LABORATORY SERVICES

 CATEGORIES

1. Routine Tests 

2.Haematological tests 

3. Biochemical tests 

4. Microbiological and serology 

5. Virology tests.

A.  Routine Tests.

    A method of examination, as to determine the presence or absence of a definite disease or of some substance in any of the fluids, tissues, or excretions of the body, or to determine the presence or degree of a psychological or behavioral trait.

These Tests are done regularly in the laboratory. These routine Tests includes the following corresponding to Laboratory of Sua hospital includes;

• Urine test. is a test of your urine. It's used to detect and manage a wide range of disorders, such as urinary tract infections, kidney disease and diabetes.

  A urinalysis involves checking the appearance, concentration and content of urine. For example, a urinary tract infection can make urine look cloudy instead of clear. Increased levels of protein in urine can be a sign of kidney disease.

• A stool test is used to detect the presence of blood or other gastrointestinal abnormalities, such as colon or gastric cancer, inflammatory bowel disease, hemorrhoids, anal fissures or infections.

 doctor may order a stool collection to test for a variety of possible conditions, including:

• allergy or inflammation in the body, such as part of the evaluation of milk protein allergy in infants
• infection, as caused by some types of bacteria, viruses, or parasites that invade the gastrointestinal system
• digestive problems, such as the malabsorption of certain sugars, fats, or nutrients
• bleeding inside of the gastrointestinal tract.      
• 
  
•          3. The diagnosis of malaria is confirmed by blood tests and can be divided into microscopic and non-microscopic tests.

• Microscopic Tests

  The microscopic tests involve staining and direct visualization of the parasite under the microscope. For more than hundred years, the direct microscopic visualization of the parasite on the thick and/or thin blood smears has been the accepted method for the diagnosis of malaria in most settings, from the clinical laboratory to the field surveys. The careful examination of a well-prepared and well-stained blood film currently remains the “gold standard” for malaria diagnosis. The most commonly used microscopic tests include the peripheral smear study and the Quantitative Buffy Coat (QBC) test.

  The simplest and surest test is the time-honoured peripheral smear study for malarial parasites. None of the other newer tests have surpassed the ‘gold standard’ peripheral smear study.

  Remember this:

  • Ask for MP test in all cases of fever and related symptoms and also whenever there is high level of suspicion
  • MP test can be done at any time. Do not wait for typical symptoms and signs or for chills
  • A negative test DOES NOT rule out malaria. Repeated tests may have to be done in all doubtful cases. Duration of the illness, level of parasitemia, expertise of the technician and the method of examination may all have a bearing on the result of the M.P. test

  Peripheral smear study for malarial parasites – The MP test

  Light microscopy of thick and thin stained blood smears remains the standard method for diagnosing malaria. It involves collection of a blood smear, its staining with Romanowsky stains and examination of the Red Blood Cells for intracellular malarial parasites. Thick smears are 20–40 times more sensitive than thin smears for screening of Plasmodium parasites, with a detection limit of 10–50 trophozoites/μl. Thin smears allow one to identify malaria species (including the diagnosis of mixed infections), quantify parasitemia, and assess for the presence of schizonts, gametocytes, and malarial pigment in neutrophils and monocytes.

  The peripheral blood smear provides comprehensive information on the species, the stages, and the density of parasitemia. The efficiency of the test depends on the quality of the equipment and reagents, the type and quality of the smear, skill of the technician, the parasite density, and the time spent on reading the smear. The test takes about 20 to 60 minutes depending on the proximity of the laboratory and other factors mentioned above. It is estimated to cost about 12 to 40 US cents per slide in the endemic countries.

  Before reporting a negative result, at least 200 oil immersion visual fields at a magnification of 1000× should be examined on both thick and thin smears, which has a sensitivity of 90%. The level of parasitemia may be expressed either as a percentage of parasitized erythrocytes or as the number of parasites per microliter of blood. In nonfalciparum malaria, parasitemia rarely exceeds 2%, whereas it can be considerably higher (>50%) in falciparum malaria. In nonimmune individuals, hyperparasitemia (>5% parasitemia or >250 000 parasites/μl) is generally associated with severe disease.

  The smear can be prepared from blood collected by venipuncture, finger prick and ear lobe stab. In obstetric practice, cord blood and placental impression smears can be used. In fatal cases, post-mortem smears of cerebral grey matter obtained by needle necropsy through the foramen magnum, superior orbital fissure, ethmoid sinus via the nose or through fontanelle in young children can be used.

  Preparation of the smear: Use universal precautions while preparing the smears for malarial parasites – use gloves; use only disposable needles/lancets; wash hands; handle and dispose the sharp instruments and other materials contaminated with blood carefully to avoid injury.

  • Hold the third finger of the left hand and wipe its tip with spirit/Savlon swab; allow to dry
  • Prick the finger with disposable needle/lancet; allow the blood to ooze out
  • Take a clean glass slide. Take 3 drops of blood 1 cm from the edge of the slide, take another drop of blood one cm from the first drop of blood
  • Take another clean slide with smooth edges and use it as a spreader and make thick and thin smears. Allow it to dry
  • Slide number can be marked on the thin smear with a lead pencil

  Thick smear: The thick smear of correct thickness is the one through which newsprint is barely visible. It is dried for 30 minutes and not fixed with methanol. This allows the red blood cells to be hemolyzed and leukocytes and any malaria parasites present will be the only detectable elements. However, due to the hemolysis and slow drying, the plasmodia morphology can get distorted, making differentiation of species difficult. Thick smears are therefore used to detect infection, and to estimate parasite concentration.

  Thin smear: Air dry the thin smear for 10 minutes. After drying, the thin smear should be fixed in methanol. This can be done by either dipping the thin smear into methanol for 5 seconds or by dabbing the thin smear with a methanol-soaked cotton ball. While fixing the thin smear, all care should be taken to avoid exposure of the thick smear to methanol.

  Staining: A number of Romanowsky stains like Field’s, Giemsa’s, Wright’s and Leishman’s are suitable for staining the smears. Thick films are ideally stained by the rapid Field’s technique or Giemsa’s stain for screening of parasites. The sensitivity of a thick blood film is 5-10 parasites/µl. Thin blood films stained by Giemsa’s or Leishman’s stain are useful for specification of parasites and for the stippling of infected red cells and have a sensitivity of 200 parasites/µl. The optimal pH of the stain is 7.2.

  Slides should be clean and dry. It is better to use neutral distilled water.

  Thick films: The thick film is first de-hemoglobinised in water and then stained with Giemsa.

  Rapid Giemsa: Prepare a 10% Giemsa in buffered water at pH 7.1. Immerse the slide in the stain for 5 minutes. Rinse gently for 1 or 2 seconds in a jar of tap water. Drain, dry and examine.

  Standard Giemsa: Prepare a 4% Giemsa in buffered solution at pH 7.1. Immerse the slide (at least 12 hours old) in stain for 30 minutes. Rinse with fresh water, drain, dry and examine.

  Thin films: Thin film examination is the gold standard in diagnosis of malarial infection.

  Giemsa stain: Fix with 1-2 drops of methanol. Cover the film with 10% Giemsa stain and leave for 30 minutes, wash with distilled water, drain, dry and examine.

  Leishman’s stain: Add 7-8 drops of the stain and leave for 1-2 minutes. Then add 12-15 drops of buffered distilled water, mix thoroughly, leave for 4 – 8 minutes. Then wash off with clean water, drain, dry and examine.

  Diagnosis of malaria involves identification of malaria parasite or its antigens/products in the blood of the patient. Although this seems simple, the efficacy of the diagnosis is subject to many factors. The different forms of the four malaria species; the different stages of erythrocytic schizogony; the endemicity of different species; the population movements; the inter-relation between the levels of transmission, immunity, parasitemia, and the symptoms; the problems of recurrent malaria, drug resistance, persisting viable or non-viable parasitemia, and sequestration of the parasites in the deeper tissues; and the use of chemoprophylaxis or even presumptive treatment on the basis of clinical diagnosis can all have a bearing on the identification and interpretation of malaria parasitemia on a diagnostic test.