A routine urine test, or urinalysis, is a common, non-invasive diagnostic procedure that provides insight into a person’s overall health and the function of their urinary system. These tests examine the chemical, microscopic, and visual properties of urine, often resulting in a complex report filled with confusing abbreviations. Understanding these shorthand notations is necessary for patients interpreting their health information. This article clarifies one specific finding that frequently causes concern: the abbreviation OCC, which appears on many standard laboratory reports.
Decoding the OCC Abbreviation
The abbreviation OCC in a urine test stands for “Occult Blood.” The term “occult” means hidden or concealed, indicating that the blood is not visible to the naked eye. This condition is medically known as microscopic hematuria, distinguishing it from gross hematuria, where the urine appears visibly pink, red, or cola-colored due to a high concentration of blood.
Occult blood is detected through a chemical reaction, typically using a sensitive dipstick test. This test reacts to the presence of hemoglobin, the protein found in red blood cells, identifying minute amounts of blood that a visual inspection would miss. The presence of red blood cells in the urine is considered significant if microscopic examination reveals three or more red blood cells per high-power field (RBC/hpf).
Why Occult Blood is Tested
Including an occult blood screen in a standard urinalysis provides a broad and cost-effective method for monitoring urinary tract health. The urinary tract, which includes the kidneys, ureters, bladder, and urethra, is a closed system that should not normally contain blood. Therefore, detecting even microscopic amounts of blood acts as a flag for potential underlying pathology anywhere along this system.
Testing for occult blood allows for the early detection of issues that might otherwise be asymptomatic, meaning the person would have no outward signs or discomfort. Since microscopic hematuria does not change the color of the urine, patients are often unaware of the finding until a routine health check.
Common Reasons for a Positive Result
A positive result for occult blood indicates that red blood cells or their components were present in the urine sample, but this is not a diagnosis on its own. The causes range widely from temporary and benign factors to more serious health concerns. One common temporary reason is strenuous physical activity, such as long-distance running, which can cause temporary irritation and bleeding in the bladder, often called “runner’s bladder.”
Other transient factors include contamination from menstruation or recent trauma to the urinary tract. These causes usually resolve quickly and do not indicate a chronic disease. However, persistent occult blood often points toward an underlying issue requiring further investigation.
Infections are frequent culprits. Urinary Tract Infections (UTIs) are a primary cause, as bacteria inflame the lining of the urinary tract and cause microscopic bleeding. Kidney infections can also lead to occult blood, often accompanied by pain and fever. Structural issues, such as kidney stones or bladder stones, can cause irritation and bleeding as they move against the lining of the urinary system.
More serious conditions signaled by a positive OCC result include certain kidney diseases, such as glomerulonephritis, which affects the filtering units of the kidney. The finding also requires the exclusion of malignancy, particularly cancers of the bladder or kidney, as these can cause painless, intermittent microscopic bleeding in early stages. Certain medications, including blood thinners, can also contribute to a positive result.
What Happens After a Positive OCC Result
When a urinalysis returns a positive OCC result, the first step is confirmation to ensure the finding is accurate and persistent. The healthcare provider will often request a repeat urinalysis on a fresh sample. This is sometimes followed by a microscopic analysis to definitively count the number of red blood cells per high-power field, as finding three or more RBCs generally warrants a full workup.
The investigative process is systematic, aimed at pinpointing the source of the bleeding within the urinary system. A urine culture may be ordered to rule out a bacterial infection, which is treated with antibiotics if confirmed. Imaging studies, such as an ultrasound, CT scan, or MRI, are commonly used to visualize the kidneys, ureters, and bladder to check for stones, tumors, or structural abnormalities.
Depending on the patient’s age and risk factors, the doctor may recommend a referral to a specialist, such as a urologist or a nephrologist. A urologist might perform a cystoscopy, which involves inserting a thin, lighted tube into the bladder to inspect the lining directly for any lesions or sources of bleeding. Additional blood tests may also be conducted to assess overall kidney function and rule out systemic causes.