What is defined as a biopsy?

A biopsy is defined as a procedure where tissue is sampled for examination. This process is crucial in medical practice as it allows healthcare providers to investigate the cellular composition of tissues and diagnose diseases, particularly cancer. During a biopsy, tissue may be collected through various methods, including needle aspiration, endoscopic techniques, or surgical excision, depending on the location and type of tissue needed for analysis.

The other options describe different medical procedures or concepts. For instance, the removal of an entire organ refers to an organ resection, which is typically done for more extensive disease, rather than tissue sampling. Treating infections involves methods such as administering antibiotics or antiviral medications, which is unrelated to the diagnostic purpose of a biopsy. A diagnostic test for blood circulation, such as angiography or Doppler ultrasound, focuses on blood flow analysis rather than tissue examination. Thus, the definition of a biopsy specifically encompasses the aspect of sampling tissue for diagnostic purposes, making it the correct choice.