It is estimated that up to 25,000 Australians are affected by asplenia or hyposplenism.¹  Many are unaware of the fact, and its potential consequences. The spleen plays an important role in immune function, in particular the prevention of infection due to some specific organisms (Table 1).

Infection Risk

Infection is a relatively common occurrence in those without a functioning spleen. Overwhelming post-splenectomy infection (OPSI), occurs in up to 5% of asplenic patients and has a mortality rate of over 50%. The risk is particularly high in children aged under five, and in the first three years post-splenectomy. However, the risk is lifelong.¹

Organisms of Concern

Table 1:     Organisms of Concern

Agent	Comment
Streptococcus pneumoniae	Accounts for >50% of severe infections. Vaccine available and recommended
Neiserria meningitidis	Vaccine available and recommended.
Haemophilus influenza type B	Vaccine available and recommended.
Capnocytophagia species	Oral flora in animals. Risk of acquisition after animal bites.
Bordetella holmesii	Newly recognised pathogen.
Plasmodia species (Malaria) Babesia, Ehrlichia	Potential risk for travellers. Seek pre-travel advice.

 

Causes of Asplenia and Hyposplenism

Asplenia maybe congenital but is more often acquired as a result of trauma or the surgical removal of the spleen due to haematological conditions, or after incidental splenic damage incurred during intra-abdominal surgery. Functional hyposplenism also confers an increased risk of infection and may occur as a result of a number of medical conditions (Table 2).   Table 2:    Medical conditions associated with hyposplenism

Coeliac disease

SLE

Sickle Cell disease

Rheumatoid arthritis

Malignant infiltration e.g. lymphoma

Splenic infarction or radiation

Graft versus host disease

 

Detection of Asplenia and Hyposplenism

The presence of Howell-Jolly bodies in a blood film may be a clue to the presence of unrecognised asplenia or hyposplenism.  Other investigations that may be of assistance in suspected cases are imaging studies such as ultrasound or CT.

Prevention of Infection

Evidence suggests it is possible to significantly decrease the incidence of infection in asplenic and or hyposplenic patients. Spleen Australia has recently demonstrated a 69% reduction in serious infections in patients on their registry.² The key strategies utilised by Spleen Australia include; 1. Education

• Informing patients and their families of the risk of infection, signs and symptoms of sepsis and the need to develop a management plan should these occur:
  • Importance of seeking urgent medical attention if symptomatic.
  • Maintaining a standby supply of antibiotics for emergency use.
• Provision of advice regarding travel and other potential exposure risks e.g. animal contact.
• Encouraging the wearing of a Medical Alert bracelet.

2.  Provision of advice regarding appropriate antibiotic therapy (as per Therapeutic Guidelines)

• Consider antibiotic prophylaxis, particular in first three years post-splenectomy (With either penicillin or roxithromycin).
• Maintain a standby emergency supply of antibiotics in case of sepsis (usually Amoxil 3g).

3.  Provision of current, detailed, practical guidelines for vaccination (As per Immunisation Handbook)

• Pneumococcal, Meningococcal, Haemophilus influenza type B vaccines - initial course and ongoing boosters as required.
• Annual influenza vaccine - to minimise the chance of post-influenza bacterial infection.

Currently, persons resident in Victoria, Queensland and Tasmania are able to register with Spleen Australia and will then receive regular newsletters and reminders when vaccines are due. It is hoped that this service will be extended to other states. See www.spleen.org.au for details.  

Key Messages

• Infection is a significant, life-long risk in asplenic and hyposplenic patients.
• The risks can be mitigated by:
  • The early recognition of the underlying condition,
  • Comprehensive patient education,
  • Appropriate use of use of prophylactic and empirical antibiotics, and
  • Ensuring that patients receive recommended initial and ongoing vaccinations.

Spleen Australia provides an excellent range of resources and is happy to assist in the management of these patients if required.  

References

1. Spleen Australia. Welcome to Spleen Australia: a clinical service and registry for people with a non-functioning spleen. Melbourne VIC: Diabetes Australia. Available from: www.spleen.org.au
2. Arnott A, Jones P, Franklin LJ, Spelman D, Leder K, Cheng AC. A Registry for Patients With Asplenia/Hyposplenism Reduces the Risk of Infections With Encapsulated Organisms. Clin Infect Dis. 2018 Aug 1; 67(4): 557-61. Available from: https://doi.org/10.1093/cid/ciy141

  General Practice Pathology is a new regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs. The authors provide this editorial, free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.