A specimen also called a sample, is any biological material produced or taken from specific parts of the body suspected to be infected by a microbial organism, parasites or altered by the influx or decline of hormonal elements of the body, which is examined for diagnosis and treatment of infection. For example, stool samples serve as the specimen in the diagnosis of microbial or parasitic invasion in the Gastro-Intestinal tract or region; urine samples are used in diagnosing for Urinary Tract Infections, Blood samples for diagnosing for blood infections and diseases, etc.
Different specimens are collected for different examination and are thus despatched to their respective laboratories. Below is a table showing some specimens and its respective lab.
A sterile swab stick is used to take specimens from the ear, throat and pus or mucus from the mucus linings of the body, or lesions, abrasions or wounds. The swab stick is a long plastic stick, with a bud of cotton at one end for brushing slightly the specimen. It is covered with the bud facing downwards in the plastic cover usually containing normal saline.
Asides blood samples, other samples are collected in a sterile universal container otherwise called “McCarthy bottle”, except if specific modifications are needed, as in the case of a stool sample, where a spatula is attached underneath the cover of the container, for easy and convenient scooping of the specimen. All samples should be properly labelled with the patient’s name, lab identity number and test request(s).
Urine samples for culture tests should be produced as aseptically as possible so as to avoid contamination, for the yield of a proper result. Also, first urine passed in the morning should be the urine sample for ‘fasting urine sugar’ test .Urinalysis test doesn’t have any specificity at the time of production.
Semen samples should not stand for more than 20 minutes from the time of production to the time of transportation and examination, as sperm cells have a limited life span.
Patients should ensure that sputum is produced first in the morning prior to brushing or even rinsing the mouth. The lab attendant should note that sputum and not saliva is produced by the patient.
When producing stool sample, it is advised not to scoop from the specimen directly from the rectum in order to avoid contamination by normal flora for proper results.
Blood samples are collected using a sterile syringe, but in most cases via a vacuum-based device which uses the principle of pressure to allow for blood sample collection. It is made up of a sterile needle which has a screw that allows for the firm fixation of needle to tube holder, right under the screw is the ‘male adaptor’ which comprises of the base end of the needle protected by a plastic cover. The male adaptor pieces into the vacuum filled tube thereby releasing pressure and thus the difference between the vacuum in the tube and the pressure of blood exerted by the veins allows for blood flow from the veins into the tube. The art of collecting blood samples from the vein is termed “venepuncture” and the art of venipuncture, or capillary blood collection or arterial blood collection from neonates, children and adults is termed “Phlebotomy”.
Phlebotomy is carried out on the cubical faucet of the arm, from one of the three major veins; median, cephalic or basilica veins, most preferably the median vein because it’s easily located and most prominent of all. In children, phlebotomy is carried out on the feet or ear. Capillary blood is collected on the tip of the fore, index and thumb fingers by using a lancing device.
Tubes in which blood samples are collected are classified based on the type of additive or substance it contains, which could be a coagulant or an anti-coagulant and they are distinguished by the various colours of their tops/covers. Therefore, the nature of blood test to be performed will determine the type of tube to be used, thus, the category of the laboratory to be despatched at. It is also important to use the appropriate tube, as using the wrong tube can render the sample useless.