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Approach to the Critical Patient
Immediate priorities
Life threats in aplastic crisis
Overwhelming infection from neutropenia
ANC < 0.5 x 10^9/l severe risk
ANC < 0.2 x 10^9/l very severe risk
Hemorrhage from thrombocytopenia
Platelets < 10 x 10^9/l spontaneous bleeding risk
Intracranial or GI hemorrhage threat
Symptomatic anemia
High output cardiac failure
Demand ischemia with Hb < 70 g/l
Time critical actions
Febrile neutropenia is an oncologic emergency
Temperature >= 38.3 C with ANC < 0.5 x 10^9/l
If febrile neutropenia, broad spectrum antibiotics within 1 hour
Active uncontrolled bleeding
Platelet transfusion for platelets < 10 x 10^9/l or active bleeding
If intracranial hemorrhage suspected, emergent CT head
Hemodynamic instability
If septic shock, fluid resuscitation and early vasopressors
Massive transfusion planning for hemorrhagic shock
Monitoring and targets
Monitoring bundle
Continuous cardiac and pulse oximetry
SpO2 target >= 92%
Tachycardia trend from anemia
Frequent vital sign cadence
Temperature surveillance for occult infection
Mental status trend for intracranial bleed
Transfusion targets
pRBC for Hb < 70 g/l or symptomatic anemia
Irradiated leukoreduced products
CMV safe if transplant candidate
Platelet threshold
< 10 x 10^9/l prophylactic
Higher threshold with fever or active bleeding
Immediate consults
Consultation triggers
Hematology for all suspected cases
Urgent bone marrow biopsy planning
Definitive therapy decision
Transplant team early
HLA typing if eligible
Sibling donor search
Infectious disease
Invasive fungal infection concern
Persistent febrile neutropenia
History
Presentation pattern
Core syndrome
Progressive fatigue
Exertional dyspnea
Pallor over weeks to months
Bleeding symptoms
Gingival bleeding and epistaxis
Petechiae and easy bruising
Menorrhagia
Infection symptoms
Recurrent fevers
Sore throat and oral ulcers
Crisis features
Febrile neutropenia
Temperature >= 38.3 C
Rigors and sepsis symptoms
Major hemorrhage
Melena or hematuria
Headache suggesting intracranial bleed
Triggers and exposures
Preceding events
Viral illness 2 to 3 months prior
Non-A non-B non-C hepatitis association
Parvovirus B19 or EBV or CMV
New medication exposure
Recent antibiotic or antiepileptic start
Checkpoint inhibitor therapy
Chemical or toxin exposure
Benzene and solvents
Pesticides and radiation
Hepatitis associated clues
Cholestatic hepatitis preceding pancytopenia
Jaundice roughly 3 weeks before cytopenias
Young male predominance
Risk factors and family history
Acquired risk factors
Autoimmune disease
Rheumatoid arthritis
Systemic lupus erythematosus
Idiopathic most common
Roughly 50 to 70 percent of cases
No identifiable trigger
Inherited bone marrow failure
Fanconi anemia
Short stature and cafe-au-lait spots
Thumb and radial anomalies
Dyskeratosis congenita
Nail dystrophy and oral leukoplakia
Abnormal skin pigmentation
Important negatives
No bone pain
Argues against leukemia
Argues against marrow infiltration
No lymphadenopathy or organomegaly
Argues against lymphoma
Argues against infiltrative process
Physical Exam
Vitals and general
Stability snapshot
Temperature
Fever as infection marker
Hypothermia as severe sepsis marker
Hemodynamics
Tachycardia from anemia or sepsis
Hypotension from hemorrhage or sepsis
General appearance
Pallor and ill appearance
Tachypnea
Anemia signs
Conjunctival and nail bed pallor
Flow murmur on auscultation
High output failure signs
Functional limitation
Exertional dyspnea
Lightheadedness
Bleeding and infection exam
Mucocutaneous bleeding
Skin findings
Petechiae and purpura
Ecchymoses
Mucosal findings
Gingival bleeding
Epistaxis
Fundoscopy
Retinal hemorrhages
Roth spots
Infection screen
Oral cavity
Oral ulcers
Mucositis
Neurologic
Altered mental status from CNS bleed
Meningismus from CNS infection
Discriminating findings
Absent features supporting aplastic anemia
No hepatosplenomegaly
Splenomegaly suggests leukemia or PNH
Splenomegaly suggests myelofibrosis
No lymphadenopathy
Presence suggests lymphoma
Presence suggests acute leukemia
Stigmata of inherited syndromes
Skeletal anomalies
Short stature
Radial ray defects
Dermatologic clues
Cafe-au-lait macules
Nail dystrophy
Differential Diagnosis
Life threats and primary mimics
Hematologic malignancy
Acute leukemia
Blasts on peripheral smear
Bone pain and organomegaly
ICD-10 C95.90
Myelodysplastic syndrome
Dysplasia and cytogenetic abnormalities
Most important mimic
ICD-10 D46.9
Hairy cell leukemia
Splenomegaly with pancytopenia
Fried egg cells on smear
Clonal and reversible causes
Paroxysmal nocturnal hemoglobinuria
Hemolysis and thrombosis
Overlaps with aplastic anemia
ICD-10 D59.5
Megaloblastic anemia
Macrocytosis with hypersegmented neutrophils
Reversible with B12 or folate
Copper deficiency
Post gastric bypass
Excess zinc supplementation
Infiltrative and infectious mimics
Marrow infiltration
Myelofibrosis
Dry tap on aspirate
Leukoerythroblastic smear
Disseminated infection
Tuberculosis
Histoplasmosis
Immune and viral
Hemophagocytic lymphohistiocytosis
Hyperferritinemia and hypertriglyceridemia
Fever with splenomegaly
HIV associated cytopenia
Marrow suppression
Opportunistic infection risk
Laboratory Tests
Core hematology
Complete blood count with differential
Pancytopenia
Low hemoglobin
Low white cell count
Low platelets
Absolute neutrophil count
< 0.5 x 10^9/l severe
< 0.2 x 10^9/l very severe
Reticulocyte count
Depressed reticulocytes
Reticulocyte production index < 2
Hallmark of production failure
Corrected count interpretation
Distinguishes hypoproliferative state
Excludes hemolysis as cause
Peripheral blood smear
Normocytic or macrocytic red cells
No blasts
No dysplasia
Exclusion findings
No schistocytes
No leukoerythroblastic features
Etiology and overlap workup
Hemolysis and overlap panel
LDH and haptoglobin and indirect bilirubin
Rule out hemolysis
Screen for PNH overlap
Flow cytometry FLAER
PNH clone in 10 to 20 percent
Recommended at diagnosis
Reversible cause screen
B12 and RBC folate and methylmalonic acid
Rule out megaloblastic anemia
Reversible with supplementation
Iron studies and ferritin
Transfusional iron overload
Exclude iron deficiency
Viral serologies
Hepatitis A B C panel
Hepatitis associated aplastic anemia
Cholestatic pattern
HIV EBV CMV parvovirus B19
IgM and IgG or PCR if immunocompromised
Viral trigger identification
Acute crisis labs
Infection workup
Blood cultures if febrile
Two sets before antibiotics when feasible
Catheter and peripheral sites
Comprehensive metabolic panel
Hepatic function for hepatitis associated disease
Renal function for drug dosing
Coagulation and HLH screen
PT INR aPTT fibrinogen
Rule out DIC
Assess coagulopathy
Ferritin and triglycerides
If HLH suspected
Hyperferritinemia marker
Pre-transfusion testing
Blood type and screen
Crossmatch for active bleeding
Antibody screen
HLA typing
Early if transplant candidate
Before alloimmunization
Diagnostic Tests
Scoring Systems
Modified Camitta severity criteria
Severe aplastic anemia
Marrow cellularity < 25 percent
Plus at least 2 of three cytopenia criteria
Cytopenia criteria
ANC < 0.5 x 10^9/l
Platelets < 20 x 10^9/l
Reticulocytes < 60 x 10^9/l
Very severe aplastic anemia
Same as severe
ANC < 0.2 x 10^9/l
Risk and prognosis tools
MELD or hepatic scores
If hepatitis associated disease
Guides hepatology involvement
Severity drives urgency
Determines transplant versus IST
Determines admission level
MRI
MRI role
Limited diagnostic utility
Diagnosis requires marrow biopsy
Not first line in crisis
Problem solving indications
Marrow fat fraction assessment
Suspected marrow infiltration
Brain MRI
Suspected CNS infection
Characterize intracranial bleed when stable
CT
CT head non-contrast
Indications
Altered mental status
Headache with thrombocytopenia
Findings
Intracranial hemorrhage
Mass effect
CT chest
Invasive fungal infection
Halo sign of aspergillosis
Air crescent sign
Protocol considerations
Without contrast if thrombocytopenic
In persistent febrile neutropenia
Evidence note
Early CT chest in neutropenic fever supports fungal diagnosis
IDSA supported for high risk patients
Ultrasound
Abdominal ultrasound
Spleen assessment
Normal spleen in aplastic anemia
Splenomegaly suggests alternative diagnosis
Liver assessment
Hepatitis associated disease evaluation
Biliary obstruction screen
Point of care ultrasound
Cardiac POCUS
High output state assessment
Pericardial effusion screen
Vascular access
Ultrasound guided central line
Reduces bleeding complications
Disposition
Level of care selection
Admission indications
Severe or very severe disease
ANC < 0.5 x 10^9/l
Platelets < 20 x 10^9/l
Acute decompensation
Febrile neutropenia
Active hemorrhage
New diagnosis
Urgent marrow biopsy needed
Initiation of therapy
ICU indications
Septic shock
Vasopressor requirement
Rising lactate despite resuscitation
Catastrophic hemorrhage
Intracranial hemorrhage
Massive GI or pulmonary bleed
Respiratory failure
Pneumonia with hypoxemia
Need for ventilatory support
Service and follow up
Specialist disposition
Hematology or oncology service
All severe cases
Coordination of definitive therapy
Consult network
Transplant team for eligible patients
Hepatology for hepatitis associated disease
Outpatient pathway
Non-severe stable disease
Stable counts without bleeding or infection
Close hematology follow up
Monitoring cadence
CBC 2 to 3 times weekly in acute phase
Weekly to biweekly once stabilized
Treatment
Initial stabilization
Resuscitation measures
ABCs and IV access
Continuous monitoring
Two large bore lines for hemorrhage
Oxygen for symptomatic anemia
Titrate to SpO2 >= 92%
Reduce myocardial demand
Transfusion support
pRBC transfusion
Symptomatic anemia or Hb < 70 g/l
Irradiated leukoreduced CMV safe products
Platelet transfusion
Active bleeding or platelets < 10 x 10^9/l
Higher threshold with fever or sepsis
Alloimmunization prevention
Avoid unnecessary transfusions
Minimize donor exposures if transplant candidate
Febrile neutropenia and prophylaxis
Empiric antibiotics
Antipseudomonal beta lactam within 1 hour
Piperacillin-tazobactam 4.5 g IV every 6 hours
Cefepime 2 g IV every 8 hours
Carbapenem alternative
Meropenem 1 g IV every 8 hours
For severe sepsis or resistance risk
Escalation
If beta lactam allergy, aztreonam plus vancomycin
Add vancomycin for catheter or skin source
Antifungal coverage
Persistent fever 48 to 72 hours
Voriconazole for invasive aspergillosis
Liposomal amphotericin B alternative
If no response, broaden empirically
Echinocandin for candidemia
Reassess source
Antimicrobial prophylaxis
Severe neutropenia prophylaxis
Fluoroquinolone antibacterial
Antifungal posaconazole or voriconazole
Antiviral and supportive
Acyclovir if HSV seropositive
Growth factor support per hematology
Definitive therapy
Hematopoietic stem cell transplant
Matched sibling donor first line
Patients younger than 40 years
Best long term outcomes
Matched unrelated donor
Option for younger patients
When no sibling donor
Conditioning considerations
Minimize transfusions pre-transplant
Early HLA typing
Immunosuppressive therapy
Triple therapy standard
Horse ATG plus cyclosporine plus eltrombopag
For patients not proceeding to upfront HSCT
Response data
Response rate 70 to 80 percent with IST plus eltrombopag
Eltrombopag improves hematologic response
Age based selection
IST preferred over transplant for patients over 40 years
Cyclosporine level monitoring
Growth factor and special situations
Growth factor support
G-CSF for severe neutropenia
Eltrombopag or romiplostim thrombopoietin mimetics
Checkpoint inhibitor related disease
Discontinue immunotherapy
Methylprednisolone 1 to 2 mg/kg/day
If no response in 7 days, IVIG or cyclosporine or ATG
Bleeding management
Active hemorrhage
Platelet transfusion to control bleeding
Target platelets > 50 x 10^9/l for major bleed
Target > 100 x 10^9/l for CNS hemorrhage
Antifibrinolytics
Tranexamic acid for mucosal bleeding
Avoid in hematuria or DIC
Avoidance precautions
No aspirin or NSAIDs
Platelet dysfunction risk
Worsens bleeding
No intramuscular injections
Hematoma risk
Use oral or IV route
Special Populations
Pregnancy
Pregnancy considerations
Rare association with aplastic anemia
May present or worsen in pregnancy
May remit postpartum
Treatment modifications
Cyclosporine can be continued
Avoid ATG and eltrombopag if possible
Transfusion strategy
Maintain platelets > 20 x 10^9/l
Higher platelet target for delivery
Imaging approach
Shield abdomen for chest imaging
Limit CT to essential indications
Geriatric
Older adult features
Second incidence peak
Patients over 60 years
Worse prognosis
Treatment selection
IST preferred over transplant
Reduced intensity approaches
Comorbidity impact
Higher infection mortality
Cardiac risk from anemia
MDS overlap
Higher pretest probability of MDS
Cytogenetics essential
Pediatrics
Pediatric differences
Inherited syndrome screen
Chromosomal breakage testing for Fanconi anemia
Telomere length for dyskeratosis congenita
Hepatitis associated disease
Severe cholestatic hepatitis
Lymphopenia characteristic
Transplant outcomes
Matched sibling HSCT first line
Excellent survival in children
Weight based dosing
Cefepime 50 mg/kg IV every 8 hours for febrile neutropenia
Platelet transfusion 10 ml/kg
Background
Epidemiology
Incidence and distribution
Rare disorder
Roughly 2 per million per year in Western countries
2 to 3 times higher in East Asia
Bimodal age distribution
Young adults 15 to 25 years
Older adults over 60 years
Outcome burden
Mortality without treatment
2 year mortality approaches 80 percent in severe disease
Infection and hemorrhage are leading causes
Long term complications
Clonal evolution to MDS or AML in 10 to 15 percent
Relapse after IST in 30 to 40 percent
Pathophysiology
Mechanism of marrow failure
Immune mediated destruction
Cytotoxic T cell attack on stem cells
Interferon gamma and TNF mediated suppression
Marrow hypocellularity
Cellularity < 25 percent
Fat replacement without fibrosis
Triggers and clonal biology
Inciting triggers
Viral antigens
Drug haptens and toxins
Clonal hematopoiesis
PNH clones in 10 to 20 percent
PIGA and BCOR mutations favorable
RUNX1 and ASXL1 raise evolution risk
Therapeutic Considerations
Treatment strategy principles
Severity drives modality
Transplant for young patients with donor
IST for older patients or no donor
Transfusion stewardship
Minimize alloimmunization
Irradiated CMV safe products
Supportive care importance
Infection prophylaxis
Antibacterial and antifungal coverage
Neutropenic precautions
Iron overload management
Chelation for chronic transfusion
Ferritin monitoring
Causative drug avoidance
Discontinue offending agents
Antiepileptics and sulfonamides
Chloramphenicol and gold salts
Minimize myelosuppression
Avoid unnecessary medications
Review every new drug
Patient Discharge Instructions
copy discharge instructions
Aplastic anemia home care
Take all medications exactly as prescribed
Keep all blood count and hematology appointments
Strict hand hygiene and avoid sick contacts
Avoid crowds during low blood counts
Bleeding precautions
No aspirin or anti-inflammatory medicines
Use a soft toothbrush and electric razor
Avoid contact sports and bleeding risk activities
No intramuscular injections
Infection precautions
Avoid raw meats and unpasteurized dairy
Wash all raw fruits and vegetables
Report any fever immediately and do not take fever medicine first
Warning signs to return to ER
Fever of 38 C or higher
New or worsening bleeding from gums nose or bowels
Severe headache or confusion
Dizziness fainting or chest pain
Shortness of breath or new cough
Follow up
Hematology follow up as scheduled
Frequent blood count checks
Bring updated medication list to every visit
References
Guidelines and key sources
Society guidelines
American Society of Hematology 2026 severe aplastic anemia guideline
British Society for Haematology aplastic anaemia guideline
NCCN myelodysplastic syndromes guideline for overlap
Landmark evidence
Eltrombopag added to immunosuppression in severe aplastic anemia NEJM 2022
Pathophysiology of acquired aplastic anemia NEJM review
Haploidentical BMT for relapsed or refractory severe aplastic anemia BMT CTN 1502
Coding standards
ICD-10 D61.9 aplastic anemia unspecified
ICD-10 D61.1 drug-induced aplastic anemia
SNOMED CT aplastic anemia disorder concept
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.