Blood visible in the urine, known medically as gross hematuria, suggests significant bleeding within the urinary tract. The presence of blood clots indicates that the body’s natural clotting mechanisms are working to stop the hemorrhage. Seeing clotted blood in the urine is not a normal finding and always warrants a professional medical evaluation to determine the underlying source of the bleeding. This symptom serves as a clear physical sign that an issue within the kidneys, ureters, bladder, or urethra requires immediate attention.
Visual Identification: Appearance and Characteristics
Blood clots in urine present with a wide range of appearances, offering initial clues about where the bleeding originates. Color varies significantly, from bright red to dark brownish-red or blackish, depending on the volume of blood and how long it remained in the urinary tract. Fresh, bright red clots typically indicate a more recent bleed, often closer to the exit point of the urinary system.
The consistency of the clots is highly variable; they may appear as amorphous, jelly-like blobs, or as more solid, dense chunks. Some individuals pass stringy or worm-like masses. These long, thin clots, often called “casts,” suggest the blood clotted within the narrow, tube-like structures of the ureters or urethra, which molded the clot into that specific shape.
Clots that form and remain in the bladder, a larger, more open space, tend to be more irregular or gelatinous. A large volume of clots can cause the urine itself to become visibly thick and opaque.
Common Medical Conditions That Cause Clots
A range of medical conditions cause significant bleeding that leads to blood clot formation within the urinary tract. One common cause is kidney or bladder stones (nephrolithiasis or urolithiasis). As these hard mineral deposits travel, they mechanically irritate and tear the delicate lining of the urinary passages, leading to hemorrhage.
Severe urinary tract infections (UTIs), including kidney infections (pyelonephritis), cause inflammation and tissue damage severe enough to result in bleeding and subsequent clotting. Certain medications, particularly blood thinners like anticoagulants, increase the propensity for bleeding, making it more likely that minor irritation will result in gross hematuria and clot formation.
More serious conditions, such as malignancies of the bladder or kidney, also present with blood clots. Tumors within the urinary system are often highly vascularized, and as they grow, they can bleed profusely into the urine stream. In men, an enlarged prostate (benign prostatic hyperplasia or BPH) can cause blood vessels around the urethra to stretch and rupture, leading to visible blood and clotting.
When Immediate Medical Attention Is Necessary
While all visible blood in the urine requires medical evaluation, certain accompanying symptoms necessitate urgent medical attention. The most concerning acute sign is the inability to urinate, known as acute urinary retention. This occurs when large blood clots obstruct the bladder neck or the urethra, trapping urine and requiring immediate intervention to remove the blockage.
Severe, sudden pain in the flank, abdomen, or lower back, especially with heavy clotting, suggests a possible kidney stone passage or a significant bleed. The presence of high fever and shaking chills alongside blood clots can signal a severe systemic infection, such as pyelonephritis or urosepsis, which requires prompt antibiotic treatment. Signs of excessive blood loss, such as lightheadedness or weakness, also necessitate immediate emergency care.
Diagnostic Procedures to Determine the Source
Once a patient presents with blood clots in the urine, healthcare providers initiate a structured series of tests to pinpoint the source of the bleeding.
Initial Laboratory Work
Initial steps typically involve a urinalysis to confirm the presence of red blood cells and check for signs of infection, such as white blood cells or bacteria. Blood tests are often performed concurrently to assess kidney function and look for signs of a bleeding disorder or systemic disease.
Imaging
Imaging tests are a fundamental part of the workup to visualize the entire urinary tract. A computed tomography (CT) scan, often performed with contrast dye (CT urography), provides detailed images of the kidneys, ureters, and bladder, helping to identify masses, stones, or structural abnormalities. Ultrasound is an alternative imaging modality, useful for initial assessment or in patients where radiation exposure should be limited.
Direct Visualization
To directly examine the bladder lining, a procedure called cystoscopy is frequently performed. A thin, flexible instrument with a camera (a cystoscope) is passed through the urethra into the bladder. This allows the physician to visually inspect the interior for tumors, inflammation, or active bleeding sites. This combined approach of laboratory work, imaging, and direct visualization is necessary to accurately diagnose the underlying cause.