What are the main sources of error in the microscopic examination of urine?
OverviewWhat is a urinalysis?A urinalysis (also known as a urine test) is a test that examines the visual, chemical and microscopic aspects of your urine (pee). It can include a variety of tests that detect and measure various compounds that pass through your urine using a single sample of urine. Show
Healthcare providers often use urinalysis to screen for or monitor certain common health conditions, such as liver disease, kidney disease and diabetes, and to diagnose urinary tract infections (UTIs). While several different aspects of your health can be tested with a urine sample, your healthcare provider will choose which tests to order under a urinalysis depending on your symptoms and situation. What tests are included in urinalysis?Your healthcare provider can include several different tests in a urinalysis. Depending on your symptoms, existing health conditions, and/or situation, your provider will choose which urine tests to order under a urinalysis. In general, a healthcare provider or laboratory technician can examine a urinalysis urine sample for the following broad aspects:
Urine color and appearanceFor most urinalysis tests, a healthcare provider examines how the urine sample looks to the “naked eye.” They check if it’s clear or cloudy and if it’s pale, dark yellow or another color. Normal urine color is usually some shade of yellow and can range from colorless or pale yellow to deep amber, depending on how concentrated or diluted (watery) your urine is. Many things can affect the color of your urine, including certain medications and supplements and certain foods you eat, such as beets. However, an unusual urine color can also be a sign of disease. For example, red-colored urine can happen when blood is present in your urine and can be an indicator of disease or damage to a part of your urinary system. Cloudy urine doesn’t always indicate unhealthy urine. For example, sperm and skin cells are harmless and could make your urine appear cloudy. Other substances that can make your urine cloudy, such as red blood cells, white blood cells and bacteria, may indicate several different medical conditions, including:
Urine chemical findingsTo examine chemical aspects of a urine sample, healthcare providers or lab technicians often use special test strips called dipsticks to test for certain chemical substances in the urine sample. The strips have pads of chemicals that change color when they come in contact with specific substances. The degree of color change on the dipstick can give an estimate of the amount of substance present. For example, a slight color change in the test pad for protein may indicate a small amount of protein present in the urine sample, whereas a deep color change may indicate a large amount. Common types of tests that use a dipstick that providers may include in a urinalysis include:
Urine microscopic findingsA lab technician may examine a urine sample under a microscope to look for tiny substances in the urine, including:
Microscopic tests that providers may include in a urinalysis include:
Why do I need urinalysis?Healthcare providers order urinalysis tests for several reasons since a urine sample can provide many insights into your health. Your provider may order a urinalysis for you for one or more of the following reasons:
How common are urinalysis tests?Urinalysis tests are very common. They’re a simple and non-invasive way to check several different aspects of your health. What’s the difference between urinalysis and a urine culture?A urine culture involves growing bacteria from a urine sample in a lab to diagnose urinary tract infections and other infections. Urine cultures are not part of routine urinalysis tests. Like a urinalysis, a urine culture sample must be obtained by the clean catch method or by inserting a catheter through the urethra into the bladder. If your urinalysis results indicate a UTI is likely, your healthcare provider may order a urine culture for a laboratory to run off the urine sample you gave for the original urinalysis. A urine culture can determine the type of bacterium that caused the UTI. Urinalysis can include several different tests, measurements and assessments of aspects of your urine. Test DetailsHow do I prepare for a urinalysis?Before your urinalysis test, you’ll need to make sure you’ve drunk enough liquids, such as water, to be able to go to the bathroom and produce a urine sample. Depending on the reason for the urinalysis, your healthcare provider may want the urine sample to be the first time you pee in the morning (first morning void). Your provider will let you know if this is the case. Certain medications can change the color of your urine. Your healthcare provider may tell you to stop taking certain medications that can affect urinalysis test results. Only stop taking medications if your provider tells you to do so. If you’re menstruating (on your period), it’s important to let your provider know before collecting your urine sample. Menstrual blood, as well as vaginal discharge, can interfere with certain urinalysis test results. What can I expect during a urinalysis?In most cases, you’ll perform a urinalysis at your healthcare provider’s office or at a laboratory using the “clean catch” method, which is intended to help prevent contamination of your urine sample with cells from your genitals. You or your healthcare provider can also collect a urine sample using a catheter. For the clean catch method, your provider will give you a specimen cup, sterile wipes and specific instructions for collecting your urine sample. Your provider will tell you what to do with your urine sample after you’ve collected it. It’s important to wash your hands with soap and water before you collect the sample. Collecting a clean catch urine sample if you have labiaIf you have labia, use the following steps to get a clean catch urine sample:
Collecting a clean catch urine sample if you have a penisIf you have a penis, use the following steps to get a clean catch urine sample:
Collecting a urine sample with a catheterYou or a healthcare provider can also collect a urine sample with a catheter using the following steps:
What should I expect after urinalysis?Once you've collected your urine sample, your healthcare provider will send it to a laboratory for testing and viewing under a microscope. In some cases, your provider may examine the sample immediately and run dipstick tests on it. Are there any risks to urinalysis?The clean-catch method of urine sample collecting for a urinalysis doesn’t have any risks. It’s a painless and non-invasive test. If you or your provider use a catheter to collect a urine sample for a urinalysis, there’s a risk of infection. It may also cause pain or discomfort. When should I know the results of my urinalysis?In most cases, it’ll take one to two business days to get your urinalysis results back. Results and Follow-UpHow do I read my urine test results?Depending on which tests your healthcare provider ordered for your urinalysis, there may only be a few or several measurements on your test results. Laboratory reports, including urinalysis reports, usually provide the following information:
Urine clarity refers to how clear your urine sample was. Most laboratories categorize the clarity of urine as one of the following:
If you had a chemical urine test, such as a glucose urine test or nitrite urine test, the results may be categorized as negative or positive and/or indicate the amount of the substance. If you had a microscopic urine test, such as one that checked for red blood cells (RBC) or bacteria, the laboratory will likely categorize the number (results) of the substance as one of the following:
What do the results of a urinalysis mean?Urinalysis results can have several interpretations due to the variety of tests. Abnormal results may indicate — but not necessarily guarantee — that there’s a medical issue. In most cases of abnormal urinalysis results, you’ll need further testing, such as blood tests or imaging tests, in order for your healthcare provider to diagnose a condition. In general, the greater the concentration or level of the atypical substance, such as high levels of glucose or red blood cells, the more likely that there’s a medical condition that needs treatment. Again, providers rarely use urinalysis tests alone to diagnose conditions. Instead, urinalysis results can provide helpful insight and help point providers in the right direction toward a diagnosis. If you have questions about your results, don’t be afraid to ask your provider. Should I be concerned if I have an abnormal result on my urinalysis?If one of your urinalysis test results is abnormal, it doesn't necessarily mean that you have a medical condition. Several factors can affect or interfere with urinalysis test results, including:
Your healthcare provider will consider your medical history, current medications and your results and let you know if you need to repeat the test or undergo further testing. When should I call my doctor?If you notice any changes in your urine, such as a persistent change of color, odor or consistency, contact your healthcare provider. If you’re experiencing symptoms of a urinary tract infection (UTI), such as a strong, persistent urge to urinate, and/or a burning sensation when urinating, contact your healthcare provider or go to an urgent care facility. A note from Cleveland Clinic A urinalysis is a helpful and common test that can give insight into several aspects of your health. Know that having an abnormal result for one of your urinalysis tests doesn’t necessarily mean you have a medical condition. Many factors can affect your results. Your healthcare provider will let you know if you need to undergo further tests to determine the cause of the abnormal level. Don’t be afraid to ask your provider questions. They’re there to help you. What are some factors which can affect the results of urinalysis?Several factors can affect or interfere with urinalysis test results, including: Certain medications and supplements, such as metronidazole and vitamin C supplements. Contamination of germs or other substances, such as vaginal discharge or menstrual blood, during the urine sample collection.
What is the most common contaminant in urine specimens?The two most common sources of contamination in urine from young children are faeces and skin. E. coli and enterococci are common faecal organisms and as such would be represented highly in contaminated urines; however, E. coli is also the most common cause of UTI.
What causes a urine sample to be contaminated?If the urine is not collected in a sterile manner the urine sample may be 'contaminated' by bacteria that originate from the skin or genital area, and not from the urinary tract. This is often described by the clinical laboratory as 'mixed growth bacteria'.
What abnormalities in the urine may be detected on a microscopic exam?The results of a microscopic urinalysis may point to a urinary tract infection (UTI), kidney problems, a metabolic disorder such as diabetes, or a urinary tract injury. If test results are abnormal, other tests may be needed before a definite diagnosis can be made.
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