- PHYSIOLOGY
- Overview
- The spleen is a fist-shaped organ located in the upper, posterior left abdomen. The spleen lies adjacent to the stomach in the area of the 9th to 11th rib. [spleen illustration]
- The spleen receives blood from a large branch of the celiac trunk (splenic artery) and returns blood through a large vein (splenic vein)
- The spleen functions as a giant lymph node, filtering blood and removing pathogens
- Main functions of the spleen include:
- Removal of IgG-coated bacteria
- Removal of encapsulated bacteria (e.g. Streptococcus pneumoniae). Encapsulated bacteria are resistant to opsonization by complement and antibody. The spleen is the most proficient organ for removing encapsulated bacteria.
- Removal of antibody-coated cells and blood components (e.g. platelets in ITP)
- Initiation of immune responses to pathogens. Asplenic patients have a decreased humoral (antibody) immune response.
- Removal of aging and abnormal red blood cells. Recycling of iron from aging red blood cells.
- Removal of abnormal particles within red blood cells (e.g. Howell-Jolly bodies, Heinz bodies) [1,2,3,5]
- CAUSES AND RISK FACTORS FOR ASPLENIA/HYPOSPLENISM
Causes and Risk Factors for Asplenia and Hyposplenia | |
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Cause/Risk factor | Comment |
Trauma |
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Immune thrombocytopenia (ITP) |
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Sickle cell anemia |
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Chronic graft vs host disease |
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Celiac disease |
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Hereditary spherocytosis |
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Spleen irradiation |
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HIV |
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Congenital asplenia |
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- RISK OF INFECTION IN ASPLENIC/HYPOSPLENIC PATIENTS
- Overview
- The spleen is the main organ responsible for removing encapsulated bacteria from the blood. Asplenic/hyposplenic patients are at increased risk of sepsis from these organisms, primarily S pneumoniae, N meningitidis, and H influenzae type b. Asplenic/hyposplenic patients may also be at increased risk of sepsis from other organisms (see table below).
- In one review, the incidence of sepsis among asplenic patients was 3.2% over a median follow-up of 6.9 years. Sepsis was fatal in 44% of patients.
- Certain factors may increase the risk of sepsis in asplenic patients
- Risk-enhancing factors for sepsis in patients with asplenia/hyposplenism
- Sickle cell anemia (particularly homozygous for hemoglobin S)
- β-thalassemia
- Hereditary spherocytosis
- Hodgkin's lymphoma
- Recent splenectomy (< 1 year)
- Children < 5 years old
- Immune thrombocytopenia (ITP)
- Portal hypertension [1,3,6]
High-risk infections in asplenic/hyposplenic patients | |
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Organism | Comment |
Streptococcus pneumoniae |
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Haemophilus influenzae type b |
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Neisseria meningitidis |
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Malaria |
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Capnocytophaga species (canimorsus and cynodegmi) |
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Babesiosis |
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- MEASURES OF SPLEEN FUNCTION
- Overview
- The gold standard for measuring spleen function is Technetium-99m-labelled heat-damaged autologous erythrocyte clearance. This test is expensive and not widely available.
- Other methods for measuring spleen function are less precise but more practical
- Patients with conditions that are strongly associated with hyposplenism (e.g. sickle cell anemia) should be assumed to be hyposplenic/asplenic
- Methods for assessing spleen function are reviewed in the table below
Methods for measuring spleen function | |
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Method | Comment |
Technetium-99m-labelled heat-damaged autologous erythrocyte clearance |
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Detection of Howell-Jolly bodies |
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Spleen imaging |
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Measurement of pitted erythrocytes |
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- IMMUNIZATIONS
- Immunization recommendations from the CDC for asplenic patients are available at the links below. For patients undergoing elective splenectomy, vaccinations should be completed at least 2 weeks before surgery if possible.
- Asplenic adult immunization schedule
- Asplenic childhood (0 - 18 years) immunization schedule
- ANTIBIOTIC PROPHYLAXIS
- Overview
- Given the increased risk of infection in asplenic/hyposplenic patients, daily antibiotic prophylaxis has been proposed by some experts
- There is no consensus on the optimal method and duration of antibiotic prophylaxis in asplenic/hyposplenic patients. Furthermore, data from relevant clinical trials is lacking.
- Recommendations from medical societies who have published guidelines are presented in the table below
Antibiotic prophylaxis recommendations in asplenic/hyposplenic patients |
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American Academy of Pediatrics
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Canadian Pediatric Society
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British Committee for Standards in Haematology
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- FEBRILE ILLNESS PRECAUTIONS
- Overview
- Asplenic/hyposplenic patients who develop fever need to be evaluated immediately because fulminant sepsis can develop rapidly
- There is no consensus guideline for managing febrile asplenic patients, but most experts recommend immediate administration of empiric antibiotics and evaluation at a hospital
- General recommendations for the initial care of febrile asplenic/hyposplenic patients:
- Evaluation at a hospital
- Blood cultures
- Empiric IV antibiotics
- If IV antibiotics are not readily available, then the following may be given:
- Children - one of the following:
- Ceftriaxone 100 mg/kg/dose IM (maximum 2000 mg)
- Amoxicillin 45 mg/kg/dose (maximum 2000 mg)
- If pen allergic: Levofloxacin 10 mg/kg/dose (maximum 750 mg)
- Adults - one of the following:
- Ceftriaxone 2000 mg IM
- Amoxicillin 2000 mg
- Levofloxacin 750 mg
- Moxifloxacin 400 mg [3,4]
- BIBLIOGRAPHY
- 1 - PMID 21474172 Post-splenectomy and hyposplenic states, Lancet 2011
- 2 - PMID 24238338 The spleen in local and systemic regulation of immunity, Immunity 2013
- 3 - PMID 25054718 Care of the Asplenic Patient, NEJM 2014
- 4 - PMID 24855431 Preventing and treating infections in children with asplenia or hyposplenia, Canadian Paediatric Society, 2014
- 5 - PMID 21988145 Review of guidelines for the prevention and treatment of infection in patients with an absent or dysfunctional spleen, British Journal of Haematology, 2011
- 6 - PMID 11798256 Risk of infection and death among post-splenectomy patients, Journal of Infection, 2001
- 7 - 2012 Red Book Report of the Committee on Infectious Diseases