Microscopic blood in urine but no infection

​Blood in urine (hematuria) can be caused by certain medications. Find out the causes from th​e Department of Urology at Singapore General Hospital.

Blood in urine (hematuria) may not always be a cause for worry.

It’s almost a natural response – when we see blood, we think something must be wrong. However, blood in urine, termed hematuria by doctors, isn’t always a cause for concern.

“Blood in urine is one of the most common issues affecting both younger and older patients seen in the urology clinic,” says Dr Nor A​​zhari Bin Mohd Zam, Consultant, Department of Urology, Singapore General Hospital (SGH), a member of the SingHealth group.

“In the young, the most common causes are urinary stones or a urinary tract infection (UTI). In older patients, it is more likely to be bladder or kidney cancer, especially if the blood in the urine is painless and the patient has a history of smoking,” he adds.

When blood in urine is not serious

Certain medications including aspirin, heparin or warfarin (a blood thinner) and anti-cancer drug cyclophosphamide have been known to cause blood in urine.

Sometimes, it’s just tiny traces that can only be seen under a microscope. This is called microscopic hematuria. Blood which is visible to the naked eye is termed gross hematuria. The chance of finding a significant urological disease is much higher in patients with gross, rather than microscopic, hematuria.

Apart from medicine, certain foods such as beets, rhubarb and berries, consumed in large quantities, can also cause your urine to turn reddish for up to a few days. Even strenuous exercise can bring about gross hematuria, though it’s unclear why.

It is always best to see a doctor upon discovering blood in your urine, so more serious causes can be ruled out.

When blood in urine could be serious

Conditions affecting the kidney, ureter, bladder or prostate can lead to blood in urine.

Kidney

Hematuria may be caused by kidney inflammation (a condition known as glomerulonephritis) or by a kidney infection, especially when associated with fever and loin pain.

Another possible cause is a kidney stone, but perhaps the most severe cause is kidney cancer. In kidney cancer, there can be a lot of blood and clots in the urine, but it is usually painless.

Ureter and bladder

When the blood in urine originates from the ureter, a likely cause is a urinary stone. The patient will usually have accompanying pain in the loin. A tumour in the ureter, although uncommon, is usually malignant and generally causes painless hematuria.

However, if blood in urine is accompanied by painful urination, urinary frequency and possibly fever, then it could be due to a UTI. UTIs are treated by oral antibiotics or, in more serious cases, by intravenous antibiotics.

A bladder stone is another common cause for hematuria. However, if the patient is a male smoker, aged 50 and above, who experiences painless blood in his urine, there is a chance he could be suffering from bladder cancer.

Prostate

Hematuria resulting from a bleeding prostate could be a sign of either a prostate infection, a benign enlargement of the prostate or prostate cancer. Typically, patients with a prostate condition encounter difficulty in urinating or frequent urination, as well as poor urinary flow.

Tips to prevent hematuria

Blood in urine may be difficult to prevent but here are some steps you can take to reduce your risk.

• If you have kidney stones: Drink sufficient fluids, monitor your salt intake and reduce your intake of foods rich in oxalates and animal protein.

• If you have gout: Reduce your intake of foods rich in purine to keep your uric acid in check.

• If you’re a smoker: To minimise your risk of kidney or bladder cancer, the most effective way is to avoid smoking. “The risk of having bladder cancer is 4-5 times higher in smokers than non-smokers. In addition, smokers are twice as likely to develop kidney cancer,” explains Dr Nor Azhari.

Ref: S13

You may have noticed blood in your urine or completed a urine test at a doctor’s office that detected higher than average number of red blood cells in the urine on microscopic analysis of your urine specimen. In either case, you may be wondering if it could be a serious problem and what happens next.

Herbert Ruckle, MD, FACS, chair of Loma Linda University Health’s Urology Department, answers your top questions about hematuria — blood in the urine — and what to expect after reporting seeing blood in your urine or receiving urinalysis test results.

Hematuria (visible or seen only under the microscope) could be an early sign of bladder cancer, Ruckle says, and Bladder Cancer Awareness Month presents a timely opportunity to brush up on your awareness of the disease’s detection and treatment.

What is hematuria, and how does urinalysis testing work?

There are two types of hematuria:

• gross hematuria: visible blood in the urine
• microscopic hematuria: blood in the urine visible only via microscope

If you have seen blood in your urine, or gross hematuria, Ruckle advises to visit your doctor as soon as possible and discuss the issue with them — even if it goes away.

"If there's any question that you had blood in your urine, you need to be proactive," Ruckle says. “Do not make assumptions just because symptoms ( hematuria goes?) go away or you hear it's okay because the urine has cleared.”

Your doctor will request a test of your urine, called a urinalysis, that will provide more information on what is happening in your body. Even if you have not seen any blood in your urine, a urinalysis can be administered during a general checkup and picks up on microscopic hematuria.

Hematuria is usually caused by benign (non-cancer) problems — such as urinary tract infections, kidney disease, stones, blood thinners, local trauma — but it also can be the first sign of bladder cancer. There are no official guidelines for bladder cancer screening for the general population, Ruckle says, so it is essential to be aware of the risk factors for bladder cancer, remain vigilant of any changes in your urological health, and complete urinalysis when needed.

A urinalysis’s detection of higher-than-allowed levels of hematuria provides a basis for further investigation, Ruckle says. Hematuria is “elevated” in a urinalysis when there are three or more red blood cells present per high-powered field; a high-powered field indicates the size of the field of view when a microscope reaches its maximum magnification power.

You and your doctor will discuss options for further evaluation after a urinalysis shows elevated hematuria.

My hematuria levels are “elevated” — what could it mean?

First, realize that elevated hematuria does not necessarily mean you have cancer in your bladder, Ruckle says. Other causes of elevated hematuria include but are not limited to:

• urinary tract infections
• instrumentation, disruption, or trauma of the urinary tract
• viral illness, such as hepatitis
• Conditions like endometriosis, sickle cell disease, kidney disease, or blood-clotting disorders
• Benign microhematuria — a tendency for the kidneys to leak more blood than usual without posing a danger
• Exertional microhematuria — rigorous exercise, such as running a marathon
• Other factors include sexual activity, menstruation, or anti-coagulation medications

You and your doctor will work together to identify any of these possible contributing factors to your higher hematuria and discuss bladder cancer risk factors. Taken together, Ruckle says these factors will inform the type and extent of diagnostic testing you’ll undergo:

• Renal or kidney ultrasound — The noninvasive diagnostic exam produces images that help physicians assess the kidney's and bladder's size, shape, location, and blood flow. If you are considered low-risk for cancer, you will likely undergo this test.
• CT scan — You will undergo a CT scan of the abdomen and pelvis outlining the urinary tract, which is usually followed by a cystoscopy if you fall into a slightly higher risk group.
• MRI — You will undergo an MRI that might be followed by a cystoscopy if you fall in a slightly higher risk group and are allergic to the contrast solution used in CT scans
• Cystoscopy — The two-minute procedure involves the insertion of a thin, tube-like instrument into the urethra that allows physicians to look inside the bladder with a tiny camera and check for abnormalities. Physicians may also perform a biopsy by collecting tissue samples of the bladder to analyze under a microscope.

If diagnostic test results return negative for cancer, you will proceed with the appropriate treatment or follow-up for the cause or condition behind the elevated hematuria. In addition, Ruckle says you may undergo repeat or routine urinalysis to monitor hematuria levels.

What if my diagnostic results are positive for bladder cancer?

Following a positive result for bladder cancer, the next step is to determine the cancer’s staging — the extent to which cancer has developed by growing and possibly spreading.

Bladder cancer is treatable for most patients through a minimally invasive procedure called an endoscopy, Ruckle says. An endoscopy involves the insertion of a scope into the urethra through which a physician uses tools to cut and remove the tumor from the bladder.

Ruckle says a final step aims to eliminate straggler cancer cells and minimize the chances of the cancer’s return. After the operation, the physician will fill the bladder with chemotherapy and let it sit for an hour. Then it will be drained in the recovery room. In the case of immunotherapy, it can be given intravenously or placed into the bladder.

The most common type of immunotherapy for bladder cancer is BCG (a vaccine previously used against tuberculosis), which is administered intravesically in the clinic a few weeks after the tumor removal procedure. A catheter is inserted into the bladder to drain the urine, the BCG solution is inserted, the catheter is removed, and the patient then holds the solution in the bladder for two hours before urinating it out. Following treatment, you will undergo regular cystoscopy screenings to monitor the bladder.

Surgical bladder removal is an option for the quarter of patients whose bladder cancer has invaded (put roots down) into the organ’s muscle wall at an advanced stage, Ruckle says. Bladder removal surgery (usually performed robotically) may be accompanied by chemotherapy, occasionally radiation treatment, or both. In addition, a subset of these patients may opt for bladder reconstruction surgery that creates a new bladder fashioned from intestine in the body.

Talk with your healthcare provider if you have questions about bladder cancer. To learn more about the variety of resources and support Loma Linda University Cancer Center offers both cancer patients and their loved ones, visit lluh.org/cancer-center or call 800-782-2623.

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