Investigations involve obtaining samples like tissue, blood, or urine from patients and examining them to identify the nature of diseases. The appropriate tests must be chosen based on the history and exam findings. Samples should come from areas likely to contain abnormalities and be collected correctly according to guidelines to ensure test validity. Providing detailed request information aids the laboratory's examination and diagnosis. Common investigations include hematological tests like complete blood counts, serum chemistry exams like glucose tests, microbiology cultures, immunological particle agglutination, and radiological scans.

4. INVESTIGATION
Investigations or laboratory studies are an
extension of physical examination in which
tissue, blood, urine or other specimens are
obtained from patients and subjected to
microscopic, biochemical, microbiological or
immunological examination. Information
obtained from these investigations help us in
identifying the nature of the disease.

5. DIAGNOSTIC ASSESSMENT
A diagnostic test is any approach used to
gather clinical information for the purpose of
making a clinical decision (i.e., diagnosis).
Some examples of diagnostic tests include X-
rays, biopsies,
pregnancy tests, medical histories, and
results from physical examinations.

9. What investigation is appropriate?
Often a practitioner is faced with a
dilemma of what investigation to order in
a given clinical scenario.
The plan of investigation should be
therefore decided from the facts obtained
from history taking and clinical
examination.

10. Cont.....
Investigations are useful only when the
appropriate tests are requested, and
interpreted in the light of history, clinical
findings, knowledge and experience.

11. What sample to be collected for the
Test?
Samples should optimally be
the most likely entity which
harbours the causative
organism or abnormal
constituents of body fluids
like electrolytes, chemical
compounds or antigens.

12. How to collect specimens?
Success or failure of the investigation depends on the
procedures carried out in collection, preservation and
transport of the specimens.
In cases of microbiological and culture tests, the
specimen must be material from the actual site of
infection and should be collected with minimum of
contamination from adjacent tissues or secretions.

13. Cont......
In cases of tissue collection, the site of collection as well
as the vicinity with respect to the lesion assumes
importance.
Apart from this the timing (When) of specimen collection is
also important.
In general specimens collected from swabs are inferior in
material collection when compared to aspirates.
In cases of collection of blood samples for haematology, it
can be collected either via skin , venous or arterial
puncture.

14. What Information to be furnished to the
laboratory?
Specimens should accompany
properly filled out forms from the
clinician
Preliminary details include: Name,
Address, Hosp. No. , Gender & Date of
Birth

15. Cont.....
Other important details are-
Exact nature of the specimen
Source of the specimen
Nature of investigation requested
Date and time of specimen collection
Brief Clinical Details
Tentative Diagnosis
Current Therapy if any

16. Hematological investigation:
Haemoglobin(Hb) :
Oxygen carrying component of
erythrocytes.
Hence, amount of Hb in the RBCs
indicates the level at which it can
supply oxygen to the tissues
Normal range – Adult male : 14 -18
g% Adult female : 12 – 16 g%
Low values indicate anaemia while
high values indicate polycythaemia
27

17. Peripheral Smear
Provides info concerning the size
and shape of the red blood cells.
Identification of sickle cell &
normocytic, microcytic and
macrocytic anaemia.
Evaluation of Hb pigmentation of
individual cells to be classified as
normochromic, hypochromic or
hyper chromic.

18. Serum chemistry investigation
Blood Glucose estimations:
Fasting Blood Sugar(FBS):
Normal values – 70-90
mg/100ml
Random Blood Sugar(RBS):
110-130 mg/100ml
Post Prandial Blood
Sugar(PPBS): <140 mg/100ml

19. Oral Glucose Tolerance Test
Used for the definitive diagnosis of diabetes
mellitus and for distinguishing diabetes from
other causes of hyperglycaemia like
hyperthyroidism
Should be performed on only healthy
ambulatory patients who are not under any
drugs which may interfere with glucose
estimation

20. Microbiology investigation
Culture and sensitivity tests are used to isolate and
identify causative micro organisms of an infection.
May be obtained from blood or urine
Particularly helpful in evaluating infections related to
throat, sinuses, root canals or bone.
Sensitivity tests may also be ordered when patient
relapses, the identification of the organism is
uncertain or the disease is severe

21. Immunology
Particle Agglutination:
a)Relatively simple and fast
b)Capable of detecting lower concentration of
antibodies
Designed to detect antibodies to viruses,
subsequent to vaccination

22. Histopathology and Cytopathology
Histopathology refers to the microscopic
examination of tissue in order to study the
manifestations of the disease
Cytopathology refers to the scientific
study of role of individual cells or cell types
in disease

23. Radiology
CT scan
A noninvasive medical test
that uses special X-ray
equipment with
sophisticated computers
to produce multiple
images or pictures of the
inside of the body.

24. Fluoroscopy
A medical test in which a
continuous X-ray beam is
passed through the body
part being examined and
is transmitted to a TV-like
monitor so that the body
part and its motion can be
seen in detail.

25. Magnetic resonance imaging (MRI)
scan
A noninvasive medical
test or examination that
uses a large magnet and
a computer to take
pictures of the inside of
your body.

26. Ultrasound
Sometimes called
sonography, this is a
medical test that uses
high-frequency sound
waves and a computer to
create images of blood
vessels, tissues, and
organs.

27. Virtual colonoscopy
A medical imaging
procedure which uses CT
scanning and advanced
computer software to
produce 2D and 3D
images of the colon that
can be viewed on a video
screen.

28. X-rays
A medical test that
uses invisible
electromagnetic energy
beams to produce
images of internal
tissues, bones, and
organs on film.

29. Interventional Radiology (IR) services
Biopsy
The removal of sample of
cells or tissue via a hollow
needle or scalpel to
discover the presence,
cause, or extent of a
disease.

30. Nuclear Imaging services
Bone density scan
• An enhanced form of X-
ray technology that is
used to measure bone
loss or density.

31. Cardiac PET perfusion
An evaluation of the blood
flow (perfusion) to the
walls of your heart using a
high resolution PET
scanner. Usually
performed using a cardiac
stress test.