tissuesampling

Tissue sampling is the process of obtaining cells or tissue from a living organism for examination by pathologists or researchers. The objective is to establish a diagnosis, assess disease extent, guide management, or study tissue characteristics. Sampling can be cytology, which analyzes individual cells or small clusters, or histology, which analyzes a piece of tissue.

Common techniques include surgical biopsy (excisions or incisions to remove tissue), core-needle biopsy (a hollow needle withdraws a cylinder of tissue), and fine-needle aspiration (a thin needle aspirates cells). Additional methods include punch biopsies for skin, endoscopic biopsies from mucosal surfaces, and brushings or washings for cytology. Image-guided approaches using ultrasound, CT, or MRI are often used to target deep or difficult locations.

Specimens require appropriate handling. Histology samples are fixed in formalin to preserve tissue and embedded in paraffin for microscopic evaluation. Cytology specimens may be prepared as stained smears or cell blocks and may require rapid onsite evaluation. Accurate labeling, timely transport, and an adequate sample size are important for diagnostic quality.

Indications include suspected malignancy, infectious or inflammatory disease, autoimmune conditions, transplantation surveillance, and research. Risks include bleeding, infection, pain, and rarely injury to adjacent structures; sampling results may be non-diagnostic or may not capture the most representative tissue, which can necessitate repeat procedures.

Ethical considerations include informed consent and weighing risks and benefits, especially in vulnerable populations. Overall, tissue sampling is a cornerstone of diagnostic medicine and biomedical research, with methods chosen to balance diagnostic yield, safety, and patient factors.