Asplenia
Asplenia | |
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Specialty | Medical genetics |
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.
Functional asplenia occurs when splenic tissue is present but does not work well (e.g. sickle-cell disease, polysplenia) – such patients are managed as if asplenic – while in anatomic asplenia, the spleen itself is absent.
Causes
Congenital
Acquired
- Following tumor
- After splenectomy with the goal of interfering with splenic function, as a treatment for diseases (e.g. idiopathic thrombocytopenic purpura, thalassemia, spherocytosis), in which the spleen's usual activity exacerbates the disease
- After splenectomy with the goal of arresting the progression of cancers ()
- Due to underlying diseases that destroy the spleen (sickle-cell disease.
- it was the second most common cause of abnormalities of red blood cells linked to hyposplenism, after surgical splenectomy.
Functional asplenia
Functional asplenia can occur when patients with metabolic or haematological disorders have their splenic tissue organisation altered. This can lead to results similar to those seen in patients who have undergone a splenectomy e.g. becoming infected with encapsulated bacteria such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis. Patients who have some form of asplenia have an increased susceptibility to these encapsulated bacterial infections mainly because they lack IgM memory B cells and their non-adherence to polysaccharide vaccines. Furthermore, there is a deficiency of other splenic cells e.g. splenic macrophages. This combined with the lack of B cells can provide an environment favourable for the development of bacterial infections.[8]
Partial splenectomy and preservation of splenic function
In an effort to preserve some of the spleen's protective roles,[9] attempts are now often made to preserve a small part of the spleen when performing either surgical subtotal (partial) splenectomy,[10] or partial splenic embolization.[11] This may be particularly important in poorer countries where protective measures for patients with asplenia are not available.[12] However, it has been advised that preoperative vaccination is advisable until the remnant splenic tissue can reestablish its function.[13]
Risks
Asplenia is a form of
The increased risk of infection is due to inability to clear opsonised bacteria from circulating blood. There is also a deficiency of T-cell independent antibodies, such as those reactive to the polysaccharide capsule of Streptococcus pneumoniae.[16]
The risk to asplenic patients has been expressed as equivalent to an adult dying in a road traffic accident (1 to 5 percent of people without spleens would develop a severe infection per decade) (reference UK Splenectomy Trust Advice)—hence sensible precautions are advisable.
Diagnosis
Diagnosis is confirmed by abdominal ultrasonography and detection of Howell-Jolly bodies in red blood cells.[18]
Management
To minimise the risks associated with splenectomy,
Antibiotic prophylaxis
Because of the increased risk of infection, physicians administer oral antibiotics as
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. Even with a course of antibiotics and even with a history of relevant vaccination, persons without a functional spleen are at risk for Overwhelming post-splenectomy infection.[23]
In an emergency room or hospital setting, appropriate evaluation and treatment for an asplenic febrile patient should include a complete blood count with differential, blood culture with Gram stain, arterial blood gas analysis, chest x-ray, and consideration for lumbar puncture with CSF studies. None of these evaluations should delay the initiation of appropriate broad-spectrum intravenous antibiotics. The Surviving Sepsis Campaign guidelines state that antibiotics should be administered to a patient suspected of sepsis within 1 hour of presentation. Delay in starting antibiotics for any reason is associated with a poor outcome.[24]
Vaccinations
It is suggested that splenectomized persons receive the following vaccinations, and ideally prior to planned splenectomy surgery:
- Pneumococcal polysaccharide vaccine (not before 2 years of age). Children may first need one or more boosters of pneumococcal conjugate vaccine if they did not complete the full childhood series.
- Haemophilus influenzae type b vaccine, especially if not received in childhood. For adults who have not been previously vaccinated, two doses given two months apart was advised in the new 2006 UK vaccination guidelines (in the UK may be given as a combined Hib/MenC vaccine).[25]
- Meningococcal conjugate vaccine, especially if not received in adolescence. Previously vaccinated adults require a single booster and non-immunised adults advised, in UK since 2006, to have two doses given two months apart.[25] Children too young for the conjugate vaccine should receive meningococcal polysaccharide vaccine in the interim.[15]
- Influenza vaccine, every winter, to help prevent getting secondary bacterial infection.
Travel measures
In addition to the normal immunizations advised for the countries to be visited, Group A
Those lacking a functional spleen are at higher risk of contracting malaria,[28] 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.[19]
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.
Additional measures
- Surgical and dental procedures - Antibiotic prophylaxis may be required before certain surgical or dental procedures.
- Animal bites - adequate antibiotic cover is required after even minor dog or other animal bites. Asplenic patients are particularly susceptible to infection by amoxicillin/clavulanate (erythromycin in patients allergic to penicillin).[29]
- Tick bites - Babesiosis is a rare tickborne infection. Patients should check themselves or have themselves inspected for tick bites if they are in an at-risk situation. Presentation with fever, fatigue, and haemolytic anaemia requires diagnostic confirmation by identifying the parasites within red blood cells on blood film and by specific serology. Quinine (with or without clindamycin) is usually an effective treatment.[29]
- Alert warning - People without a working spleen can carry a card, or wear a special bracelet or necklet which says that they do not have a working spleen. This would alert a healthcare professional to take rapid action if they become seriously ill and cannot notify them of their condition.[30]
References
- ^ Online Mendelian Inheritance in Man. OMIM entry 208530: Right atrial isomerism; RAI. Johns Hopkins University. [1]
- ^ Online Mendelian Inheritance in Man. Johns Hopkins University. OMIM entry 271400: Asplenia, isolated congenital; ICAS.
- ^ Leukemia & Lymphoma Society (2017). "Chronic Lymphocytic Leukemia" (PDF). p. 15. Archived from the original (PDF) on 18 June 2018. Retrieved 18 June 2018.
- PMID 5539576. Retrieved 18 June 2018.
- S2CID 20986297.
- PMID 16973955.
- PMID 4189238.
- PMID 23801854.
- PMID 957066.
- S2CID 22741973.
- S2CID 41343243.
- PMID 18031639.
- PMID 9660206.
- ^ PMID 11272299.
- ^ a b AAP Red Book 2006.
- ^ Kasper, D. et al (2015) Harrison's principles of internal medicine. New York, NY: McGraw-Hill Education
- ^ "Splenectomy and Infection" (PDF). Splenectomy Trust. March 2002. Archived from the original (PDF) on 2007-09-28. Retrieved 2006-12-12. - reprint from Kent and Medway NHS and Social Care Partnership Trust
- ^ "Asplenia/Hyposplenia". Unbound Medicine, Inc. Retrieved 9 July 2021.
- ^ PMID 8601117.
- PMID 8601117. - published as a response by original authors
- PMID 12448592. Archived from the original(PDF) on 2009-11-05. Retrieved 2010-02-01.
- PMID 11253134.
- ^ Wick, Jeannette (September 1, 2006). "Asplenia Poses Management Challenges". Pharmacy Times. Archived from the original on April 12, 2013. Retrieved 18 June 2018.
- PMID 26130882.
- ^ ISBN 978-0-11-322528-6. Archived from the originalon 2 December 2008. Retrieved 22 July 2007. - see pages 50-1 and table 7.1
- ^ "Meningococcal - Children and adults with asplenia or splenic dysfunction" (PDF). Immunization against infectious disease - 'The Green Book' (PDF). 24 August 2009 [2006]. p. 244.
- ^ Chief Medical Officer (2001). "Meningococcal immunisation for asplenic patients" (PDF). Professional Letter: Chief Medical Officer - Current Vaccine and Immunization Issues. 1. Department of Health: 4. Retrieved 2009-11-07.[permanent dead link]
- PMID 7496237.
- ^ a b "Guidelines for the prevention and treatment of infection in patients with an absent or dysfunctional spleen" (PDF). Wilton, Cork, Ireland: Health Service Executive, Southern Area. September 2002.
- ^ HSC Public Health Agency. "Splenectomy wallet card". HSC Public Health Agency. Belfast. Archived from the original on 2 August 2019. Retrieved 1 August 2019.