Hematuria
Imagine noticing a reddish tint to your urine — it's a sight that can certainly grab your attention. This phenomenon, known as hematuria, means there's blood, or red blood cells, in your urine, and it can be a sign of many things, from the utterly harmless to something quite serious. Unraveling the mystery behind this crimson warning requires a closer look at the body's intricate filtering system. Hematuria can be visibly obvious, making urine appear red or brown, or it can be microscopic, detectable only through lab tests. The presence of blood in urine has a wide range of potential causes, from benign conditions like intense exercise to more serious issues like kidney stones or cancer. Careful investigation is crucial to distinguish true hematuria from harmless mimics and to identify the underlying source, guiding appropriate treatment.
AI Summary
Imagine noticing a reddish tint to your urine — it's a sight that can certainly grab your attention. This phenomenon, known as hematuria, means there's blood, or red blood cells, in your urine, and it can be a sign of many things, from the utterly harmless to something quite serious. Unraveling the mystery behind this crimson warning requires a closer look at the body's intricate filtering system.
- Hematuria can be visibly obvious, making urine appear red or brown, or it can be microscopic, detectable only through lab tests.
- The presence of blood in urine has a wide range of potential causes, from benign conditions like intense exercise to more serious issues like kidney stones or cancer.
- Careful investigation is crucial to distinguish true hematuria from harmless mimics and to identify the underlying source, guiding appropriate treatment.
The Red Flag in Your Urine
Hematuria is simply the medical term for blood in your urine. It might sound alarming, but it's a symptom, not a disease itself, and it can manifest in two main ways: either 'gross' or 'microscopic'.
When you have 'gross hematuria,' the blood is clearly visible, turning your urine red, brown, or even a tea-like color. 'Microscopic hematuria,' on the other hand, is invisible to the naked eye, only revealed under a microscope or with specialized lab tests. Both need attention.
Where Does the Blood Come From?
Blood mixing with urine can originate anywhere along your urinary system's pathway. This includes the kidneys, which filter your blood; the ureters, tubes that carry urine to the bladder; the bladder itself; and the urethra, where urine exits the body.
In men, the prostate gland, located near the bladder, can also be a source. Understanding the potential origin helps doctors narrow down the possible causes, which range from simple infections to more complex issues.
Not Always Blood: The Great Impostors
Before jumping to conclusions, it's important to remember that not all red urine signals actual blood. Many things can change your urine's color, creating a false alarm known as pigmenturia.
Certain foods, like beets, blackberries, or rhubarb, are notorious for lending a reddish hue to urine. Even some medications, such as phenazopyridine (for urinary pain) or rifampicin (an antibiotic), can produce vivid orange or red urine.
For women, menstruation can lead to blood in a urine sample, causing a positive test. A simple urine dipstick test might also give a 'false positive' if other substances, like muscle protein (myoglobin) from severe muscle breakdown, are present.
To truly confirm hematuria, doctors look for three or more red blood cells under a microscope in a 'high power field.' This microscopic confirmation distinguishes true blood from its colorful impostors.
Unraveling the Mystery: Categories of Hematuria
To pinpoint the cause, doctors classify hematuria in several ways: by its visibility, its anatomical origin within the urinary system, and even the timing of its appearance during urination.
Glomerular Clues: Kidney's Filter Trouble
When hematuria stems from the glomeruli — the tiny filtering units within your kidneys — it often presents with distinct features. These include 'dysmorphic' or misshapen red blood cells, which have been squeezed and damaged passing through the kidney's filters.
Another tell-tale sign of a glomerular source is the presence of 'red blood cell casts.' These are tiny, cylindrical structures formed in the kidney tubules, acting like molds of the tubes, and indicating that red blood cells are escaping where they shouldn't.
Glomerular causes often involve inflammatory conditions affecting the kidneys themselves. These can range from immune disorders like IgA nephropathy to post-infectious glomerulonephritis, which can occur after certain bacterial or viral infections.
Non-Glomerular Sources: A Wider Net
Non-glomerular hematuria means the blood is coming from somewhere else in the urinary tract, outside the kidney's filtering units. A key indicator here can be the presence of visible blood clots in the urine, which are typically not seen with glomerular issues.
Common non-glomerular culprits include urinary tract infections (UTIs) affecting the bladder or kidneys, and kidney stones scraping against the delicate lining of the urinary passages as they move.
Other causes can be more serious, such as cancers of the kidney, bladder, or prostate. Even intense exercise, trauma to the urinary tract, or an enlarged prostate in men can lead to non-glomerular bleeding.
When to Investigate: The Evaluation Process
Anytime blood appears in your urine, especially if it's visible, it warrants investigation. Visible hematuria is a red flag, as it's associated with a higher risk of serious underlying conditions, including urinary tract cancers, in a significant percentage of cases.
The initial evaluation always starts with a thorough medical history and physical exam. Your doctor will ask about your lifestyle, medications, and any other symptoms, as these details can offer vital clues to the cause.
If true hematuria is confirmed, further steps depend on whether it's visible or microscopic, and your individual risk factors. This might involve additional lab tests, specialized imaging like CT scans or ultrasounds, and sometimes a cystoscopy — a procedure to look inside the bladder with a tiny camera.
When Hematuria Becomes an Emergency
While many causes of hematuria are treatable and not immediately life-threatening, a few situations demand urgent attention. One such emergency is 'acute clot retention,' where blood clots form in the bladder and obstruct the outflow of urine.
These clots can be incredibly painful and can prevent the bladder from emptying, leading to acute urinary retention. What's more, clots in the bladder can actually promote further bleeding due to natural anticoagulants produced during their breakdown.
Immediate management often involves placing a specialized catheter to irrigate the bladder and evacuate the clots. If bleeding continues, a cystoscopy in the operating room might be necessary to identify and control the source.
Another critical concern is 'urosepsis,' a severe, body-wide inflammatory response to a urinary tract infection. Symptoms can include fever, rapid heart rate, and low blood pressure. Urosepsis requires prompt treatment with antibiotics and intravenous fluids to prevent serious complications.
Who Gets Hematuria? The Epidemiology
Hematuria is surprisingly common, with microscopic forms affecting anywhere from 2% to 31% of the population in the United States. The prevalence tends to increase with age, particularly in individuals over 60, and those with a history of smoking.
While concerning, only a small fraction of individuals with microscopic hematuria are ultimately diagnosed with a urologic cancer. However, certain risk factors, like a significant smoking history, chemical exposure, or previous radiation therapy, warrant a much higher index of suspicion.
Globally, the prevalence of hematuria can be significantly influenced by regional factors. For example, in North Africa, a parasitic infection called Schistosoma haematobium, which chronically infects the urinary tract, leads to a very high rate of hematuria.
In children, microscopic hematuria affects about 0.5% to 2%, with older age and female gender being slight risk factors. While cancer diagnoses are rare, macroscopic hematuria in children, just like adults, demands careful investigation, as it has a higher association with serious underlying issues.
Article
Hematuria
Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with a microscope or laboratory test. Blood that enters and mixes with the urine can come from any location within the urinary system, including the kidney, ureter, urinary bladder, urethra, and in men, the prostate. Common causes of hematuria include urinary tract infection (UTI), kidney stones, viral illness, trauma, bladder cancer, and exercise. These causes are grouped into glomerular and non-glomerular causes, depending on the involvement of the glomerulus of the kidney. But not all red urine is hematuria. Other substances such as certain medications and some foods (e.g. blackberries, beets, food dyes) can cause urine to appear red. Menstruation in women may also cause the appearance of hematuria and may result in a positive urine dipstick test for hematuria. A urine dipstick test may also give an incorrect positive result for hematuria if there are other substances in the urine such as myoglobin, a protein excreted into urine during rhabdomyolysis. A positive urine dipstick test should be confirmed with microscopy, where hematuria is defined by three or more red blood cells per high power field. When hematuria is detected, a thorough history and physical examination with appropriate further evaluation (e.g. laboratory testing) can help determine the underlying cause.
Differential diagnosis
Hematuria
Hematuria can be classified according to visibility, anatomical origin, and timing of blood during urination.
• In terms of visibility, hematuria can be visible to the naked eye (termed "gross hematuria") and may appear red or brown (sometimes referred to as tea-colored), or it can be microscopic (i.e. not visible but detected with a microscope or laboratory test). Microscopic hematuria is present when there are three or more red blood cells per high power field. • In terms of the anatomical origin, blood or red blood cells can enter and mix with urine at multiple anatomical sites within the urinary system, including the kidney, ureter, urinary bladder, and urethra, and in men, the prostate. Additionally, menstruation in women may cause the appearance of hematuria and may result in a positive urine dipstick test for hematuria. The causes corresponding to these anatomic locations can be divided into glomerular and non-glomerular causes, referring to the involvement of the glomerulus of the kidney. Non-glomerular causes can be further subdivided into the upper urinary tract and lower urinary tract causes. • In terms of the timing during urination, hematuria can be initial, total or terminal, meaning blood can appear in the urine at the onset, midstream, or later. If it appears soon after the onset of urination, a distal site is suggested. Hematuria that occurs throughout urination suggests that bleeding is occurring above the level of the bladder. A longer delay suggests a more proximal lesion.
Many causes may present as either visible hematuria or microscopic hematuria, and so the differential diagnosis is frequently organized based on glomerular and non-glomerular causes.
Glomerular hematuria
Postrenal hematuria - the presence of blood in urine (because of damage to the urethra and prostate).
Hematuria due to a glomerular source commonly presents as dysmorphic red blood cells (misshapen red blood cells) or red cell casts (small tubular structures made up of red blood cell components) on urine microscopy. This occurs due to the red blood cells being deformed as they pass through the glomerular capillaries into the renal tubules and eventually into the urinary system. Normally, red blood cells should never pass from the glomerular capillary into the renal tubule, and this is always a pathological process. Glomerular causes include:
• IgA nephropathy • Thin glomerular basement membrane disease • Hereditary nephritis (Alport's disease) • Hemolytic uremic syndrome • Postinfectious glomerulonephritis (group A β-hemolytic streptococcus pyogenes) • Membranoproliferative glomerulonephritis • Lupus nephritis • Henoch–Schönlein purpura • Nephritic syndrome • Nephrotic syndrome • Polycystic kidney disease • Idiopathic hematuria
Non-glomerular hematuria
Visible blood clots in the urine indicate a non-glomerular cause. Non-glomerular causes include:
• Urinary tract infections, such as pyelonephritis, cystitis, prostatitis, and urethritis • Kidney stones • Cancers, such as renal cell carcinoma and bladder cancer (particularly transitional cell carcinoma), and in men, prostate cancer • Urinary tract strictures • Benign prostatic hyperplasia • Renal papillary necrosis • Trauma or damage to the lining of the urinary tract • Intense exercise • Increased tendency to bleed due to acquired or genetic conditions (e.g. sickle cell disease or vitamin K deficiency bleeding) or certain medications (e.g. blood thinners)
Pigmenturia
Not all red or brown urine is caused by hematuria. Other substances such as certain medications and certain foods can cause urine to appear red.
Medications that may cause urine to appear red include:
• Phenazopyridine • Nitrofurantoin • Doxorubicin • Rifampicin
• Blackberries • Food dyes. • Beets • Rhubarb • Fava beans
False positive urine dipstick
A urine dipstick may be falsely positive for hematuria due to other substances in the urine. While the urine dipstick test is able to recognize heme in red blood cells, it also identifies free hemoglobin and myoglobin. Free hemoglobin may be found in the urine resulting from hemolysis, and myoglobin may be found in the urine resulting from rhabdomyolysis (muscle breakdown). Thus, a positive dipstick test does not necessarily indicate hematuria; rather, microscopy of the urine showing three of more red blood cells per high power field confirms hematuria.
Menstruation
In women, menstruation may cause the appearance of hematuria and may result in a urine dipstick test positive for hematuria. Menstruation can be ruled out as a cause of hematuria by inquiring about menstruation history and ensuring the urine specimen is collected without menstrual blood.
In children
Hematuria
• Fever • Strenuous exercise • Acute nephritis • Congenital abnormalities: • Non-vascular: ureteropelvic junction obstruction, posterior urethral valves, urethral prolapse, urethral diverticulum and multicystic dysplastic kidney • Vascular: arteriovenous malformations, hereditary hemorrhagic telangiectasias, renal vein thrombosis in newborns. • Urinary stones. • Coagulation disorders. • Mechanical trauma: masturbation, foreign body. • Nephritic syndrome: IgA nephropathy, Post-streptococcal glomerulonephritis, Benign familial hematuria, Alport syndrome. • Sickle cell trait or disease.
Evaluation
Hematuria
The evaluation of hematuria is dependent upon the visibility of the blood in the urine (i.e. visible/gross vs microscopic hematuria). Visible hematuria must be investigated, as it may be due to a pathological cause. In those with visible hematuria, urological cancer (most frequently bladder or kidney cancer) is discovered in 20–25%. Hematuria alone without accompanying symptoms should be raise suspicion of malignancy of the urinary tract until proven otherwise. The initial evaluation of patients presenting with signs and symptoms that are consistent of hematuria include assessment of hemodynamic status, underlying cause of hematuria, and ensuring urinary drainage. These steps include assessment of the patient's heart rate, blood pressure, a physician exam taken by a healthcare professional, and blood work to ensure the patient's hemodynamic status is adequate. It is important to obtain a detailed history from the patient (i.e. recreational, occupational, and medication exposures) as this information can be helpful in suggesting a cause of hematuria. The physical exam can also be helpful in identifying a cause of the hematuria as certain signs found on the physical exam can suggest specific causes of the hematuria. In the event the initial evaluation of hematuria does not reveal an underlying cause then evaluation by a physician who specializes in Urology may proceed. This medical evaluation may consist of, but is not limited too, a history and physical exam taken by healthcare personnel, laboratory studies (i.e. blood work), cystoscopy, and specialized imaging procedures (i.e. CT or MRI).
Visible hematuria
The first step in evaluation of red or brown colored urine is to confirm true hematuria with urinalysis and urine microscopy, where hematuria is defined by three of more red blood cells per high power field. Although a urine dipstick test may be used, it can give false positive or false negative results. In gathering information, it is important to inquire about recent trauma, urologic procedures, menses, and culture-documented urinary tract infection. If any of these are present, it is appropriate to repeat a urinalysis with urine microscopy in 1 to 2 weeks or after treatment of the infection. If the results of the urinalysis and urine microscopy reveal a glomerular origin of hematuria (indicated by proteinuria or red blood cell casts), consultation with a nephrologist should be made. If the results of the urinalysis indicate a non-glomerular origin, a microbiological culture of the urine should be performed, if it has not been done already. If the culture is positive (indicating a bladder infection), urinalysis and urine microscopy should be repeated following treatment to confirm resolution of the hematuria. If the culture is negative or if hematuria persists after treatment, CT urogram or renal ultrasound and cystoscopy should be performed. Hemodynamic stability should be monitored and a complete blood count should be ordered to assess for anemia.
Microscopic hematuria
Red blood cells seen on light microscopy on urinary cytology, next to benign urothelial cells (pap stain).
After detecting and confirming hematuria with urinalysis and urine microscopy, the first step in evaluation of microhematuria is to rule out benign causes. Benign causes include urinary tract infection, viral illness, kidney stone, recent intense exercise, menses, recent trauma, or recent urological procedure. After benign causes have resolved or been treated, a repeat urinalysis and urine microscopy is warranted to ensure cessation of hematuria. If hematuria persists (even if there is a suspected cause), the next step is to stratify the risk of the person for urothelial cancer into low, intermediate, or high risk to determine next steps. To be in the low risk category, one must satisfy all of the following criteria: Has never smoked tobacco or smoked less than 10 pack-years; is a female less than 50 years old or a male less than 40 years old; has 3–10 red blood cells per high power field; has not had microscopic hematuria before; and has no other risk factors for urothelial cancer. To be in the intermediate risk category, one must satisfy any of the following criteria: Has smoked 10–30 pack-years; is a female 50–59 years old or a male aged 40–59 years old; has 11–25 red blood cells per high power field; or was previously a low-risk patient with persistent microscopic hematuria and has 3–25 red blood cells per high power field. To be in the high risk category, one must satisfy any of the following criteria: Has smoked more than 30 pack-years; is older than 60 years of age; or has above 25 red blood cells per high power field on any urinalysis. For the low risk category, the next step is to either repeat a urinalysis with urine microscopy in 6 months or perform a cystoscopy and renal ultrasound. For the intermediate risk category, the next step is to perform a cystoscopy and renal ultrasound. For the high risk category, the next step is to perform a cystoscopy and CT urogram. If an underlying cause for hematuria is discovered, it should be managed appropriately. However, if no underlying cause is discovered, the hematuria should be re-evaluated with urinalysis and urine microscopy within 12 months. Additionally, for all risk categories, if a nephrologic origin is suspected, consultation of a nephrologist should be made.
Pathophysiology
Hematuria
The pathophysiology of hematuria can often be explained by damage to the structures of the urinary system, including the kidney, ureter, urinary bladder, and urethra, and in men, the prostate. Common mechanisms include structural disruption to the glomerular basement membrane and mechanical or chemical erosion of the mucosal surfaces of the genitourinary tract.
Management
Medical emergency: acute clot retention
A 60cc/mL Toomey syringe.
Acute clot retention is one of three emergencies that can occur with hematuria. The other two are anemia and shock. Blood clots can prevent urine outflow through either ureter or the bladder. This is known as acute urinary retention.
Blood clots that remain in the bladder are digested by urinary urokinase producing fibrin fragments. These fibrin fragments are natural anticoagulants and promote ongoing bleeding from the urinary tract. Removing all blood clots prevents the formation of this natural anticoagulant. This in turns facilitates the cessation of bleeding from the urinary tract.
The acute management of obstructing clots is the placement of a large (22–24 French) urethral Foley catheter. Clots are evacuated with a Toomey syringe and saline irrigation. If this does not control the bleeding, management should escalate to continuous bladder irrigation (CBI) via a three-port urethral catheter. If both a large urethral Foley catheter and CBI fail, an urgent cystoscopy in the operating room will be necessary. Lastly, a transfusion and/or a correction of a coexisting coagulopathy may be necessary.
Medical emergency: urosepsis
Urosepsis is defined as sepsis caused by a urogenital tract infection and comprises about 25% of all sepsis cases. Urosepsis is the result of a systemic inflammatory response to infection and can be identified by numerous signs and symptoms (e.g. fever, hypothermia, tachycardia, and leukocytosis). Signs and symptoms that indicate a urogential tract infection is the source of the sepsis may include, but are not limited to, flank pain, costovertebral angle tenderness, pain with micturition, urinary retention, and scrotal pain. In terms of the visibility, hematuria can be visible to the naked eye (termed "gross hematuria") and may appear red or brown (sometimes referred to as tea-colored), or it can be microscopic (i.e. not visible to the eye but detected of urosepsis. In addition to imaging tests, patients may be treated with antibiotics to relieve the infection and intravenous fluids to maintain cardiovascular and renal perfusion. Acute management of hemodynamic status, in the event intravenous fluids are unsuccessful, may include the use of vasopressor medications and the placement of a central venous line.
Epidemiology
Hematuria
In the United States, microscopic hematuria has a prevalence of somewhere between 2% and 31%. Higher rates exist in individuals older than 60 years of age and those with a current or prior history of smoking. Only a fraction of individuals with microhematuria are diagnosed with a urologic cancer. When asymptomatic populations are screened with dipstick and/or microscopy medical testing about 2% to 3% of those with hematuria have a urologic malignancy. Routine screening is not recommended. Individuals with risk factors who undergo repeated testing have higher rates of urologic malignancies. These risks factors include age (> 40 years), male gender, previous or current smoking, chemical exposure (e.g., benzenes, hydrocarbons, aromatic amines), history of chemotherapy (alkylating agents, ifosfamide), prolonged foreign body in the bladder (such as a bladder catheter), prior pelvic radiation therapy, or greater than 25 red blood cells per high powered field on urine microscopy.
The prevalence of microscopic hematuria in North Africa is very high due to the high prevalence of the blood fluke schistosoma haematobium, which chronically infects the urinary tract.
In pediatric populations, the prevalence is 0.5–2%. Risks factor include older age and female gender. About 5% of individuals with microscopic hematuria receive a cancer diagnosis. 40% of individuals with macroscopic hematuria (blood easily visible in the urine) receive a cancer diagnosis.