What Does Equivocal Result Mean?

Every test is built to sort results into categories. Positive or negative. Present or absent. Above or below a cutoff.

Equivocal means your result did not land cleanly in either box. The number, the stain or the image sat close to the dividing line.

Read that as a statement about the test. It is not a third diagnosis sitting halfway between well and ill.

Most equivocal results come from one of these, and none of them involves anything unusual about you.

• The value was genuinely borderline. Biology is continuous; the cutoffs are lines drawn across it.
• The sample was not good enough. NCI describes an unsatisfactory Pap result as one where the lab did not have enough cells, or the cells were clumped together or hidden by blood or mucus.
• The method has limits. Every assay has a range where it stops discriminating well.

NCI also points out something worth holding onto. For many tests it is possible to have normal results even with cancer, and possible to have results outside the normal range while healthy. Tests are useful, and they are not oracles.

Breast cancer HER2 testing is the clearest published example of a borderline result being handled properly.

The first test is usually a stain. The ASCO and College of American Pathologists guideline defines a 2 plus stain as weak to moderate complete membrane staining in more than 10 percent of tumor cells. That is the borderline band.

A 2 plus result does not stand as the final answer. It triggers a second test that counts gene copies, and the guideline requires the stain and the gene count to be interpreted together to reach a designation of positive or negative.

So in this setting, an equivocal first test is not a dead end. It is a documented route to a clear one.

Three distinctions are worth keeping straight, because reports use these words loosely.

Equivocal is not abnormal. Abnormal means the test gave an answer, and the answer was outside the expected range.

Equivocal is not unsatisfactory. Unsatisfactory means the lab could not read the sample at all.

Equivocal is not indeterminate in the imaging sense, where a radiologist can see a thing clearly but cannot say what it is.

Repeating the identical test on the identical sample often reproduces the identical borderline answer. So the useful next steps are usually different in kind:

• a different method that measures something else, as with the gene count after a borderline stain.
• a fresh or larger sample, when the problem was the specimen.
• a repeat after an interval, when the question is whether something is changing.
• comparison with your older results, which sometimes settles it on its own.

Ask what decision is waiting on this result.

If nothing changes either way, the equivocal reading may not need chasing at all. If a treatment choice hangs on it, the team has a reason to push for a definite answer, and you have a reason to ask when.

Understanding Your Pathology Report explains how the sections of a report fit together. What Does Indeterminate Mean on a Scan? covers the imaging version of the same problem.

• National Cancer Institute — Tests and Procedures Used to Diagnose Cancer
• National Cancer Institute — HPV and Pap Test Results: Next Steps after an Abnormal Cervical Cancer Screening Test
• Wolff AC et al. HER2 Testing in Breast Cancer: ASCO/CAP Clinical Practice Guideline Focused Update. Arch Pathol Lab Med. 2018;142(11):1364-1382
• National Cancer Institute — Tumor Markers