PROCESSING OF LABORATORY SAMPLES IN CYTOLOGY
PREPARED BY MR. ABHIJIT DAS
PROCESSING OF SPUTUM
Sputum processing in cytology is performed to examine
respiratory cells for infections, malignancies, or other lung diseases. Here’s
the general process:
1.
Collection:
o Sputum
is best collected in the morning
when mucus is more concentrated.
o Patients
cough deeply to bring up mucus from the lungs, which is then stored in a sterile
container.
2.
Fixation:
o The
sample can be fixed immediately with a solution like Saccomanno’s fixative (ethanol with polyethylene glycol), which preserves
cells and prevents degradation.
3.
Preparation:
o Direct
Smear: A thin smear is made on a slide, air-dried for stains like
Giemsa or fixed
with alcohol for Pap staining.
o Concentration
Techniques: Sputum may be centrifuged to concentrate cells for better
examination.
4.
Staining:
o Papanicolaou
(Pap) Stain is commonly used to visualize cell
morphology.
o Giemsa
Stain is used when examining for infections, inflammatory
cells, or specific pathogens.
5.
Microscopic Examination:
o The
stained slide is examined under a microscope to identify abnormal cells,
pathogens, or inflammatory markers, aiding in diagnosing lung conditions.
PROCESSING OF BODY FLUIDS
1. Urine Cytology Processing:
- Collection:
Fresh midstream urine is collected to minimize contamination. Early morning samples are
often avoided as they may contain degenerative cells.
- Preparation:
Urine samples are often centrifuged
at low speed to concentrate cells. The sediment (cell pellet) is then
smeared onto a slide.
- Fixation:
After smearing, slides are fixed in 95% ethanol or a spray fixative for
Papanicolaou (Pap) staining.
- Staining:
Pap stain is
commonly used for urine samples to assess cell morphology.
2. Lavage Fluid Processing (e.g.,
Bronchoalveolar Lavage or Peritoneal Lavage):
- Collection:
Lavage fluids are obtained by instilling saline into a body cavity (e.g.,
lungs, abdomen) and then aspirating it back.
- Concentration:
The fluid is centrifuged to concentrate cells.
- Smearing
and Fixation: The cell pellet is smeared on
slides and fixed with 95% ethanol for staining.
- Staining:
Pap stain or Giemsa stain may be used to help visualize inflammatory
cells, pathogens, or abnormal cells.
{Lavage fluid is a liquid
used to wash out or rinse a body cavity or organ}
3. Millipore Filtration in Cytology:
- Purpose:
Millipore filtration is a method used when fluid samples contain very few cells,
such as cerebrospinal fluid (CSF) or urine
in low-concentration cellular samples.
- Procedure:
- The
fluid sample is passed through a Millipore filter with a specific pore
size.
- Cells
are trapped
on the filter’s surface, which is then placed onto a glass slide.
- Fixation
and Staining: The filter can be directly fixed followed
by staining to visualize the cells.
- Application: This technique enhances cell recovery from low-cellularity fluids, making it useful for detecting rare cells in samples like CSF or urine.
PROCESSING OF HAEMORRHAGIC
FLUID
Steps in Processing Hemorrhagic Fluids:
1.
Collection:
o The
fluid is collected in a sterile
container, often with an anticoagulant (e.g., heparin) to prevent clotting.
2.
Centrifugation:
o Hemorrhagic
fluids are usually centrifuged
to concentrate the cells, separating red blood cells from other cellular
components.
o After
centrifugation, the supernatant is removed, and the cell pellet is used for slide
preparation.
3.
Red Blood Cell (RBC) Lysis:
o Some
labs treat the sample with an RBC lysis solution (e.g., ammonium chloride) to reduce the number of red
blood cells, enhancing
the visibility of diagnostic cells like inflammatory cells, or malignant
cells.
4.
Smear Preparation:
o A thin smear of the cell pellet is made on a slide.
5.
Fixation and Staining:
o Slides
are typically fixed in 95% ethanol and stained with Papanicolaou
(Pap) stain or Giemsa stain to differentiate cell types and
highlight abnormal cells.
6.
Microscopic Examination:
o The
processed slides are examined under a microscope to identify cell types (e.g.,
inflammatory cells, mesothelial cells, or malignant cells) and detect any
abnormalities.