Hematuria

Kerry Weinberg and Kathryn Kuntz

Objectives

• Describe the sonographic appearance of the genitourinary system.

• List the causes of hematuria.

• Describe the sonographic appearance of urolithiasis.

• Describe the sonographic appearance of common benign neoplasms of the kidney.

• Describe the sonographic appearance of common malignant neoplasms of the kidney.

• Describe the clinical signs and symptoms and laboratory tests associated with hematuria.

CLINICAL SCENARIO

A 65-year-old man is referred for an abdominal sonogram following an episode of right upper quadrant pain. During the physical examination and interview, the patient reports that he also has painless hematuria. His physician suspects gallstones. The patient is mildly obese, is mildly hypertensive, and smokes. The sonogram reveals a normal gallbladder, an incidental finding of a small aortic aneurysm, and a 5-cm mass arising from the midlateral aspect of the right kidney (Fig. 5-1). What does the renal mass most likely represent?

FIGURE 5-1 Solid mass arising from the kidney.

Hematuria is often the first sign of a urinary tract problem. The cause of hematuria may be anywhere within the urinary system (kidney, ureters, bladder, or urethra) or outside the urinary system (enlarged prostate or gynecologic problem). The amount of blood in the urine can vary from gross (visible) hematuria to microscopic hematuria. Problems of the lower urinary tract (i.e., ureter or bladder) are more likely to have gross hematuria than are problems of the upper urinary tract (i.e., kidney). Patients presenting with gross hematuria are at a higher risk of having a malignancy than patients with microscopic hematuria.¹

Hematuria is a nonspecific finding, and the most common causes are acute infection (see Chapter 6), stones within the urinary tract, or tumor. Other, less common causes include trauma, congenital anomaly, renal vein thrombosis, renal cysts, renal infarction, sickle cell disease, enlarged prostate (see Chapter 30), and bleeding disorders, or the cause may be unknown or undetected. In children, blunt or penetrating trauma is the most common cause of urinary tract injury. Hematuria in children may also be caused by nephroblastomas (see Chapter 9). In most cases of microscopic hematuria, imaging is not necessary unless there are associated injuries.

Urinary tract diseases may not be diagnosed during the early stages, when many patients are asymptomatic and do not have urine discoloration, unless the amount of red blood cells is significant. The symptoms are primarily related to the cause of the hematuria. Patients with a bladder or kidney tumor, polycystic renal disease, hydronephrosis, benign prostatic hyperplasia, or urolithiasis may not have pain. Patients passing a stone have pain or renal colic. Other symptoms include flank pain, fever, vomiting, nausea, fatigue, and dysuria.

Urinalysis is performed to confirm the presence of blood in the urine. A culture may also be performed to detect whether bacteria or tumor cells are present in the urine. Patients who are at high risk for significant renal disease have a history of smoking, have a history of occupational exposure to toxic chemicals and dyes, are older than age 40, have had prior urinary tract infections or symptoms of irritative voiding, or have had prior urinary tract disease. Patients who have abused analgesics or have had pelvic irradiation are also at a higher risk for microscopic hematuria. When hematuria is detected, a urologic consultation, cystoscopy, intravenous pyelogram (IVP) or excretory urography, computed tomography (CT), magnetic resonance imaging (MRI), renal sonographic examination, or transurethral sonography may be performed to determine the pathology. The use of three-dimensional sonography and three-dimensional contrast-enhanced sonographic examinations has shown promise in differentiating between noninvasive and invasive tumors, especially in the case of bladder tumors.² This chapter presents some conditions responsible for hematuria that can be evaluated sonographically.

Genitourinary System

Normal Sonographic Anatomy

The kidneys are oval or bean-shaped organs that measure approximately 11 cm × 7 cm × 3 cm. They are retroperitoneal and lie anterior to the psoas muscles in the paralumbar region at the level of the twelfth thoracic vertebra (T12) and the third lumbar vertebra (L3). The upper poles lie more medial than the lower poles. The liver usually causes the right kidney to be situated slightly lower than the left kidney.

The kidneys have a well-defined border with three layers of protective tissue. The inner or true layer is a fibrous capsule that is continuous with the outer layer of the ureters. It protects the kidney from infection. The middle layer is called the perinephric capsule and is composed of adipose tissue. It helps hold the kidney in place and protects the kidney from trauma. The outer layer, which surrounds the kidney and adrenal gland, is called Gerota’s fascia. It consists of fibrous connective tissues that protect and anchor the kidney.

The inner anatomy of the kidney consists of the following three distinct sections: the renal parenchyma (cortex), medullary pyramids (which collect and transport urine to the collecting system), and renal sinus (which contains the collecting system, vessels, fat, and lymphatic tissue) (Fig. 5-2).

FIGURE 5-2 Internal anatomy of the kidney.

Sonographically, the renal sinus is the echogenic oval region in the midportion of the kidney, the renal cortex has a midlevel echogenicity, and the medullary pyramids are less echogenic than the cortex. When the renal cortex is compared with the liver, it is hypoechoic (Fig. 5-3).

FIGURE 5-3 **(A),** Sagittal image of normal right kidney. **(B),** Transverse image of normal right kidney.

The ureters are not usually imaged on a sonogram unless they are dilated. The ureters exit from the medial aspect of the kidneys and follow a vertical course anterior to the psoas muscle to the posterior-lateral aspect of the urinary bladder. When the ureter is dilated, it appears as a linear anechoic or sonolucent structure on a sagittal view (Fig. 5-4) and a round anechoic structure on a transverse view.

FIGURE 5-4 Dilated ureter. **(A),** Longitudinal image. **(B),** Transverse image at the level of the bladder.

The urinary bladder is visualized only when it is distended, and then it appears as a fluid-filled, anechoic, thin-walled, symmetric structure. Reverberations may be seen in the anterior portion of the fluid-filled urinary bladder. The urethra is a tubular structure that extends from the base of the urinary bladder to the outside of the body. The urethra in women is much shorter than in men. It is typically not imaged unless an obstruction exists at the urethral level. With sonographic imaging, the urethra appears as a short anechoic or sonolucent tubular structure (Fig. 5-5).

FIGURE 5-5 Dilated urethra caused by posterior urethral valves (PUV).

Urolithiasis

Nephrolithiasis

Calculi, or stones, can form anywhere within the urinary tract. Most stones originate within the kidney (nephrolithiasis). The development of calculi is influenced by heredity, familial predisposition, geographic location (living in a dry, hot climate), high concentrations of stone constituents (uric acid, calcium salts, or a combination of calcium oxalate and calcium phosphate), changes in urine pH, or the presence of bacteria. Development may also be idiopathic. Stones are more commonly found in men. The clinical presentation varies depending on the size or location of the stone or whether the stone is being passed. Calculi located in the kidney or proximal portion of the ureter may cause either no pain or dull flank pain, whereas stones in the distal ureter or bladder may cause lower back pain radiating down the pelvis. Severe, sharp pain (renal colic) is usually caused by the passage of a stone down the urinary tract. Other clinical symptoms may include nausea, vomiting, fever, chills, or painful urination. Depending on the presence of obstruction, oliguria may also be present. If the hematuria is due to infection, the laboratory findings may consist of increased white blood cell count and bacteria in the urine and bloodstream.

Stones can cause obstruction of the renal collecting system, or they may pass into the ureter and obstruct it, causing a hydroureter. The two most common sites of obstruction are the ureteropelvic junction and the ureterovesical junction. Sonographic documentation of a ureteral stone may be difficult to obtain because of the small size of the calculi, posterior location of the ureter (where the area of interest may not be in the focal zone), lack of fluid surrounding the stone, and adjacent bowel gas. A staghorn calculus is a stone that fills the renal pelvis and extends into the infundibulum and calyces, causing dilation of the calyces. Stones may also pass into the urinary bladder or, in rare cases, obstruct the urethra.

Sonographic Findings

Calculi appear sonographically as crescent-shaped, echogenic foci. The presence of posterior acoustic shadowing varies according to the size and composition of the stone. Very small stones may not have posterior acoustic shadowing, or shadowing may be difficult to demonstrate (Fig. 5-6, A). The use of tissue harmonics when small calculi are suspected increases the chance of seeing posterior acoustic shadowing. A color Doppler artifact, the twinkle sign (Fig 5-6, B; see Color Plate 7), may be seen with small stones and may be helpful when shadowing cannot be demonstrated. When seen, this artifact appears as rapidly changing color with a comet tail posterior to the stone.

FIGURE 5-6 Renal calculi. **(A),** Calculi in the kidney—no shadowing. **(B),** Multiple colors are seen posterior to renal stone (twinkle sign). (Courtesy Aubrey Rybyinski, BS, RDMS, RVT, Department of Radiology Ultrasound Section, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.)

A calculus in the kidney may cause obstructive hydronephrosis (see Chapter 6). Stones that pass into the ureter may obstruct it, leading to ureteral dilation proximal to the site of the obstruction. A stone that causes a complete unilateral obstruction results in absence of a ureteral jet on the affected side (Fig. 5-7, A). A stone causing a partial ureteral obstruction may cause a weak ureteral jet (Fig. 5-7, B) or powerful jets of urine flow into the bladder, which has a color Doppler pattern that resembles a burning candle (candle sign) (Fig. 5-7, C).

FIGURE 5-7 Partial ureteral obstruction of the ureter at the ureterovesical junction. **(A),** Stone in lower ureter. **(B),** Weak ureteral jet. **(C),** Powerful ureteral jet—color Doppler burning candle sign.

Stones in the urinary bladder appear as echogenic foci that move when patient position is changed. An abdominal radiograph, intravenous urogram, or antegrade or retrograde study may be used in the diagnosis of small stones that are not imaged on a sonographic study.

Bladder Neoplasms

Malignant bladder neoplasms are more common than benign neoplasms. Bladder malignancy has a higher incidence of occurrence than other urinary tract malignancies. The most common bladder neoplasm is transitional cell carcinoma (TCC). Squamous cell neoplasms, adenocarcinomas, lymphomas, and rhabdomyosarcomas in children are rare.

In advanced cases of malignancy, patients present with lower back pain, swelling of the legs, suprapubic pain, dysuria, urinary frequency with a small amount of urine being passed, and blood or blood clots in the urine. Bladder cancer occurs more frequently in men with a peak incidence at age 60 to 70 years. Most masses are superficial and located at the trigone and along the lateral and posterior walls of the bladder.

Sonographic Findings

The sonographic appearance of bladder cancer varies and may have the same echogenicity as a benign neoplasm. Malignant neoplasms tend to appear as an echogenic, irregularly shaped mass projecting into the bladder lumen (Fig. 5-8). Hypervascular bladder wall thickness may also be present. The use of three-dimensional ultrasound imaging increases the distinction of the layers of the bladder wall to differentiate between noninvasive and invasive tumors.³

FIGURE 5-8 **(A),** Irregular-shaped mass projecting into the bladder lumen. **(B),** Echogenic mass projecting into the bladder lumen. **(C),** MRI of bladder tumor projecting into the bladder lumen.

Malignant Neoplasms

Renal Cell Carcinoma

Renal cell carcinoma (RCC) is also referred to as hypernephroma or adenocarcinoma. RCC accounts for most clinically relevant renal tumors. There is a significant predominance of men over women, with peak incidence occurring between age 60 and 70.⁴ Etiologic factors include lifestyle factors, such as smoking, obesity, and hypertension. Cigarette smoking is a definite risk factor for RCC. The roles of obesity and hypertension as risk factors for RCC have not been as definitively clarified. Chemical exposure (e.g., asbestos, cadmium), long-term kidney dialysis, and von Hippel-Lindau disease are also linked to the development of RCC.

Some patients with RCC have hematuria. Other clinical signs include a palpable mass, flank pain, weight loss, fever, or hypertension. Because of the increased detection of tumors with the use of imaging, a growing number of incidentally diagnosed RCCs are found. These tumors are more often smaller and of lower stage. Today, more than 50% of RCCs are detected incidentally using noninvasive imaging for the evaluation of various nonspecific symptoms.⁴ The previously reported classic triad of flank pain, gross hematuria, and palpable abdominal mass is now rarely found. In addition, abnormal laboratory findings may be seen, such as erythropoietin blood level; red blood cells, white blood cells, and bacteria in the urine; and elevated creatinine and blood urea nitrogen (BUN) levels. The tumor may spread throughout the kidney and perinephric fat, invade the renal vein, and travel to the inferior vena cava (IVC). Approximately one-third of patients have metastasis at the time of diagnosis. Metastasis to the regional lymph nodes, lungs, bone, contralateral kidney, liver, adrenal glands, and brain may occur. At the time of diagnosis, a very small percentage of RCCs are bilateral. Prognosis depends on the stage of the disease at diagnosis. RCCs can be staged using the American Joint Committee on Cancer TNM (tumor, node, metastases) classification, as follows:

• Stage 1 RCCs are 7 cm or smaller and confined to the kidney.

• Stage 2 RCCs are larger than 7 cm but still confined to the kidney.

• Stage 3 tumors extend into the renal vein or vena cava, involve the ipsilateral adrenal gland or perinephric fat or both, or have spread to one local lymph node.

• Stage 4 tumors extend beyond Gerota’s fascia to more than one local node or have distant metastases.

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