What is asplenia?
The term asplenia indicates a severe functional deficit of the spleen, which very often involves serious infectious risks.
Spleen functions
For a better understanding of the article that follows, we briefly summarize the functions of the spleen:
- Hemocateresis: disposal of old or damaged red blood cells and recovery of the iron contained in hemoglobin (accumulated in hemosiderin and ferritin).
- Peripheral lymphoid function, therefore IMMUNITY: maturation and specialization of lymphocytes.
- Storage of figurative elements of the blood (especially lymphocytes).
- In prenatal age, from the third month to birth, the spleen also has a hematopoietic function.
Causes
What are the main causes of asplenia?
The causes of asplenia can be congenital or acquired.
Congenital asplenia
Congenital asplenia is rare and differs in two types: the syndrome of heterotaxia and isolated congenital separation ( isolated congenital asplenia ).
Acquired asplenia
Acquired asplenia can occur for several reasons:
- Following splenectomy (surgical removal of the spleen), performed following splenic rupture from trauma or tumor.
- Following splenectomy practiced with the aim of interfering with splenic function, for example in the treatment of certain diseases (such as idiopathic thrombocytopenic purpura, thalassemia, spherocytosis, etc.) in which the normal activity of the spleen exacerbates the disorder.
- Due to diseases that destroy the spleen (autosplenectomy), such as sickle cell anemia.
Among the cases of acquired asplenia it is also important to mention functional asplenia, which occurs when the splenic tissue is present but does not work, as in polysplenia or in sickle cell disease; these patients are managed as if they were asplenics.
Partial splenectomy
Partial splenectomy and conservation of splenic function
During the execution of a surgical splenectomy or splenic embolization, in an attempt to preserve some protective roles of the organ, some surgeons can only attempt a partial removal of the parenchyma. This can be very useful in poor countries, where the necessary protective measures are not available for patients with asplenia. In these cases, it is necessary to apply a preoperative vaccination that guarantees coverage until the splenic function is restored.
risks
Risks of asplenia
Asplenia is a form of primitive immunodeficiency, which increases the risk of sepsis caused, in particular, by polysaccharide-encapsulated bacteria.
It can therefore promote post-splenectomy infection (OPSI), which often proves fatal within a few hours. OPSI infections are mainly caused by: Streptococcus pneumoniae, Haemophilus influenzae and meningococcus .
The risk is 350 times higher than the norm.
Management
Specific antibiotic and vaccination protocols have been established to minimize the risks associated with splenectomy. However, these solutions find little adherence both by doctors and patients, due to the complications arising from antibiotic prophylaxis. First of all is the development of an overpopulation of Clostridium difficile in the intestinal tract.
Antibiotic prophylaxis
After surgical splenectomy, doctors are administering oral antibiotics as a prophylaxis against septicemia due to the increased risk of infections. In cases of congenital asplenia or functional asplenia, this can also occur in the neonatal age3
Those suffering from asplenia are also encouraged to start a complete course of antibiotics at the first symptoms of upper or lower respiratory tract infection (for example, sore throat or cough), or at least on the onset of fever.
Vaccinations
It is to be hoped that, before surgery, people to splenectomize receive the following vaccinations:
- Pneumococcal polysaccharide vaccine (no earlier than 2 years). If treatment is not completed in childhood, one or more boosters of pneumococcal conjugate vaccine may be required.
- Haemophilus influenzae type b vaccine, especially if not received in childhood.
- Meningococcal conjugate vaccine, especially if not received in adolescence. Children too young for the conjugate vaccine should receive, in the meantime, the vaccine against meningococcal polysaccharides.
- Influenza vaccine, every winter, to help prevent secondary bacterial infection resulting from the viral disease.
Precautions
Safety measures in case of travel
In the case of trips abroad to countries at risk (for example sub-Saharan Africa), in addition to the normal vaccinations recommended for the countries of destination, it is advisable to get vaccinated for meningococcus of group A.
Unconjugated vaccines for meningitis A and C, commonly used for this purpose, give only 3 years of coverage and are generally less effective than the conjugate form.
Those who do not have a functional spleen also have a higher risk of contracting malaria, which usually occurs in severe form. It is therefore recommended to avoid the areas most affected by malaria and, in any case, it is essential to take the most appropriate anti-malaria drug and limit the risk of mosquito bites as much as possible.
National pneumococcal vaccinations do not cover some of the strains found only in other countries. The antibiotic resistance of the pathogen may also vary, requiring a different pharmacological choice.
Additional measures
- Surgical and dental technician procedures: antibiotic prophylaxis may be necessary before certain operations.
- Animal bite: adequate antibiotic coverage is required even after the bite of a dog or other animals. Asplenic patients are particularly susceptible to Capnocytophaga canimorsus infection and, in this case, a 5-day cycle of amoxicillin / clavulanate should follow (for patients allergic to penicillin we recommend erythromycin).
- Tick bite and babesiosis: it is a rare infection but those suffering from asplenia, in risky conditions, must monitor themselves and undergo a thorough inspection. The appearance of fever, fatigue and haemolytic anemia requires diagnostic investigation and detection of parasites. Quinine (with or without clindamycin) is almost always an effective treatment.
- Warning: people without a spleen can wear a special bracelet or necklace as a warning of their condition. This, in the event of a loss of consciousness, helps health professionals to act quickly.
