Haemostasis
By
Dr. Sadat A. Aziz
Haemostasis:
It means prevention of blood loss. Whenever, a blood vessel is injured or ruptured
Mechanisms of haemostasis:
1. Vascular spasm
2. Platelets plug formation
3. Coagulation
Strength of capillary wall evaluation:
This test is used to evaluate the strength and integrity of the capillary walls.
Procedure:
1. Make a circle at the volar aspect of the forearm.
2.
Place a blood pressure cuff on the patients arm above the elbow and inflate it to 50-60 mmHg for
about 15-20 minutes.
3.
Look for the appearance of blood spot at the site if not presence it means normal vascular integrity
and strength.
Bleeding time test: it shows the ability of the platelets to stop bleeding and can be used to
evaluate the platelets function. Upon vessel injury, platelets adhere and form a platelet plug
formation.
Bleeding time performed as a screening procedure used to detect both congenital and
acquired disorders of platelet function. there are several methods of performing the
bleeding time:
1- Duke method.
2- IVY method
1-Procedure of Duke method: (normal bleeding time for this procedure is 1 to 5 minutes)
A. Clean the site (lobe of the ear or tip of a finger) with alcohol and let it dry properly.
B. Make a puncture (about 3 mm deep) at the site with a lancet, start the stopwatch directly
after puncture.
C. Blot the blood with a filter paper at regular 30 second intervals. Without exerting pressure
or touching the incision with the filter paper.
D. When the bleeding cease, stop the stopwatch and record the time.
E. Then divide the number of the spots on the paper by 2 to find the bleeding time
2-Procedure of IVY method: (normal values of 1 to 6 minutes)
A. Place a blood pressure cuff on the patients arm above the elbow. inflate the cuff and
maintain pressure at 40mm Hg.
B. Clean the volar aspect of the forearm with alcohol wipe. Allow it to dry properly. the
selected area should be free of all superficial veins.
C. Make three small punctures (about 3mm deep and 1.5cm a part), start the stopwatch.
D. Blot the blood at regular 30 second intervals with the filter. Avoid exerting pressure on
the wound during using the filter paper.
E. When the filter paper no longer shows signs of blood ,stop the stopwatch.
F. The average of the times for bleeding to stop from the three puncture sites is record as
the bleeding time similar to that of the Duke`s method .
Contraindication:
1. In patients with a low platelet count (less than 100000/µL.
2. In patients with sever bleeding disorders
3. In patients who take aspirin within 5 days before the test
4. In patient has skin infection
Note/ if the bleeding persist for more than 20 minutes discontinue the test and try stop
the bleeding.
Coagulation time test: (normal clotting time is 5 to 10 minutes)
It is the time required for blood to clot without the presence of any substance .
Capillary tube method (Non-heparinized).
Procedure:
1) Clean your finger properly and let it to dry completely before making the puncture.
2) Pricked the finger by lancet .remove the first drop of blood.
3) Squeeze the finger to obtain a larger drop of blood and fill the capillary tube with blood.
4) Let the blood to stand in the tube for 2 minutes.
5) Then start breaking small pieces of the capillary tube every 30 second until a fibrin thread is seen
between the two broken ends.
6) Calculate the coagulation time by dividing the number of pieces on 2 then plus 2
𝐶𝑜𝑎𝑔𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 =
𝑛𝑢𝑚𝑏𝑒𝑟𝑜𝑓𝑝𝑒𝑖𝑐𝑒𝑠
+2
2
Cause of have long duration of bleeding time:
1. Disorders of blood vessels
2. Thrombocytopenia: This term is uses when the platelet count is less than its normal value. The bleeding time test
should not be performed if the platelet count is less than 1,00,000/ml. It may be difficult to control the bleeding if
the platelet count is very low.
3. Disorder of platelet function