AKT · Haematology/Transfusion, spleen & immunity

Hyposplenism & asplenia

Absent/reduced splenic function → susceptibility to encapsulated bacteria (overwhelming sepsis)

Overview

Reduced or absent splenic function — after splenectomy (trauma, ITP, spherocytosis), or functional (sickle cell disease, coeliac disease, inflammatory bowel disease). The spleen clears encapsulated organisms, so hyposplenic patients are at lifelong risk of OVERWHELMING POST-SPLENECTOMY INFECTION (OPSI) — fulminant sepsis with encapsulated bacteria (pneumococcus, Haemophilus, meningococcus). Prevention is vaccination + prophylactic penicillin + patient awareness.

Recognise

Blood film clues to hyposplenism: HOWELL-JOLLY BODIES, target cells, thrombocytosis (and the surgical history)
Risk of overwhelming infection (OPSI) with ENCAPSULATED organisms — Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis; also severe malaria, Capnocytophaga (dog bites)
Causes: splenectomy (trauma, ITP, hereditary spherocytosis), functional asplenia (sickle cell autosplenectomy), coeliac/IBD

Red flags

Fever in an asplenic patient = potential OPSI → urgent antibiotics and assessment (medical emergency)
Asplenic travel to malarial areas → meticulous prophylaxis (severe malaria risk)

Differentials & how to tell them apart

Other causes of fever/sepsisbut in an asplenic patient, fever is OPSI until proven otherwise — treat urgently

Other blood-film changesHowell-Jolly bodies are characteristic of hyposplenism; reactive thrombocytosis has other causes

Howell-Jolly bodies (nuclear remnants) of hyposplenism (blood film)
Prof. Erhabor Osaro / CC BY-SA 4.0 — Wikimedia Commons

Investigations

Blood film (Howell-Jolly bodies, target cells, thrombocytosis); recognise the surgical/functional history; ensure the vaccination and prophylaxis record is up to date; investigate fever urgently as possible OPSI.

Management

Vaccinate (pneumococcal/Hib/meningococcal/flu) + prophylactic penicillin + treat any fever urgently (OPSI)

1Recognise hyposplenism (Howell-Jolly bodies/target cells/thrombocytosis + surgical or functional history). Prevent OPSI: vaccinate (pneumococcal, Hib, meningococcal ACWY+B, flu) and give prophylactic penicillin V, ideally ≥2 weeks before elective splenectomy.Gate: Fever in an asplenic patient is OPSI until proven otherwise → urgent broad-spectrum antibiotics and assessment; give patients standby antibiotics, an alert card and malaria advice.
2Lifelong (or long-term) penicillin prophylaxis, up-to-date vaccinations, patient education and prompt treatment of every febrile episode.

VACCINATION: pneumococcal, Haemophilus influenzae type b, meningococcal (ACWY + B), annual influenza — ideally ≥2 weeks before elective splenectomy (or after emergency splenectomy); the cornerstone of prevention

Prophylactic penicillin V (lifelong, or at least the high-risk years) — penicillin V (or a macrolide if allergic); prevents pneumococcal OPSI

Patient awareness + a card/alert + standby antibiotics — seek urgent care for any fever; standby antibiotics for prompt self-start

Urgent broad-spectrum antibiotics for any febrile episode (suspected OPSI) — treat fever as a medical emergency; malaria prophylaxis for travel

Key points

Howell-Jolly bodies + target cells + thrombocytosis + splenectomy/sickle/coeliac = hyposplenism → lifelong risk of OVERWHELMING infection with ENCAPSULATED bacteria (pneumococcus/Hib/meningococcus). Prevent: vaccinate (≥2 wk before elective splenectomy) + prophylactic penicillin + patient awareness/standby antibiotics. Fever = treat as OPSI emergency.

Monitor & prognosis

Vaccination/prophylaxis record, patient awareness, prompt response to fevers.

Excellent with prevention; OPSI carries very high mortality if treatment is delayed.

Source: BSH/UK guidelines on asplenia; cross-ref child_health (sickle), gastroenterology (coeliac)