This test is done to look for protein, crystals, blood, nitrites and white & red blood cells in the urine. There are two types of urinalysis, namely urine chemical dipstick analysis and microscopic urinalysis. Urine chemical dipstick analysis is a fast way to look for any urinary abnormality stated above. It can be interpreted instantly in the clinic and it is cheap and quick to do. The limitation of a dipstick test is that abnormalities in the urine cannot be quantified. The advantage of microscopic urinalysis is that abnormalities can be quantified to help diagnose and manage the condition, but its limitation is the turn-around time, which usually takes 1 to 1½ hours for results to be available.
Urine chemical dipstick analysis
The urine produced by the body has a
pH value of between 6.0 to about 7.4. However, depending on the body’s metabolic needs, urinary pH may range from as low as 4.5 to as high as 8.0.
Specific gravity indicates the ability of the kidneys to concentrate or dilute the urine compared to that of blood plasma.
Dipstick screening for
protein is done on whole urine, and is used as a screening tool for urinary tract infections, kidney diseases etc. Proteins may also be found due to contamination from vaginal discharge.
nitrite test indicates that bacteria may be present, indicating a urinary tract infection. Bacteria such as Escherichia coli are more likely to give a positive test. This will require a urine culture and sensitivity examination to confirm a urinary tract infection.
leukocyte esterase test indicates the presence of white blood cells, and is suggestive of a probable bacterial urinary tract infection.
A urine sample is spun down to collect the solid material, which is examined under the microscope to identify crystals, casts, bacteria, blood cells, squamous cells and other cell types. The following descriptions are some significant microscopic observations.
Haematuria is the presence of
red blood cells in urine and is associated with disease; such as urinary tract infection, kidney or bladder stones, and cancerous growth of the kidney or bladder. Red blood cells may clump together to form red cell casts or stones, which usually indicate a kidney disease such as glomerulonephritis.
White blood cells may appear with infection in either the upper or lower urinary tract or with kidney diseases like acute glomerulonephritis. White blood cells from the vagina, especially in the presence of vaginal and cervical infections, may contaminate the urine.
Renal tubular epithelial cells normally slough into the urine in small numbers. However, with kidney diseases like nephrotic syndrome and in conditions leading to kidney tissue damage, the number of these cells is increased.
Transitional epithelial cells line the collecting system of the kidneys, ureters, bladder and the urethra. Abnormal-looking transitional epithelial cells may indicate cancerous change.
Squamous epithelial cells from the skin surface or from the outer urethra can appear in urine. Excessive numbers represent possible contamination of the specimen from cells and bacteria found on external skin surfaces.
Urinary casts & crystals
When present on microscopic evaluation,
urinary casts hold medical significance. Although the most common forms are benign, other forms are indicative of certain types of kidney disease. Hyaline casts, granular casts and waxy casts are all different types of casts that can be found in urine specimens. They can occur in situations like dehydration, after vigorous exercise, underlying chronic kidney disease and renal failure
Common crystals are seen in healthy patients, and they include calcium oxalate, triple phosphate and amorphous phosphate crystals. Uncommon crystals include cystine crystals in patients with congenital cystinuria or severe liver disease, tyrosine crystals in patients with congenital tyrosinosis or marked liver impairment, and leucine crystals in patients with severe liver disease or with maple syrup urine disease. These are the crystals of clinical significance and should be paid due attention when they are observed in urine specimens.
*Urinalysis should not be performed if the patient had her periods, sexual intercourse or Pap smear in the past 5 to 7 days to avoid contamination of the urine.
Urine culture is performed when urinary tract infection is suspected. This test aims to identify the organism responsible for the infection and the sensitivities to a range of antibiotics are tested in order to identify the most suitable antibiotic to treat the infection.
Bacteria are common in urine specimens because of the abundant normal microbial flora of the vagina and urethral opening and because of their ability to rapidly multiply in urine standing at room temperature. Therefore, microbial organisms found in all but the most scrupulously collected urines should be interpreted in view of clinical symptoms. Diagnosis of suspected urinary tract infection requires bacterial culturing and antibiotic sensitivity testing. Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Neiserria gonorrhoeae are some of the organisms that can cause urinary tract infections.
Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and
Neiserria gonorrhoeae are some of the organisms that can cause urinary tract infections.
Yeast cells may be contaminants or they may represent a true yeast infection. The commonest is
Candida albicans, a common culprit causing vaginal candidiasis (fungal infection), which may colonise the bladder, urethra, or vagina.
Urine phase contrast
Urine phase contrast is performed to identify the source of blood in patients with haematuria (blood in urine). A high percentage of dysmorphic red blood cells suggests that the source of blood may be originating from the upper urinary tract, such as the kidney. Referral to a kidney specialist may be required in such cases. A high percentage of isomorphic red blood cells suggests that the source of blood may be originating from the lower urinary tract, such as the bladder. Further investigations with cystoscopy and CT scan may be required to ascertain the cause.
Urine cytology is performed to identify any cancerous cells in the urine that may account for the patient’s symptoms. It is common to perform this test in patients who have haematuria (blood in urine), recurrent urinary tract infection, or overactive bladder not responding to conventional treatment.
Erect stress test
The patient is required to remove her clothing from the waist down and cough vigorously in a standing position onto a pre-weighed absorbent sheet to demonstrate urinary leakage and quantify the amount of leakage.
Urodynamic studies are a group of tests to assess how the bladder and urethra control the storage and release of urine. Urodynamic tests help your doctor or nurse explain symptoms such as:
Preparing for the test
Please drink some water, and come for assessment with at least a half-full bladder.
Types of urodynamic tests
1) Uroflowmetry (measurement of urine speed and volume)
A uroflowmeter automatically measures the amount of urine and the flow rate, i.e. how fast the urine is expelled. You will be asked to urinate into a toilet that contains a collection device and scale. A computer generated graph shows changes in flow rate from second to second so the doctor can see the peak flow rate and how many seconds it took to complete urination. Results of this test will be abnormal if the bladder muscle is weak or urine flow is obstructed.
2) Measurement of post-void residual urine (amount of urine remaining in the bladder after urination)
After you have emptied your urine, you may still have some urine remaining in your bladder. To measure this post-void residual urine, the nurse may use a catheter which is gently inserted into the urethra to measure the amount of residual urine or perform the measurement using ultrasound. A post-void residual urine of more than 50 ml requires further evaluation.
3) Cystometry (measurement of bladder pressure)
A cystometrogram measures how much urine your bladder can hold, the amount of pressure that builds up inside your bladder as it stores urine, and the amount of urine in your bladder which causes you to have the feeling of urge to urinate. The nurse will use a catheter to empty your bladder completely. A fine catheter will then be inserted into the bladder and another placed in the rectum to record pressures in both areas. Your bladder is slowly filled with sterile water. During this time, you will be asked how your bladder feels and when you feel the need to urinate. The volume of water and the bladder pressure will be recorded. You are asked to cough or strain during this procedure to identify a variety of bladder conditions, such as stress urinary incontinence. The procedure is generally well tolerated by patients.
4) Urethral pressure profile (UPP)
The UPP is done as part of cystometry to assess the pressure along the urethra and to locate any obstruction. During the procedure, a special probe is inserted into the urethra, and the probe withdrawn slowly to measure the peak urethral pressure. This test is useful to determine the severity of incontinence and it can help the doctor determine the right treatment for your urinary incontinence.
5) Pressure flow study
At the end of cystometry, you will be asked to empty your bladder. Measurements of the bladder pressure required to urinate, and the flow rate that a given pressure generates are recorded. This pressure flow study helps to identify bladder outlet obstruction, which can occur with a prolapsed bladder, a weakened bladder which cannot contract adequately, a urethral stricture or rarely after a surgical procedure for urinary incontinence.
6) Electromyography (measurement of nerve impulses and muscle contractions)
If your doctor or nurse thinks that your urinary problem is related to nerve or muscle damage, you may be asked to undergo an electromyography test. This test measures muscular contraction in and around the urethral sphincter by using special sensors. The sensors are placed on the skin near the urethra and rectum. Muscle activity is recorded on a machine. The patterns of the impulses will show whether the messages sent to the bladder and urethra are coordinated correctly.
*Time for completion of a typical urodynamic study is approximately 30 minutes.
What is ultrasound?
Ultrasound is a high frequency sound emitted and detected by specialised equipment that generates an image of the organ(s) of interest.
What does an ultrasound scan involve?
You will be asked to lie down and an operator will place a probe on your skin, over the part of your body to be examined. Lubricating jelly will be put on your skin so the probe makes good contact with your body. The ultrasound waves are projected through the various structures in the body; and the probe detects the returning echoes which are analysed by the machine. Information is displayed as a picture on the monitor in real-time, so detailed assessments can be made.
What is an ultrasound test used for?
We use ultrasound in urogynaecology to examine the pelvis, bladder, kidneys, ureters and the female reproductive organs, such as the cervix, uterus, fallopian tubes and ovaries.
What are the different routes of doing an ultrasound in urogynaecology?
Ultrasound can be performed on the abdomen (trans-abdominal scan), as well as in the vagina (trans-vaginal scan). Trans-vaginal scan is only performed on patients who have prior sexual intercourse. The benefit of performing a trans-vaginal scan is that the organs of interest are close to the probe and therefore will provide clearer and better assessments.
What should I do to prepare for the test?
You should have a full bladder for trans-abdominal scans. You should eat and drink normally before and after the test unless otherwise instructed. If you are on regular medications, you should continue them as usual.
*Time for completion of scan is approximately 5 to 30 minutes
A Pap smear is a screening test to check for changes in the cells of your cervix, such as pre-cancer and cancerous changes. It is a simple procedure where cells are collected from your cervix and sent to a laboratory where they are examined under a microscope to look for cellular abnormalities and changes. All women aged between 25 and 69 years, with a past history of sexual intercourse, are advised to have a Pap smear done once every one to three years.
Cystoscopy is a procedure that allows your doctor to examine the lining of your bladder and the tube that carries urine out of your body (urethra). This is usually performed in operating theatre under local anaesthesia. A cystoscope attached to a camera is gently inserted into the urethra and slowly advanced into the bladder to look for abnormalities that may explain your urinary symptoms. Biopsy of abnormal areas in the bladder lining can be performed at the same time. Conditions such as haematuria (blood in urine), overactive bladder, painful urination and recurrent urinary tract infection are the commonest indications for performing a cystoscope. Through this procedure, bladder diseases such as bladder cancer, bladder stones and bladder inflammation can be identified.
CT urogram is an imaging examination of the entire urinary tract. CT uses X-rays to generate multiple images of a slice of the area in your body being studied. These images are then reconstructed using a computer to generate detailed images. It is useful in patients who present with haematuria (blood in urine) and recurrent urinary tract infection. During the scan, an X-ray dye (contrast solution) is injected into a vein in your hand or arm in order to outline your kidneys, ureters and bladder well. Diseases such as urinary stones and urinary tumours can be identified using this imaging test.
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