Makindo Medical Notes

⚠️ The spleen plays a key role in filtering abnormal red cells and clearing encapsulated bacteria. Loss of splenic function (asplenia or hyposplenism) → increased risk of life-threatening infection. By far the most important pathogen is Streptococcus pneumoniae. 👉 Lifelong penicillin prophylaxis is usually recommended.

🔪 Indications for Splenectomy

• Trauma (most common cause in UK)
• Hereditary spherocytosis
• Idiopathic thrombocytopenic purpura (ITP)
• Myelofibrosis with massive splenomegaly
• Occasionally for staging/treatment of haematological malignancy

🧬 Medical Causes of Hyposplenism

• Sickle cell disease (auto-infarction of spleen)
• Coeliac disease (functional hyposplenism in 30–50%)
• Inflammatory bowel disease (less common)
• Blood film may mimic post-splenectomy findings

🦠 Infection Risk Post-Splenectomy

Patients are at risk of severe infection with encapsulated organisms:

• Streptococcus pneumoniae (most common;>80%)
• Haemophilus influenzae type B
• Neisseria meningitidis
• Escherichia coli
• Pseudomonas aeruginosa (in some cases)
• Other unusual organisms: Capnocytophaga canimorsus (dog bites), malaria, babesiosis

🩻 Blood Film Findings (Post-Splenectomy / Hyposplenism)

• Howell–Jolly bodies (nuclear DNA remnants)
• Pappenheimer bodies (iron granules)
• Target cells 🎯 (bullseye appearance)
• Acanthocytes (spiky RBCs)
• Thrombocytosis (reactive, due to splenic sequestration loss)

⚠️ Risks of Hyposplenism

• Overwhelming Post-Splenectomy Infection (OPSI): fulminant sepsis, most often pneumococcal.
• 50% mortality despite treatment.
• Increased susceptibility to malaria, babesiosis (protozoa).
• ↑ Risk of vascular disease, thrombosis, and autoimmune disorders.

🛡 Prevention of Infection

• Pneumococcal vaccine: Conjugate vaccine (PCV-13) preferred → induces T-cell dependent response. Booster with PPSV-23 at 5 years.
• Meningococcal vaccines: ACWY conjugate series + MenB vaccine.
• Hib vaccine: If not previously given.
• Antibiotic prophylaxis: Life-long penicillin V 250 mg BD (especially children, immunocompromised, first 2 years post-splenectomy).
• Education: Patients should carry “splenectomy card” or alert bracelet. Prompt antibiotics for fever.
• Travel advice: Malaria prophylaxis essential for endemic areas; avoid dog bites (risk of Capnocytophaga).

📚 Organisms to Know in Hyposplenic Patients

• Streptococcus pneumoniae (major pathogen)
• Haemophilus influenzae type B
• Neisseria meningitidis
• Escherichia coli, Pseudomonas
• Malaria (mosquito vector)
• Babesiosis (tick-borne)
• Capnocytophaga canimorsus (dog bites) 🐶

🎯 Exam Pearls

• OPSI = medical emergency: treat any fever in asplenic patient with urgent IV antibiotics.
• Blood film: Howell–Jolly bodies = classic clue.
• Vaccination + lifelong antibiotics = cornerstones of prevention.
• Hyposplenism (e.g. coeliac, sickle cell) carries same infection risk as surgical splenectomy.