Hey. I've been attached to Haematology lab for 3 weeks and i think, it's the most busiest lab. In this post, i'm going to share about Bleeding Time and Dengue Serology.
Bleeding Time
Bleeding time is done to estimate the integrity of haemostatic plug which will be formed at the site of injury to arrest bleeding. It is also used in the diagnosis of haemostatic defects and platelet dysfunction. A minor incision is made on the forearm and the time between the infliction of incision and the moment bleeding stops is measured. The formation of haemostatic plug on the site of injury depends on the adequate amount of platelets to adhere to the subendothelium and to form aggregates. A prolonged bleeding time does not itself diagnose underlying platelet disorder. It does indicate the need for further tests such as platelet count, platelet aggregation studies etc.
The items needed to conduct the test for bleeding time are sphygmomanometer, filter paper, antiseptic swab, stopwatch, plaster and single-use Surgicutt blade. The sphygmomanometer cuff is wrapped on the upper arm. Cuff will be inflated to 40mmHg and will remain at exact pressure throughout the test. The time between inflation of cuff and incision should be 20-60seconds. For a newborn, the pressure should be maintained in accordance with the weight of newborn. (<1kg-> 2 kg- 30mmHg) The forearm must be cleaned with alcohol swab before incision. Area with veins, scars or bruises should be avoided. Minimal pressure is used on Surgicutt device so that it lightly touches the skin. After incision, the timing will start. Every 30seconds, the blood is blot with the filter paper until it no longer stains the paper. For neonates lesser than 5 months, the test can be stopped at 5 minutes and bleeding is reported as more than 5 minutes. For adult and pediatrics, the test can be stopped at 20 minutes and bleeding time is reported as more than 20 minutes. The reference range based on Surgicutt’s insert, 2 to 8 minutes for adult, 1.30 to 8.99 minutes for junior (5 months to 15 years old) and 0.85 to 1.65 minutes for newborn (1 to 4 months).
The estimation of the integrity of haemostatic plug measures the interaction between the capillaries and platelets, platelet defects and vascular disorders. It measures the interaction between the capillaries and clotting mechanisms in vivo. However, the test does have limitations. It is not always positive in platelet function defects because of the mildness of the defect or variability in the condition. The results of this test alone are not sufficient to diagnose specific conditions. Further tests are needed.
Dengue Serology
Dengue serology test is performed to obtain a qualitative presumptive detection of IgG and IgM Dengue, a flavivirus, is found in large areas of the tropics and subtropics. Transmission is by mosquito, principally Aedes aegypti and Aedes albopictus. Dengue virus infection causes a spectrum of clinical manifestations ranging from asymptotic to fatal haemorrhagic disease.
When the virus is present in the patient's serum, dengue-specified IgM or IgG antibodies bind to anti-human IgM or IgG antibodies immobolized in 2 lines across the cassette membrane. Colloidal gold complexes containing recombinant dengue 1-4 antigens are captured by the bound patient's IgM or IgG to visible pink line(s).
Procedure:
1. Centrifuge the blood sample at 3000rpm for 10 minutes.
2. Sample serum should be preferably clear, non-haemolysed, non-lipaemic and non-icteric.
3. Before running the assay, allow the buffer to equilibrate to room temperature after taking it out from the fridge.
4. Remove cassette from pouch.
5. Add 10uL of serum in circular well using mechanical pipette.
6. Allow sample to absorb entirely into specimen pad within circular well.
7. Add 2 drops of buffer to square well at base of cassette. Ensure buffer bottle is held vertically.
8. Read results in exactly 15 minutes after adding buffer. All reactions are visualised as pink lines.
9. For assay to be valid, the control line must appear.
Retrieved from: http://www.panbio.com.au/download/Dengue%20Duo%20Cassette%20procedure.pdf
Hope u guys understand.
Hardina Hamzah
Tg01











Hi,
So far in your attachment, have you met any difficulties? If there is, can you share?
By the way, you mention that if the orientation of the tissue is not done properly, then it will hinder the sectioning. So what happen if this really happens? Does your lab redo it or just leave it as it is? The samples obtained are limited right?
Thanks. That's all.
Xin Yi
TG02