Blood in Urine & Normal CT Scan: 7 Possible Causes
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1. UTI (severe cystitis or pyelonephritis).
UTI is often caused by bacteria invading the urinary tract outside through the urethra.
Common risk factors & causes of UTI:
- Being a sexually active female.
- The use of spermicide-coated condoms and diaphragms.
- Being diabetic.
- Recent use of urinary catheters.
- People with large stones in the kidney or the urinary bladder.
- Recent catheterization.
Symptoms & diagnosis:
UTI may present with blood in urine with normal CT scan results. As doctors, we suspect UTIs based on characteristic symptoms. Urine analysis or urine culture usually confirms the UTI.
- Dysuria: burning or pain in the urethra when you pee.
- Urgency: sudden severe urgency to pee.
- Frequency: Frequent urge to pee but only a small amount of urine comes out.
- Suprapubic (lower abdominal) pain.
- Turbid (cloudy) urine may also be present.
- Blood in urine
- The symptoms may be very mild, with a strange feeling in the bladder and urethra.
- Also, UTI may become complicated (reaching the kidneys), causing high fever, flank pain, chills, etc.
- The diagnosis is often established by urine analysis and culture. CT scans are often normal with UTIs, even with blood in the urine.
What to do:
UTI is a very common cause of abnormal urinary symptoms in females. Consult your doctor to confirm the diagnosis if you have symptoms consistent with UTI.
UTIs are treated mainly by antibiotics (such as Nitrofurantoin and Trimethoprim-sulfamethoxazole).
The blood in urine often resolves with antibiotic treatment. However, if it doesn’t go away after UTI treatment, you should tell your doctor, as it may be due to other causes.
An over-the-counter urinary analgesic such as Oral phenazopyridine may help relieve the dysuria and uncomfortable urethral sensations.
Glomerulonephritis is inflammation and damage to the tiny urine filters inside your kidneys (the glomeruli).
Glomeruli nephritis is a relatively common disease and may cause significant kidney damage if left undiagnosed or untreated.
Causes of glomerulonephritis:
- Infections (bacterial, viral, etc.).
- Medications (such as some antibiotics and nonsteroidal anti-inflammatory drugs).
- Some chemicals are harmful to the kidney.
- Autoimmune diseases such as systemic lupus erythematosus.
- Severe Hypertension.
- Long-lasting or uncontrolled diabetes mellitus.
- Many cases occur due to unknown causes.
Symptoms and signs:
The CT scans of acute cases of glomerulonephritis often reveal normal findings. Also there are two main types of glomerulonephritis:
- Nephritic Syndrome: mainly characterized by blood in the urine (light brown or pink) and hypertension.
- Nephrotic Syndrome: characterized by foamy urine (due to proteinuria), swelling of eyes (especially in the morning), and lower limbs.
The symptoms may include one or more of the following:
- Bloody urine (often pink, light brown, or tea-colored).
- Foamy urine (foams form on the surface of the toilet water after peeing).
- Sometimes, Fever, sore throat, and other signs of infection.
- The amount of urine may remain normal or decrease. Some patients may completely stop urination.
- Swelling of the face and eyelids (more noticeable in the morning).
- Swelling of the lower limbs.
- Some patients may present with acute kidney failure symptoms (severe shortness of breath, hiccups, headaches, dizziness, confusion, or loss of consciousness).
Diagnosis and what to do:
- Your doctor suspect glomerulonephritis based on its characteristic symptoms and signs.
- The presence of blood in urine with normal CT scans without evidence of UTI should raise the suspicion of glomerulonephritis.
- Urine analysis may show blood in the urine (Red blood cells or RBCs) and may be proteinuria (protein in urine).
- Blood tests to detect low protein (serum albumin), infection (high white blood cell count, kidney function, and others.
- Additional tests to detect the cause include blood sugar assessment, antibody testing, searching for infections, etc.
- Imaging studies such as ultrasound and CT scans (can be normal in the acute stage).
- A kidney biopsy is often needed to confirm the condition, especially if there is a normal CT scan with unexplained blood in the urine.
Trauma to the kidney, ureters, urinary bladder, or urethra may cause blood in the urine. Urinary tract trauma often results from:
- Recent urinary catheter insertion.
- Recent cystoscopy ( a cystoscope is a small device that allows your doctor to see the inside of the urinary bladder. It is introduced through the urethra).
- Major pelvic trauma (as with road traffic accidents).
- Kidney trauma (blunt trauma to the flanks).
The trauma is often minor (with a normal CT scan and ultrasound results). However, a history of a recent catheterization or trauma to the urinary tract is an important clue.
Report any history of recent trauma to the urethra, pelvis, or flanks to your doctor.
The small tube that connects your bladder to the outside is called the urethra. Sometimes, The urethra becomes inflamed (urethritis) due to infections, chemicals, or trauma.
Urethral inflammation or trauma may cause blood in urine with normal CT scans.
Common causes include (reference):
- Chemical (non-specific) urethritis: as with over-washing with soaps, bubble baths, feminine hygiene products, or using spermicide-coated diaphragms or condoms.
- Infections: common examples are gonorrhea and chlamydia (often associated with vaginitis and cervicitis).
- Trauma to the urethra.
- Urethral diverticulum.
- Skin allergy around the urethral opening (contact irritant dermatitis).
Common symptoms of urethritis:
- Severe burning pain in the urethra.
- Blood before or after urination.
- Urethral discharge (pus or bloody pus).
- Painful urination (dysuria).
- Itching around the urethra.
- Pain during sexual intercourse (dyspareunia).
Learn More about Urethritis.
4. False blood in the urine.
Bloody urine can be either due to other reddish or brown dyes in urine. For example:
- Hemoglobin: it results from the breakdown of red blood cells inside the blood vessels (intravascular hemolysis). It often leads to dark brown to reddish urine. Hemoglobinuria (hemoglobin in the urine) occurs due to diseases such as sickle cell anemia, severe burns, incompatible blood transfusions, and many other causes. Learn More.
- Myoglobinuria: Myoglobin is a protein found in muscles that may appear in the urine as brownish or reddish urine. Mygolobinuria occurs due to severe muscle diseases (muscle damage), as with major trauma, drug abuse, and alcohol abuse.
- Some medications, such as rifampin, Pyridium, nitrofurantoin, phenytoin, etc.
- Beeturia: deep red or pink urine due to ingestion of beetroot.
In the above conditions, your urine may appear to have blood with normal imaging studies (such as ultrasound and CT scans). However, a history of drug or beet ingestion is often present besides the symptoms of muscle affection or blood hemolysis.
5. Exercise-induced hematuria.
Blood in the urine may appear after stressful exercises or sports. The exact cause is still unclear. However, exercise-induced hematuria is a benign condition that is not known to cause serious or long-term kidney diseases.
Exercise-induced hematuria can occur with (reference):
- Vigorous contact sports such as boxing and football.
- Non-contact sports such as marathon running, rowing, and swimming.
- It can also occur with long-distance cycling (but rare).
Possible mechanisms (reference):
- Traumatic: trauma to the kidneys or the urinary bladder with vigorous contact sports or long-distance running.
- Blood shifting from the kidneys to the muscle leads to ischemic inflammation of the kidneys.
- Lactic acidosis from excessive muscle work makes your kidneys more permeable to red blood cells (hence the blood appears in urine).
Symptoms and features:
- Often starts after stressful or prolonged sports such as boxing, football, marathon running, etc.
- It may be associated with bladder or kidney pain.
- The condition improves with rest (after a few days to one week).
- Often, it doesn’t lead to significant kidney disease or kidney failure.
- Imaging studies (such as Ultrasound or CT scans) are often normal.
- Your doctor should thoroughly investigate hematuria that continues for more than a week from the last exercise.
- Exercise-induced hematuria in people above 50 should also be investigated thoroughly due to the high risk of bladder cancer.
6. Passed stone.
Stones in the urinary tract are one of the most common causes of blood in the urine. But they often appear in a CT scan.
However, the passage of the stone with urine may cause bloody urine for a few days with a normal CT scan (the stone is already passed at the time of the scan).
The only clue to this cause of blood in urine is the presence of symptoms of urinary stones or visualizing the passed stone in the toilet.
The symptoms of passing stone include:
- Renal colic: sudden severe pain in the flanks or groin. The pain is often colicky and extreme. It comes and goes in attacks that may last for hours.
- Severe burning pain during urination.
- Cloudy urine.
- Nausea or vomiting during the attack.
- You may notice the stone passing during urination.
- Hematuria (Blood in urine) often starts with the passage of the stone and continues a few days later. However, later CT scans are often normal as the stone has already passed.
7. Other causes of hematuria with normal CT scans.
- Taking blood-thinning medications such as Warfarin, heparin, etc.
- Extremely low platelet counts as with Idiopathic thrombocytopenic purpura.
- Endometriosis of the urinary tract.
- Hypercalciuria (a genetic condition that leads to increased calcium excretion in urine with hematuria).
- Hyperuricosuria: increased uric acid excretion in urine sometimes cause unexplained blood in urine with normal kidney scans.
- Chemotherapy-induced hemorrhagic cystitis.
- Loin pain-hematuria syndrome.
- Written by a doctor.
MD, Internal Medicine and Nephrology specialist.
Dr. Esraa A. MagidAuthor