What Causes Blood in Urine With No Pain in Females?

Hematuria is the medical term for blood in the urine. The two types, which can occur with or without pain, are:

• Gross hematuria means blood in the urine is visible to the naked eye, making it look orange, pink, bright or dark red, or tea-colored.
• Microscopic hematuria means the urine looks normal—yellow or clear—but blood can be seen under a microscope.

Painless hematuria in females has many potential causes, like vigorous exercise, infection, kidney disease, or a side effect of a medication. Most seriously, it can be a sign of a urinary tract cancer like bladder or kidney cancer.

This article reviews the possible causes of painless hematuria in females and when to see a healthcare provider. It also briefly explores risk factors for bladder and kidney cancer.

Common Causes of Blood in Urine With No Pain

Hematuria occurs when red blood cells enter the urine from an organ within the urinary tract system in the following ways:

• The kidneys are bean-shaped organs that serve several vital functions, including removing extra salt, water, and waste products from the body through urine.
• The ureters are thin muscular tubes that carry urine from the kidneys to the bladder.
• The bladder is a hollow organ in the lower abdomen that stores urine.
• The urethra is a short tube that carries urine from the lower part of the bladder to the outside of the body.

Potential causes of painless hematuria in females include the following.

Exercise

Strenuous or prolonged exercises, such as long-distance running, rowing, or swimming, can cause painless hematuria.

Experts suspect blood vessels feeding the kidney narrow to improve blood supply to the exercising muscles. As a result of this blood vessel narrowing, red blood cells leak into the urine.

Hematuria following exercise can be gross or microscopic and is related to the intensity or degree of the activity rather than its duration.

It’s generally short-lived, resolving within a day or two, although it can last up to a week.

Other causes of exercise-induced hematuria are:

• Direct trauma to the kidney or bladder from contact sports (e.g., boxing or karate)
• Biking-related hematuria in females that’s caused by the repeated collision of the perineum (the area between the anus and vagina) with the bicycle seat
• Bladder bruising from long-distance running, as the bladder walls repeatedly get bumped during the impact of running

While relatively common, exercise-induced hematuria should be investigated to rule out injury to the urinary tract system or concerning, although less common, findings like urinary tract cancer.

Seeking evaluation is especially crucial if your exercise-induced hematuria lasts more than one week, you are an adult over the age of 40, or you have risk factors for urinary tract cancer, like a history of smoking.

Trauma

Injury to any organ in the urinary tract system can cause hematuria, although the kidneys are the most vulnerable, involved in a little over 3% of all trauma cases.

Examples of such forms of trauma include:

• Blunt trauma like from a motor vehicle accident, fall, pedestrian accident, motorcycling, and playground accidents (in children)
• Penetrating trauma from a firearm or stab wound

Symptoms of trauma to a urinary tract organ like the kidney can cause gross or microscopic hematuria.

Depending on the extent of the injury, the hematuria may be painless or associated with other symptoms like tenderness and swelling of the flank (the area in your lower back just below your lower ribs), bruising, and rib fractures.

Urinary Tract Infection (UTI)

Urinary tract infections are usually caused by bacteria. Hematuria is a common symptom of a UTI, although other urinary symptoms, namely discomfort or pain, are also typically present.

Two types of UTIs include:

• Cystitis occurs when bacteria travel to and infect the bladder. Symptoms may include burning pain when urinating, frequent and strong urges to urinate, tenderness in the lower abdomen, and visible blood in the urine.
• Pyelonephritis occurs when bacteria travel to and infect one or both kidneys. Symptoms may include fever, chills, flank pain, nausea and vomiting, and sometimes symptoms of cystitis.

Kidney or Bladder Stones

Kidney stones are hard lumps of minerals that anchor themselves within the kidney.

Most people with kidney stones—what’s known as nephrolithiasis—have gross or microscopic hematuria.

Depending on factors like the size of the stone and whether it’s blocking the flow of urine from the kidney to the bladder, other symptoms may be present, such as:

• Waves of pain, often severe, occurring in the flank or lower abdomen and traveling to the groin area
• Nausea or vomiting
• Strong urge to urinate
• Pain when urinating

Like kidney stones, bladder stones are hardened mineral deposits anchored in the bladder. However, they often originate in the kidney, and their symptoms are similar to those of kidney stones.

Kidney Diseases

Certain kidney diseases can cause hematuria. A common cause is glomerulonephritisa disease affecting the part of the kidney responsible for filtering blood.

There are several types of glomerulonephritis, with unique causes (e.g., lupus, diabetes, or viral infection) and varying degrees of severity.

In addition to hematuria, other symptoms include proteinuria (protein in the urine), which causes foamy urine, and swelling in the ankles, hands, and around the eyes.

Cancer

Bladder or kidney cancer can cause painless hematuria.

Bladder Cancer

Blood in the urine is the predominant initial symptom of bladder cancer. It’s typically painless, gross (but can be microscopic), and intermittent, appearing one day and disappearing the next.

Other potential symptoms of bladder cancer, especially in the early stages, are similar to those seen with a urinary tract infection, like burning during urination and having a frequent and strong urge to urinate.

Overall, females have a 3 to 4 times lower risk of developing bladder cancer compared to males. Still, females are more likely to have advanced disease upon diagnosis.

Kidney Cancer

Globally, kidney cancer is the 10th most common type of cancer in females.

Most cases are diagnosed between the ages of 60 and 70 years. Like bladder cancer, kidney cancer is more common in males.

Gross or microscopic hematuria without pain is a possible sign of kidney cancer, along with fever and symptoms of cystitis with no infection. Flank or lower back pain on one side that feels deep and may be located beneath the rib cage may also occur.

Angiomyolipomas

Angiomyolipomawhile rare, is the most common benign (noncancerous) kidney tumor, and it usually develops in females.

Angiomyolipomas are composed of blood vessels, muscle, and fat cells. They are associated with the genetic condition tuberous sclerosis but can also develop randomly.

Symptoms are often absent, but if they are present, they can include painless hematuria and flank pain. If they enlarge and rupture (break open), they can cause life-threatening bleeding, requiring immediate treatment.

Other Possible Causes

While not an exhaustive list, other possible causes of hematuria include:

• Adverse effects from a urinary tract-related procedure, like placing or removing a Foley catheter or a kidney biopsy
• Radiation-induced bladder inflammation (radiation cystitis)
• Blood vessel problems—for example, blockage of the main artery feeding the kidney

Side effects from medications or various inherited diseases may also cause hematuria.

Medication Side Effects

Compared to other drugs, blood thinners are the most frequent cause of hematuria.

Of blood thinners, research suggests that Jantoven (warfarin) and Xarelto (rivaroxaban) perhaps present the most risk of triggering hematuria, while Eliquis (apixaban) is the safest.

Other drugs linked to serious hematuria episodes, specifically hemorrhagic cystitis, include the chemotherapy drug cyclophosphamide.

Inherited Diseases

A few diseases that run in families may cause hematuria. Examples include:

• Polycystic kidney disease is characterized by cysts (fluid-filled punches) that grow within the kidneys, potentially affecting their function.
• Alport syndrome is associated with kidney disease, hearing loss, and eye problems.
• Sickle cell disease is associated with abnormally shaped red blood cells that can block blood flow in blood vessels, causing severe pain episodes. Hematuria may develop if the kidneys’ internal blood vessels are affected.

What Are the Risk Factors for Hematuria?

Risk factors for hematuria depend on the underlying cause.

For example, factors that increase a person’s risk for bladder cancer include:

• Smoking and tobacco use
• Increased body mass index (BMI)
• Workplace exposure to certain chemicals like hair dyes and diesel fumes
• Exposure to certain drugs, like the diabetes drug Actos (pioglitazone) or cyclophosphamide
• Infection with a parasitic worm, schistosomiasis (very rare in the United States)

Likewise, risk factors for kidney cancer include:

• High blood pressure
• Tobacco use, including smoking
• Having obesity
• Workplace exposure to trichloroethylene
• Family history of certain genetic syndromes, especially von Hippel-Lindau disease

When to Contact a Healthcare Provider

All cases of hematuria require investigation, with gross hematuria often requiring a more extensive workup. If you are experiencing blood in your urine, contact a healthcare provider.

All said, it’s important to note that blood in the urine, whether pink, red, or tea-colored, is not always due to red blood cells. Notably, uterine or vaginal bleeding may be mistaken for hematuria.

Moreover, dehydration can cause the urine to turn a dark yellow, sometimes mistaken for blood.

Other causes in people of any sex include:

• Myoglobin (a protein found in muscle) in urine may occur from rhabdomyolysis (when muscle tissue becomes severely injured, leading to the release of myoglobin)
• Most types of porphyriaa rare group of inherited disorders associated with problems making heme, are an important component of hemoglobin.
• Certain medications, like rifampin (a tuberculosis drug) and Pyridium (phenazopyridine), a drug that relieves symptoms of a UTI
• Certain foods, namely beets and rhubarb

Summary

Hematuria is red blood cells in the urine. It can be associated with or without pain and be gross (visible) or microscopic (only visible under a microscope).

Multiple potential causes of painless hematuria exist, including strenuous or prolonged exercise, kidney disease, and, most seriously, bladder or kidney cancer.

Bladder or kidney infections and stones can also cause hematuria, although they are generally associated with discomfort when urinating and lower abdominal/flank pain, respectively.

If you are experiencing hematuria, see a healthcare provider for further evaluation. While it may be a transient (passing) or benign finding, you will want to get to the root cause so you can be treated, if necessary.