Diagnostic Criteria for Aplastic Anemia (AA)

Aplastic anaemia is a rare and heterogeneous disorder. It is defined as pancytopenia with a hypocellular bone marrow in the absence of an abnormal infiltrate or marrow fibrosis.

Clinical features and diagnosis

Proposed diagnostic criteria (both I and II must be fulfilled in the absence of neoplasia):
I- At least 2 of the following complete blood count (CBC) findings: granulocytes < 500/L, platelets < 20,000/μL, corrected reticulocyte count < 20.000/μL
II- Bone marrow must be either markedly hypoplastic (< 25% of NAAC*) or moderately hypoplastic (25-50% of NAAC*) with <30% of cells being hematopoietic (*NAAC = normal age appropriate cellularity)

The modified Camitta criteria are used to assess severity:

  • Severe AA (SAA): Marrow cellularity <25% (or 25–50% with <30% residual haematopoietic cells), plus at least 2 of: (i) neutrophils <500/μL, (ii) platelets <20.000/μL, (iii) reticulocyte count <20.000/μL.
  • Very Severe AA (VSAA): As for SAA but neutrophils <200/μL.
  • Non‐severe AA (NSAA): AA not fulfilling the criteria for SAA or VSAA



  1. Killick SB, Bown N, Cavenagh J, Dokal I, Foukaneli T, Hill A, Hillmen P, Ireland R, Kulasekararaj A, Mufti G, Snowden JA, Samarasinghe S, Wood A, Marsh JC; British Society for Standards in Haematology. Guidelines for the diagnosis and management of adult aplastic anaemia. Br J Haematol. 2016 Jan;172(2):187-207. [Medline]
  2. Clucas D, Fox LC, Wood EM, Hong FS, Gibson J, Bajel A, Szer J, Blombery P, McQuilten ZK, Hiwase D, Firkin F, Cole-Sinclair MF; Australian Aplastic Anaemia Registry Steering Committee. Revisiting acquired aplastic anaemia: Current concepts in diagnosis and management. Intern Med J. 2018 Oct 15. [Medline]


Created Nov 02, 2018.