What is a frozen-section biopsy?
One commonly encounters the phrase “frozen-section biopsy” when an operation is being contemplated. What is it?
First of all, what is a biopsy?
A biopsy is the microscopic examination of a human body sample (tissue or fluid) to get to a diagnosis (statement of a medical condition). This is usually done by a pathologist (a physician specializing in laboratory diagnosis of diseases).
There are many types of biopsy. The type is usually suggested by the noun-adjective preceding the word biopsy. Examples are excision biopsy; incision biopsy; section biopsy; punch biopsy; fine-needle biopsy; core-needle biopsy; cell block biopsy; paraffin-section biopsy; and frozen-section biopsy.
In this paper, discussion will be limited to frozen-section biopsy. Unavoidably, paraffin-section biopsy is also discussed.
Paraffin-section biopsy and frozen-section biopsy are biopsy procedures that carry different procedures in fixing the specimens prior to sectioning them into thin slices to be mounted on glass slides for microscopic examination.
Paraffin-section biopsy implies the specimen is being fixed and embedded in paraffin wax prior to sectioning.
Frozen-section biopsy implies the specimen is being fixed by freezing and embedded in ice cube prior to sectioning.
The three other differences that are important to know are:
- In frozen-section biopsy, the processing of the specimen up to the time the microscopic slide is ready to be read by the pathologist usually takes about 30 minutes. In paraffin-section biopsy, the processing of the specimen up to the time the microscopic slide is ready to be read by the pathologist usually takes several hours, usually 48 hours. Thus, frozen-section biopsy can be said to be a rush biopsy procedure.
- The frozen-section biopsy usually do not show features of the specimen as clearly as those seen in paraffin-section biopsy. However, most of the time, they are good enough. There are situations in which frozen-section biopsy is not recommended because of known limitations. Examples, it is not recommended in wire-localized breast lesions, which are microscopic to start with. It is not recommended in certain lesions which are hard to diagnose with frozen-section but more reliable on paraffin-section.
- The expenses are more in case a frozen-section biopsy is done as they entail added laboratory procedure on top of the paraffin-section biopsy (which is usually routinely done even after a frozen-section biopsy). They also entail additional professional fee from a pathologist who will read the slides of the frozen-section biopsy. Furthermore, if the patient is under general anesthesia, the waiting time of 30 minutes to less than an hour for the result of the frozen-section biopsy to come in will entail consumption and therefore, additional expenses, of anesthetic gases equivalent to the duration of the waiting.
What are the indications for a frozen-section biopsy?
There are essentially two indications for frozen-section biopsy. These are:
- When there is a need for a more definitive diagnosis during an operation which will guide the surgeon on what to do, particularly on the extent of operation. The assumption here is that the frozen-section biopsy can be relied upon to give a more definitive diagnosis. As much as possible, a definitive diagnosis should be gotten before the operation. However, in instances when it is difficult to get one, then one may be forced to do a frozen-section biopsy but only if it is needed to guide the surgeon on what to do regarding the extent of operation. If the extent of operation will be the same regardless of the diagnosis, then the frozen-section is not indicated.
- When there is a need to know the status of the margins of resection particularly in cancer surgery which will guide the surgeon on the extent of operation or resection.
Conversely, a frozen-section biopsy is not indicated when:
- There is already a definitive pre-operative diagnosis and there is an agreed definitive plan of operation.
- It is difficult to make an accurate diagnosis on frozen-section biopsy.
- The extent of operation will not differ at all or significantly regardless of a frozen-section biopsy diagnosis.
- There is no need to determine the margins of resection for one reason or another such as there will be a wide resection that will be done that ensures a high chance of free margin.
The final decision on whether to do a frozen-section biopsy will be derived after a benefit-risk-cost-availability analysis. Thereafter, an informed consent or refusal from the patient should be obtained.
Benefits consists of the indications and non-indications of frozen-section biopsy cited above (which carries the highest priority).
Risk consists of the potential ill-effects of prolonged operation and anesthesia associated with frozen-section biopsy.
Cost consists of the additional expenses that will be incurred with frozen-section biopsy.
Availability consists of presence of ready capacity and quality capability of the laboratory department of a medical center for frozen-section biopsy.