Clinical Laboratory – CDT04209 CLINICAL LAB SESSION 2 PART TWO
Read the complete lesson in an organized slide-by-slide format. This topic contains 58 learning sections from the source presentation.
LESSON CONTENTS — 58 SECTIONS
Learning objectives
- Collect urine specimen.
- Collect stool specimen.
- Collect blood specimen.
- Transport specimen to laboratory
Materials Used for Collecting Venous Blood and Finger Prick
Sterile swab
Used for cleaning the skin
70% alcohol or Methanol.
Used for disinfecting the skin
Gloves
Used to protect the phlebotomist from contamination
Disposal bucket
Used for disposing used materials
Sharps box or container
Used for disposing sharp materials
Cont.
Lancet
Is used for piercing{make a hole} of the skin
Specific materials for venous blood collection
Syringes (2.5ml, 5ml and 10ml) and needles 19G, 21G and 23G)
For drawing blood
Vacuum (needle, holder and tubes)
For drawing blood
Blood containers
For putting blood
Tourniquet
For dilating veins
Procedure of Finger Prick
Purpose of finger prick blood collection
Is to obtain capillary blood which is may be used for haematological examinations, including haemoglobin estimation, total and differential white blood cell counts and blood cell morphology, detection of blood parasites, and sickle-cell screening.
Cont.
Procedure for Finger Prick
Wear gloves
Clean the puncture area with a cotton wool swab soaked in 70% methanol or an alcohol swab; allow area to dry
Using a sterile lancet, make a rapid puncture using the side of the finger in adults and children sufficiently deep to allow the free flow of blood avoid the tip of the finger
Cont.
Wipe away the first drop of blood with a piece of dry cotton wool. Use the next few drops and transfer onto clean glass slides or into a capillary tube or pipette.
When sufficient blood has been collected, press the piece of dry cotton wool firmly on the puncture area until the bleeding stops.
Place used lancet in the sharps box or container marked “SHARPS”. Place the materials for wrapping the lancet and the cotton wool in the bucket marked “INCINERATOR”.
Cont.
Make sure the site is warm to ensure blood flows freely.
Do not squeeze the finger too hard as this will lead to haemodilution from tissue fluid and may give unreliable results.
On cold days, sock the hand (or foot of an infant) in warm water and dry before collecting the sample.
Procedure of Finger Pricking
Cont.
Cont.
Discard the used materials (sharps and infectious) in appropriate containers
Procedure of Venous Blood Collection
Purpose of venous blood collection
Venous blood is used for all blood examinations, including haematological, parasitological, biochemical and serological tests, and for blood culture. Blood samples are collected into plain tubes or tubes containing anticoagulant, or into blood bottles, as required.
Cont.
Safety Precautions during Collection of Blood Sample from Patients
Always follow standard safety precautions when drawing blood
Consider every person (patient or staff) as potentially infectious and susceptible to infection
Wash hands before and after taking a sample from each patient
Cont.
Put on new gloves before collecting blood
If blood is spilled, mop and disinfect area immediately
Keep work area organized, clean, and disinfected
Discard all used items in appropriate containers
• Overview of Vein Anatomy (Location of veins)
Overview of Vein Anatomy (Location of veins)
Superficial Veins of the upper limb
Median Cubital Vein. A superficial vein, most commonly used for venepuncture. It lies over the cubital fossa and serves as an anastomosis between the cephalic and basilic vein
Cephalic veins. Shown in both the forearm and arm, it can be followed where it empties into the axillary vein
Basilic Vein. Seen in the forearm and arm, it dives to join the brachial; best area for venepuncture is antecubital fossa area
Procedure for collecting venous blood
Apply tourniquet to increase pressure in the veins and aid in site selection. Ask the patient to make a tight fist, so the veins become more prominent.
The tourniquet should not be left on for longer than ONE minute
Using the index finger, feel for a suitable vein, selecting a sufficiently large vein that does not roll and with a direction that can be felt.
Wearing gloves clean the site with a cotton swab soaked in 70% methanol or an alcohol swab and allow to air dry. Do not retouch the cleaned area.
Cont.
Screw the needle into the handle
With the thumb of the left hand holding down the skin below the puncture site, insert the needle along the line of the vein with the bevel of the needle facing directly upwards.
Insert needle at a 15 to 30 degree angle using a quick smooth motion.
Push the tube on to the end of the needle which is located in the handle.
When sufficient blood has been collected, release the tourniquet and instruct the patient to open his or her fist. Remove the needle from the vein and press firmly on the venipuncture site with a piece of dry cotton. Remove the tourniquet and instruct the patient to continue pressing on the puncture site with the arm raised until bleeding stops.
Cont.
Label the tubes{ coz resource of time}.
Check to ensure bleeding from the venipuncture site has stopped. Cover the area with a small dressing, if needed.
Place the needle in the sharps box. Place other contaminated materials in the bucket marked “INCINERATION”.
Procedure of Taking a Venous Blood Sample
Organise materials and equipment
Cont.
Clean Venipuncture Site with Alcohol Using a Circular Motion (after palpating path of vein) and Allow Area to Dry
Cont.
Use Your Thumb to Draw Skin Tight About 1- 2” Below Venepuncture Site
Cont.
Insert Needle, Bevel Side Up, Into Vein and Penetrate Vein at a 15 Degree Angle
Cont.
Push Vacutainer Tube Completely onto Needle. Blood Should Begin to Flow into
Tube and Release Tourniquet
Cont.
Place Dry Gauze over the Venepuncture Site and Apply Mild Pressure to Pad and Slowly Remove Needle
COLLECTION OF STOOL SPECIMEN
IMPORTANCE OF STOOL EXAMINATION
Stool examination is used to identify parasites causing several infections and infestations.
The identification of parasites can also assist in the control of local parasitic infections.
COLLECTION OF STOOL SPECIMEN PROCEDURE
For stool examination, a fresh specimen is collected in a clean, dry and leak-proof container.
The specimen should not be contaminated with urine, so be sure to instruct the patient correctly.
The collection of several specimens on alternate days may be required to detect parasites.
You have been asked to collect a stool specimen for laboratory analysis.
Give a patient a specimen collection container and a spatula and instruct collect to collect the stool specimen as follows:
You have been asked to collect a stool specimen for laboratory analysis.
Please wash your hands before beginning the procedure.
DO NOT pass the specimen into the toilet
DO NOT pass the specimen directly into the collection vial.
DO NOT urinate on the specimen or into the collection vial.
DO NOT allow any water to mix with the specimen.
Instructions for Stool collection cont……
Pass the stool specimen into any clean and dry container such as a bedpan, plastic plate, or newspaper.
Carefully open a specimen collection container o Using the spatula, collect small amounts of stool from areas that are slimy, watery, or bloody and place them into a specimen collection container.
Instructions for Stool collection cont……
If the stool is hard, collect small amounts from both ends and the middle and place into a specimen collection container.
Fill the specimen collection container with enough specimen (About 1 spoonful or 10ml if it is a liquid specimen.)
Collection of stool specimen procedure cont…
Obtain a stool sample (in the container) from a patient.
Adhere to infection prevention and control standards.
Write patient’s name, date, & time of collection on the container
The specimen must be transported as soon as possible to the lab and must be accompanied by a doctors request form.
Stool samples must be examined within one hour after collection.
MACROSCOPIC EXAMINATION OF STOOL
A macroscopic examination reports the physical appearance of a specimen.
This includes a description of
colour (yellow, brown or black)
consistency (formed, semi formed, watery or rice water)
visible contents (blood, mucus or worms)
COLOUR
Normal Stool: Appears brownish due to the presence of stercobilinogen. Stool from infants appear yellow brown or yellow green.
Colorless Stool: Pale colored stool is due to
The absence of stercobilinogen as a result of obstructive jaundice,
Abnormal fat absorption in the intestine as that occurs during Giardiasis.
Brown/Black Stool: Can be a result of
Iron therapy,
Gastro intestinal bleeding
Hookworm infection.
CONSISTENCY OF STOOL
Normal Stool: Usually well formed.
Unformed, Semi formed/Watery Stool: Indicates
Bacterial infection.
Parasitic infection.
Rice Water Stool: Indicates cholera.
VISIBLE CONTENTS IN STOOL
Normal Stool: Usually have no visible abnormal contents.
Blood in Stool: May be due to certain;
Parasites (e.g. Entamoeba histolytica, Schistosoma mansoni) or to
Bacteria (Shigella sp. Enterohemorrhagic Escherichia coli)
colonic or rectal malignancies.
Cont……
Mucus: Usually due to;
Entamoeba histolytica
Tumor
Dysentery
Bacterial infection.
Worms: Worms or segments of worms may be seen when the following are the causative agents of the infection
Ascaris
Taenia
Enterobius vermicularis.
MICROSCOPIC EXAMINATION OF STOOL
Saline and Iodine Preparation of Stool (Wet Mount/Wet Preparation/Saline Mount)
Routinely stool specimens are examined using the saline and iodine preparation to detect
Parasites
Cysts
Cells.
After the macroscopic examination the stool specimen is prepared as follows:
After the macroscopic examination the stool specimen is prepared as follows
Place a drop of saline near one end of a slide and a drop of iodine near the other end.
Iodine is used to stain the nuclear structure of cysts e.g. that of Entamoeba histolytica (four nuclei) and Entamoeba coli (eight nuclei).
Using a wooden applicator stick, mix a small amount of specimen with the saline and a similar amount with the iodine to make a smooth thin preparation and cover with a cover glass.
Examine the slide systematically, first using the 10X objective with the iris sufficiently closed to give good contrast.
Use 40X objective to examine in greater detail after parasite/cyst/ova is seen.
Report your findings
COLLECTION OF URINE SPECIMEN
Urine is formed and excreted by the kidneys.
The production and composition of urine depends on the following;
Glomerular filtration,
Tubular selective reabsorption and
Tubular secretion.
Cont….
A urine sample is easily collected and will provide useful information about the following;
Metabolism status,
Kidney function and the
Urinary tract state.
Cont….
A specimen can be examined
Macroscopically
biochemically
microscopically
To detect;
Bleeding
Infection
Glucose
Protein
Cells
Presence of micro-organisms.
TYPE OF URINE SAMPLES
For routine examination urine is collected in a clean leak-proof container.
For culture purposes midstream urine is collected in a sterile leak proof container.
Mid-stream urine is the portion of urine that does not contain the first and last portions of the sample.
PROCEDURE FOR COLLECTING URINE SPECIMEN FOR ROUTINE EXAMINATION
Provide the patient with a clean container.
Instruct the patient to collect about 20 ml of urine directly into the clean container
Receive the specimen from the patient.
Adhere to infection prevention and control standards.
Secure the lid of the container immediately
Label container with patients name, age and address and send to the laboratory for investigation with a filled in request form to perform the test.
PROCEDURE FOR COLLECTING MIDSTREAM URINE
Provide the patient with a clean container
Instruct the patient to collect urine specimen in the following steps:
Wash genital area
Begin to urinate without collecting urine
After a few ml have passed, collect urine in container (10-20 ml if possible)
Finish urinating without collecting
Cover the container with its lid and send it to the clinician
Cont….
Receive the specimen from the patient.
Adhere to IPC
Label the container with patients name, age and address and send to the laboratory for investigation with a filled in request form.
Tests on urine specimens should be performed within one hour to prevent the specimen from being contaminated due to bacterial growth.
EXAMINATION OF URINE
Materials required to prepare for the examination of urine include
Gloves
Biohazard waste containers
Liquid soap
Register and Request forms
Urine specimen container
Centrifuge machine
Test tubes
Slides
Cover slips
Microscope
Pasteur pipettes
Hand towels (preferably single use
EXAMINATION OF URINE
MACROSCOPIC EXAMINATION
Is performed by reporting the physical appearance of a specimen.
This report can include features like
Color
Transparency
Smell
Normal urine appears yellow and clear with a characteristic aromatic smell.
Some changes in the physical appearance can indicate a disease.
MACROSCOPIC EXAMINATION OF URINE PROCEDURE
Specimen of urine with normal sample and other pathological samples
Take different samples of urine in different container
Show the colour of urine comparing with the normal urine
Normal urine is pale yellow (amber colour)
Pathological urine has different
Colour
turbidity
smelly
Colour changes in urine can also be caused by some foods or drugs!
Appearance of Urine
Possible Cause
Cloudy
Urinary tract infection (UTI)
Red and Cloudy
UTI, Schistosomiasis
Brown and cloudy
Black water fever
Silvery shine or milky
Pus, bacteria or epithelial cells
Black
Certain poison e.g. phenol
Yellow/green/brown
Liver disease, viral hepatitis, jaundice Colour due to presence of bile or urobilinogen
Milky white
Bancroftian Filiraiasis
Transporting the Specimen:
Transporting the Specimen
Check samples and forms before they leave the phlebotomy area
Before the samples leave the clinic they should be checked for errors:
Are sample tubes labelled correctly?
Are the forms completed correctly?
Is there a form for every sample?
Is there a sample for every form?
Does the information on the form match that of the corresponding sample?
This check is critical because once a sample leaves clinic it may be impossible to correct certain errors
Proper Handling of Specimen:
Proper Handling of Specimen
Specimens must be properly handled from point of collection to delivery in the laboratory
Results of laboratory investigations are only as good as the sample received by the laboratory.
Use appropriate collection containers for specific testing needs
Store specimens upright, in racks at the appropriate temperature
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