Asplenia

Classification according to ICD-10
D73.0	Hyposplenism - asplenia after splenectomy - atrophy of the spleen
Q89.0	Congenital malformations of the spleen - asplenia (congenital)
ICD-10 online (WHO version 2019)

In medicine, asplenia is the inability of the spleen to function properly . The organ can be absent ( anatomical asplenia ), either congenital (congenital asplenia) or after surgical removal ( splenectomy - surgical asplenia), or it fails, which is known as functional asplenia . The hyposplenism means a reduced, but still present function of the spleen.

root cause

A congenital malformation is very rare and can occur in combination with other midline defects such as congenital heart defects. Such a combination is called the Ivemark symptom complex after its first description and belongs to the so-called heterotaxies .

The functional Asplenia , in the context of sickle cell anemia , in systemic autoimmune diseases , wherein amyloidosis or after the transplantation of stem cells arise (allergic reaction). In this case, the spleen is present, but no longer functional.

An autosplenectomy is an asplenia due to i. d. Typically multiple splenic infarctions , bleeding, fibrosis or involution, it corresponds to an anatomical asplenia.

A splenectomy can be performed as a result of trauma or because of a hematological or oncological indication, primarily in the case of spheroidal cell anemia , idiopathic thrombocytopenic purpura , hypersplenism, or sickle cell anemia .

In sickle cell anemia, functional asplenia occurs around the first year of life and, if left untreated, anatomical asplenia develops at 6–8 years of age due to splenic infarction.

A chronic graft-versus-host reaction after stem cell transplantation and an untreated HIV infection cause hyposplenia in around 50% of all affected patients.

diagnosis

Asplenia can be diagnosed from a blood count . The Howell-Jolly bodies , which are otherwise broken down by the spleen, are detected. The functional asplenia does not show as severe changes in the blood count as the anatomical asplenia.

The anatomical absence of the spleen can also be determined by imaging techniques such as sonography , computer or magnetic resonance imaging .

hazards

Asplenia increases the risk of infection for the patient . In particular, capsule-bearing bacteria such as pneumococci can cause severe sepsis ( overwhelming post-splenectomy infection , OPSI ) in asplenia . Asplenia also increases the risk of fungal infections.

Mortality for haematogenous infections after splenectomy is up to 46% regardless of the age of the patient, the length of time since the splenectomy and the original indication. Based on American data from the 1980s, the risk of fatal post-splenectomy sepsis is around 0.29 per 100 patient-years in children and 0.10-0.13 in adults. In long-term observations from the 1980s, the median risk of post- splenectomy sepsis was 3.2% after 6.9 years, with a mortality of up to two thirds of patients. The risk of meningitis and pneumonia was also significantly increased in splenectomized patients.

The increased risk of haematogenic infection in asplenia is explained by the reduced clearance (cleaning) of the bacteria from the blood and by a reduced humoral immune response . The spleen is the most effective organ for removing bacteria that have already been populated (marked) with immunoglobulin G and very important for removing virulent encapsulated bacteria that have not been "marked" ( opsonized ). A significantly stronger opsonization is necessary for cleaning in the liver. Asplenia patients also have significantly fewer IgM antibodies directed against polysaccharides in the serum and fewer B memory cells that produce immunoglobulin M. Since the formation of polysaccharide IgM antibodies is disturbed, the effect of a vaccination is also slowed down and reduced.

Post-splenectomy sepsis is most commonly triggered by pneumococci both after splenectomy and in children with sickle cell anemia . Haemophilus influenzae was the main culprit in children under 5 years of age, but has only rarely been the culprit since the global introduction of HIB vaccination . Also, meningococcal , Escherichia coli and Staphylococcus aureus are responsible for a small proportion of cases of sepsis. Asplenia is also an important risk factor for infections with Capnocytophaga canimorsus and Capnocytophaga cynodegmi, especially after animal bites , for babesiosis after tick bites and infection with Bordetella holmesii .

prevention

Asplenia patients must be trained that every fever event and also every severe disease symptomatology without fever can be an indication of a life-threatening infection. Immediate empirical antibiotic treatment, such as intravenous or intramuscular ceftriaxone with or without vancomycin, should be given for fever . Patients should possibly already be prescribed an antibiotic in advance that they can take on their own, such as: B. Amoxicillin 2 g or Levofloxacin 750 mg.

In children with asplenia who are less than five years old, permanent prophylactic antibiosis, such as oral penicillin, is recommended twice a day and should also be performed in older children and adults in the first two years after splenectomy. In a placebo- controlled clinical trial in children 3-36 months of age with sickle cell disease, the incidence of pneumococcal sepsis decreased by 84% with oral penicillin V (125 mg twice daily). However, all studies on the usefulness of prophylactic antibiosis relate to the time before the introduction of the pneumococcal vaccine, which means that the need for and benefits of prophylactic antibiotic therapy are unclear today.

Lifelong antibiotic prophylaxis is recommended even after a one-time post-splenectomy sepsis.

In addition, vaccinations are required which can significantly reduce the risk of post-splenectomy sepsis (which is why the figures from the 1980s on the danger of post-splenectomy sepsis have no longer been valid since vaccinations were introduced). With elective splenectomy, vaccinations should all start before the planned operation. Vaccinations against pneumococci , haemophilus influenza type B , meningococci and annual flu vaccinations are urgently recommended .

Web links

• Asplenie-Net - Recommendations on vaccinations, antibiotic prophylaxis and emergency therapy

Individual evidence

1. ^ Pschyrembel Clinical Dictionary, 259th edition, Walter de Gruyter, Berlin, 2002, p. 160
2. ^ Lorry G. Rubin, William Schaffner: Care of the Asplenic Patient . New England Journal of Medicine 2014, Volume 371, Issue 4, July 24, 2014, pages 349-356, DOI: 10.1056 / NEJMcp1314291

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !