Hyposplenism - Prevent of Infection (BSH 2024)
Intro
Immune functions of the spleen
Phagocytic filter of:
Old or damaged cells
Opsonised (antibody-marked) blood borne infectious organisms
Cytoplasmic solid particles in red cells
Production of IgM antibodies by memory B cells
Definitions
Hyposplenism = Asplenia or Functional hyposplenism
Asplenia = absence of the spleen, i.e. congenital or splenectomy
Functional hyposplenism = acquired impairment of splenic function
Non-exhaustive list of causes of hyposplenism
Asplenia
Surgical - e.g. traumatic, treatment of haematological disorders
Congenital (rare)
Functional hyposplenism
Physiological - neonates and older age
Infiltrative - Lymphoma, MPN, Amyloid, Sarcoidosis, Gaucher disease, Cysts/Haemangiomas
Congestive - malaria, splenic vein thrombosis, portal hypertension, pulmonary hypertension
Recurrent infarction (“auto-splenectomy”) - sickle cell disease, SLE, APS, RA
Thrombotic - splenic artery thrombosis, therapeutic splenic embolization
Other - bone marrow transplant
Diagnosis of Hyposplenism
Presence of Howell Jolly bodies considered to indicate splenic hypofunction
Incidental findings of small spleens on imaging should —> blood film examination to assess function
Other blood film features:
Thrombocytosis, acanthocytes, target cells, Heinz bodies, Pappenheimer bodies, leukocytosis
Post-Splenectomy Infection Principles
Risk is highest in ages 0-2 and >60
Risk highest in first 3 years but does persist long-term
Risk varies according to underlying condition, eg trauma vs lymphoma
Current vaccines do not cover all strains of pneumococcal / meningococcal / haemophilus infection
Patient Education / Identification
Alert card / pendant / bracelet
Overseas travel considerations, esp. malaria / animal bites
BSH 2024 guideline calls for a national registry (not currently in place)
Vaccination in uk Adults
Pneumococcal Vaccination
23-valent pneumococcal (PPV23) is current recommended choice (Green Book for updates)
Give one dose 2 weeks before or 2 weeks after splenectomy, or at diagnosis for functional hyposplenism
Booster: every 5 years
Note: Pneumococcal antibody testing is not routinely recommended due to limitations of test
Meningococcal Vaccination
Quadrivalent MenACWY is current recommended choice (Green Book for updates)
Give one dose at same time as the PPV23 pneumococcal vaccination
Booster: Not required unless travelling to a high risk country (use MenACWY two weeks prior to travel)
If not vaccinated for MenB as a child, then should also receive two doses of 4CMenB
Other Routinely Recommended Vaccines
COVID-19 as per national schedules
Seasonal influenza
Confirm patient has a complete vaccination record prior to onset of hyposplenism
No longer routinely recommended in UK
Haemophilus influenza B (Hib) - no longer required due to very low incidence of severe disease following national infant immunisation schedule
Antibiotic prophylaxis in Adults
All patients
Prophylaxis for at least 1-3 years post onset of hyposplenism, e.g. Phenoxymethylpenicillin 250mg BD
Provide supply of appropriate rescue antibiotics for emergency use
High Risk patients
Continue to offer ongoing prophylaxis indefinitely
High risk = Prev. treatment for haem malignancy, Prev. invasive pneumococcal disease, Age >65, Age <5