The changes which occur in the organism in different diseases can be divided into several categories. It means that the changes in different organs and tissues are similar, they develop in different cells no matter where they are located: in the liver, kidneys, heart. These common pathological processes are studied by the branch of Pathological Anatomy which is called general course (general pathological anatomy). It deals with information about the signs of death, disturbances of local and general circulation, disturbance of metabolism, inflammation, morphology
of immune reactions, disturbances of growth and development, compensatory processes and tumors. All these processes are the subject of general pathological anatomy which studies general regularities of the processes.
Special Pathological Anatomy also studies morphology, etiology and pathogenesis of diseases, their complications, outcomes, as well as classification of the diseases and phenomena of pathomorphism.
The changes in the morphological picture of the disease under the influence of medicinal preparations and improvement in the life conditions are called pathomorphism.
Pathological Anatomy has its methods of investigation: autopsy (dissection), biopsy, experiment.
Autopsy allows to reveal the cause of death, peculiarities of the course of the disease, to evaluate the efficiency of the drugs, instruments that is to perform clinical anatomical testing to improve the quality of diagnosis and thus to improve the qualification of a specialist. An autopsy demonstrates neglected disease which caused death. But it also gives information about morphological manifestations of the disease in case the pathologist studies the changes in the systems and organs which are not involved by the process. For example, all stages of tuberculosis which are well known to the physician were studied in this manner. This method was also used to study the
manifestations of cancer and pre-cancerous states. Dissection of the copse is not the purpose but means of investigation, it is necessary to enrich medical practice with new knowledge or to aid justice. Ethical duties of the pathologist include professional secret about everything found during the study.
An autopsy is performed on a cadaver or on organs removed in toto. First of all, the topographic relationships of individual organs are examined before their removal. This is followed by a macroscopic assessment, description of findings, and diagnosis. This method enables the autopsy to be performed quickly. After samples have been taken for histologic study, the organs are replaced in the body cavities. This autopsy technique is not suitable to demonstrate topographic relationships to a clinician (particularly a surgeon) or to a student.
Biopsy is also very important to study the disease pathology. It consists in visual examination of pieces of tissue or entire organs removed surgically. Biopsy includes research of the material taken from a living organism. This term was introduced in 1879 by E. Besnier. The first biopsy investigation was done in 1864 by Dushen de Boulogne for diagnosis of pseudohypertrophic mastopathy.
Biopsy is performed with the purpose of early diagnosis of the tumour, verification of the tumour, ascertainment of the histogenesis and anaplasia degree for tumours, determination of efficacy for operative
procedures and prognosis for tumor, determination of characteristics of non neoplastic processes.
Biopsy of tissues can be performed by several techniques and material processed for histology.
Excision biopsy - total dissection of the injured tissue or organ with subsequent study.
Incision biopsy - taking of a part of the injured tissue for studying.
Open (operative) biopsy - taking biopsy after surgical opening of the injured focus.
Needle (aspiration) biopsy - taking of the specimen by drawing it off through a needle or trochar.
Endoscopic biopsy - taking of the specimen by instrument through the endoscope or by needle under endoscopic control.
Puncture biopsy-taking of the small cylindrical specimen through puncture or small incision.
Brush biopsy-taking of the biopsy material with help of the brush catheter with subsequent study of the attached specimen.
Shave biopsy-taking the material with the help of the razor or surgical edge (is used for biopsy of the tissue which is prominent above the skin or upper layers of the derma).
Trepanobiopsy, curettage, smear, smear-imprint, forceps biopsy, biopsy by wash-out of operative wound and ulcerative defect, casual biopsy are also used.
Samples can also be assessed by electron microscopy.
Experiment is performed in scientific research to reveal distinctive features of the diseases, as well as the efficiency of the drugs and other.