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