A biopsy is a medical procedure where a small sample of tissue is removed for examination under a microscope. The frozen section biopsy, also known as cryosection, is a specialized version designed for immediate analysis while a patient is still in the operating room. This method bypasses the lengthy preparation process of a standard biopsy, providing a preliminary diagnosis in a matter of minutes. The speed of the frozen section is an invaluable tool for guiding a surgeon’s decisions during an ongoing operation.
The Purpose of Rapid Diagnosis During Surgery
The primary application of the frozen section method is to provide pathologists and surgeons with real-time diagnostic information that can significantly alter the course of a procedure. Instead of waiting days for a full pathology report, the surgeon can receive an answer within 10 to 20 minutes, allowing for immediate surgical adjustments. This rapid response is particularly relevant in oncologic surgery, where the extent of the operation is often dependent on whether a mass is benign or malignant.
One of the most frequent uses is the assessment of surgical margins, which are the edges of the tissue removed during tumor excision. The pathologist examines these margins to ensure they are clear of cancer cells. If cancer cells are detected at the margin, the surgeon knows immediately that more tissue must be removed during the same operation to achieve a complete resection.
The technique also helps determine the nature of an unknown mass discovered during the procedure, identifying it as either a harmless growth or a cancerous tumor. This distinction dictates the level of surgical intervention needed, such as deciding between a minimally invasive procedure or a more extensive operation, like a major organ removal or lymph node dissection.
Lymph Node Assessment
For instance, in certain cancers, the pathologist may examine a sentinel lymph node to see if cancer cells have spread. This assessment informs the surgeon’s decision on whether to remove additional lymph nodes.
Step-by-Step: The Frozen Section Process
Once removed, the tissue sample is immediately transported to a specialized pathology lab, often near the operating room. The pathologist first performs a gross examination, selecting the most representative area for microscopic analysis. The speed of the analysis is achieved by replacing traditional chemical fixation and wax embedding with rapid freezing.
The selected tissue is placed on a metal holder, encased in a gel-like medium, and rapidly frozen to a temperature typically between -20 and -30 degrees Celsius. This freezing occurs inside a specialized instrument called a cryostat, which is a microtome housed within a freezing chamber. The extreme cold hardens the tissue, allowing it to be sliced without chemical preservation.
The cryostat then cuts the frozen tissue into ultra-thin sections, usually five to ten micrometers thick. These fragile sections are picked up onto a glass slide and immediately stained using rapid chemical solutions, most commonly a modified hematoxylin and eosin (H&E) stain. The staining process highlights cellular structures, making the nuclei and cytoplasm visible. Finally, the pathologist examines the slide under a microscope to make a provisional diagnosis, which is then communicated back to the surgical team, often via an intercom.
Interpreting Results and Reliability
The diagnosis provided by a frozen section is considered a provisional result, guiding immediate surgical steps rather than serving as the final, definitive word. The entire process, from receiving the tissue to communicating the result, generally takes about 10 to 20 minutes, which is a fraction of the time required for standard tissue processing. This speed comes with a trade-off: the rapid freezing and quick staining yield slides of slightly lower quality compared to those prepared through traditional methods.
Despite technical limitations, the frozen section technique demonstrates a high degree of diagnostic accuracy, often reported to be 90 to 98 percent compared to the final pathology report. However, in cases involving complex tissue architecture, small lesions, or certain tumors, the pathologist may determine the frozen section is inconclusive. In these situations, the diagnosis is deferred, and the surgeon must wait for the final, permanent section report to confirm the nature of the tissue.
The permanent section involves fixing the tissue in formalin and embedding it in paraffin wax, a process that takes one to two days but produces slides with superior cellular detail. After surgery, all excised tissue is processed using this standard, slower method. The final pathology report, based on the permanent section, serves as the definitive diagnosis and is used for long-term treatment planning and patient management.