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How aplastic anaemia is diagnosed, from blood count to bone marrow test | CION Cancer Clinics
Aplastic anaemia is confirmed by a bone marrow test that shows an almost empty marrow, alongside a blood count where red cells, white cells and platelets are all low. Before that, blood tests rule out common causes such as low vitamin B12 or infection. After it, extra tests check for PNH, early marrow cancers and inherited causes. Here is each step, what it feels like and what the report words mean. At CION Cancer Clinics, our haematologist cares for anaemia, bleeding, clotting and inherited blood disorders, with ArogyaSri, CGHS and cashless insurance accepted.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- How is aplastic anaemia diagnosed?
- What happens between the first low report and a diagnosis?
- What exactly is taken during a bone marrow test?
- Which conditions can look like aplastic anaemia?
- What worries families about the bone marrow test?
- What do the words on a marrow report mean?
- What should you ask, and what can the result not tell you?
- Common questions about diagnosing aplastic anaemia
The short answer
How is aplastic anaemia diagnosed?
Aplastic anaemia is diagnosed with a bone marrow test that shows an almost empty marrow, together with a blood count where red cells, white cells and platelets are all low. Doctors also have to rule out the other conditions that can look the same.
Why one blood test is not enough
A full blood count tells you the numbers are low. It does not tell you why. Low vitamin B12, a viral infection, some medicines, an enlarged spleen and early marrow cancers can all produce a very similar report. Treating the wrong cause wastes time, and some treatments for aplastic anaemia are unsafe if the real problem is something else.
What the bone marrow test adds
The marrow is where blood cells are made. Looking at it directly shows whether the factory is empty, full of abnormal cells or working normally while cells are lost elsewhere. That single difference points to very different treatments.
How long it usually takes
Some results come back within days. Special tests on the marrow sample, such as gene and chromosome studies, can take longer. Your team may start supportive care, such as transfusions, while the full picture comes together.
This page explains the usual pathway. It cannot tell you what your own report means. Bring it to a haematologist.The pathway
What happens between the first low report and a diagnosis?
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The first abnormal blood count
Often found during a check for tiredness, fever or bruising, or by chance before surgery. Reference ranges differ between laboratories, so the doctor reads your result against the range printed on your own report, along with your symptoms.
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A repeat count and a blood film
The count is repeated to confirm it. A trained person looks at the blood under a microscope for abnormal or immature cells, and a reticulocyte count shows how many young red cells the marrow is releasing.
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Blood tests for common look-alikes
Vitamin B12, folate, liver and kidney tests, thyroid tests and viral tests such as hepatitis and HIV. These find treatable causes that are far more common than aplastic anaemia.
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Referral to a haematologist
If all three cell lines stay low with no clear cause, a haematologist reviews the case and plans a bone marrow test.
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The bone marrow test
Two samples are taken from the back of the hip bone in one sitting. Most adults go home the same day.
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Extra tests and a final review
A PNH blood test, chromosome studies and, in younger people, tests for inherited marrow failure. The results together confirm the diagnosis and its severity.
Not sure whether this applies to you?
Ask an oncologistInside the marrow test
What exactly is taken during a bone marrow test?
Two different samples, each answering a different question. Both are needed for aplastic anaemia.
The aspirate
A thin needle draws out a little liquid marrow. It is spread on glass slides so the individual cells can be looked at under a microscope.
It helps show
- Whether cells look normal
- Early signs of marrow cancers
The trephine biopsy
A slightly wider needle removes a small core of bone with marrow inside it. This keeps the structure intact, so the pathologist can judge how full or empty the marrow is. In aplastic anaemia, this is the key sample.
How it feels
The skin and bone surface are numbed with local anaesthetic. You feel pressure, and a brief dragging ache as the liquid is drawn out. Children and very anxious adults may be given sedation.
Expect a sore hip for a few days.Tests run on the sample
Part of the sample goes for special studies that can take longer to report.
- Chromosome studies (cytogenetics)
- Flow cytometry, a cell-marker test
- Gene tests, where needed
Ruling things out
Which conditions can look like aplastic anaemia?
Condition that can look similar
How it is usually told apart
Low vitamin B12 or folate
Blood levels, and large red cells on the blood film
Myelodysplastic syndrome, an early marrow cancer
Abnormal-looking cells and chromosome changes in the marrow
Some leukaemias
A marrow crowded with immature cells rather than empty
PNH, a condition that breaks down red cells
A flow cytometry blood test for missing surface proteins
Fanconi anaemia and other inherited types
A chromosome breakage test and gene tests, mainly in younger people
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Commonly believed
What worries families about the bone marrow test?
"The needle goes into the spine and can cause paralysis."
The sample is taken from the back of the hip bone, not the spine. The needle does not go near the spinal cord or its nerves. Serious problems are uncommon, and the team checks your platelet count and bleeding risk beforehand.
"Taking marrow out will make the marrow weaker."
The amount taken is tiny compared with the marrow spread through all your bones. It does not lower your blood counts or slow recovery. Not doing the test is the bigger risk, because treatment then rests on a guess.
"If the scan and blood tests are done, the marrow test is optional."
Scans do not show how full the marrow is, and blood tests cannot separate aplastic anaemia from early marrow cancers. The trephine sample is the part that confirms the diagnosis. Without it, most haematologists will not start specific treatment.
"We should try tonics for a few months before any test."
Tonics and iron do not restart an empty marrow. Very low counts can lead to serious infection or bleeding while you wait. Delaying the test only delays the answer, and the right treatment with it.
On your report
What do the words on a marrow report mean?
- Cellularity
- How much of the marrow space holds blood-making cells rather than fat. Normal cellularity falls with age.
- Hypocellular or aplastic marrow
- Far fewer blood-making cells than expected for your age. This is the central finding in aplastic anaemia.
- Dysplasia
- Cells that look abnormal in shape. Its presence points more towards an early marrow cancer than aplastic anaemia.
- Cytogenetics
- A study of the chromosomes inside marrow cells. Certain changes suggest a different diagnosis.
- PNH clone
- A group of blood cells missing certain surface proteins. It is often found alongside aplastic anaemia and is watched over time.
- Reticulocyte count
- The number of young red cells in the blood. A low count means the marrow is not keeping up.
Being straight with you
What should you ask, and what can the result not tell you?
A diagnosis of aplastic anaemia tells you what is wrong with the marrow. On its own it does not tell you how you will respond to treatment or how things will go over the years. That depends on the severity, your age, your general health and how your counts respond.
Questions worth taking to the appointment
Ask how severe the condition is and which counts decided that. Ask whether inherited causes and PNH have been checked. Ask whether brothers or sisters should have tissue-type testing for a possible transplant, and where each test will be done. Ask what to do if a fever or bleeding starts at night.
How CION fits in
CION's haematology team reviews your blood and marrow reports, presents the case to a tumour board and coordinates specialist tests, transplant assessment and treatment with qualified centres where needed. We will tell you plainly where each step happens.
If you have low counts and develop a fever or bleeding that will not stop, go to the nearest emergency department or call 108 the same day.Questions we are asked
Common questions about diagnosing aplastic anaemia
Does a bone marrow test hurt?
The area is numbed first, so the sharp part is mostly the numbing injection. You will feel pressure and a short dragging ache when the liquid sample is drawn. It is over in minutes. A sore hip for a few days is common, and plain pain relief suggested by your team usually helps.
Do I need to be admitted for the test?
Most adults have it as a day procedure and go home after a short rest. Children often need sedation, so they stay a little longer. If your platelets are very low, the team may give a platelet transfusion first. Someone should come with you, especially if you have been sedated.
Can a normal blood count rule out aplastic anaemia?
A truly normal count, repeated, makes it very unlikely, because the condition lowers the counts. But a single borderline result is not enough to decide either way. Read it with your symptoms and a repeat test, and ask a doctor if you still have bruising, bleeding or repeated infections.
How soon will we know the result?
A first look at the aspirate can come quickly. The trephine biopsy needs processing, and chromosome and gene studies take longer still. Your haematologist may share an early impression and confirm it when every result is in. Ask the team for an expected date so you are not left waiting without news.
Why do they want to test my brothers and sisters?
For two reasons. A brother or sister may be a matched donor if a stem cell transplant is considered. And if an inherited cause is suspected, siblings may carry the same gene change without knowing it. The team will explain each test and ask for consent before anything is done.
Will I need the marrow test more than once?
Often, yes. It may be repeated to check how the marrow is responding to treatment, or if counts change in a way that raises a new question. Repeat tests are part of normal follow-up. They do not by themselves mean something has gone wrong.
Can a transfusion affect the tests?
Yes. Transfused cells mix with your own and can change some blood results, including certain PNH and gene tests. That is why your team may take some samples before a transfusion if it is safe to do so. Never delay a transfusion your doctors say is urgent just to protect a test.
Are these tests covered by Aarogyasri or insurance?
Diagnostic tests are often covered when they are part of an approved care plan, under Aarogyasri, PM-JAY, CGHS, ECHS, EHS or cashless insurance. Special gene tests are sometimes treated differently, and scheme rules change. Call the helpline with your card details and check the current rules before the test.
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Meet CION's haematologist. One specialist for your blood report and your plan.
Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- NHS — Aplastic anaemia: diagnosis
- National Heart, Lung, and Blood Institute — Aplastic Anemia: Diagnosis
- Cancer Research UK — Bone marrow test
- National Cancer Institute — Definition of bone marrow aspiration and biopsy
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Aplastic Anaemia ExplainedWhat the condition is, its causes and treatmentSeverity Grading in Aplastic AnaemiaHow the results decide moderate, severe or very severePNH and Its Overlap With Aplastic AnaemiaWhat a PNH clone on your report meansFanconi Anaemia and Inherited Marrow FailureWhy younger patients are tested for inherited causesBiopsy guideMore on biopsies and what to expect
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