How to perform a pathological examination
Nov 05, 2025
Source: Cainiu Health
Dr. Yang Ziqi
Introduction
In general, pathological examination requires standardized procedures to determine the nature of lesions. The main process includes sample collection, sample fixation and processing, section preparation, staining and microscopic observation, and issuance of a pathology report. When undergoing pathological examination, patients need to cooperate with their physicians in completing sample collection. Subsequently, based on the results of the pathology report, treatment or follow-up plans can be developed under medical guidance.
In general, pathological examination requires standardized procedures to determine the nature of lesions. The main process includes sample collection, sample fixation and processing, section preparation, staining and observation, and issuance of a pathology report. A detailed analysis is as follows:
1. Sample Collection: Doctors select appropriate collection methods based on the location and type of lesion. For lesions located on the body surface or mucous membranes, small tissue samples are usually obtained directly using biopsy forceps. For lesions in internal organs, samples may be collected via endoscopy or needle aspiration.
2. Sample Fixation and Processing: Collected samples must be immediately placed into fixative solution, with typical fixation lasting 6–24 hours. Fixation prevents tissue decay and autolysis, preserving the original cellular and tissue morphology to provide a stable basis for subsequent processing and observation. Inadequate or delayed fixation may compromise diagnostic accuracy.
3. Section Preparation: After fixation, samples undergo dehydration, clearing, and paraffin infiltration, then are embedded in paraffin blocks. Using a microtome, the tissue is sliced into thin sections only 3–5 micrometers thick. These sections are carefully mounted onto glass slides, dried, and deparaffinized so that the tissue adheres firmly to the slide, preparing it for staining.
4. Staining and Observation: Prepared sections are stained, most commonly with hematoxylin and eosin (H&E) stain. After staining, cell nuclei appear blue, while cytoplasm and stroma appear pink, allowing pathologists to clearly observe cellular morphology, structure, arrangement, and any abnormal changes under the microscope.
5. Issuance of Pathology Report: Based on microscopic findings and integrated with the patient’s clinical history and imaging results, the pathologist determines the nature of the lesion and issues a formal pathology report.
During pathological examination, patients should cooperate with doctors during sample collection. Subsequently, treatment or follow-up plans can be developed according to the pathology report under medical guidance. Additionally, proper care of the sampling site is important to prevent infection.
