Spleen : Immunization and OPSI

OPSI: Overwhelming Post-splenectomy Infection

OPSI Risk:
3-5% lifetime risk
0.2-0.4% annual risk
Risk highest in first year (adults ~1%, children ~5%)

Risk Factors:
Lower in trauma
Higher in haematological disorders
- especially immunocompromised
Higher in extremes of age

Pathophysiology
Caused by decreased antigen clearance
Strep pneumoniae most common agent, often begins with urti that soon becomes severe sepsis.
- recovered in 50-90% of isolates
Then: H. Influenza B, Strep B, Staph aureus, E. coli, other coliforms
N Meningitidis risk is not well clarified

Management
Emergencies; require immediate IV antibiotics and intensive care.
Mortality approaches 40%

Immunizations
Optimal at 14d prior to surgery
If they did not receive it before surgery then can give it just before discharge
- however, probably better after several weeks as improved immune response
Recommended protocol:
- pneumococcal, meningicoccal, and Haemophilus.
- pneumovax protects against 75% active organisms; others unproven but recommended.
Current guidelines favours pneumovax booster every 5-10 years.
- some also recommend meningococcus ever 5y
- H influenzae AB titres can be monitored to asses need for booster doses.

Counselling and Antibiotics
Warn all patients regarding OPSI risk.
Seek immediate care if develop febrile illness.
Long term prophylactic antibiotics remains controversial.
- promotes resistant strains.
Evidence supports use in selected child populations but no evidence yet in adults.
--> Discharge patients with a supply of oral antibiotics with clear instructions to initiate therapy with onset of infective symptoms while seeking medical aid.
--> In children, common to do 2y prophylaxis
Beware dog bits - capnocytophaga canimorus
If travelling to malarial areas, need cautious prophylaxis