Asplenia
Encyclopedia
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.
.
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.
, 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 Pneumococcus, Haemophilus influenzae
, and meningococcus. The risk is elevated as much as 350–fold.
The risk to asplenic patients has been expressed as equivalent to a child dying in a home accident, or equivalent to an adult dying in a road traffic accident (reference UK Splenectomy Trust Advice)—hence sensible precautions are advisable.
and vaccination
protocols have been established, but are often poorly adhered to by doctors and patients due to the complications resulting from antibiotic prophylaxis such as development of an overpopulation of Clostridium difficile
in the intestinal tract.
Patients 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.
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.
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
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.
Congenital
- Congenital asplenia (rare) may be due to genetic disorders, (i.e. heterotaxy syndrome).
Acquired
- AcquiredAcquired disorderAn acquired disorder is a medical condition which develops post-fetally; in contrast with a congenital disorder, which is present at birth. A congenital disorder may be antecedent to an acquired disorder ....
asplenia occurs for several reasons:- Following splenectomySplenectomyA splenectomy is a surgical procedure that partially or completely removes the spleen.-Indications:The spleen, similar in structure to a large lymph node, acts as a blood filter. Current knowledge of its purpose includes the removal of old red blood cells and platelets, and the detection and fight...
due to splenic rupture from traumaPhysical traumaTrauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
or because of tumorTumorA tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer... - After splenectomy with the goal of interfering with splenic function, as a treatment for diseases (e.g. idiopathic thrombocytopenic purpuraIdiopathic thrombocytopenic purpuraIdiopathic thrombocytopenic purpura is the condition of having an abnormally low platelet count of no known cause . As most incidents of ITP appear to be related to the production of antibodies against platelets, immune thrombocytopenic purpura or immune thrombocytopenia are terms also used to...
, thalessemia, spherocytosisSpherocytosisSpherocytosis is an auto-hemolytic anemia characterized by the production of red blood cells , or erythrocytes, that are sphere-shaped, rather than bi-concave disk shaped. Spherocytes are found in hereditary spherocytosis and autoimmune hemolytic anemia.It almost always refers to hereditary...
), in which the spleen's usual activity exacerbates the disease - Due to underlying diseases that destroy the spleen (autosplenectomyAutosplenectomyAn autosplenectomy occurs when a disease damages the spleen to such an extent that it ends up shrunk.-Consequences:...
), e.g. sickle-cell diseaseSickle-cell diseaseSickle-cell disease , or sickle-cell anaemia or drepanocytosis, is an autosomal recessive genetic blood disorder with overdominance, characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various...
.
- Following splenectomy
- Functional asplenia occurs when splenic tissue is present but does not work well, e.g. sickle-cell disease, polyspleniaPolysplenia-Associated conditions:There are frequent associated congenital anomalies all related to deviations in the development of anatomical asymmetries in early embryonic stages...
; such patients are managed as if asplenic.
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 embolizationEmbolization
Embolization is a non-surgical, minimally-invasive procedure performed by an interventional radiologist and interventional neuroradiologists. It involves the selective occlusion of blood vessels by purposely introducing emboli.-Therapeutic applications:...
.
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 immunodeficiencyImmunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
, increasing the risk of sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
from polysaccharide encapsulated bacteria
Polysaccharide encapsulated bacteria
Polysaccharide encapsulated bacteria, frequently referred to simply as encapsulated bacteria and less precisely called encapsulated organisms, are a group of bacteria that have an outer covering, a bacterial capsule, made of polysaccharide....
, and can result in overwhelming post splenectomy infection (OPSI), often fatal within a few hours. In particular, patients are at risk from Pneumococcus, Haemophilus influenzae
Haemophilus influenzae
Haemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...
, and meningococcus. The risk is elevated as much as 350–fold.
The risk to asplenic patients has been expressed as equivalent to a child dying in a home accident, or equivalent to an adult dying in a road traffic accident (reference UK Splenectomy Trust Advice)—hence sensible precautions are advisable.
Management
To minimise the risks associated with splenectomy, antibioticAntibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
and vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
protocols have been established, but are often poorly adhered to by doctors and patients due to the complications resulting from antibiotic prophylaxis such as development of an overpopulation of Clostridium difficile
Clostridium difficile
Clostridium difficile , also known as "CDF/cdf", or "C...
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). The duration suggested varies: one suggestion is that antibiotics be taken for two years or until the age of sixteen years old is reached, whichever is longer.Patients are also cautioned to start a full-dose course of antibiotics at the first onset of an upper
Upper respiratory tract infection
Upper respiratory tract infections are the illnesses caused by an acute infection which involves the upper respiratory tract: nose, sinuses, pharynx or larynx...
or lower respiratory tract infection
Lower respiratory tract infection
Lower respiratory tract infection while often used as a synonym for pneumonia, can also be applied to other types of infection including lung abscess and acute bronchitis...
(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:- Pneumococcal polysaccharide vaccinePneumococcal polysaccharide vaccinePneumococcal polysaccharide vaccine — the latest version is known as Pneumovax 23 — is the first pneumococcal vaccine, the first vaccine derived from a capsular polysaccharide, and an important landmark in medical history...
(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).
- 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. Children too young for the conjugate vaccine should receive meningococcal polysaccharide vaccine in the interim.
- Influenza vaccine, every winter, to help prevent getting secondary bacterial infection.
Travel measures
In addition to the normal immunisations 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
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
, 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.
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 capnocytophaga canimorsusCapnocytophaga canimorsusCapnocytophaga canimorsus is a Gram-negative bacillus bacterium that causes a zoonotic disease, most commonly in asplenic patients. It is a member of the normal gingival flora of dogs and cats...
and should receive a five day course of co-amoxiclavCo-amoxiclavAmoxicillin/clavulanic acid or co-amoxiclav is a combination antibiotic consisting of amoxicillin trihydrate, a β-lactam antibiotic, and potassium clavulanate, a β-lactamase inhibitor...
(erythromycinErythromycinErythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...
in patients allergic to penicillin). - Tick bites - BabesiosisBabesiosisBabesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. After trypanosomes, Babesia are thought to be the second most common blood parasites of mammals and they can have a major impact on health of domestic animals in areas without severe...
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 serologySerologySerology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
. QuinineQuinineQuinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an anti-arrhythmic...
(with or without clindamycinClindamycinClindamycin rINN is a lincosamide antibiotic. It is usually used to treat infections with anaerobic bacteria but can also be used to treat some protozoal diseases, such as malaria...
) is usually an effective treatment. - 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 are seriously ill and cannot notify them of their condition.