List causes for asplenia.
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)
Describe hematological changes in asplenic patients.
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
What is a general risk for asplenic patients?
Increased risk of fulminant and life-threatening infections and sepsis for up to 30 years or longer after splenectomy
Describe Overwhelming postsplenectomy infection (OPSI) and asplenic sepsis.
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
Mnemonic pathogens that most commonly cause asplenic sepsis.
Asplenic individuals Have No Spleen: H. influenzae, N. meningitidis, and S. pneumonia are the pathogens that most commonly cause asplenic sepsis.
List general measures of management of asplenic patients.
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
Describe infection prevention.
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)
Describe thrombosis prevention.
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
Last changeda year ago