Specialty medical genetics ICD-9-CM 289.59, 759.01 eMedicine ped/150 radio/58 | ICD-10 D73.0, Q89.0 OMIM 208530 %271400 208540 Patient UK Asplenia | |
Asplenia refers to the absence of normal spleen function and is associated with some serious infection risks. Hyposplenism is used to describe reduced ('hypo-') splenic functioning, but not as severely affected as with asplenism.
Contents
Congenital
Acquired
Partial splenectomy and preservation of splenic function
In an effort to preserve some of the spleen's protective roles, attempts are now often made to preserve a small part of the spleen when performing either surgical subtotal (partial) splenectomy, or partial splenic embolization. This may be particularly important in poorer countries where protective measures for patients with asplenia are not available. However, it has been advised that preoperative vaccination is advisable until the remnant splenic tissue can reestablish its function.
Risks
Asplenia is a form of immunodeficiency, increasing the risk of sepsis from polysaccharide encapsulated bacteria, and can result in overwhelming post splenectomy infection (OPSI), often fatal within a few hours. In particular, patients are at risk from Streptococcus pneumoniae, Haemophilus influenzae, and meningococcus. The risk is elevated as much as 350–fold.
The risk to asplenic patients has been expressed as equivalent to an adult dying in a road traffic accident (in every 100 people without spleens, 1 to 5 would develop a severe infection per decade) (reference UK Splenectomy Trust Advice)—hence sensible precautions are advisable. Increased platelet counts can be seen in individuals without a functioning spleen.
Management
To minimise the risks associated with splenectomy, antibiotic and vaccination protocols have been established, but are often poorly adhered to by physicians and patients due to the complications resulting from antibiotic prophylaxis such as development of an overpopulation of Clostridium difficile in the intestinal tract.
Antibiotic prophylaxis
Because of the increased risk of infection, physicians administer oral antibiotics as a prophylaxis after a surgical splenectomy (or starting at birth, for congenital asplenia or functional asplenia).
Those with asplenia are also cautioned to start a full-dose course of antibiotics at the first onset of an upper or lower respiratory tract infection (for example, sore throat or cough), or at the onset of any fever.
Vaccinations
It is suggested that splenectomized persons receive the following vaccinations, and ideally prior to planned splenectomy surgery:
Travel measures
In addition to the normal immunizations advised for the countries to be visited, Group A meningococcus should be included if visiting countries of particular risk (e.g. sub-saharan Africa). The non-conjugated Meningitis A and C vaccines usually used for this purpose give only 3 years coverage and provide less-effective long-term cover for Meningitis C than the conjugated form already mentioned.
Those lacking a functional spleen are at higher risk of contracting malaria, and succumbing to its effects. Travel to malarial areas will carry greater risks and is best avoided. Travellers should take the most appropriate anti-malarial prophylaxis medication and be extra vigilant over measures to prevent mosquito bites.
The pneumococcal vaccinations may not cover some of the other strains of pneumococcal bacteria present in other countries. Likewise their antibiotic resistance may also vary, requiring a different choice of stand-by antibiotic.