Hematologic Emergencies



Hematologic Emergencies


Amina Lalani

Rahim Valani



Introduction



  • Immune thrombocytopenic purpura


  • Hemolytic uremic syndrome


  • Henoch-Schonlein purpura


  • Anemia


  • Hemophilia


Immune Thrombocytopenic Purpura (ITP)



  • Most common platelet disorder in children ages 1-4 yrs


  • Presents classically in preschool age, M = F


  • Autoimmune disorder: autoantibodies to platelets


  • Develop low platelet count and mucocutaneous bleeding


  • May be primary or secondary to underlying disorder


  • Two forms: acute < 6 months, chronic > 6 months


  • Sudden onset of petechiae or purpura in otherwise healthy child


  • Usually recent viral or bacterial illness


  • Resolves within 6 months in majority


  • Risk of bleeding decreases after first week of illness


  • Compensatory increase in platelet production


Clinical Manifestations



  • Petechiae, ecchymoses, conjunctival hemorrhage, epistaxis, gum bleeds, hematuria, menorrhagia


  • Spleen tip palpable in 10%


  • Major complication: intracranial hemorrhage (ICH), often without trauma: may have only mild symptoms such as headache



Diagnosis



  • Diagnosis of exclusion


  • Thrombocytopenia in absence of underlying disease


  • May be secondary to SLE, immunodeficiencies, infections, drugs


  • Infants < 3 months: exclude passively acquired antibodies from mother


Investigations



  • Bloodwork: decreased platelets, normal WBC and Hg


  • Peripheral smear


  • Bone marrow aspirate: controversial, must be performed if atypical features


Treatment



  • Controversial because favorable outcome in majority without treatment


  • Based on risk of ICH and activity restrictions


  • Incidence of ICH 0.2-1%



    • Risk increases if plt < 20,000 and highest if < 10,000


    • Risk factors: head trauma, antiplatelet drugs


    • Most ICH occurs within 4 weeks of presentation, usually in first week


  • Consult hematology if atypical features


Treatment Options


Observation



  • Most children with typical ITP recover completely within few weeks without treatment


  • No proof that treatment prevents ICH


  • Need to follow as outpatient


IVIG



  • Shortens duration of severe thrombocytopenia (< 20,000)


  • Blocks uptake of antibody-coated platelets by macrophages in spleen



  • Dose 0.8-1 g/kg, second dose 24 hrs later if platelets < 40,000-50,000


  • Adverse reactions: headache, fever, aseptic meningitis (rare)


Anti-D Immune Globulin (Rhogam®)



  • Antibody vs D antigen of red blood cells


  • Effective in Rh+ patients


  • Dose 50-75 mcg/kg


  • Adverse reactions: headache (rare), hemolytic anemia


  • Preferred over IVIG if Rh positive due to ease of administration and cost


  • Response rate 70%, lasts ˜ 3 weeks


Oral Steroids



  • May need high-dose steroids: significant side effects


  • Controversial for newly diagnosed patient with no serious bleeding


  • Consult hematology prior to starting steroids: may require BMA


Emergency Management—Intracranial Hemorrhage



  • Rare if platelets > 50,000


  • For mild head trauma and no signs of bleeding:



    • Observe


    • Give IVIG or antiD IG if platelets < 20, signs of easy bruising, within 1 week of diagnosis or uncertain follow-up


  • For severe head trauma:



    • Consult hematology


    • Methylprednisolone 30 mg/kg/d IV over 20-30 mins, max 1 g/d × 2-3 days


    • IVIG 1 g/kg/d × 2-3 days


    • Platelet infusion


    • Consider splenectomy


  • For mucosal bleeding, consider antifibrinolytic therapy (aminocaproic acid)


  • For persistent epistaxis, use nasal packing



Hemolytic Uremic Syndrome



  • Microangiopathic hemolytic anemia, thrombocytopenia and renal dysfunction


  • Mainly affects infants and young children < 5 yrs


  • Multisystem disorder; most common cause of renal failure in young children


  • Vascular endothelial injury results in thrombi that cause clinical manifestations


  • Platelets are consumed at sites of vascular injury


  • Caused by bacterial and viral infections


  • Occurs sporadically and in epidemics


  • Two forms: with diarrhea (D+ HUS) and without diarrhea (D- HUS)

Diarrhea Form (75%)



  • Usually healthy children < age 5 yrs


  • Prodrome of diarrhea, develop hemorrhagic colitis


  • Usual cause is enterohemorrhagic E. coli 0157:H7: produces verotoxins or Shiga toxins


  • Risk of HUS with E. coli 0157:H7 infection is 15%


  • Incidence highest in summer and fall


  • Infected via ingestion of poorly cooked meats and unpasteurized milk


  • Toxin causes glomerular injury

Nondiarrhea Form (25%)



  • Sporadic form, not associated with toxin


  • Rare in children, may relapse, worse prognosis


  • May be caused by pneumococcus, OCP, malignancy, pregnancy, medications


Clinical Presentation



  • Usually abrupt onset


  • History of abdominal pain, diarrhea, vomiting, bloody stools



  • Rarely fever in E. coli 0157 infections


  • Pallor, listless, irritable, dehydrated, oliguria


  • May have edema, hypertension, petechiae, hepatosplenomegaly, encephalopathy, neurologic abnormalities


Diagnosis



  • Mainly clinical diagnosis: combination of hemolytic anemia, thrombocytopenia, and renal failure


  • Obtain blood: CBC, reticulocytes, coagulation profile, electrolytes, urea, creatinine, liver function tests


  • Anemia often severe: Hg 50-90


  • Increased urea, metabolic acidosis, hyperbilirubinemia, increased LDH


  • Peripheral smear: helmet cells, burr cells, schistocytes


  • Urinalysis: hematuria, proteinuria, casts


  • Stool culture including 0157 antigen


Treatment

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Jun 22, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Hematologic Emergencies

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