Specimen Collection

A disease can be diagnosed partly by their signs and symptoms. But this does not reveal the full information about the causative organisms and the disease severity. So, to identify the disease causing organism, specimens are collected accordingly. This includes many rules and measures before collection. A specimen must be always collected under aseptic conditions. The different types of specimens and their respective containers are discussed below;

A Quality specimen/sample:

A sample is considered as a good quality sample, when it contains only the infective organisms of the infection and not the environmental contaminations.
A sample collected at a right time of diagnosis of the disease.
A specifically collected sample.
A sample collected before any antibiotic treatment.
A sample collected in a sterile container under aseptic conditions.

Collection of Blood:

The blood consists of a fluid of complicated and variable composition, the plasma, in which suspended erythrocytes, leukocytes and platelets. By using an anticoagulant the formed elements can be separated from plasma. When blood coagulates, the fluid that remains after separation of the clot is serum.

Ways of obtaining blood:

(a) Capillary or peripheral blood:

1. blood can be taken by pricking;
è the lobe of the ear
è the palmer surfaces of the tip of the finger
è in infants, from the plantar surfaces of the heel or the great toe
2. Puncture should be about 3mm deep.
3. An edematous or a congested part should not be used.
4. If the area to be punctured is cold or cyanotic, warm it by massaging or else erroneous may obtain.
5. Clean the site with spirit or alcohols, let dry and puncture.
6. Wipe off the first drop of blood, never press out blood.
7. Having obtained the requisite amount of blood let the patient apply slight pressure over the area with sterile swab.

(b) Venous Blood:

1. Reassure the patient about what is to be done.
2. Inspect the vein, using a tourniquet.
3. Use a syringe of a size according to the amount of blood.
4. Needles of gauze 22 should be used and be 1-1½ inches long.
5. Ask the patient to open and close the first several times.
6. Under aseptic precautions puncture the vein.
7. If it is difficult, first the skin around the vein is punctured and then the vein.
8. Make sure that the bleeding has stopped before the patient leaves.
9. Transfer blood from syringe into the container gently (not through the needle).