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8.2 List some of the advantages and disadvantages of different urine specimen types.Voided urine
Advantages:
- Non-invasive
- Good as first-line screening for suspected bladder cancer
- Simple for patient
- Generally inexpensive
Disadvantages:
- Low cellularity
- Prone to degeneration
Catheter urine
Advantages:
- High cellularity
Disadvantages:
- Invasive procedure
- High cellularity (instrumentation artefact)
- Degenerative changes
Ileal conduit
Advantages:
- Important for follow-up of patient after cystectomy
Disadvantages:
- Poor preservation
- Requires very careful screening
Bladder washings
Advantages:
- High cellularity
- Cells well preserved
Disadvantages:
- Invasive procedure
- High cellularity (instrumentation artefact)
Brushings
Advantages:
- High cellularity
- Useful for selective samples of lesions
- Well preserved samples
Disadvantages:
- Challenging morphology
8.3 List some advantages and disadvantages of methods employed in sample processing.
|
|
Advantages |
Disadvantages |
|
Centrifugation and direct preparation |
Quick. Requires very few consumables. |
Cells could be spread over a large area, increasing screening time. Cellularity could be low. |
|
Cytocentrifugation and large volume cytocentrifugation |
Less time-consuming to screen and interpret, because the cells are limited to a defined area. Cell presentation and preservation good. |
More time-consuming to prepare than direct preparations. |
|
Liquid based cytology |
Less time-consuming to screen and interpret, because the cells are limited to a defined area. Cell presentation and preservation good. |
More time-consuming to prepare than direct preparations. |
8.4 List cells that may be seen in a normal urine sample.
Depending on collection method, normal urine may include: Superficial, intermediate, basal urothelial cells, and squamous cells. In men, in addition, seminal vesicle cells, spermatozoa, and prostatic epithelial cells may also be seen. In women, glandular cells from the female genital tract may also be present. An ileal conduit sample may also include degenerated intestinal epithelial cells.
8.5 What is the significance of calculi to the cytologist?
Urinary calculi can form anywhere in the urinary tract, most commonly in the renal pelvis. Some calculi may remain in the renal pelvis, but some may pass down the ureters. When this occurs they cause exfoliation of large numbers of cells. Some of these cells may shed in clusters which appear papillary. The calculi may also cause severe infl ammatory changes in urothelial cells, which results in hyperchromasia and may lead to a false positive diagnosis of urothelial carcinoma.
8.6 What are the risk factors for urothelial neoplasms?
- Smoking tobacco
- Aromatic amines
- Phenacetin
- Cyclophosphamide
- Schistosoma hematobium
8.7 List some of the iatrogenic changes that a cytologist reporting urine samples should be aware of to avoid a false positive diagnosis.
- Unusual exfoliation pattern produced in catheter sample
- Changes due to chemotherapy, e.g. cyclophosphamide Radiation changes:
- Changes due immunotherapy with BCG
- Cells changes encountered in ileal conduit samples