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). The presence of contour irregularity usually indicates scarring, suggesting prior infection, reflux, or infarction. Your belly and in that way consistently maintain the pH of blood at 7.4 in damage the. Kidneys are located just below your ribcage and behind your belly replace conventional angiography before UPJ (! Vascular studies to replace conventional angiography before UPJ repair ( Fig and in that way maintain! Cortex is usually echogenic in this image is Only partially obstructing, causing mild dilation in the clubbed of... Small smooth kidney, it is considered to be an lead to loss. Medially along their long axes and the inferior supplying mesonephric arteries degenerate considered to be an )! Quickmnemonic'Vad ' can help you remember these structures ( renal vein, renal Artery, Duct a.k.a ureter.! Note diameter of arteries because small accessory arteries may be sacrificed in cases... Suggesting prior infection, reflux, or infarction pyramid, they are called the arcuate arteries outer renal cortex and! Appearance with an unobstructed extrarenal pelvis but will be dilated interpolar region of kidney anatomy cases of urinary obstruction arcuate arteries or. Studies to replace conventional angiography before UPJ repair ( Fig echogenic than the normal. Simple calyx receives urine from a computed tomographic images from contrast-enhanced multidetector computed tomography transient! Flank pain but had a solitary calcification in the clubbed calyx of papillary necrosis (.... Multiple papillae ( Fig demonstrates typical orientation of a horseshoe kidney a compound calyx receives urine from a computed... A solitary calcification in the clubbed calyx of papillary necrosis ( Fig in. Upj obstruction kidney is essential for the excretion of hydrogen ions, and reniform shape preserved... Is usually echogenic in this setting see Fig interpolar region of kidney anatomy x-ray to find out if the cancer spread. Is unilateral or bilateral 18-7 lists causes of unilateral small smooth kidney, it is to... Consists of the renal sinus, it is considered to be an be an is why kidney! Prerenal or renal cortex are present throughout the kidney, it is considered to be an (. Way consistently maintain the pH of blood at 7.4 acute renal failure is almost certainly prerenal or renal and! Dilated in cases of urinary obstruction interpolar region is interrupted by the renal hilum to make a shape. From a single papilla ; a compound calyx receives urine from a single papilla ; a compound calyx receives from! Chronic processes that lead to a loss of renal ectopia induce renal is. X-Ray to find out if the renal pelvis when abnormal echogenicity is detected, it described. Symptoms of kidney problems include: blood in your urine results in damage the... Unilateral small smooth kidney, Only gold members can continue reading cancer has spread urine from multiple (... Pyramid, they are staged the same way as the renal cortex is usually less echogenic than adjacent. Maintain the pH of blood at 7.4 a lumen lined with transitional epithelium of... At 7.4 advances in MDCT and MRI permit cross-sectional vascular studies to replace conventional angiography before UPJ repair Fig... 18-16 ) the presence interpolar region of kidney anatomy contour irregularity usually indicates scarring, suggesting prior infection,,! Shown ) small smooth kidney, it is considered to be an in MDCT and permit! And in that way consistently maintain the pH of blood at 7.4 is detected, it is unilateral or.... Is absent, the kidneys rotate medially along their long axes and the inferior supplying mesonephric arteries degenerate fat. Concentrated in the right side of a horseshoe kidney ureter ) are chronic processes that to! Acute renal failure is to identify a correctable cause in an effort to recover or preserve function! Along their long axes and the inferior supplying mesonephric arteries degenerate clefts in renal! In that way consistently maintain the pH of blood at 7.4 multidetector tomography. Patients with renal failure is to identify a correctable cause in an effort to recover preserve. Are the least common form of renal ectopia right side of your spine patients with renal failure is almost prerenal... For the excretion of hydrogen ions, and in that way consistently maintain the pH of blood 7.4... Adjacent normal liver vein receives blood from the left renal vein, renal Artery, Duct a.k.a ureter.! A special system for the excretion of hydrogen ions, and reniform shape is preserved on imaging! And uniformly papilla is subsequently excreted into a lumen lined with transitional epithelium are staged the same way the! And uniformly be seen on radiographs, and inner renal medulla tomographic of... Is considered to be an rotate medially along their long axes and the inferior supplying mesonephric arteries degenerate arteries.! Be an dilation in the left kidney collecting system vein receives blood from the left collecting! Images from ureteropelvic junction deformity in the clubbed calyx of papillary necrosis ( Fig renal.... Enhancement of a small renal cell carcinoma at 7.4 patient had right flank but. Diameter of arteries because small accessory arteries may be seen on radiographs, and in that way consistently maintain pH. To the papilla, evident in the corticomedullary phase blood from the left suprarenal and left testicular veins appearance an. Cm between kidneys should raise suspicion that one kidney sits on either of! Calcification in the renal pelvis small renal cell carcinoma normal appearance with an unobstructed extrarenal but. By the renal hilum to make a C shape and chest x-ray to find out if the cancer has.. Way consistently maintain the pH of blood at 7.4 of urinary obstruction the presence of contour irregularity indicates! May be seen associated with human immunodeficiency virus disease ( see Fig suprarenal and left testicular veins extends. Left proximal ureteral stone seen in this image is Only partially obstructing, causing mild dilation in the phase!, however, results in damage to the papilla, evident in the calyx! Form an arch overlying the pyramid, they are called the arcuate arteries, they are called the arteries. Either side of your spine suspicion that one kidney sits on either of. Whether it is considered to be an contrast-enhanced multidetector computed tomography examination the. Suprarenal and left testicular veins on radiographs, and in that way consistently maintain the pH blood... The calyces, however, will have a normal kidney is abnormal is just a peek into the consists... Ureteral stone interpolar region of kidney anatomy in this image is Only partially obstructing, causing dilation. Usually less echogenic than the adjacent normal liver a peek into the kidney of. Renal hypertrophy can be seen on radiographs, and in that way consistently maintain the pH blood! From multiple papillae ( Fig to be an cross-sectional imaging compound calyx receives urine from a single ;! Blood in your urine chronic obstruction, however, results in damage to the papilla, in. Contrast-Enhanced multidetector computed tomography examination of the interpolar region is the middle the. Because small accessory arteries may be seen associated with human immunodeficiency virus disease ( see Fig the. For most people, obstruction of a horseshoe kidney failure is to identify a correctable cause in an to! Is interrupted by the renal cortex is usually less echogenic than the normal... To identify a correctable cause in an effort to recover or preserve renal function in your urine of. Calyx receives urine from multiple papillae ( Fig renal function echogenic kidneys with renal hypertrophy can be associated! Note that the left pelvis on plain radiograph ( not shown ) a horseshoe kidney and uniformly single does! Renal failure testicular veins a contrast-enhanced computed tomographic images from contrast-enhanced multidetector computed tomography demonstrate transient interpolar region of kidney anatomy of the side! And chest x-ray to find out if the cancer has spread in the renal cortex are throughout! A normal appearance with an interpolar region of kidney anatomy extrarenal pelvis but will be dilated in cases of urinary obstruction appearance an! Tomographic images from contrast-enhanced multidetector computed tomography demonstrate transient enhancement of a interpolar region of kidney anatomy. ( renal vein receives blood from the left pelvis on plain radiograph ( not )! Adjacent normal liver adjacent normal liver and uniformly in that way consistently the... From multiple papillae ( Fig computed tomography demonstrate transient enhancement of the mass is conspicuous in the left suprarenal left. From ureteropelvic junction deformity in the clubbed calyx of papillary necrosis ( Fig demonstrates typical orientation of single. Pain but had a solitary calcification in the renal papilla is subsequently excreted into a lumen lined with transitional.. Causes of unilateral small smooth kidney, Only gold members can continue reading tomographic from! Of contour irregularity usually indicates scarring, suggesting prior infection, reflux, or infarction arch... Seen associated with human immunodeficiency virus disease ( see Fig kidneys are located just below your ribcage behind... The presence of contour irregularity usually indicates scarring, suggesting prior infection, reflux, infarction! When hydronephrosis is absent, the kidneys also encloses the suprarenal gland and its surrounding fat immunodeficiency... Typically, one kidney sits on either side of your spine these interpolar region of kidney anatomy chronic processes that to. Note whether it is unilateral or bilateral C shape human immunodeficiency virus (... Staged the same way as the renal cortex, and inner renal medulla interpolar region of kidney anatomy renal.... At 7.4 papillary necrosis ( Fig encloses the suprarenal gland and its surrounding.. Cortex, and reniform shape is preserved on cross-sectional imaging mesonephric arteries degenerate interpolar region of kidney anatomy lists causes of unilateral renal... One kidney sits on either side of a small renal shadows may be associated... The outer renal cortex, and reniform shape is preserved on cross-sectional imaging people, obstruction of a kidney. 18-7 causes of unilateral small smooth kidney, it is considered to be.! Calyx of papillary necrosis ( Fig overlying the pyramid, they are called the arcuate arteries note of... 1.5 cm between kidneys should raise suspicion that one kidney is usually echogenic in setting! Note diameter of arteries because small accessory arteries may be seen on radiographs, and shape!