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Diagnosis and tests

When results are ready

One of the hardest feelings during diagnosis is waiting. Some results arrive within hours, others take weeks. This topic explains why, roughly when each result comes and how to get through the waiting time more calmly.

Last updated: ~5 min read
A soft golden light slowly rising over the horizon on a dark navy background; bands of light of different lengths — some fully open, others still on their way; a calm, hopeful mood.
Figure 1.Concept: results arrive in waves, like morning light.

01Short answer

In a leukemia diagnosis, results arrive in stages. A full blood count is usually ready within a few hours, and a blood film the same day or the next. Flow cytometry and microscopy of the bone marrow aspirate often confirm a preliminary diagnosis within 1–3 days. FISH and urgent PCR tests (for example, for PML::RARA or BCR::ABL1) take a few days, while the karyotype and broad NGS panels usually take 1–3 weeks, because cells must be grown or complex analysis carried out. Histology of the trephine biopsy can take from a few days to 1–2 weeks because the bone must first be softened. Timings depend on the laboratory and on urgency. Treatment sometimes starts before every result is in and is then refined according to the genetic findings. Always go through your results with your own doctor.

02Simple explanation

Results do not come all at once but in waves: fast tests first, then deeper ones.

Fast tests (blood count, blood film, flow cytometry) answer “is there leukemia, and which group is it?”.

Slow tests (karyotype, NGS) answer “what is the exact subtype, and what is the risk?”.

Slowness is not the lab being lazy: some tests need cells to be grown or thousands of DNA fragments to be read.

Waiting is hard. Writing down questions, talking to loved ones and asking the team for clear dates all help.

03Scientific explanation

Why are some tests fast? A full blood count is measured by automated analysers in minutes. Flow cytometry identifies markers on the cell surface within hours. According to MedlinePlus, bone marrow aspirate smears can be looked at quickly under the microscope once they are stained.

Why are others slow? The ACS explains that for a karyotype, cells are made to divide in the laboratory, and only then can the chromosomes be seen. A trephine sample has to be softened before it can be cut. NGS panels read many genes at once, and the result needs bioinformatic analysis and expert review.

Urgent tests. The NHS and CRUK note that some results come back in a few days and others in a few weeks. When APL is suspected, doctors start ATRA without waiting for genetic confirmation. The ELN 2022 recommendations stress that genetic results that affect AML treatment, such as FLT3, should be obtained as quickly as possible — within a few days.

Preliminary and final reports. According to the NCI, a pathology report sometimes arrives in stages: first a preliminary result, then a final report including additional tests. There may also be an addendum or a corrected report. This is not a mistake; it is the information being completed.

04What happens in the body?

The first hours and days

The full blood count and blood film come back quickly and are often the reason a hematologist is called. The bone marrow aspirate and flow cytometry usually give the answer “this is leukemia, and this is the type” within 1–3 days. It is often at this stage that the doctor first has a detailed conversation with you.

Glowing sample capsules moving at different speeds along translucent laboratory lanes on a dark navy background: one already at the finish, others still passing incubator and gene-reading stations; no people.
Figure 2.In the laboratory, tests move at different speeds.

The following weeks

FISH and urgent PCR results come within a few days, and the karyotype and NGS panel usually within 1–3 weeks. These findings determine the risk group, whether targeted drugs are needed and whether a transplant should be discussed. The plan may change because of them — this is normal.

When does treatment start?

This depends on the type of leukemia and on how you are. In APL and when someone is very unwell, treatment starts immediately. In stable AML, the doctor sometimes waits a few days for genetic results to choose the most suitable regimen. In chronic leukemias there is usually no need to rush.

How to get through the wait

The NCI stresses that fear and worry are natural at this time. Ask the team which result is expected when, and write it down. Keep a question notebook. Rather than searching the internet alone late at night, read trusted sources and talk to the people close to you. If you can see a psychologist or social worker, make use of it.

A quiet waiting room in dark navy tones; soft morning light falls through the window, and an open notebook and a cup of tea rest on an armchair; no faces.
Figure 3.Calm and support matter while you wait.

Who gives you the result?

Usually your hematologist or their team explains the result at an appointment or by phone. If you see a result on a portal before you have spoken to the doctor, try not to panic or draw conclusions alone — ask at your next appointment.

05Waves of results

From a quick answer to a precise picture.

Hours — Full blood count, blood film.1HoursFull blood count, blood film.
1–3 days — Bone marrow microscopy, flow cytometry.21–3 daysBone marrow microscopy, flow cytometry.
A few days — FISH, urgent PCR.3A few daysFISH, urgent PCR.
1–3 weeks — Karyotype, NGS, histology.41–3 weeksKaryotype, NGS, histology.
Clear expectationsYou know what will come when.
The full pictureThe plan is refined by genetics.
A calm conversationResults are read with your doctor.

06Approximate result times

TestApproximate timeWhy
Full blood countA few hoursAutomated analyser
Blood filmSame day – next dayStaining and microscopy
Flow cytometry1–2 daysRapid marker identification
Bone marrow aspirate (microscopy)1–3 daysStaining and expert review
FISH, urgent PCRA few daysTargeted genetic search
Karyotype1–3 weeksGrowing cells in the laboratory
NGS panel1–3 weeksReading and analysing many genes
Trephine biopsy (histology)A few days – 2 weeksSoftening the bone

* Timings are a general guide and depend on the laboratory, urgency and public holidays. Ask the team when to expect your own results.

07Key terms

Preliminary result
A first, incomplete answer that is enough for urgent decisions.
Final report
The complete result taking all additional tests into account.
Addendum
An addition to an earlier report based on tests that came later.
Karyotype
A description of all the chromosomes in a cell under the microscope.
NGS
Next-generation sequencing, which reads many genes at once.
Trephine biopsy
A bone marrow sample in the form of a small core of bone.
Decalcification
Softening a bone sample before it is cut.
Turnaround time
The time from taking a sample to the result being ready.

08Key points

  • Results arrive in stages.
  • A blood count takes hours; flow cytometry and microscopy take days.
  • Karyotype and NGS usually take 1–3 weeks.
  • In urgent cases, treatment starts on the first results.
  • The plan may change once genetic results arrive.
  • Ask who will give you the result, and when.
  • Asking for support while you wait is normal.

09Frequently asked questions

Why won’t they tell me the result over the phone?

Serious and complex results are usually better explained in person, so your questions can be answered straight away. You can tell the team how you prefer to receive information.

My results are very delayed. Is this a bad sign?

No. Delays are usually due to the technical nature of the test, extra checks or the laboratory’s workload, not to the result itself.

I saw my result on the portal but I don’t understand it.

This happens a lot. Try not to interpret numbers and terms alone. Write down your questions and ask your doctor to explain at your next appointment.

Treatment has started but the genetic results aren’t back yet. Is that right?

Yes, this is common. Initial treatment is based on the first findings; once the genetic results arrive, decisions are made about the next phases, targeted drugs or a transplant.

Can I get copies of my results?

In most countries, patients have the right to copies of their own medical records. They are useful for a second opinion and for future care.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Why won’t they tell me the result over the phone?

  2. My results are very delayed. Is this a bad sign?

  3. I saw my result on the portal but I don’t understand it.

  4. Treatment has started but the genetic results aren’t back yet. Is that right?

  5. Can I get copies of my results?

My questions

12Sources

  1. NHS. Acute myeloid leukaemia — Tests and next steps
  2. NHS. Acute lymphoblastic leukaemia — Tests and next steps
  3. NHS. Blood tests
  4. Cancer Research UK. Tests for acute myeloid leukaemia (AML)
  5. Cancer Research UK. Tests for acute lymphoblastic leukaemia (ALL)
  6. Cancer Research UK. Bone marrow test
  7. American Cancer Society. Testing Biopsy and Cytology Specimens for Cancer
  8. American Cancer Society. Understanding Your Pathology Report
  9. National Cancer Institute (NCI). Pathology Reports
  10. MedlinePlus (U.S. National Library of Medicine). How to Understand Your Lab Results
  11. MedlinePlus (U.S. National Library of Medicine). Bone Marrow Tests
  12. National Cancer Institute (NCI). Feelings and Cancer
  13. Blood (American Society of Hematology), 2022. Dohner H, et al. Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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