ALL

• Acquired asplenia

  • Anatomic asplenia: due to splenectomy, which may be indicated in

    • Thrombocytopenia (e.g., refractory idiopathic thrombocytopenic purpura)

    • Severe hemolytic anemias (e.g., spherocytosis)

    • Splenic rupture (e.g., from blunt abdominal trauma)

    • Hypersplenism with splenomegaly (See “Pathophysiology” in “Splenomegaly”)

  • Functional asplenia

    • Autosplenectomy: sickle cell anemia

    • Splenic infarction (splenic artery thrombosis)

    • Tumor infiltration

• Congenital asplenia: very rare (incidence is up to 1:10,000)

• Peripheral blood smear

  • Howell-Jolly bodies (a lack of Howell-Jolly bodies on peripheral blood smear in an asplenic patient indicates an accessory spleen)

  • Target cells

• Lymphocytosis

• Neutrophilia

• Decreased production of immunoglobulins (IgG, IgM): leads to decreased complement activation and C3b opsonization

• Reactive thrombocytosis: usually for the first weeks to months after splenectomy

Howell-Jolly bodies in asplenia

• Increased risk of fulminant and life-threatening infections and sepsis for up to 30 years or longer after splenectomy

• Definition: a bacterial infection that rapidly progresses to fulminant, overwhelming sepsis in the setting of anatomic or functional asplenia

• Etiology: encapsulated bacteria (e.g., Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae)

• Pathophysiology

  • Normally, encapsulated pathogens are opsonized with antibodies and then phagocytosed by specialized macrophages in the spleen.

  • Individuals with asplenia lack these specialized macrophages, so pathogens are able to spread and cause sepsis.

• Clinical features: initially flu-like symptoms, followed by rapid deterioration within hours with fever, severe malaise, signs of sepsis, and meningitis

• Therapy

  • Immediate IV antibiotic therapy with vancomycin plus ceftriaxone or cefotaxime

  • See “Management of asplenic patients” below.

• Prognosis [2]

  • Mortality 70% without treatment

  • Mortality can be reduced to ∼ 10–40% with early treatment

Asplenic individuals Have No Spleen: H. influenzae, N. meningitidis, and S. pneumonia are the pathogens that most commonly cause asplenic sepsis.

• Patient identification card or Medic Alert® bracelet/necklace

• Take precautions to avoid dog and tick bites

• Caution is recommended when travelling to malaria-endemic areas

• Immunization against Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b (see “Immunization schedule”)

  • If elective surgery: vaccination should be performed 14 days prior

  • Prevention steps if emergency splenectomy

    • S. pneumoniae vaccines

      • 2 weeks after surgery → administer 15-valent pneumococcal conjugate vaccine (PCV15)

      • 8 weeks after PCV15 → administer 23-valent pneumococcal polysaccharide vaccine (PPSV23)

      • 5 years later and at 65 years of age → revaccinate with PPSV23

    • Meningococcal quadrivalent vaccine → once 2 weeks after surgery and then every 5 years

    • Hib vaccine → once 2 weeks after surgery

  • Annual inactivated influenza vaccination

• Daily antibiotic prophylaxis: oral penicillin or amoxicillin administration in asplenic children up to at least 5 years of age and at least one year after splenectomy

• Early empiric antibiotic therapy

  • If signs of infection appear (e.g., fever, chills), patients should immediately begin treatment.

  • Oral amoxicillin-clavulanate or cefuroxime or fluoroquinolones (e.g., levofloxacin)

• Antibiotic prophylaxis prior to diagnostic and surgical procedures

  • Not routinely indicated

  • Recommended for patients undergoing procedures that increase the risk of infection with encapsulated bacteria (e.g., bronchoscopy)

• Indication: Severe reactive thrombocytosis after splenectomy and risk factors for thrombosis (e.g., malignancy)

• Treatment

  • Low-dose heparin for at least 4 weeks

  • Optionally acetylsalicylic acid (100 mg daily) for one year