Pathophysiology and Clinical Features
Definitions and Etiology
- Denotes complete lack of splenic tissue.
- Includes surgical asplenia, congenital asplenia, and functional asplenia.
- Sickle cell disease causes functional asplenia.
- Isolated congenital asplenia linked to pathogenic variants in RPSA protein.
Diagnostic Markers
- Presence of Howell-Jolly bodies on peripheral blood smear.
- Lack of detectable spleen on abdominal ultrasound.
Infection Susceptibility
- Splenectomy increases risk of overwhelming sepsis.
- Extreme susceptibility to encapsulated bacteria.
- Key pathogens include Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b.
- Defective clearance of intra-erythrocytic parasites worsens malaria and babesiosis.
Timing of Immunization
Elective Splenectomy
- Complete all vaccine schedules at least two weeks before elective surgery.
- Ensures superior immunologic response prior to organ removal.
Emergency Splenectomy
- Delay vaccination until two weeks after surgical removal.
- Yields superior functional antibody response compared to immediate postoperative vaccination.
- Initiation of vaccines at hospital discharge remains acceptable alternative.
Specific Vaccine Protocols
Pneumococcal Immunization
- Conjugated vaccines preferred over unconjugated vaccines.
- Administer pneumococcal conjugate vaccine (PCV13) first.
- Follow with pneumococcal polysaccharide vaccine (PPSV23) at least eight weeks later.
- Administer second polysaccharide booster five years after initial polysaccharide dose.
- Restrict polysaccharide vaccine to maximum two lifetime doses due to immune hyporesponsiveness.
- Separate conjugate pneumococcal vaccine and specific meningococcal vaccines (MenACWY-D) by four weeks, giving pneumococcal conjugate first.
Meningococcal Immunization
- Administer quadrivalent conjugate meningococcal vaccine.
- Require two primary doses separated by at least eight weeks.
- Administer booster doses every five years lifelong to maintain protection.
Haemophilus Influenzae Type B Immunization
- Indicated for all affected children and adults.
- Administer single dose regardless of prior vaccination history for individuals over five years of age.
Additional Vaccines
- Administer typhoid conjugate vaccine.
- Provide annual inactivated influenza vaccination to prevent secondary pneumococcal superinfections.
- Administer all routine live vaccines safely post-splenectomy.
Adjunctive Management Strategies
Antimicrobial Prophylaxis
- Initiate long-term oral penicillin prophylaxis routinely.
- Prescribe amoxicillin 10 mg/kg twice daily up to maximum 250 mg.
- Alternative under three years: Penicillin V 125 mg twice daily.
- Alternative over three years: Penicillin 250 mg twice daily.
- Administer intravenous antibiotics early during any febrile illnesses.
Patient Education
- Treat fever as life-threatening medical emergency.
- Initiate home antibiotic therapy immediately upon fever onset.
