After the specimen is removed from the patient, it's put in a container with a special type of liquid to preserve the sample. The pathologist or trained lab assistant reviews the specimen by the naked eye. This means without using a microscope. The pathologist looks at, measures, feels, or takes pictures of the specimen. This type of exam helps the pathologist determine which part of the specimen is the most important. That part will be looked at under a microscope to help diagnose a disease or condition.
Next, the pathologist or a trained lab assistant gets the specimen ready to look at under a microscope. Specimens are processed based on the type of sample sent to the pathology lab. They can be prepared as a histologic section or a smear, as described below.
- Histologic sections are very thin slices of the specimen that are stained, placed on a glass slide, and then covered with a thin piece of glass called a coverslip.
- Smears are done when the specimen is a liquid or there are small, solid chunks suspended in a liquid. These are "smeared" onto a slide. They are then allowed to dry or are fixed. The fixed smears are stained, covered with a coverslip, and then examined under a microscope
Routine processing and histology can take one day or more. Sometimes information about a tissue sample is needed during surgery to make immediate decisions. A pathology consult can be done during surgery if the surgeon can't wait for routine processing and histology. This is often called a frozen section exam and usually takes 10 to 20 minutes.