Blood visible in the urine, known as gross hematuria, can be startling and is always a sign that bleeding is occurring somewhere within the urinary system. The appearance of blood clots indicates a more significant volume of bleeding than simple microscopic hematuria. The urinary tract—which includes the kidneys, ureters, bladder, and urethra—is not meant to pass blood or clots. This symptom requires prompt medical evaluation to determine the underlying source, as ignoring clots can lead to complications, including the blockage of urine flow.
How Blood Clots in Urine Appear
The visual characteristics of blood clots in urine can vary widely, offering clues about the amount and location of the bleeding. Clots may appear as small, dark specks, often described as reddish or brownish chunks floating in the urine. The color can range from bright red, indicating fresh blood, to dark maroon or brown, suggesting the blood is older or has been in the urinary tract longer.
In some cases, the clots can be larger and more gelatinous, resembling jelly-like blobs. A particularly distinct appearance is the “worm-like” or stringy clot, which forms when blood clots inside the narrow tubes of the ureter or urethra before being expelled. The shape of the clot is molded by the tubular structures it passes through. These clots can vary in size from a few millimeters to several centimeters long.
Common Medical Conditions That Cause Clots
The formation of blood clots in the urine is the body’s natural response to significant bleeding within the urinary tract, which can be triggered by several medical conditions.
Urinary tract infections (UTIs) or pyelonephritis, which is a kidney infection, are common causes. Inflammation and irritation of the lining of the bladder or kidney can lead to blood vessel damage and subsequent bleeding. Infections cause the tissues to become swollen, making them fragile and prone to hemorrhage.
Another frequent cause is the presence of kidney stones or bladder stones, which are hard mineral deposits that can develop anywhere in the urinary system. As these stones move or attempt to pass, their rough edges scrape and irritate the lining of the ureters, bladder, or urethra, causing trauma that results in substantial bleeding and clot formation.
In men, issues related to the prostate gland, such as benign prostatic hyperplasia (BPH) or prostate cancer, are common sources of bleeding. An enlarged prostate gland can cause small blood vessels on its surface to burst, particularly during urination, leading to gross hematuria with clots. Trauma or injury to the kidneys or bladder, such as from a fall or accident, can also cause immediate and severe bleeding.
Cancer of the bladder, kidney, or prostate must be considered as a possible cause, especially in individuals with risk factors like smoking or older age. Tumors in these organs can be highly vascular, meaning they contain many blood vessels, and as the tumor grows or ulcerates, it can bleed profusely into the urinary space. This bleeding is often painless and can produce large, irregular clots that require thorough investigation.
When to Seek Urgent Medical Attention
Seeing blood clots in the urine should always prompt a visit to a healthcare provider for a full evaluation. Certain accompanying symptoms, however, indicate a medical emergency requiring immediate attention. The greatest risk is clot retention, where clots become lodged in the urethra or bladder neck and completely block the flow of urine. Inability to urinate, even with a strong urge, is an urgent symptom that necessitates a trip to the emergency room.
Other signs of a serious problem include severe pain in the lower back, side, or abdomen, which could indicate a large stone or severe infection. If the clots are accompanied by a high fever, shaking chills, nausea, or vomiting, this may suggest a severe kidney infection or a systemic issue. A doctor will typically begin the diagnostic process with a urinalysis and urine culture to check for infection. Imaging tests like an ultrasound or CT scan are then used to visualize the urinary tract and locate the source of the bleeding.