Insufficient or Non-Diagnostic Samples: What It Means When a Sample Cannot Give a Diagnosis

Section Editor: Jason Wasserman MD PhD FRCPC
November 9, 2026

A nondiagnostic result means the pathologist could not make a diagnosis from the sample that was sent. Reports may also call it insufficient for diagnosis, inadequate, or unsatisfactory for evaluation. The result does not mean that something bad was found, and it does not mean that everything is normal. It means the sample could not answer the question it was taken to answer.

This article explains what a nondiagnostic or insufficient sample means and the words reports use to describe it. It also explains why it happens, how it differs from a negative result, and what usually happens next.

What does a nondiagnostic result mean?

A nondiagnostic result means the sample did not contain enough suitable tissue or cells for the pathologist to reach a conclusion. Every biopsy, needle sample, or Pap test is taken to answer a question, such as whether a lump is cancer. When the material is too scant, damaged, or unrepresentative to answer that question, the pathologist reports it as nondiagnostic.

A pathologist will not guess at a diagnosis, because a diagnosis based on an unsupportive sample could lead to the wrong treatment or false reassurance. Reporting the sample as nondiagnostic is the accurate answer when the material is not enough.

Nondiagnostic results are common in some sample types and rare in others. They are seen more often with small needle samples, such as a fine needle aspiration, than with tissue removed during surgery.

What words do reports use for a nondiagnostic sample?

Reports describe a nondiagnostic or insufficient sample in several ways, and the exact wording depends on the sample type and the laboratory. A few examples of how these lines appear in real reports:

THYROID, RIGHT LOBE, FINE NEEDLE ASPIRATION:
– NONDIAGNOSTIC. CYST FLUID ONLY.

LUNG, RIGHT UPPER LOBE, CT-GUIDED CORE BIOPSY:
– INSUFFICIENT FOR DIAGNOSIS. BLOOD AND FIBRIN ONLY; NO LESIONAL TISSUE IDENTIFIED.

CERVIX, PAP TEST:
– UNSATISFACTORY FOR EVALUATION DUE TO OBSCURING BLOOD.

These phrases fall along a range, from samples that could not be assessed at all to samples that could be assessed with some limits:

Nondiagnostic, insufficient, or unsatisfactory. The sample could not be used to make a diagnosis. Our dictionary entries on nondiagnostic and insufficient for diagnosis define these terms.
“No lesional tissue identified.” Tissue was received, but it does not include the abnormal area the doctor was aiming for. The tissue present may be normal, but it does not show the abnormal area.
Limited or “suboptimal.” The pathologist could assess the sample, but something reduced their confidence, such as few cells or damaged tissue. A report might say “limited for interpretation” or “satisfactory but limited by low cellularity.” The diagnosis is given, with a caution attached.
Scant. Only a small amount of material was present. “Scant” is a description and does not, by itself, make a sample nondiagnostic.

The difference between “unsatisfactory” and “satisfactory but limited” matters. An unsatisfactory sample does not answer, while a limited sample gives an answer that your doctor may want to confirm.

Looking up a word in your report?

Our Pathology Dictionary explains individual terms you may see beside a nondiagnostic result, such as “hypocellular,” “cautery artifact,” and “limited for interpretation.”

Why are some samples nondiagnostic?

A sample is nondiagnostic for one of a small number of reasons, and the report often says which one applies. Most of these reasons are not anyone’s fault, and they reflect how hard it can be to sample a small or hidden area of the body.

Too few cells or too little tissue. The needle or brush collected only a small amount of material. Reports may call a sample like this hypocellular or scant.
The abnormal area was missed. Small, deep, or moving targets are hard to reach so that the needle may sample normal tissue beside the abnormal area instead.
Blood or inflammation hides the cells. A large amount of blood or inflammation can cover the cells the pathologist needs to see. This is a common reason for an unsatisfactory Pap test.
The tissue is damaged. Crushing, heat from cautery, or drying before preservation can distort cells beyond recognition. Our entry on cautery artifact explains one type of damage.
Only dead tissue or fluid was collected. Some tumors contain large areas of dead tissue, called necrosis, and some nodules, such as a thyroid cyst, are mostly fluid. A sample made only of necrosis or fluid may not show which disease is present.

Some of these reasons point toward a solution. A sample that missed the target may need repeating, while a sample made only of necrosis may need a different approach that reaches living tissue.

Is a nondiagnostic result the same as a negative result?

A nondiagnostic result is not the same as a negative result. The two can look similar on a report because neither one names a disease, but they mean very different things.

Negative. The sample was adequate, and the pathologist looked for the disease and did not find it. A negative for malignancy result on an adequate sample is reassuring.
Nondiagnostic. The sample was not adequate, so the pathologist could not tell whether the disease was present. The result is neither reassuring nor worrying.

For this reason, a nondiagnostic result usually needs follow-up, even when nothing abnormal was seen. If you are unsure what your result means, ask your doctor whether the sample was adequate. Our section-by-section guide to the pathology report explains how to find the final diagnosis.

How do cytology reports handle nondiagnostic samples?

Cytology samples, which contain loose cells rather than tissue pieces, use standard reporting systems that include a category for nondiagnostic samples. Each system defines what an adequate sample must contain for that organ. Our article on the cytology report explains how these reports are organized.

Thyroid fine needle aspiration. The Bethesda System for Reporting Thyroid Cytopathology, 2023 edition, places these samples in category I, called “nondiagnostic.” The risk of cancer in a nodule with this result is estimated at 13%, within a range of 5% to 20%. A repeat sample guided by ultrasound gives a diagnosis in about 7 in 10 cases.
Pap test. A Pap test is reported as either “satisfactory for evaluation” or “unsatisfactory for evaluation.” A satisfactory sample may still carry a comment, such as “transformation zone component absent” or “scant cellularity.” These comments describe the sample but do not make it unsatisfactory.
Urine cytology. The Paris System for Reporting Urinary Cytology, 2022 edition, starts with a “nondiagnostic” category. Some urine samples are reported as “satisfactory but limited by low cellularity” instead. Unsatisfactory urine samples are uncommon.

Our thyroid nodule and NILM Pap test articles explain the other results these tests can give.

What if the biopsy does not match the scan?

Sometimes a biopsy result is technically adequate but does not explain what the scan showed. The sample may contain only normal tissue, even though the imaging suggested a mass. Pathologists and radiologists compare the two results to check whether they fit together.

When they do not fit, the result is treated much like a nondiagnostic one. The needle may have sampled tissue beside the abnormal area rather than the area itself. Our article on pathology reports and imaging reports explains how this comparison works and what happens when the results disagree.

Can the pathologist get more from the same sample?

Before calling a sample nondiagnostic, the pathologist often tries to get more from the material already in the laboratory, so a new procedure is not always needed.

Deeper sections. The laboratory can cut new slices deeper into the tissue block, because a small abnormal area may appear only in a deeper slice. Reports may call these “levels” or “deeper levels.”
Additional stains. Stains such as immunohistochemistry can sometimes identify a few abnormal cells that are hard to see on routine slides.
A cell block. For fluid and needle samples, leftover material can be spun down and processed like tissue, giving the pathologist more to examine.

These steps help when some useful material is present. When the sample contains no suitable cells, no amount of extra work on the same sample can produce a diagnosis.

What happens after a nondiagnostic result?

The next step after a nondiagnostic result depends on what was being investigated and how concerned your care team is. Options include repeating the test, using a different method, or monitoring the area over time, and your doctor will explain what applies to you.

Repeating the sample. This is the most common next step after a nondiagnostic result. For a thyroid nodule, the Bethesda System (2023 edition) recommends a repeat ultrasound-guided fine needle aspiration. For an unsatisfactory Pap test, the 2019 ASCCP management guidelines recommend repeating the test in 2 to 4 months.
Using a different method. A core needle biopsy collects more tissue than a fine needle aspiration, and surgical removal collects the whole area. Some procedures also use rapid on-site evaluation, where a pathologist checks the sample during the procedure to confirm it is adequate.
Watching the area. When imaging makes cancer very unlikely, your team may suggest repeat imaging instead of an immediate repeat biopsy.

When an HPV test is done at the same time as an unsatisfactory Pap test, a negative HPV result is not considered reliable, so both tests are repeated. If the repeat Pap test is again unsatisfactory, the 2019 ASCCP guidelines recommend colposcopy.

Reading the report from a specific procedure?

Our Procedures section explains the full pathology report from common procedures. Guides include the breast biopsy and bone marrow biopsy reports, and each walks through every result the report can contain.

Questions to ask your doctor

Was my sample nondiagnostic, or was it adequate but negative?
Why was my sample nondiagnostic?
Was the abnormal area sampled, or did the biopsy miss it?
Did the pathologist do extra work on the sample, such as deeper sections or stains?
Does my biopsy result match what my imaging showed?
Do I need a repeat biopsy or test, and when?
Would a different type of biopsy be more likely to answer?
Is it safe to watch the area with imaging instead of repeating the biopsy?
What is the chance that the area is cancer, given that the sample was nondiagnostic?
If my report says the sample was limited, how confident is the diagnosis?