What Does Occult Blood In Urine Mean and How Is It Treated?

Occult blood refers to blood in the urine that isn’t visible to the naked eye and is identified only on microscopic examination. Treatment varies according to the infection or other underlying causes and may include antibiotics or different interventions.

Being informed that blood was detected in your urine can be unsettling, particularly when you don’t actually see any blood.

In medical terminology, “occult” means hidden. Occult blood in urine indicates the presence of blood that’s only detectable under a microscope.

Below is an overview of what this finding signifies, possible causes, and the further tests you might face.

What is occult blood in your urine?

The clinical term for blood in the urine is hematuria.

When blood is visible in the urine it may tint it pink or red; this is called gross hematuria.

If blood is present but the urine appears normal to the eye — without pink, red, or clots — it’s termed occult or microscopic hematuria.

Are there different levels or stages of occult blood in urine?

Clinicians commonly categorize microscopic hematuria by the number of red blood cells seen per high-power field (hpf) on microscopy.

• Significant microscopic hematuria: 3 or more red blood cells per hpf (≥ 3 RBC/hpf)
• Insignificant microscopic hematuria: 2 or fewer red blood cells per hpf (0–2 RBC/hpf)

Significant microscopic hematuria generally prompts additional investigation.

Readings within the insignificant range typically do not require extra testing unless symptoms or other concerns arise.

What are the most common causes of occult blood?

Many factors can lead to blood in the urine. Some are medical conditions such as infections or cancers; others stem from activities or trauma.

Common causes include:

• bladder infection
• kidney infection
• other infections (urethra, prostate, etc.)
• stones in the urinary tract
• benign prostatic hyperplasia (BPH)
• endometriosis
• trauma

Blood in the urine can also be linked to more serious problems:

• bladder cancer
• kidney cancer
• prostate cancer
• hemophilia and other clotting disorders
• sickle cell disease
• kidney disease involving the glomeruli

Can dehydration cause occult blood in urine?

Dehydration can produce blood in the urine. When this occurs, it’s considered a false positive because it’s not due to disease. Other reasons for false positives on a urine dipstick test include:

• strenuous exercise
• contamination with menstrual blood
• recent sexual activity
• presence of free hemoglobin or myoglobin

How do you know if you have occult blood in your urine?

Physicians and laboratories use several tests to detect blood in urine.

After a dipstick test, urinalysis with microscopic examination is usually the next step. You’ll provide a urine sample in a cup, taking care to perform a “clean catch” per instructions to avoid contamination. The laboratory will then examine the specimen under a microscope.

Further testing might include:

• blood tests to assess kidney function, autoimmune disease markers, or cancer indicators
• cystoscopy, where a small camera inspects the inside of the urinary tract
• kidney biopsy to examine tissue for disease or damage
• imaging to visualize the bladder, kidneys, and nearby organs — such as computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound

What if you get a false positive or negative test result?

False positive dipstick results for occult blood are relatively common (about 22%).

To truly be a false positive, the microscopy must also be negative. False negatives occur less often (approximately 4%).

Factors such as diet, vigorous exercise, medications, and hydration status can all influence results. If you worry about your findings, discuss with your doctor whether repeating the test makes sense.

How is occult blood in urine treated?

Treatment depends on the underlying cause.

Examples of management include:

• antibiotics for infections
• fluid replacement for dehydration
• medications for an enlarged prostate
• lithotripsy (sound-wave treatment) for bladder or kidney stones

When blood in the urine is due to harmless causes — such as intense exercise or menstrual contamination — no specific treatment may be necessary.

Takeaway

You can have blood in your urine without visible discoloration. A positive test for hematuria doesn’t always mean more testing is required.

Decisions about next steps depend on the amount of blood seen on microscopy and any accompanying symptoms.