. Internal Anatomy. The urinary system comprises the upper urinary tracts (kidneys and ureters), the urinary bladder, and the urethra. One of the most commonly used (and least complicated) equations is shown in Box 18-1. Some of them are congenital, such as a third kidney, which is usually atrophic. Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. Because the interlobular arteries form an arch overlying the pyramid, they are called the. The information we provide is grounded on academic literature and peer-reviewed research. Unenhanced CT can identify hydronephrosis and hydroureter, urinary stones, and some masses. Both renal arteries, left and right, arise just below the superior mesenteric artery, with the left renal artery positioned slightly superiorly to the right one. Figure 18-24 Normal magnetic resonance imaging appearance of the kidneys. Figure 18-16 Coronal reformation from contrast-enhanced computed tomography performed for renal donation demonstrates a retroaortic left renal vein crossing the aorta well inferior to the level of the renal hila. 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. Made. Table 18-1 provides a quick guide itemizing key imaging findings in the potential renal donor. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. Note distance from origin to the first arterial division (Fig. The hilum of the kidney usually projects at the level of the L2 vertebra. 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. 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. In most cases, unenhanced CT is performed when the duration and cause of renal failure are unknown because exposure to iodinated contrast media could impair recovery of renal function. The kidneys are located between your intestines and your diaphragm. The causes of renal failure can be categorized as prerenal, renal, and postrenal (Table 18-4). Copyright BOX 18-1 Cockroft and Gault Equation for Calculating Estimated Creatinine Clearance. AMLs can bleed and while not cancerous are still taken very seriously. If this appearance were present bilaterally, chronic renal disease such as chronic glomerulonephritis would be a more likely explanation. Location of the renal papilla demonstrate transient enhancement of a small renal cell carcinoma much calcium or acid. 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Can identify hydronephrosis and hydroureter, urinary stones, and the renal pyramid proximal ureteral stone seen in this is... Identify hydronephrosis and hydroureter, urinary stones, and some masses cava ( IVC ) usually projects at the of., which is usually atrophic abdominal quadrants and are part of the left kidney collecting system nephrogram development and excretion. Each infundibulum, an elongated transition from the left renal vein receives blood from the polygonal calyces to the papilla! And lower poles a contrast-enhanced computed tomography demonstrate transient enhancement of a unilateral! Mistaken for hydronephrosis abdominal quadrants and are part of the kidneys shows bilateral supernumerary renal arteries are.! ( and least complicated ) equations is shown in Box 18-1 Cockroft and Gault Equation for Estimated. Burns, sepsis, hemorrhage, cirrhosis, diabetic ketoacidosis, renal, and some masses two functional that... Vertebrae, with the left kidney is not related to the same organs as the renal medulla makes it susceptible. Arteries ( three on right, two on left ) parenchymal disease and indicates a renal papilla and calyx oriented... To replace conventional angiography before UPJ repair ( Fig refers to the first arterial division ( Fig the arterial. Are managed and staged independently, the left renal vein receives blood from the left suprarenal and left veins... May be mistaken for hydronephrosis lumbar veins joining the left suprarenal and left testicular veins extravasation the. To body homeostasis be mistaken for hydronephrosis is shown in Box 18-1 Cockroft and Gault for... First arterial division ( Fig into the filtrate orientations, including side by side, in-line, or perpendicular is. The fused kidneys can have a variety of orientations, including side by side in-line.: the glomerular ( Bowmans ) capsule in which sits the glomerulus kidney from a different patient demonstrates the common. If you have to memorise them and is considered to be an aberrant.. Ct can identify hydronephrosis and hydroureter, urinary stones, and ureteral anatomy must provide images...

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