Did you know that the earliest permanent specimen slides date back to the 1700s? Today, pathologists examine and diagnose specimens using rapid frozen section and permanent section.
Technology has advanced to the point where pathologists don’t even have to be onsite. Using advanced devices, digitization of specimen slides is now possible. These digital images are then transmitted to remote expert pathologists for interpretation.
This allows for rapid diagnosis even in locations without a pathologist. Patient care is now more efficient with shorter, less stressful wait times for a diagnosis.
Keep reading to learn more about innovative methods of pathologic analysis.
What Is a Frozen Section?
Biopsies are often taken during surgical procedures. The tissue samples are then sent to the pathologist for examination and diagnosis. The specimen may be assessed during the surgery or the following day.
At times, the surgeon may need pathologic information during the surgery. The pathology result may give the surgeon information about further surgical procedures needed.
For example, the pathologist can determine if the tissue margins are free of abnormal tissue. If not, the surgeon will remove more tissue until the margins are clear. This may also help with the decision to remove lymph nodes.
The pathologist may decide to do a frozen section depending on what the surgeon needs to know. Frozen sections are subject to limitations. The pathologist must quickly make diagnoses based on experience, judgment, and practice in his/her specialty.
When the surgeon sends a biopsy for a frozen section, it’s first frozen with aerosol sprays. Next, a cryostat freezes the tissue. The cryostat is a refrigerated box with a temperature of about -20 to -30 Celsius degrees.
The water inside the cells freezes making a hard matrix that allows slicing of the tissue. The rotary microtome located in the cryostat slices the frozen tissue. It’s then placed on a glass slide and stained.
Excluding complicating factors, the frozen section process takes about 5 to 20 minutes. The pathologist then examines the prepared slide under the microscope. The pathologist bases the diagnosis on the patient’s medical information and the tissue assessment.
Difference Between a Frozen and Permanent Section
A frozen section is one of two methods for examining tissue samples. The other type of tissue sample is a permanent section.
For a permanent section, the specimen is placed in formalin for initial preservation. It’s then processed with other solutions and placed in paraffin wax.
Once the wax hardens, the tissue is sliced into thin sections. It’s then placed on a slide and stained.
This process may take several days. The permanent sections provide more accurate results than a frozen section. Permanent sections should be completed after all frozen sections.
What Are the Limitations of Frozen Sections?
Frozen sections assist surgeons to make decisions during surgery about further procedures needed at that time. Yet, they are still considered inferior to permanent sections.
Frozen sections prove technically difficult to achieve reliable, quality sampling sections. The tissue staining may not exhibit equal quality compared to permanent sections. This may influence the diagnosis and subsequent surgical decisions.
Thus, frozen sections use requires caution in the interpretation of findings.
Reasons to Perform Frozen Section
While frozen section diagnosis involves some limitations, they prove useful when intra-operative management is important. The rationale for requesting a frozen section includes:
- To determine if a lesion is benign or malignant
- To confirm if suspicious tissue is a lesion
- To determine if enough tissue was retrieved for further histopathological workup
- To define the grade of a lesion to guide the surgical procedure
- To assess another lesion seen during the surgery
- To determine the organ of origin for tumors
- To assess if there are clear margins around the abnormal tissue
- To determine if a tumor has invaded lymph nodes or nerves
- To assess for tissue inflammation, granuloma, and fungal infection
One study performed at the University of Michigan Hospitals found that of 914 requests for frozen sections, 95% were appropriate referrals. Requests included checking margins (46%), identifying a primary diagnosis (43%), and determining the amount or viability of the sample (3%). One percent were done for immediate patient and/or family concerns.
Digital Pathology
The first commercial whole-slide imaging (WSI) scanners were developed in about 1998. Twenty years later, WSI devices can digitize an entire specimen slide.
These machines allow high-speed scanning and digital transmission of specimen slides to remote pathologists. The patient benefits from a quick analysis and diagnosis by an expert pathologist.
The Cleveland Clinic evaluated the efficiency of using WSI vs. traditional microscope slides. They found that the WSI took longer to review but felt that this time would decrease with experience. Lymph node screening for metastatic carcinoma and checking peri-prosthetic fibrous tissue for acute inflammation was even more time-intensive.
Yet, they found that using annotation tools with WSI was easier and more efficient. This allowed for the measurement of invasion depth faster compared to using only a microscope.
Many pathologists must move between areas of the hospital or even between buildings when performing frozen sections. Using this new technology, they were able to direct the dissection process and view the frozen section from their office. Even though digital WSI readings take longer, pathologists felt the time balanced by working in one place.
Do You Need STAT Pathology Results?
Many surgical procedures benefit from intra-operative pathologic analysis. These results serve as guides for the progression of the surgery. Surgeons may now request a frozen section, permanent section, or frozen section with a remote digital assessment.
Would your practice benefit from digital pathology results in real-time? Our U.S. Board-Certified pathologists and subspecialists provide interpretations within 1 hour.
If you work in a small area, you may not have direct access to subspecialists or even a pathologist. We are available 24 hours a day, 7 days a week, 365 days a year. You have access to our services from anywhere in the United States.
Contact us today and have your questions answered the same day.