How to MASTER the Foley Catheter Insertion + Advanced Tips & Tricks

How to MASTER the Foley

Foley Catheter Insertion + Advanced Tips & Tricks

A foley collection bag half filled with urine

William Kelly, MSN, FNP-C

Author | Nurse Practitioner

What is a Foley Catheter Insertion?

Foley catheter insertion is one of the main procedures you will learn as a nurse in school, and you will have to put in a LOT of foley catheters if you work as a bedside nurse in the hospital. 

The term ‘catheter’ is just a term that refers to a flexible tube that is inserted into a part of the body. Some examples include an intravenous catheter (IV), cardiac catheterization, and urinary catheters.

Foley catheters are also referred to as indwelling urinary catheters. These are essentially just a tube that is inserted into the bladder to allow urine to drain into a bag instead of staying in the bladder.

A foley is intended for both short and long-term use, both within and outside of the hospital. 

Foley catheter insertion Indications

Foley catheter insertions are ordered for various reasons, but long story short. -they are ordered when the patient cannot effectively drain their bladder. It’s also ordered when this is anticipated (like with surgery… see below).

Urinary Retention

An enlarged prostate and urinary retention

Urinary retention With obstruction

Also called a bladder outlet obstruction, this is when something is blocking or obstructing the ability of the bladder to empty.

Common causes include Benign Prostatic Hyperplasia (BPH), tumors, blood clots, or severe constipation. Other causes include infections, scarring, strictures, or trauma. 

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Neurogenic Bladder

This is when the bladder doesn’t work normally due to a central cause – aka there’s something with the brain. This could be from a stroke, degenerative diseases like MS, spinal cord injuries, or nerve damage. 

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Pharmacologic Urinary Retention

Certain medications can lead to the bladder being unable to fully empty itself, requiring a foley catheter insertion.

Medications that weaken the bladder muscles include anticholinergics like Tricyclic antidepressants and diphenhydramine (Benadryl).

Medications that increase the tone of the prostate and bladder neck include decongestants, stimulants, or other sympathomimetics.

There are many other medications that can cause urinary retention, including muscle relaxers, certain antipsychotics, hormones, or even NSAIDs and opioids

Other Reasons to place a foley catheter

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Acute Hematuria

If a patient has significant bleeding in their urine, a foley catheter insertion can be ordered to monitor their output.

When there is significant amount of bleeding, this often clots, causing an obstruction and a distended bladder, along with severe discomfort.

A three-way catheter is usually placed and CBI (continuous bladder irrigation) is started to prevent the patient’s urinary tract from obstructing again. 

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Urine Output Monitoring

Patients who need strict I&Os done may have a foley catheter insertion ordered. This is often critically ill patients in the ICU, like with severe CHF or renal failure.

For hourly output, make sure your foley bag has a urometer. This way the urine first drains into the urometer, then each hour can be emptied into the main collection bag.

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Intubated Patients or critically ill

Patients who are intubated and many of those who are critically ill are unable to empty their bladder on their own. To prevent skin breakdown as well as monitor their urinary output, foleys can beneficial.

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All the Tubes

After intubation, once the endotracheal tube is placed, that isn’t the last tube you have to worry about.

Immediately after intubation, you will need to place a foley catheter, as well as an Nasogastric or Orogastric tube to decompress the stomach and prevent aspiration.

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Surgery

Foleys are placed before/during surgery to monitor fluid status and prevent bladder overdistention.

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Immobilized patients

Patient’s who are immobilized from spinal cord injuries, strokes, or pelvic fractures often have foley catheters placed.

Hip fractures will almost always be going for surgery anyway, so a foley can help offer quite a bit of comfort.

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Open Wounds

If the patient is incontinent and has open sacral or coccygeal wounds, sitting in their urine can make the breakdown worse and make it more difficult to heal. A foley can help promote wound healing in these cases.

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Patient Comfort (End of Life)

Patients who are reaching their end of life often are very weak and uncomfortable, and a foley catheter insertion gives them one less thing to worry about and can make them feel more comfortable overall.

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Incontinence?

Foley catheters really shouldn’t be used to manage urinary incontinence. This is an inappropriate use of foleys and the potential complications and longer hospital stay outweigh any benefit. 

When to NOT put in a foley?

There really is only one absolute contraindication to a foley catheter insertion, which is trauma with hematuria. This should be managed by a urologist.

There are some relative contraindications, which include urethral strictures, recent UTIs, or artificial sphincters.

Of course, benefits and risks should always be weighed. Introducing anything invasive into the body increases the risk of causing infection, which is very common but can be lethal. See monitoring parameters below.

What are the different types of Urinary catheters?

While this article specifically focuses on foley catheter insertion, there are other types of urinary catheters that work similarly but may be used for alternate scenarios.

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Foley Catheter

This indwelling catheter is placed in the bladder and left in place. This foley catheter insertion is ordered when ongoing use is anticipated. It is secured to the patient’s leg and drains into a leg bag or a larger collection bag that hangs on the patient’s bed.

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Straight Cath

Sometimes referred to as intermittent bladder catheterization, this is for once or as needed emptying of the bladder. This often ordered for short-term urinary retention, where the benefits of putting in an indwelling foley don’t outweigh the risks (i.e. infection).

This drains into a plastic collection chamber for drainage. Once the urine is completely drained, the catheter is immediately removed

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Suprapubic Catheter

This is when a catheter is surgically placed through the peritoneum by a urologist or general surgeon. You’ll see this stitched in place below their belly button. This is placed in some patients with chronic incontinence/urologic issues. Nurses should never replace these.

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Three-way Cath

No – this isn’t THAT kind of Three-way…

Also called a triple-lumen catheter, this is essentially a larger catheter that has 3 tips.

  1. The urine drainage port, which is in the middle and is connected to the tubing to drain into the collection bag as usual.
  2. The balloon port, which is used to inflate the 10mL balloon once successfully placed.
  3. An irrigation port, which is not found on regular foley catheters. This allows irrigation to be manually done, or allows CBI (continuous bladder irrigation) to be connected to prevent clotting. 

A three-way is typically only ordered for significant hematuria when clotting and obstruction are occurring or trying to be prevented. 

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Coude Catheter

This is a catheter with a special-shaped tip that helps you maneuver past an enlarged prostate. 

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Using a Coude

Make sure nurses are able to use coude catheters at your facility. This may be reserved for Providers or Urology to use. 

 There are some alternatives to foley catheter insertion that can sometimes be used. These are non-invasive so they do not carry the same risks as causing infection. These are excellent solutions when the main issue is incontinence.

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Texas Catheter

Also called a condom catheter, this fits over a man’s penis that drains incontinent urine into a suction canister. 

An enlarged prostate and urinary retention

Purewick Catheter

This is the same concept but placed in incontinence women attached to suction. 

Choosing a catheter size

Just like IV sizes and gauges, foley catheters have specific sizes as well. For foleys, these sizes are called “French units”. Each french unit increases the size of the diameter of the catheter by 0.33mm

For most adult patients, a 14-16 Fr catheter is standard. If you are worried about obstruction from sediment, a larger size is better. If you are worried about blood clotting, a three-way may be a better option.

Neonatal
3.5 - 5 Fr
Pediatric
6 - 10 Fr
Adult
14 - 16 Fr
Three-way
20 - 24 Fr
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kangaroo nasogastric Tubing

Your facility may or may not have specific foley catheters for infants, depending on which facility and unit you work on.

Some units may use the purple kangaroo PVC nasogastric tubing to catheterize infants and toddlers.  These are also sized in French units, so using a 5 french is common. Make sure you are always following facility and unit protocols.

Foley Catheter insertion procedure

 

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Collect your Equipment

Make sure you have all of the required equipment for the procedure. This usually includes:

  • Foley catheter insertion tray
    • Foley Catheter connected to tubing & foley bag
    • Lubricant
    • Betadine swabs or solution/cotton swabs/forceps
    • Sterile gloves
  • Cath-secure device or tape
  • Sterile gloves
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Prepare the Patient

Make sure to explain the procedure and obtain verbal consent from the patient. Also verify there is an order (verbal or otherwise) to insert the foley.

Ask or help the patient remove everything from the waist down, and place them in a hospital gown. Position them supine.

If they are female, have them extend their legs in a “frog” position. Males can remain with relaxed legs.

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Pre-clean and pre-locate
It can be super helpful to clean the peri-area before setting up your equipment. You can do this with soap and water, or bath wipes depending on your facility’s protocol. This area is. notclean enough for most hospitalized patients, but this also gives you an opportunity to visually inspect and pre-locate the urethra.

“If you can find it clean, you won’t miss it sterile!”

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Lighting is Everything

Setting up for the actual procedure may be just as important as actually performing it. Make sure you have proper lighting in order to see where you need to go. If the room has one of those adjustable overhead lights, this would work perfectly.

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Set up your equipment

Wash your hands and open your foley kit, which is best placed in-between the patient’s legs. Open up the sterile drapes of the kit so you can have access to the sterile contents inside once you get sterile.

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Apply Sterile Gloves

Apply sterile gloves as this is a sterile procedure. This minimizes the risk of introducing pathogens into the patient’s bladder, which can cause infection.

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Extra Sterile Gloves

The foley tray kit usually comes with gloves, but these are small and not very stretchy, and often rip (especially for someone with larger hands).

This is where an additional pair of sterile gloves come in handy. You can choose your specific size, and these gloves are much stretchier and easier to maneuver (anyone else a 7.5?)

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PrEP Sterile Field

Once your sterile gloves are on, utilize the sterile drapes inside the kit to carefully place underneath the patient’s buttock, and place the fenestrated drape over their vagina/penis. Be careful not to touch the patient or bed with your sterile gloves. 

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Lubricate the Catheter

Remove the catheter from its plastic covering, and place it inside a sterile lube package. The lubricant will help glide the catheter into the urethra, and placing it in the package will help keep your catheter from flopping around.

Your kit may instead have a pre-filled syringe with lube. If so, this is squirted onto your sterile tray, and stick the catheter in the lube where it isn’t going to fly off.

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Attach Syringe to balloon port

Attach the 10mL pre-filled syringe to the balloon port on the foley.

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Testing the balloon?

It used to be standard practice to test the balloon by inflating. the full 10mL into the balloon and then allow it to flow back into the syringe. This is no longer recommended and has the potential to stretch and distort the catheter and lead to more trauma during insertion.

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Clean with Betadine

Using pre-packaged betadine swabs, or betadine and cotton swabs/forceps, gently cleanse the region surrounding the urethra.

In females, swab in one direction front to back on the left, then the right, and finally down the middle.

In males, swab in one direction around the left side of the glans, then the right, then down the middle. 

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Prepare for Insertion

Now that everything is ready, it’s time to get ready to insert the catheter.

In females, spread apart the labia with your non-dominant hand to better visualize the urethra and make sure nothing gets in the way.

In males, retract any foreskin and stabilize the penis between your rounded hand.

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Insert the Catheter

Insert the catheter into the urethra with steady force. Advance until you see urine in the tube. Once you do, advance a little more before blowing up the balloon.

A sterile gloved hand holding the vagina open, and inserting a yellow catheter inside the urethra. There is betadine surrounding the urethra and vulva.
A sterile gloved hand holding the penis, and inserting a yellow catheter inside the urethra. There is betadine surrounding the urethra.
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If at first you don't succeed...

If you meet resistance, do NOT try to apply more pressure and force it through. Remove it and consult the Provider/urology, as the patient’s prostate is likely enlarged or there are tracts or strictures.

In women, if you don’t see any urine backflow within about 5-6 centimeters, you are likely in the vagina. Do not reuse this same catheter as this will likely cause an infection. Leave the foley in place and get a new sterile kit to retry the procedure. Aim superior to this foley.

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Blow up Balloon

Steadily push the 10mL syringe to blow up the balloon. Inflating the ballon should keep it in place within the bladder.

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Retract the catheter

Gently pull back on the foley until light resistance is met. This is. to ensure the balloon is resting right at the bladder neck.

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Secure the Catheter

Secure the foley to the patient’s thigh using a cath secure, stat-lock, or tape. This is to ensure that the foley doesn’t get caught on anything or cause urethral trauma.

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Place Collection Bag

Place the collection bag below the level of the bladder but off of the floor. This prevents backflow which could lead to infection.

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Collect / Drain the Urine

Collect any urine that you may need and send it off to lab, otherwise measure and empty the urine, and document accordingly

How to Remove a Foley

Removing a foley should be quick and easy. Verify the order before doing so, or if the patient insists it be removed then remove it regardless (as long as they aren’t confused).

  1. Collect your equipment: You really only need an empty 10mL syringe.
  2. Unsecure the catheter: Remove the catheter from any cath-secure, stat lock, or tape that is securing it to the patient’s leg.
  3. Deflate the balloon: Hook an empty 10mL syringe to the balloon port and drain a full 10mL from the balloon. Remove the syringe.
  4. Remove: Gently pull on the catheter to remove it. There should not be any resistance.
  5. Dispose: Dispose of the foley catheter, tubing, and collection bag into a biohazard bag if possible.

Foley Catheter Assessment & Monitoring

Assessments of the catheter should be performed each shift along with your head-to-toe assessment. If there are any new or related symptoms or discomfort, this should be assessed more frequently.

The biggest thing to watch out for is signs and symptoms of a UTI, as foley catheters increase this risk.

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Urine

Assess the urine. Is it draining? What color is it? Is there any blood, pus, or sediment? 

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Skin

Is there any skin breakdown, erythema, or discharge near the insertion site?

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Tubing/Collection

Assess the tubing and collection bag, checking for any leakage. Make sure it is secure and in place, and that the collection bag always remains below the level of the bladder

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s/s of infection?

The main thing you are going to monitor for is the development of infection (UTI) and sepsis from the foley catheter. This is usually evidenced by fevers, tachycardia, and frequently altered mental status in the elderly hospitalized patients. 

Foley Catheter Insertion Complications

During and after foley catheter insertion, be on the lookout for complications that may occur. 

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Infection (UTI)

Infections are a common complication of UTIs. While common, UTIs can be severe and even kill patients, so preventing this is very important.

Using sterile technique is super important during the procedure to decrease the risk of infection. Also, make sure the collection bag remains below the level of the bladder at all times to prevent backflow.

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Epididymitis

Foley catheters can rarely lead to epididymitis in males and sometimes extend to orchitis (infection and pain of the testicle).

An enlarged prostate and urinary retention

Bladder perforation

While rare, catheters can cause a bladder perforation. If so, the patient will develop extreme pain, bloody urine, and signs of peritonitis (abdomen rigidity and rebound tenderness, etc). 

An enlarged prostate and urinary retention

Bladder stones

Bladder stones can form due to the presence of a foreign body within the bladder. This can lead to obstruction and pain.

Urea-splitting bacteria (like proteus mirabilis and Pseudomonas aeruginosa) are more likely to cause these stones. 

An enlarged prostate and urinary retention

Bladder fistula

A fistula is when a false passage forms between two different organs due to chronic inflammation, such as with a chronic Foley catheter. These are rare but can lead to significant complications, and infections, and will need surgery to fix it.

Foley Catheter Care

Managing a foley catheter after the foley catheter insertion is just one more aspect of the patient that you will need to care for. 

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Assessment

The foley should be assessed with each head-to-toe shift assessment. You should be monitoring for things as below. 

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Clean Meatus

Clean the insertion area with soap and water daily

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Ensure Tubing secure

To secure the tube in place and prevent any urethral trauma, secure the foley to the patient’s leg. Many facilities will have Cath secures, but basic medical tape can also be used instead. 

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Collection Bag

Keep the bag below the level of the bladder to prevent backflow. This should be drained often as well.

See if the patient is ordered I&Os, and chart how many mLs are emptied each time. 

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Collecting Urine

If a UA is ordered, you can now obtain and send this after the foley catheter insertion. 

Everything online will tell you NOT to use the collection bag to obtain urine samples, as they may be contaminated. But nothing seems to distinguish a foley that was just placed or one that has been already drained and in place for some time.

However, if you just put in the foley, the bag should still be sterile, so some nurses do consider this first urine as a sterile sample. Whether or not this is appropriate is unsure, but always follow your facility protocols.

The recommended method to collect urine from a foley is to clamp the foley and withdraw urine from the collection port with a needle and large syringe, then transfer the urine to a sterile specimen cup.

To learn how to actually interpret the UA results, you can check that out here!

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Routine Changing of Foley

There is no reason to change a foley catheter simply based on time. There is no evidence to support routine change, and it is not recommended by the ISDA or the CDC. Foley’s are often ordered to be changed if there is obstruction, it is not working correctly, there is infection, or if it is being discontinued altogether.

And now you know exactly how to place a foley like a pro! Let us know in the comments if you have any other helpful tips or questions!

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Urinalysis (UA) Interpretation

Urinalysis Interpretation

Everything you need to analyze the UA

A specific cup half filled with yellow urine

William Kelly, MSN, FNP-C

Author | Nurse Practitioner

Last Updated: August 29, 2022

Urinalysis or UA is a lab test frequently ordered in all types of medical settings: hospitals (ER, ICU, Inpatient floors), urgent cares, and outpatient offices. In many cases, the correct evaluation of the urinalysis is imperative to making an accurate diagnosis. To provide additional data, many labs perform urine microscopy, giving you exact details on the contents within the urine and quantifying the results. Read all about how to interpret the Urinalysis dipstick, as well as the urine microscopy in this article!

Initial Urine Assessment

Before you even run the urinalysis, you can tell quite a bit about the patient just by using your God-given senses.

Color

The color of the urine is the easiest way to determine someone’s hydration status. Surprisingly, it can indicate other aspects of health as well.

AMBER

Normal urine varies from very clear yellow to a darker amber color. Generally speaking, the less hydrated you are – the more concentrated your urine. The more hydrated you are, the more diluted the urine, leading to clear yellow urine.

The first void of the morning is typically darker and more concentrated – this is normal. 

Red or Pink

When we see red urine – we typically think of blood. Medical conditions such as kidney stones (nephrolithiasis), UTIs, glomerular damage, or even malignancy. As little as 1mL of blood can cause a color-change, and the presence of red urine does not automatically mean large amounts of blood. There are a few different causes of red urine:

  • Bloody causes: Cystitis, kidney stones, malignancy, trauma, menstrual contamination
  • Non-bloody Conditions: Rhabdo (from myoglobin)
  • Foods: Beets, Blackberries, and Rhubarb
  • Meds: Propfolol, Chlorpromazine, Ex-Lax

Orange

Causes or orange urine include:

  • Rifampin (Antibiotic for TB)
  • Pyridium or over-the-counter AZO

Blue or Green

Also very rare, blue or green urine may be caused by:

  • Conditions: Familial benign hypercalcemia, Pseudomonas infection
  • Medications: Propofol, Amitriptyline, Indomethacin,
  • Foods: Strong Food dyes

Purple

Termed “Purple Urine Syndrome” Or “Purple Urine Bag Syndrome”, this is very rare but can occur due to:

  • Conditions: UTIs with certain gram-negative bacteria with alkaline urine
  • Meds: Amitriptyline, Methylene Blue dye
  • Foods: Diet high in Tryptophan

Turbidity

Urine turbidity is how cloudy urine is. When we see cloudy urine, our first thought should be an infection which may be accurate. However, other causes of cloudy urine are cell casts or cellular debris from kidney damage.

Smell

Stronger-smelling urine tends to mean dehydration, but foul-smelling urine usually indicates infection. This odor is caused by the bacteria that split urea to form ammonia. 

Sweet-smelling urine may mean the patient is spilling glucose into the urine from hyperglycemia.

Lastly, If the urine smells like feces, a fistula might have formed somewhere between the GI tract and the Urinary tract.

Taste?

Nah I’m just kidding – but did you know they used to taste urine to detect glucose in the urine?…. GROSS!

Urinalysis dipstick

Once you’ve assessed the urine with your own senses, it’s time to assess the actual urinalysis. This can be done in the following ways:

  1. Dipping a dipstick in urine and assessing the colors next to a test strip color chart (usually printed on the dipstick bottle).
  2. Sticking the dipstick in an Automated Urine Analyzer. This will give you. a printout of the results.
  3. Send the urine off to the lab, where they will perform a urinalysis and upload the results to your electronic medical record. They will often perform microscopy if indicated, which can be used to help interpret the urine.

Glucose

Test Levels

When serum glucose spills into the urine – this is termed glucosuria. Typically, glucose in urine does not occur until the kidney glucose threshold is reached – which is around 180mg/dL. As you can tell, this can be useful for evaluating hyperglycemia in the setting of diabetes. However, periods of stress or fever have been known to cause small amounts of glucose within the urine as well, so glucose in urine does not automatically mean diabetes

Clinical Significance

  • Glucosuria can indicate hyperglycemia in undiagnosed diabetics when blood work is not obtained.
  • Fever or stress could cause mild glucosuria in non-diabetics
  • SGLT2 inhibitors like Farxiga can increase glucose in urine even without elevated glucose levels

Testing Considerations

 

  • Ascorbic Acid (vitamin C) has been known to cause false-negatives

    Bilirubin

    Test Levels

    Urinary bilirubin may be present in low amounts in the urine normally, but increased levels are due to abnormalities of bilirubin metabolism or liver function.

    Clinical Significance

    • The presence of bilirubin may indicate elevated LFTs, but overall does not seem to add significant information toward diagnosis.

    Testing Considerations

    • Must be sent immediately as bilirubin is unstable when exposed to light

      Ketones

      Test Levels

      Normal Levels: None ( 0.3 mg/dL or  0.05 mmol/L)

      Clinical Significance

      The presence of ketones in the urine (ketonuria) indicates ketosis. This is usually caused by uncontrolled diabetes or DKA. However, acute illness, stress on the body, strenuous exercise, nausea/vomiting, and keto or other low-carb diets can cause ketonuria to occur. 

      Testing Considerations

      • Parkinson’s medications (Levodopa) can cause a false positive

        Ascorbic Acid

        Test Levels

        Normally ascorbic acid is not seen in the urine dipstick.

        Clinical Significance

        Ascorbid acid is Vitamin C. The presence of this in the urine can lead to false negatives for both Heme, glucose, leukocyte esterase, and protein.

        Testing Considerations

        Some dipsticks do add a chemical to neutralize the effect of ascorbic acid on the other tests.

        Specific Gravity

        Clinical Significance

        The specific gravity indicates how dilute or concentrated the urine is. This can give the interpreter a pretty good idea of hydration status when looking at the urinalysis.

        Test Levels

        Normal Levels: 1.005 – 1.030

        Low (<1.005): May indicate diabetes insipidus, renal failure, pyelonephritis, glomerulonephritis, psychogenic polydipsia, or malignant hypertension

        High (>1.030): May indicate severe dehydration, hepatorenal syndrome, heart failure, renal artery stenosis, shock, or SIADH.

        Testing Considerations

        • Protein, ketones, and glucose, as well as recent IV contrast dye, can falsely elevate the specific gravity.
        • Medications like diuretics can also impact this (like lasix).

        Heme

        Clinical Significance

        Heme detects blood in the urine.

        There are many potential causes of hematuria including UTIs, kidney/glomerular damage, trauma, kidney stones, malignancy, vaginal contamination, or coagulopathies.

        In a patient over 50 years old who has persistent hematuria, malignancy should be ruled out. 

          Test Levels

          Normal Levels: Negative

          The test for heme is very sensitive and can detect down to 1-2 RBCs per High-powered field (HPF). So a negative dipstick excludes blood.

          Testing Considerations

          False Negative: Unlikely, but Ascorbic acid can lead to this

          False-Positives: Myoglobin (as during rhabdomyolysis), semen (recent ejaculation), alkaline urine >9.0, contamination from hemorrhoids, vaginal blood, or oxidizing compounds used to clean the perineum can all cause false-positive heme to occur in the urinalysis.

          A positive Heme requires urine microscopy for confirmation.

           

          pH

          Clinical Significance

          The pH of urine stands for the potential of hydrogen. The more hydrogen ions there are, the more acidic something is.

          The pH scale runs of 0-14, with lower numbers being more acidic, and higher numbers being more basic.

          Because the kidneys regulate your acid/base balance, any change within the body should show up in your urine. However, various different disease processes can interfere with your kidney’s ability to do this effectively.

            Test Levels

            Normal Levels: 6, but can range from 4.6 – 8

            Acidic urine <7.0 is associated with metabolic or respiratory acidosis or an E Coli UTI.

            Basic urine >7.0 is associated with most types of kidney stones, urea-splitting bacteria (proteus or klebsiella), renal tubular acidosis, or potassium depletion.

            Testing Considerations

            Diet: Cranberries and high-protein diets can cause acidic urine, whereas citrus fruits and low-carb diets can cause alkaline urine

            Medications: Sodium bicarbonate and thiazide diuretics can cause more basic urine

            Protein

            Clinical Significance

            The urine protein dipstick is specific for albumin, which is a type of protein. Any damage to the glomerular basement membrane will let albumin and other larger particles pass through the membrane and into the urine.

            Protein in urine is typically used to evaluate kidney damage in diabetics, people with Congestive Heart Failure (CHF), or other causes of kidney damage.

            Benign causes of high protein in urine include dehydration, emotional stress, fever, heat injury, inflammation, intense activity, acute illness, or an orthostatic disorder.

            All other causes of proteinuria involve the kidney – specifically the glomerulus or the renal tubules. Some common causes of glomerular proteinuria include Diabetic nephropathy, lupus nephritis, preeclampsia, various infections (HIV, hepatitis B, post-streptococcal glomerulonephritis), certain cancers, and certain drugs like Heroin, NSAIDs, and Lithium. Some causes of tubular proteinuria include interstitial cystitis, Sickle-cell, and nephrotoxicity from NSAIDs or antibiotics like aminoglycosides.

              Test Levels

              Normal Levels: Undetectable

              The urine normally has <150mg/day of protein and should be undetectable on a dipstick, but when this level exceeds 300mg/day, high protein in urine will show up on a dipstick.

              Testing Considerations

              Urinary concentration will impact the results, so correlate with the Specific Gravity. Very dilute urine can lead to underestimation of protein, and very concentrated urine can lead to overestimation.

              In general, the dipstick is a crude estimate, and evaluation by 24-hr urine specimen is the standard of care for ongoing proteinuria. If renal cause is found, a Nephrology consult is warranted.

              In the acute setting, the dipstick for protein isn’t too informative as acute illness, inflammation, stress, and dehydration are common presentations and can cause a temporary elevation in urinary protein. 

              Urobilinogen

              Clinical Significance

              Urobilinogen is a byproduct of bilirubin production, but unlike bilirubin is colorless.

              Elevated levels can indicate malaria, hemolytic anemia, liver disease, or internal bleeding.

              An increased urobilinogen level is one of the earliest signs of liver disease and hemolytic disorders.

                Test Levels

                Normal Levels: 0.1–1 Ehrlich U/dL or 1 mg/dL

                Testing Considerations

                NA

                Nitrites

                Clinical Significance

                Nitrates are present in the urine at baseline. Some species of bacteria, specifically the Enterobacteriaceae species (E. coli, Klebsiella, Proteus, Enterobacter, Citrobacter, and Pseudomonas), release an enzyme called nitrate reductase which converts urinary nitrate to nitrite, causing nitrites in urine.

                If negative, it really doesn’t mean much. If positive, then it is highly likely an infection is present.

                  Test Levels

                  Normal Levels: Negative

                  Testing Considerations

                  This reaction requires dwelling time within the bladder to occur. Urinary frequency or the presence of a Foley catheter can make this impossible. It can take up to 4 hours of dwelling before nitrites are detected.

                  A person might not intake a sufficient amount of nitrates in their diet.

                  False-Positives: Azo dye metabolites and bilirubin, as well as letting the urine sit for too long can produce false positives. Higher specific gravity reduces the sensitivity.

                  False-Negatives: Ascorbic acid can produce false-negative.

                  Leukocyte Esterase

                  Clinical Significance

                  Leukocyte esterase is a component of WBCs that is released when these white blood cells are lysed (split open).

                  The presence of leukocyte esterase supports the diagnosis of a Urinary Tract Infection (UTI). However, the presence can also indicate various autoimmune disorders, STDs, kidney stones, or intra-abdominal infections.

                  If there is no leukocyte esterase, infection is pretty much ruled out.

                    Test Levels

                    Normal Levels: Negative

                    Testing Considerations

                    False-Negatives: Proteinuria, glycosuria, excessively concentrated urine, or tetracycline.

                    False-Positives: Contamination with vaginal discharge, certain medications (ampicillin), salicylate toxicity, and strenuous exercise.

                    Urine Microscopy

                    Urine microscopy is when they look at the patient’s urine under a microscope and further characterize the presence of certain cells. 

                    Crystals

                    Crystals, as the name implies, are crystallizations within the urine. Crystals in urine can be normal as long as they are composed of substances normally found within the urine.

                    Crystallization can occur for a variety of reasons, and the type and quantity of these will depend on the urine’s pH and underlying cause. 

                    Amorphous Crystals

                    Amorphous crystals form naturally when urine cools, and are more often found in acidic urine. This is usually just some precipitation of electrolyte salts, and there is no clinical significance.

                    Uric Acid Crystal

                    Uric acid crystals are generally associated with gout. They can also be caused by kidney stones, tumor lysis syndrome, or chemotherapy

                    Calcium Oxalate

                    Calcium Oxalate crystals are usually found in acidic urine and associated with kidney stones. Dehydration and/or increased oxalate intake can cause this. Ingestion of antifreeze can also cause these.

                    Calcium Carbonate

                    Calcium carbonate crystals may be caused by too calcium supplementation, and is also associated with kidney stones.

                    Calcium Phosphate

                    Calcium phosphate crystals are more likely to precipitate in alkaline urine. This could rarely be caused by hypoparathyroidism. 

                    Triple Phosphate

                    Triple phosphate crystals, also called Struvite crystals, are made up of magnesium ammonium phosphate. These are typically found in alkaline urine and associated with kidney stones as well as UTIs with bacteria that split urea, like Proteus mirabilis and Pseudomonas aeruginosa.

                    Hippuric Acid

                    Hippuric acid crystals are rare but can be found in normal or acidic urine.

                    Cystine

                    Cystine crystals are found in acidic urine in patients with a genetic condition called cystinuria.

                    Microrganisms

                    Bacteria are NOT normally found in the urine as it should be a sterile environment. If found, it usually indicates infection or contamination.

                    A bunch of E coli bacteria swimming around

                    Bacteria

                    Bacteria multiply rapidly if the urine specimen is left standing for too long at room temperature.

                    If there are leukocyte esterase +/- nitrites present with <15-20 epithelial cells/HPF, then infection is highly likely.

                    Consider starting empiric antibiotics if symptomatic and obtain a culture and sensitivity for confirmation.

                    Cells

                    A bunch of E coli bacteria swimming around

                    Red Blood Cells

                    Normally there are less than 2 RBCs/HPF.

                    Microscopic hematuria is defined as the presence of at least 3 RBCs/HPF.

                    Microscopic hematuria confirms a heme+ dipstick.

                    A bunch of E coli bacteria swimming around

                    White Blood Cells

                    Normally there are less than 2-5 WBCs/HPF within the urine.

                    If >5 WBCS, this indicates possible infection, inflammation, or contamination.

                    Most of the WBCs found in the case of infection are neutrophils.

                    A bunch of E coli bacteria swimming around

                    Epithelial Cells

                    Squamous epithelial cells are the skin cell of the external urethra.

                    >15-20 epithelial cells/HPF indicates contamination and another urine sample should be obtained to rule out infection.

                    Casts

                    Casts are tube-like protein structures made of various cells. Low urine pH, low urine flow rate, and high urinary salt concentration promote cast formation by favoring protein denaturation and precipitation. The presence of casts, other than hyaline casts, represents pathology within the kidney itself.

                     

                    A bunch of E coli bacteria swimming around

                    Hyaline Casts

                    Hyaline casts can be present in normal healthy adults and are nonspecific.

                    They can be found after strenuous exercise or dehydration, as well as with diuretic use.

                    A bunch of E coli bacteria swimming around

                    RBC casts

                    RBC casts usually indicate glomerulonephritis or vasculitis.

                    A bunch of E coli bacteria swimming around

                    WBC casts

                    Uncommon, but when present is usually seen with tubulointerstitial nephritis and acute pyelonephritis but also seen with renal tuberculosis and vaginal infections.

                    A bunch of E coli bacteria swimming around

                    Muddy-Brown Casts

                    Muddy-Brown Granular casts are diagnostic of acute tubular necrosis, the leading cause of Acute Kidney Injury.

                    A bunch of E coli bacteria swimming around

                    Waxy Casts

                    Waxy casts are consistent with acute or chronic renal failure.

                    A bunch of E coli bacteria swimming around

                    Broad Casts

                    Broad casts are consistenet with advanced renal failure.

                    A bunch of E coli bacteria swimming around

                    Fatty Casts

                    Fatty casts indicate nephrotic syndrome.

                    A bunch of E coli bacteria swimming around

                    Renal Tubular Epithelial Casts

                    Renal tubular epithelial cells are seen in acute tubular necrosis, interstitial nephritis, and proliferative glomerulonephritis.

                    Urinalysis UA interpretation Infographic