Woman’s urine turns PURPLE after rare side effect of extreme constipation and UTI

By Cassidy Morrison Senior Health Reporter for Dailymail.Com

Updated: 8:56 PM March 10, 2023

  • The 76-year-old suffered from heart failure and suffered from kidney disease and bladder cancer
  • The woman had a urinary tract infection and was also hooked up to a catheter
  • High levels of bacteria in urine and constipation can lead to purple urinary bag syndrome

Kentucky doctors have detailed a rare case in which an elderly woman’s urine turned dark purple due to a complication of bladder infection.

The unnamed 76-year-old patient with heart failure, kidney failure and bladder cancer was hospitalized and hooked up to a catheter to take her urine away.

An infection in his urinary tract triggered a biochemical reaction producing blue and red pigments in his pee which, when oxidized in the catheter bag, turned dark purple.

Doctors issued the rare diagnosis of purple urine bag syndrome (PUBS), which occurs in 42% of patients hooked up to catheters for a long time.

A chemical reaction in the liver produces indigo pigment and indirubin, a red pigment. These pigments are combined and oxidized to turn purple in the urinary bag.

Purple urine bag syndrome (PUBS) is usually a complication of urinary tract infections (UTIs), as seen in this 76-year-old woman, where catheter bags and tubes turn purple. Although almost always benign, the violent shade of purple can be alarming to patients, families, and clinicians.

Doctors from Pikeville University in Kentucky revealed the case in the journal Oxford Medical Case Reports.

Writing in the report, they said: “Older, bedridden patients with multiple comorbidities more often require long-term indwelling catheters which increase their risk of UTI.

“These patients are more likely to be infected with rarer bacteria which can then cause PUBS.”

The patient had a long history of serious medical issues, including congestive heart failure, chronic kidney disease and bladder cancer.

She went to the hospital for shortness of breath linked to her cardiovascular problems.

To empty her bladder, doctors connected the woman to a catheter and then treated her with IV drugs to reduce swelling linked to congestive heart failure.

After four days of hospitalization, the patient’s urinary bag took on a violent purplish hue.

Dipstick tests revealed that his urine was extremely alkaline with a pH of 8.5, a symptom of his kidneys not working properly.

She also had high levels of the bacteria Proteus mirabilis, a common cause of complicated urinary tract infections.

PUBS was first clinically described in 1978.

The condition is almost always mild, but it can be alarming for patients and their loved ones.

Besides age and frailty, being a woman and suffering from kidney failure, having alkaline urine and constipation are also primary risk factors.

Stroke victim’s urine turns purple due to rare chemical reaction

An unidentified 70-year-old Frenchwoman, hospitalized and catheterized after a stroke, saw her urine turn purple 10 days later. After four days of intravenous hydration, her urine returned to normal.

The phenomenon is the result of a multi-step biological process in the gut.

Bacteria help break down the amino acid tryptophan, which becomes a compound called indole in the intestine, where it is then transported to the liver and transformed into indoxyl sulfate.

Indoxyl sulfate is metabolized to indoxyl in the urine using bacteria that produce phosphatase and sulfatase.

Indoxyl turns into indigo, the blue color, and indirubin, the red color, in alkaline urine, and these colors then mix together to form a violet color.

Purple urine usually signals to doctors that the patient has a urinary tract infection, but not always.

Chronic constipation is usually associated with an overgrowth of bacteria in the colon, which increases the conversion of tryptophan to indole.

Most people with PUBS will be fine, but immunocompromised patients are at risk of serious illness, doctors said. Fournier’s gangrene, for example, can result from urinary tract disease. It is a rare and life-threatening bacterial infection of the scrotum (which includes the testicles), penis, or perineum that causes the death and flaking of body tissue.

The doctors said: ‘The medical management of PUBS requires changing the catheter and giving appropriate antimicrobial therapy to treat the underlying bacterial infection.

“His constipation is gone and a 5 day course of antibiotics has been completed. The patient was discharged to a nursing facility with recommendations for follow-up with her outpatient nephrologist and urologist.


Doctors say the bluish discoloration of urine is triggered by a series of chemical reactions in the body.

Bacteria responsible for UTI degradation metabolites of tryptophan – an amino acid found in food.

This produces indole, which becomes indoxl sulfate, which then oxidizes to blue-colored indigo and reddish indirubin.

Doctors at King George’s Medical University in Lucknow, India, wrote in the British Medical Journal case reports last year: “The combination of indigo and indirubin imparts a purple tint to the collection bag of urine.”

However, the discoloration is completely benign, and often the underlying UTI is considered more of a concern for doctors.

Women are at a higher risk of developing PUBS because they have a shorter urethra, which makes them more susceptible to UTIs.

Constipation can also increase the odds because it gives bacteria more time to break down tryptophan metabolites in the body.

It’s unclear how common PUBS is, but it has been described as an “uncommon phenomenon”.

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