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Adapted images courtesy of Regensburger M, Huttner HB, Doerfler A, Schwab S, Staykov D. Springerplus. 2014;3:551. [Open access.] PMID: 25332856, PMCID: PMC4192142.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Normal urine coloration ranges from light yellow to pale amber; however, a multitude of pathologies and agents can change the color and/or clarity of urine. This presentation discusses several potential causes of abnormal urine color.

The neurologic imaging studies and urine samples shown were obtained in an elderly woman who underwent mild hypothermia therapy for an atypical intracerebral hemorrhage. The dark green urine on the center left occurred 48 hours following intravenous propofol administration. Reversal of the urine color to normal yellow (center right) occurred a few hours after cessation of the propofol infusion.

Image of gross hematuria courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Hematuria

The urine bag shows gross hematuria in an elderly man with a malpositioned Foley catheter; the catheter balloon was found in the prostatic urethra.

Hematuria, defined as the presence of red blood cells (RBCs) in the urine,[1] is one of the most common urologic problems that urologists encounter. It may present microscopically (defined as 3 or more RBCs per high-powered field) or be grossly visible to the naked eye, with the potential source of the RBCs ranging from the renal glomerulus to the urethral meatus.[1]

Hematuria can range from a light pink or peach color to a dark port wine color with different leveling of bleeding. The darkness of the hematuria typically indicates the severity of the bleeding.

Myriad genitourinary pathologies can cause hematuria—ranging from benign conditions such as vigorous exercise to much more concerning etiologies such as bladder or kidney cancer. Once benign conditions have been ruled out, further evaluation is required.[1]

Image of gross hematuria courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

The workup of hematuria per American Urology Association guidelines includes imaging of the upper urinary tracts. This is performed via computed tomography urography (CTU) (criterion standard) or noncontrast renal CT scanning, noncontrasted magnetic resonance imaging, or ultrasonography with retrograde pyelography.[1] These imaging modalities are used to evaluate for renal carcinoma or upper tract urothelial carcinoma. Other etiologies such as renal angiomyolipoma can also be evaluated with CT.

Evaluation of the bladder with CT or ultrasound is not sensitive or specific enough to evaluate for carcinoma in situ and therefore is performed by direct visualization via cystoscopy. Urinary cytology may be useful as an adjunct to help rule out malignant changes within the urinary tract after an initially negative evaluation or in patients with risk factors for carcinoma in situ (smoking) and irritative voiding symptoms.[1]

Image of Foley catheter malpositioned within the prostatic urethra courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Iatrogenic urinary tract trauma

This image is from the same patient discussed in Slide 2. Severe gross hematuria resulted from this placement.

Proper insertion of urinary catheters can be challenging in male patients with significantly enlarged prostates. It is essential to know how to safely insert the catheter into the bladder such that the balloon does not expand within the prostate.

When using a Foley catheter, it is important that (1) insertion is to the hub to ensure the balloon is past the prostate and (2) urine return is seen to further ensure the balloon will not be within the urethra when it is inflated.

If resistance is met during the insertion of a Foley catheter in a male patient, use of a coudé Foley catheter may be attempted as it has a stiffer, angled tip, which allows the catheter to navigate past the enlarged prostate. Other times, the patient may have a urethral stricture, which prevents placement of a Foley catheter. This can be navigated by a bedside suprapubic tube placement or cystoscopy procedure with urethral dilation or direct visual internal urethrotomy. Eventually, the best outcome for the patient with a urethral stricture is urethroplasty.

Image of E coli growing on agar from Wikimedia Commons | LenkaM. [Creative Commons ShareAlike 1.0 Generic license (CC by-SA 1.0).]

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Urinary tract infections

Urinary tract infections (UTIs) may also lead to hematuria.[1] Escherichia coli is one of the most common causative organisms.[2] In one population study comprising 3108 women with acute cystitis, E coli was isolated in approximately 78.6% of the urine cultures obtained.[3]

Treatment for acute uncomplicated cystitis consists of antibiotic therapy, commonly with trimethoprim-sulfamethoxazole, nitrofurantoin, or fosfomycin.[2]

Ciprofloxacin is no longer recommended for uncomplicated UTIs. A May 2016 US Food and Administration (FDA) safety communication warned of potential disabling adverse effects associated with the use of fluoroquinolones for these and other uncomplicated conditions.[4]

Image of a right Grade IV renal laceration courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Trauma

Another cause of gross hematuria is genitourinary trauma. Shown is a 67-year-old man who presented to the emergency department as a pedestrian versus automobile accident.

An abdominal and pelvic CT scan with intravenous contrast was obtained (after previous images were obtained with contrast) and revealed a right Grade IV renal laceration with laceration through the collecting system and active extravasation from posterior of the right kidney in addition to other polytrauma.

The kidney is the most injured genitourinary organ in trauma. Trauma to the kidneys can be managed conservatively, and, if needed, angioembolization of the kidney can be performed. Surprisingly, the degree of hematuria does not correlate well with the severity of the trauma. Renal lacerations are graded from one to five, one being the least severe and five being the most severe. Details are listed on the American Association for the Surgery of Trauma website.

The patient shown developed a delayed bleed and underwent angiography with selective embolization. He was stabilized and discharged home after follow-up imaging revealed no further bleeding.

Image of purple urine bag syndrome courtesy of Chris Atalla, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Purple urine bag syndrome

Purple urine bag syndrome (PUBS) is a rare phenomenon caused when UTIs with bacterial strains that produce indoxyl phosphatase (eg, Providencia stuartii, Providencia rettgeri, Klebsiella pneumoniae) react with the synthetic materials of urinary catheters/bags.[5]

When PUBS occurs, it is typically found in elderly patients with constipation and long-term indwelling urinary catheters in association with colonization with the above bacteria as well as with E coli, Morganella morganii, Pseudomonas aeruginosa, and Proteus and Enterococcus species.[5]

Clinicians should keep in mind that PUBS is not entirely a benign condition, because it points to underlying recurrent UTIs and, potentially, the improper care of urinary catheters and/or improper hygiene.[5,6]

Image of bladder cancer in patient with painless gross hematuria courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Malignancy

The image reveals bladder cancer found in an elderly man who presented with a 4-month history of painless gross hematuria. He was also a former smoker.

A major concern for patients with gross hematuria is the possibility of urothelial cancer in the bladder or the upper tract of the collecting system. Globally, urothelial bladder cancer is the seventh most common cancer in men and the seventh most common neoplasm in women.[7] Smoking or a previous history of smoking is the most common risk factor for this disease.[7] Commonly, patients present with complaints of irritative voiding symptoms that may mimic urinary tract infections (eg, dysuria, hematuria, and urinary frequency) with no growth found on urine cultures. It is imperative that patients be further evaluated with cystoscopy to ensure no underlying malignancy, such as carcinoma in situ, is missed.

Additionally, patients on anticoagulation therapy should be evaluated similarly to those not on anticoagulation therapy as spontaneous hematuria from blood thinners alone should not occur.

Image of a large filling defect in the bladder courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Delayed CT urogram images were obtained in a middle-aged male with a 2-month history of painless gross hematuria. CT scanning revealed a large filling defect in the bladder consistent with a bladder tumor. Cystoscopy demonstrated a large tumor. The patient underwent transurethral resection of the bladder tumor and was found to have stage pT1 disease (invasion into the lamina propria).

Image of right renal mass courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Another potential cause of hematuria is renal cell carcinoma (RCC), which accounts for 2-3% of all cancers in the United States and about 85% of malignant kidney tumors.[8] RCC is also the sixth and eighth most common cancer in US men and women, respectively.[8]

Obesity is a risk factor for, and has a linear relationship with, RCC, especially in women. Additionally, individuals with von Hippel-Lindau syndrome are at higher risk for RCC; up to 30% develop this malignancy, with nearly 70% of affected patients having RCC by age 60 years. RCC is also a major cause of death in these patients.[9]

Nephron-sparing surgery is the treatment of choice for smaller RCC tumors, with one case series showing no local recurrence.[10] This type of procedure is more technically difficult to perform and requires the proper selection of patients.[11]

The image shows a CT scan concerning for a right renal mass (red star). Final pathology after a right-sided nephrectomy revealed it was clear cell RCC. The mass was found on incidental CT scanning for a possible kidney stone.

Image of TURP operation in progress courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Benign prostatic hyperplasia (BPH) is another common cause of gross hematuria, owing to the vascularity of the primary gland itself or because of vascular prostatic regrowth after transurethral resection of the prostate (TURP).[12] An indication for TURP is gross hematuria that is not amenable to medical therapy with 5-alpha-reductase inhibitors such as finasteride.[12] This procedure may be especially helpful in men with larger prostates (>30-40 g).[13] Another, highly efficient and effective surgery is prostate enucleation. This procedure can be performed with either holmium or thulium laser energy (HoLEP or ThuLEP). This procedure can be performed on significantly larger prostates endoscopically requiring no incisions (similar to a TURP) with low complication rate and long-lasting results.[14]

The image shows a TURP operation in progress using a bipolar loop to remove prostate tissue to open the urethral channel and cauterize any bleeding vessels identified.

Image of ureteral stones removed with laser lithotripsy from a patient with left flank pain and hematuria courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Nephrolithiasis

Kidney stones are one of the most common hematuria-causing pathologies. An estimated 1 in 11 people in the United States are affected (8.8% prevalence), up from 1 in 20 people in 2004, with men more likely to develop nephrolithiasis than women (10.6% vs 7.1%, respectively).[15]

Multiple risk factors exist for kidney stone formation — several are metabolic and/or dietary in nature.

Obesity is a known risk factor, and the incidence of kidney stone disease rises with the incidence of obesity.[15] The incidence of obesity has more than doubled since 1971, and more than one third of US adults (36.5%) are obese.[16-18] Globally, approximately 39% of the adult population were considered overweight or obese in 2015.[19]

One frequent dietary cause of nephrolithiasis is inadequate fluid intake.[20,21] Another is increased intake of oxalate from foods such as black tea, dark chocolate, rhubarb, spinach, and certain types of nuts.[22] Patients with recurrent kidney stone formation should undergo a metabolic evaluation and 24-hour urine study to elucidate any potential reversible causes of their kidney stones.

Image of myoglobinuria after a high-voltage electrical injury that resulted in rhabdomyolysis courtesy of Nunn R, Chang N, Milner SM, Price LA. Eplasty. 2013;13:ic16. [Open access.] PMID: 23409207, PMCID: PMC3558850.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Myoglobinuria

Myoglobinuria usually results from rhabdomyolysis, which can arise from trauma or alcohol/drug abuse.[23] The tea-colored urine that develops is commonly confused with gross hematuria to the untrained eye. These 2 conditions can be differentiated by centrifuging the urine. If the urine has a clear center, the cause of the discoloration is myoglobinuria, whereas if there is a reddish sediment, the etiology is likely hemoglobinuria.[23] Creatinine kinase levels are also typically elevated in myoglobinuria.

Rhabdomyolysis presents with nonspecific findings, of which the three hallmarks are muscle weakness, myalgia, and dark urine.[23] Clinical suspicion is paramount to avoid potentially life-threatening complications such as acute kidney injury and disseminated intravascular coagulation.[23,24]

Obtain creatinine kinase and electrolyte levels and assess renal function by measuring blood urea nitrogen and creatinine.

The main goal of therapy in patients with rhabdomyolysis is hydration for prevention of acute kidney injury with preservation of kidney function.[23,24]

Image of pyuria courtesy of Josh Palka, DO.

10 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | June 9, 2021 | Contributor Information

Pyuria

Any patient with a long-term indwelling urinary catheter is almost guaranteed to have bacteriuria,[25] which may develop into pyuria, wherein white blood cells (or pus) are present in the urine.

To minimize the risk of infections, urinary catheters and suprapubic catheters should be changed every 3-4 weeks.[26] When possible, bladder emptying should be managed with clean intermittent catheterization to reduce the risk of bacteriuria and infection.[25]

The pyuria shown occurred in a T5 paraplegic man with a chronic suprapubic tube.

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