Polycythemia vera (PV) crisis refers to the acute, life-threatening complications of PV — primarily hyperviscosity-related thrombosis (stroke, MI, PE, splanchnic vein thrombosis), severe bleeding (from acquired von Willebrand syndrome), and symptomatic hyperviscosity — requiring emergent evaluation and intervention. The cornerstone of emergency management is urgent therapeutic phlebotomy to reduce hematocrit below 45% and anticoagulation for active thrombosis. [1-2]
1. History
- Known PV diagnosis? Current medications (hydroxyurea, aspirin, anticoagulants)? Compliance with phlebotomy schedule?
- Symptom characterization: headache, visual changes (blurring, scotomata), dizziness, tinnitus, chest pain, dyspnea, abdominal pain, erythromelalgia (burning pain in extremities) [3]
- Timing: acute onset vs. progressive worsening; last phlebotomy date; recent medication changes
- Triggers: dehydration, missed phlebotomy, surgery, immobilization, pregnancy
- Associated symptoms: aquagenic pruritus (33%), fatigue, night sweats, early satiety (splenomegaly), focal neurologic deficits [1]
- Important negatives: no bleeding (epistaxis, GI bleed, mucocutaneous), no fever, no weight loss suggesting transformation
2. Alarm Features
- Acute stroke symptoms: sudden focal weakness, aphasia, visual loss [1]
- Acute coronary syndrome: chest pain, diaphoresis (ACS occurs in ~8.3% of PV patients) [1]
- Pulmonary embolism: acute dyspnea, pleuritic chest pain, hypoxia (PE in ~2%) [1]
- Splanchnic vein thrombosis (Budd-Chiari, portal vein): acute abdominal pain, ascites, hepatomegaly — PV should be suspected in any young patient with unprovoked splanchnic thrombosis [1][3]
- Cerebral venous sinus thrombosis: headache with papilledema, seizures [1]
- Major hemorrhage: GI bleeding (especially with portal hypertension/gastric varices), mucocutaneous bleeding suggesting acquired von Willebrand syndrome (AvWS) [1-2]
- Signs of transformation: new pancytopenia, massive splenomegaly, constitutional symptoms suggesting post-PV myelofibrosis or blast phase [1]
3. Medications
- Relevant contributors: Aspirin and anticoagulants can exacerbate bleeding, especially with extreme thrombocytosis (platelets ≥1000 × 10⁹/L) and AvWS [1]
- Emergency treatments:
- Aspirin 81–100 mg/day (all PV patients without contraindication); consider BID dosing for refractory vasomotor symptoms [2]
- Therapeutic anticoagulation (LMWH, DOAC, or warfarin) for active thrombosis per ACCP guidelines [2]
- Hydroxyurea 500 mg BID as initial cytoreductive dose, titrated up to 1000 mg BID [1]
- Contraindicated: Aspirin should be withheld during active bleeding until hemorrhage is controlled. Use aspirin with caution when platelets ≥1000 × 10⁹/L due to AvWS risk [1-2][4]
- Cautions: Combining aspirin + anticoagulation increases bleeding risk — individualize. DOACs should be avoided in pregnancy/breastfeeding [2]
4. Diet
- Hydration is critical — dehydration worsens hyperviscosity and thrombotic risk
- No specific dietary triggers, but gout is a known complication (hyperuricemia from cell turnover) — limit purine-rich foods in affected patients [5]
- Iron supplementation should generally be avoided in PV, as iron deficiency from phlebotomy is an expected and sometimes therapeutic consequence
- Long-term: manage cardiovascular risk factors including diet (hypertension, hyperlipidemia) [2][6]
5. Review of Systems
- Neurologic: headache, dizziness, visual changes, tinnitus, focal deficits, seizures [3]
- Cardiovascular: chest pain, palpitations, dyspnea on exertion, claudication [1]
- GI: abdominal pain/fullness (splenomegaly), early satiety, GI bleeding, ascites [1-2]
- Dermatologic: aquagenic pruritus, erythromelalgia, plethoric facies, cyanosis [1][3]
- Hematologic: easy bruising, mucocutaneous bleeding, epistaxis [1]
- Constitutional: fatigue, night sweats, weight loss (concerning for transformation) [2]
- Musculoskeletal: gout, bone pain [2][5]
6. Collateral History and Family History
- Prior thrombotic or bleeding events; prior phlebotomy frequency and response
- Medication adherence (hydroxyurea, aspirin, anticoagulants)
- Family history of myeloproliferative neoplasms — approximately 5-fold increased risk of PV among first-degree relatives [1]
- Occupational exposures: benzene, ionizing radiation [1]
- Smoking history (both a risk factor for PV and a confounder for secondary erythrocytosis) [1]
7. Risk Factors
- Thrombosis risk stratification (the central framework for PV management):
- High-risk: age >60 years OR prior thrombosis history [1][7-8]
- Low-risk: absence of both factors
- Cardiovascular risk factors: hypertension, diabetes, hyperlipidemia, smoking, obesity [6]
- Leukocytosis and JAK2 V617F allele burden are emerging risk factors [8]
- Extreme thrombocytosis (≥1000 × 10⁹/L) paradoxically increases bleeding risk via AvWS [1]
- Immobilization, surgery, pregnancy [2]
8. Differential Diagnosis
- Secondary erythrocytosis: chronic hypoxia (COPD, OSA, high altitude), smoking, EPO-secreting tumors (renal cell carcinoma, hepatocellular carcinoma) — distinguished by elevated EPO level (PV has low/normal EPO) [1]
- Other myeloproliferative neoplasms: essential thrombocythemia, primary myelofibrosis, CML
- Relative (spurious) polycythemia (Gaisböck syndrome): dehydration, diuretic use — normal red cell mass
- Hyperviscosity from other causes: Waldenström macroglobulinemia, multiple myeloma
- Thrombotic thrombocytopenic purpura (TTP): if thrombocytopenia + microangiopathic hemolytic anemia present
- Cannot-miss mimics: Budd-Chiari syndrome from other causes, cerebral venous sinus thrombosis from other etiologies
9. Past Medical History
- Prior thrombotic events (arterial or venous) — reclassifies as high-risk [1][7]
- Prior bleeding episodes; history of AvWS
- Duration of PV diagnosis; bone marrow biopsy results; JAK2 mutation status
- Current cytoreductive therapy and response
- Surgical history (perioperative PV patients have elevated thrombotic AND bleeding risk) [2]
- Comorbidities: hypertension, diabetes, atrial fibrillation, CKD
10. Physical Exam
- Vital signs: hypertension (common), tachycardia, hypoxia (if PE), fever (if infection/transformation)
- General: plethoric (ruddy) facies, conjunctival injection
- HEENT: fundoscopic exam for retinal vein engorgement, papilledema (hyperviscosity/CVST)
- Cardiovascular: murmurs, signs of heart failure
- Abdominal: splenomegaly (36% at diagnosis) — palpate for size; hepatomegaly; ascites (Budd-Chiari) [1][3]
- Extremities: erythromelalgia (erythema, warmth, burning pain in digits), cyanosis, signs of DVT [3]
- Skin: scratch marks (pruritus), ecchymoses, petechiae
- Neurologic: complete exam for focal deficits (stroke), altered mental status (hyperviscosity)
11. Lab Studies
- Stat labs: CBC with differential (expect elevated Hgb/Hct, often leukocytosis and thrombocytosis), BMP, LDH, uric acid [1][3]
- Hematocrit: the critical value — target <45% per CYTO-PV trial data [1]
- Coagulation: PT/INR, aPTT; if bleeding or platelets ≥1000 × 10⁹/L, obtain VWF ristocetin cofactor activity (VWF:RCo) and VWF antigen to evaluate for AvWS [2][4][9]
- Erythropoietin level: low or normal in PV; elevated suggests secondary erythrocytosis [1]
- JAK2 V617F mutation (if not previously tested) — positive in >95% of PV [1][8]
- Peripheral blood smear: evaluate for leukoerythroblastic changes (transformation to myelofibrosis)
- Troponin, D-dimer as clinically indicated for ACS or VTE
- Type and screen if phlebotomy or surgery anticipated
12. Imaging
- First-line: guided by clinical presentation
- CT head (stroke), CTA chest (PE), CT abdomen with contrast (splanchnic vein thrombosis/Budd-Chiari) [1]
- Duplex ultrasound for suspected DVT
- Abdominal ultrasound with Doppler: assess spleen size, portal/hepatic vein patency [3]
- MRI/MRV brain: for suspected cerebral venous sinus thrombosis
- Echocardiography: if cardiac symptoms or concern for pulmonary hypertension
- When imaging is unnecessary: routine imaging not needed for stable, well-controlled PV without acute symptoms
13. Special Tests
- Bone marrow biopsy: not needed emergently but essential for definitive diagnosis (hypercellular marrow with panmyelosis, pleomorphic megakaryocytes) and to assess for transformation to myelofibrosis [1][10]
- JAK2 exon 12 testing: if V617F negative but PV still suspected [1]
- VWF multimer analysis: gold standard for AvWS diagnosis (loss of high-molecular-weight multimers) [4][9]
- MPN Symptom Assessment Form (MPN-SAF): validated tool for symptom burden quantification [2]
14. ECG
- Indications: chest pain, dyspnea, palpitations, syncope, or any suspected ACS
- Findings in PV: [11]
- Prolonged QTc interval and increased Tp-Te interval (markers of ventricular arrhythmia risk)
- Prolonged P-wave duration and increased P-wave dispersion (atrial arrhythmia risk)
- These changes are independent of age, BMI, and traditional cardiovascular risk factors
- Dangerous patterns: ST-elevation/depression (ACS — occurs in 8.3% of PV patients), right heart strain pattern (PE), new atrial fibrillation [1][11]
15. Assessment
PV crisis encompasses the acute, life-threatening vascular complications of uncontrolled or undertreated polycythemia vera. Thromboembolism is the most important complication and leading cause of morbidity/mortality. [8][10] The paradox of PV is that patients are simultaneously at risk for both thrombosis (from hyperviscosity and platelet activation) and hemorrhage (from AvWS, especially with extreme thrombocytosis). [1]
Severity stratification
- Mild: vasomotor symptoms (headache, dizziness, erythromelalgia) without end-organ damage
- Moderate: symptomatic hyperviscosity with visual changes, progressive symptoms
- Severe: acute thrombosis (stroke, MI, PE, splanchnic vein thrombosis), major hemorrhage, or signs of disease transformation
Complications to consider: post-PV myelofibrosis (~12.7%), AML transformation (~6.8%), portal hypertension with variceal bleeding [1][7]
16. Treatment Plan
Initial stabilization (ED)
- ABCs; IV access; continuous monitoring
- Urgent therapeutic phlebotomy: remove 250–500 mL of blood; repeat every other day or twice weekly until hematocrit <45%. In crisis, more aggressive phlebotomy may be needed with concurrent IV normal saline replacement [1][12]
- Aspirin 81–100 mg if not already on it and no active bleeding or AvWS [1-2]
- Hold aspirin if active bleeding; evaluate for AvWS [2]
For active thrombosis: [2-3]
- Initiate anticoagulation per ACCP guidelines: LMWH acutely, transition to DOAC or warfarin
- For splanchnic vein thrombosis: immediate LMWH for 1–3 months, then long-term anticoagulation; initiate hydroxyurea [3]
- Assess need for cytoreductive therapy and initiate if not already on it
Cytoreductive therapy (initiate or escalate): [1-2]
- Hydroxyurea: 500 mg BID, titrate to effect (preferred first-line for high-risk)
- Ropeginterferon alfa-2b-njft: preferred for low-risk patients needing cytoreduction per NCCN [2]
- Ruxolitinib: for hydroxyurea-resistant/intolerant patients (category 1 for high-risk PV) [2]
For bleeding: [2]
- Hold aspirin and anticoagulants until bleeding controlled
- If AvWS suspected (platelets ≥1000 × 10⁹/L or abnormal VWF:RCo): cytoreductive therapy to lower platelet count; consider DDAVP or VWF concentrate for acute hemorrhage
- GI bleeding with splenomegaly/portal hypertension: urgent GI/hepatology consultation [2]
The NCCN MPN Guidelines treatment algorithms are shown below:
17. Disposition
- Admit (ICU or monitored bed): acute stroke, MI, PE, splanchnic vein thrombosis, major hemorrhage, symptomatic hyperviscosity with end-organ dysfunction, hematocrit significantly >45% with acute symptoms
- Admit (floor): new thrombosis requiring anticoagulation initiation, need for serial phlebotomy, uncontrolled symptoms
- Observation: borderline cases with elevated hematocrit and mild symptoms responding to phlebotomy
- Discharge: stable patients with mild vasomotor symptoms, hematocrit brought to <45%, no active thrombosis or bleeding, reliable follow-up
- Specialist consultation triggers: hematology/oncology (all PV crises); vascular surgery/interventional radiology (splanchnic thrombosis); neurology (stroke/CVST); GI/hepatology (variceal bleeding, Budd-Chiari) [2-3]
18. Follow Up / Return Precautions
- Follow-up: hematology within 1–2 weeks after ED discharge; sooner if new cytoreductive therapy initiated
- Phlebotomy schedule: typically every 1–3 months to maintain hematocrit <45%; more frequently initially [1][12]
- Return immediately for: new or worsening headache, visual changes, chest pain, shortness of breath, abdominal pain, focal weakness/numbness, significant bleeding, signs of infection
- Patient counseling:
- Maintain hydration; avoid prolonged immobilization
- Medication adherence is critical (aspirin, hydroxyurea, anticoagulants)
- Do not skip phlebotomy appointments
- Avoid iron supplementation unless directed by hematologist
- Report new pruritus, night sweats, weight loss, or worsening fatigue (may indicate disease progression) [1-2]
- Expected course: PV is a chronic disease with median survival of 14–28 years from diagnosis; with appropriate management, thrombotic risk is substantially reduced [1][7]
References
1. Diagnosis and Treatment of Polycythemia Vera: A Review. — Tremblay D, Kremyanskaya M, Mascarenhas J, Hoffman R. The Journal of the American Medical Association. 2025.
2. Myeloproliferative Neoplasms. — Updated 2026-01-22. National Comprehensive Cancer Network.
3. Polycythemia vera: 2024 update on diagnosis, risk‐stratification, and management. — Tefferi A, Barbui T. American Journal of Hematology. 2023.
4. Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management. — Tefferi A, Barbui T. American Journal of Hematology. 2020.
5. Polycythemia vera. — National Library of Medicine (MedlinePlus) 2013.
6. Diagnosis and Management of Cardiovascular Risk in Patients With Polycythemia Vera. — Benevolo G, Marchetti M, Melchio R, et al. Vascular Health and Risk Management. 2023.
7. Polycythemia Vera: Historical Oversights, Diagnostic Details, and Therapeutic Views. — Tefferi A, Vannucchi AM, Barbui T. Leukemia. 2021.
8. Polycythaemia Vera. — Harrison CN, Barbui T, Bose P, et al. Nature Reviews. Disease Primers. 2025.
9. Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk‐stratification and management. — Tefferi A, Barbui T. American Journal of Hematology. 2019.
10. Polycythemia Vera. — Ellis MH, Barbui T, Tefferi A. Mayo Clinic Proceedings. 2026.
11. Electrocardiographic Findings in Patients With Polycythemia Vera. — Kayrak M, Acar K, Gul EE, et al. International Journal of Medical Sciences. 2012.
12. Polycythemia Vera: Rapid Evidence Review. — Fox S, Griffin L, Robinson Harris D. American Family Physician. 2021.