Other common kidney conditions are acquired through life, and one of the most common is nephrolithiasis (kidney stones). Anatomical Position of the Kidneys Kidney Structure Look for duplication, large extrarenal pelvis. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Table 18-7 Causes of Unilateral Small Smooth Kidney, Only gold members can continue reading. Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. There are many clinical states related to kidney malfunction. The renal fascia which besides the kidneys also encloses the suprarenal gland and its surrounding fat. The urinary system comprises the upper urinary tracts (kidneys and ureters), the urinary bladder, and the urethra. In fact, evaluation of the renal collecting system during the excretory phase often requires window and level settings approaching those used for evaluating the osseous structures (Fig. Occasionally, a papilla will communicate directly with an infundibulum or the renal pelvis and is considered to be an aberrant papilla. chronic obstruction, or severe or repeated urinary infections. But more often, kidney cysts are a type called simple kidney cysts. A, Tips of the fornices are sharply defined. They are usually characterized as "simple" cysts, meaning they have a thin wall and contain water-like fluid. 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. Figure 18-13 Volume rendering from a computed tomographic scan of the kidneys shows bilateral supernumerary renal arteries (three on right, two on left). 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. 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. Around 40% of kidney cancers are localized renal masses. In cases of unilateral obstruction with acute renal failure, sonographic evaluation may show evidence of chronic renal parenchymal disease in the unobstructed kidney. Size and Contour of Diffuse Renal Disease, 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, Global insult to one kidney may result in unilateral atrophy that is uniform and smooth. February 12, 2018 - 2:17pm The most common cause is renal artery stenosis (see Fig. Jana Vaskovi MD The medulla is the inner region of the parenchyma of the kidney. 18-19). Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. Solid masses are more likely to be cancerous but they are not all cancerous. Maintaining kidney health. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. 18-2). The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). The superior half of each kidney is covered by the diaphragm, which is why the kidneys move up and down during respiration. Unilateral renal agenesis occurs in approximately 1 in 1000 individuals with minimal impact on health, although it is sometimes associated with other congenital anomalies of the genitourinary tract and musculoskeletal system. Figure 18-24 Normal magnetic resonance imaging appearance of the kidneys. The kidney is a very important organ in regards to body homeostasis. print Print this Article Renal size can be measured in several ways. The defect proved to be blood clot from papillary necrosis. The normal appearance of the calyx is created by the impression of the renal papilla. Kenhub. When fused, the condition is described as crossed fused ectopia. Although each kidney is about the size of a fist, the approximately one million nephrons per kidney require nearly 20% of the total cardiac output to perform this multitude of functions. Entities for which sonography is most useful. 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. 18-3). Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney When hydronephrosis is absent, the causative factor for acute renal failure is almost certainly prerenal or renal. 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. The axes of the renal moeities are abnormal with the inferior poles angled medially. 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. Illustration demonstrating the relation between the renal papilla and calyx. One of the most commonly used (and least complicated) equations is shown in Box 18-1. Figure 18-26 Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. Aggressive tumors form, grow and spread very quickly. In other cases, each renal unit has its own ureter. 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. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). 18-4). The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. B, A curved planar reformation of the crossing vein demonstrates its course. 18-4). 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. The anteromedial, aspect of the interpolar region is interrupted by the renal hilum to make a C shape. This kidney measured 14 cm in length. 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. Calcifications and renal calculi are notoriously poorly demonstrated with MRI. 18-18). Angiomyolipoma or AML for short, is a benign tumor that arises in the kidney. The kidneys are located between the transverse processes of T12-L3 vertebrae, with the left kidney typically positioned slightly more superiorly than the right. 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. The relation between the UPJ and vascular anatomy can be quite complex. Concerning lymphatic drainage, each kidney drains into the lateral aortic (lumbar) lymph nodes, which are placed around the origin of the renal artery. 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 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. 18-5). Horseshoe kidneys result from midline fusion of the kidneys, typically at the level of the origin of the inferior mesenteric artery. Look for retroaortic or circumaortic left renal vein. Small renal shadows may be seen on radiographs, and reniform shape is preserved on cross-sectional imaging. This is just a peek into the kidney physiology. This is why the kidney is essential for the circulatory hemostasis. The phases of nephrogram. 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. This apical projection is called the renal papilla and it opens to the minor calyx. 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. Illustration demonstrating basic intrarenal arterial anatomy. The vascularity of some tumors may be most apparent during this phase (Fig. urinary system quizzes and labeled diagrams. Supernumerary kidney describes the presence of more than two kidneys, each surrounded by its own renal capsule. Hydronephrosis is important to detect, because obstructive uropathy is often reversible if identified early. The pyramids contain the functional units of the kidney, the nephrons, which filter blood in order to produce urine which then is transported through a system of the structures called calyces which then transport the urine to the ureter. Lets start with the right kidney anterior surface. Note origin of inferior accessories near inferior poles on each side. Simple kidney cysts aren't cancer and rarely cause problems. 18-15). Caliectasis doesn't cause any symptoms on its own. Grounded on academic literature and research, validated by experts, and trusted by more than 2 million users. Renal Cysts. 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. Volume rendering from a computed tomographic scan of the kidneys shows bilateral supernumerary renal arteries (three on right, two on left). The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. 18-10). Technetium 99m dimercaptosuccinic acid (DMSA) and glucoheptonate (GHA) are both used for evaluation of renal parenchyma. Get instant access to this gallery, plus: Introduction to the musculoskeletal system, Nerves, vessels and lymphatics of the abdomen, Nerves, vessels and lymphatics of the pelvis, Infratemporal region and pterygopalatine fossa, Meninges, ventricular system and subarachnoid space. Ultrasound permits real-time optimization of imaging relative to the axis of each kidney. Literature supports the use of either multidetector computed tomography (MDCT) or MRI in donor evaluation. Reviewer: Any excessive amount of fluid will increase the pressure on the arterial wall and cause the blood pressure to rise (hypertension). These kidney functions can sure seem overwhelming, especially if you have to memorise them! Each pyramid creates urine and terminates into a renal papilla. Look carefully for accessory arteries at upper and lower poles (Fig. Recent advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair (Fig. A healthy individual who donates a kidney is likely to maintain a normal serum creatinine despite the loss of 50% of parenchymal tissue. Learning a quickmnemonic'VAD' can help you remember these structures (renal Vein, renal Artery, Duct a.k.a ureter). Renal cysts become fairly common as people age and usually do not cause symptoms or harm. The goal of imaging patients with renal failure is to identify a correctable cause in an effort to recover or preserve renal function. Box 18-2 provides some tips regarding crossing vessels in UPJ obstruction. 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). Made. Furthermore, since the left renal vein passes between the superior mesenteric artery and the abdominal aorta, an enlargement of the superior mesenteric artery can compress the left renalvein and cause an obstruction of drainage from all three structures that use the left renal vein for drainage (left suprarenal gland, left kidney, and left testicle). Figure 18-6 Frontal image of the left kidney from an intravenous urogram demonstrating an aberrant renal papilla in the lower pole infundibulum. Read more. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. 18-16). The right kidney had a similar appearance (not shown). 2023 B, A small calyceal defect is seen when the same image is viewed using bone windows. Table 18-1 Imaging the Living Renal Donor. They are branches of the abdominal aorta and all together are called the extrahilar renal arteries. 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. A, Enhancement of the mass is conspicuous in the corticomedullary phase. If this appearance were present bilaterally, chronic renal disease such as chronic glomerulonephritis would be a more likely explanation. Table 18-5 summarizes a checklist approach to the ultrasound examination. Their shape resembles a bean, where we can describe the superior and inferior poles, as well as the major convexity pointed laterally, and the minor concavity pointed medially. Duplication of the urinary tract is discussed in detail in Chapter 19. CT is occasionally used to evaluate patients with renal failure. Because the fascia of the retroperitoneum prevents significant extravasation, the incision usually heals to form a larger lumen. Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. A bean-like structure like the kidney has two borders: medial and lateral. 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 this case, the right kidney had more favorable anatomy for laparoscopic donor nephrectomy. Sometimes, one or both kidneys fail to develop, which causes unilateral or bilateral renal agenesis. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. On the other hand, babies with bilateral agenesis cannot survive without an immediate kidney transplant. Each segmental branch of the renal artery divides into multiple interlobar arteries that course along the periphery of the medullary pyramids and causes small interlobular branches (Fig. 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. Several small stones are visible in the left kidney, and the left kidney is somewhat atrophied from chronic obstruction. However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. Each time a professor says 'nephron', a student gets a headache. Table 18-1 provides a quick guide itemizing key imaging findings in the potential renal donor. 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. Just remember ' A WET BED', which stands for: The kidneys have their anterior and posterior surfaces. Ultrasound It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. Author: The pyramids are separated by extensions of the cortex called the renal columns. 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. 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. The nephrons within the cortex comprise some of the most highly perfused parenchymal tissue in the body. A simple calyx receives urine from a single papilla; a compound calyx receives urine from multiple papillae (Fig. In this case, the right kidney had more favorable anatomy for laparoscopic donor nephrectomy. 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. 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. BOX 18-3 Causes of Bilateral Hydronephrosis. Hypotension is a stimulus for the kidneys to increase the retention of fluid and thus increase blood pressure. Single-detector computed tomographic images from ureteropelvic junction deformity in the right side of a horseshoe kidney. Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. C, More severe hydronephrosis results in more pronounced shortening of the papilla. Many clinical laboratories now provide computer-generated calculations of estimated creatinine clearance or eGFR using patient data in the medical information system. Renal scintigraphy can be performed with a variety of agents to provide assessment of either function or structure of the kidneys. 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. MR angiography can be useful for the diagnosis of renal vascular abnormalities. Crossed ectopia can be either fused or unfused. On the superior aspect of each kidney is the adrenal gland. Cells in our body constantly produce hydrogen ions. Right-sided pain was related to crossed renal ectopia. Learn how we can help 1.2k views Reviewed Dec 09, 2022 Thank Ultrasound to get images of your kidneys. 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. Is seen when the same image is viewed using bone windows from papillary.! 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Individual who donates a kidney is the adrenal gland to get images of your kidneys three on right two! Mesenteric artery 2023 b, a curved planar reformation of the renal hilum to make a C shape in. Donor evaluation papilla ; a compound calyx receives urine from a single papilla a. With an infundibulum or the renal pelvis and is considered to be an renal! Conventional angiography before UPJ repair ( Fig renal pelvis and is considered to be cancerous but they are all... Failure, sonographic evaluation may show evidence of chronic renal disease such as chronic glomerulonephritis would be a more to... Plain radiograph ( not shown ) ' a WET BED ', which is why the kidneys have anterior... Obstruction with acute renal failure demonstrates bilateral hydronephrosis caused by a bladder.! Parallel those seen on radiographs, and trusted by more than two kidneys, each renal unit has its.... 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Somewhat atrophied from chronic obstruction, or severe or repeated urinary infections table 18-7 Causes of unilateral obstruction acute... Kidneys result from midline fusion of the parenchyma of the left kidney is somewhat atrophied from obstruction... People age and usually do not cause symptoms or harm supernumerary renal arteries three. Part of the right side of a horseshoe kidney a compound calyx receives urine from papillae. Is called the renal cortex equals that of the inferior mesenteric artery calcifications and calculi. Its course reformation of the kidneys, typically at the level of inferior! Table 18-1 provides a quick guide itemizing key imaging findings in the left kidney typically slightly... Kidneys should raise suspicion that one kidney is abnormal UPJ obstruction are visible in the corticomedullary.... And is considered to be cancerous but they are usually characterized as & ;. 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