Generality
Urinary cytology is an examination that shows the presence of "abnormal" cells in the urine .
This analysis is useful, in particular, in the diagnosis of tumors of the urinary tract, since it allows the identification of the corpuscles deriving from the exfoliation of the most superficial areas of some neoplastic formations.
In fact, urine is usually devoid of cellular elements. In some cases, however, during the transit in the urinary tract - that is, from the renal pelvis to the urethra - this fluid can collect any cells that derive from the desquamation of the urothelium.
Note : the urothelium (or urinary epithelium) is the epithelial tissue that internally covers the bladder, the ureters, the renal basins and the urethra.
Urinary cytology involves the microscopic observation of urine, after the panoptic staining of the sample. In the presence of a positive result, the patient will have to undergo further investigations (laboratory tests or diagnostic procedures).
What's this
Urinary cytology consists of the microscopic analysis of a urine sample, in order to identify any cells present . Usually, this analysis is indicated by the doctor if blood ( hematuria ) is found with the standard urine test.
Based on the suspected diagnosis of neoplasia, urinary cytology is prescribed in combination with appropriate investigations, to confirm or rule out the presence of a tumor of the bladder or other organs of the urinary tract.
Urinary cytology is not a "routine" analysis (ie it is not performed as a first check), but is indicated by the doctor only when one of the values measured with standard urine tests does not fall within the normal range. The cytological examination is considered, in fact, a deepening test, in the same way as urine culture or the determination of urinary albumin.
Why do you run
Urinary cytology is a non-invasive test that shows in the urine the presence of atypical or neoplastic urothelial cells . The latter result from the exfoliation of the superficial part of some forms of urinary tract cancer.
Therefore, urinary cytology helps to diagnose bladder cancer and can signal the presence of neoplastic or inflammatory diseases affecting the kidney, ureter, urethra and prostate .
When is the exam indicated?
- The doctor may indicate the cytological examination of urine when he suspects the presence of a neoplasm of the urinary tract .
- Usually, urinary cytology is prescribed when the standard urine test shows the presence of red blood cells or hemoglobin . In these cases, in fact, it is necessary to exclude the presence of diseases affecting the kidneys, ureters and bladder that can cause bleeding (hematuria). Neoplasms are also among these pathological processes.
- Urinary cytology may also be indicated to monitor patients already treated for bladder or urinary tract cancer (" follow up "). In these cases, urinary cytology can be useful in recognizing an early recurrence of the disease.
Normal values
Under normal conditions, neoplastic cells (ie tumors) are absent in the urine.
- Urinary cytology - Normal value : negative.
High Values - Causes
The presence of urothelial cells in the urine may indicate the presence of an inflammation of the urinary tract, as can happen, for example, in case of infections or calculosis.
The finding of atypical or neoplastic cells in a urine sample may signal the development of a neoplasm, often attributable to a specific organ of the urinary tract, including:
- Bladder cancer;
- Ureter tumor;
- Urethral tumor;
- Kidney tumor;
- Prostate cancer.
The reappearance of tumor cells in patients undergoing post-treatment monitoring may indicate the development of metastases or the resumption of the disease.
Low Values - Causes
Normally, tumor cells are not detected on cytological examination of urine.
How to do it
Urinary cytology is a laboratory test that involves the microscopic analysis of cells emitted with urine. This investigation is possible after having carried out a particular procedure which is called " panoptic coloring ".
If cytological abnormalities are shown to be present, the doctor may consider the characteristics of neoplastic cells and any associated disorders, such as abdominal pain, urination disorders and fever.
Preparation
Urinary cytology involves the collection of a urine sample, for three consecutive days . Urine must be collected in a special sterile container, in which a fixative is already present (normally, it is ethyl alcohol or trichloroacetic acid).
The first morning urine should not be used for urinary cytology, as degenerated cells frequently accumulate during the night-time filling of the bladder which could influence the interpretation of the result.
For this reason, it is better to carry out the collection of the second morning urination, preferably the central part of the emission ("intermediate mitto").
How to collect the urine sample
To ensure the reliability of the result it is very important to collect the urine to be examined correctly.
- Before harvesting, a thorough washing of the external genitals must be carried out, carefully rinsing to eliminate all traces of intimate detergent.
- The sterile container for urinary cytology is supplied directly from the laboratory or is purchased at the pharmacy.
- The samples must be carefully closed and must be delivered within a short time (at the latest within an hour of collection) to avoid degenerative processes. If this is not possible, urine should be stored in the refrigerator and the three samples should be delivered only on the third day. In any case, it is advisable to carefully follow the instructions of the doctor or the reference laboratory.
Interpretation of results
Usually, in relation to the presence of a tumor, the result of urinary cytology is reported as:
- Negative : only normal urothelial cells are identified.
- Positive : in the sample, undifferentiated cells were found with certainty, ie with tumor appearance.
- Doubt : presence of atypical cells (ie different from normal urothelium), but not identifiable with certainty as malignant.
If the result is negative
It should be noted that a negative result after urinary cytology does not exclude the presence of a tumor (the negative predictive value of the cytological examination is not high).
The low sensitivity of this analysis derives from the fact that the desquamation of tumor cells is absent or very poor in the presence of poorly developed urothelial neoplasms. The possibility that the test is positive is higher, however, in the presence of large or particularly aggressive tumors.
Based on these considerations, the patient in whom the clinical suspicion for a urinary tract cancer is present should consult the specialist, for carrying out the appropriate diagnostic investigations, such as cystoscopy or computed tomography (CT).
If the result is positive
The reliability of urinary cytology in the presence of a positive result is, on the other hand, high (if the medical staff is an expert, the specificity of the cytological examination exceeds 90%).
In the presence of a positive result, the patient must undergo second-level examinations such as cystoscopy, contrast-based CT, multiple bladder biopsies (bladder mapping) and / or ureterorenoscopy (URS). Sometimes, it is also possible to analyze the alterations affecting the chromosomes of urothelial cells using the FISH technique (fluorescent in situ hybridization).
If the result is doubtful
A doubtful result from urinary cytology may indicate the development of a neoplasm with a low degree of malignancy or the presence of an inflammation of the urinary tract (eg infections or calculosis).
The finding of atypical cells in patients with inflammatory urinary symptoms requires the repetition of the cytological examination after adequate medical therapy.
Limitations
Cytological examination of urine is characterized by a high percentage of false negative results: in about 50% of cases it cannot detect the presence of neoplastic cells. In particular, urinary cytology may not detect small tumors of the urinary tract that grow more slowly.
Some false positives can occur, instead, in the presence of bladder inflammations with the response of reactive cells, which, in some cases, can resemble those of cancer.
