- Asplenia is the absence of the spleen due to either a congenital anomaly or a surgical procedure.
- Hyposplenia is the reduced or absent function of the spleen, impairing the capacity to prevent bacterial infections.
- The exact incidence is not known.
- Asplenia is present in about 3% of neonates with structural heart disease.
- Isolated asplenia is most often recognized at autopsy.
- The spleen is a major component of the reticuloendothelial system; it is important both for antibody synthesis and for clearance of opsonized organisms by phagocytosis.
- Antibody-mediated phagocytosis is the primary mechanism to destroy encapsulated microbes, such as pneumococcus, meningococcus, and Haemophilus.
- In the absence of the spleen’s phagocytic pathway, the polysaccharide-rich capsules of these bacteria protect them from destruction and permit them to effect systemic bacterial infection that may lead to overwhelming sepsis.
- For patients <4 years of age in whom few alternate routes of bacterial clearance exist, significant pathology can result from impaired splenic function.
- Surgical splenectomy
- Congenital asplenia
- In association with certain diseases or conditions (see “Differential Diagnosis”)
Commonly Associated Conditions
- Besides splenectomy, when asplenia is known, patients with certain diseases are at risk of asplenia or hyposplenia (see “Differential Diagnosis”).
- Asplenia or hyposplenia should be suspected in any patient with overwhelming infection with an encapsulated organism.
- Any patient with a condition known to be associated with asplenia/hyposplenia (see “Differential Diagnosis”) deserves evaluation for splenic function.
- In the apparently healthy child with no identified risk factors who presents with an overwhelming infection with an encapsulated organism, a blood smear should be examined for signs of hyposplenism (see “Lab”).
- The spleen may be normal, large, or nonpalpable. Therefore, the size of the spleen cannot be used as an indicator of splenic function.
- The size is most closely linked to the underlying etiology.
- Portal hypertension or complete splenic replacement by cysts, neoplasm, or amyloid can lead to splenomegaly.
- Sequestration crises such as those associated with sickle cell disease and malaria clog the spleen with cellular debris, which may also result in increased spleen size.
- Sickle cell disease patients typically have splenomegaly early in life, as the spleen tends to sequester the abnormal red cells. With time, the spleen slowly autoinfarcts and eventually becomes nonpalpable.
Diagnostic Tests and Interpretation
- The reduction or absence of splenic function can be determined by specific hematologic changes detectable on a blood smear.
- The spleen normally removes intercellular debris such as Howell-Jolly bodies (nuclear remnants), Heinz bodies (denatured hemoglobin), and Pappenheimer bodies (iron granules).
- Findings of target cells (red cells with a bull’s eye center due to excessive membrane relative to the amount of iron and hemoglobin), Howell-Jolly bodies, Heinz bodies, Pappenheimer bodies, and pitted (or pocked) erythrocytes are indicative of hyposplenia or asplenia.
- Surface indentations, pits or “pocks,” of the red cell surface when seen in >12% of red blood cells are the most sensitive indicator of hyposplenia. These are submembranous vacuoles that can be seen only in wet preparations of red cells fixed in 1% glutaraldehyde and viewed using direct interference-contrast microscopy.
- US with Doppler: to assess spleen size and direction of flow in splenic vein and portal vessels
- CT/MRI: to detect polysplenia
- Radionucleotide (technetium-99m) liver/spleen scan: to detect functional reticuloendothelial cells
Diminished splenic function is associated with the following:
- Isolated congenital asplenia
- Heterotaxy syndrome
- Sequestration crises (e.g., sickle hemoglobinopathies, essential thrombocytosis, malaria)
- Sickle cell disease
- Hereditary hemoglobinopathies
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Sjögren syndrome
- Graves disease
- Graft-versus-host disease
- Celiac disease
- Inflammatory bowel disease
- Chronic liver disease/portal hypertension
- Space-occupying lesions
- Tumors, such as lymphoma
- Hereditary spherocytosis
- Splenic artery occlusion
- Splenic vein thrombosis
- Normal infants
- Bone marrow transplant
- HIV infection
- Splenic irradiation
- Immunization with pneumococcal, meningococcal and Haemophilus vaccines should be carried out in all patients with asplenia/hyposplenia.
- In those patients who will be undergoing a scheduled splenectomy, the pneumococcal, meningococcal, and Haemophilus vaccines should be given at least 14 days prior to the operation.
- All children between 6 weeks and 59 months of age should receive the 4-dose series of the 13-valent pneumococcal conjugate vaccine (PCV13).
- In children 2–5 years of age with asplenia/hyposplenia, the 23-valent pneumococcal polysaccharide vaccine (PPSV23) should be administered following the 4-dose series of PCV13.
- A repeat of the PPSV23 should be administered 5 years after the initial dose.
- Infants between 6 weeks and 18 months of age with asplenia/hyposplenia should receive the 4-dose series of the meningococcal groups C and Y and Haemophilus influenzae b tetanus toxoid conjugate vaccine (Hib-MenCY-TT).
- Children older than 19 months should wait until 2 years of age and then receive the 2-dose series of the quadrivalent meningococcal conjugate vaccine (MenACWY).
- Revaccination is recommended every 5 years.
- Children should also receive the Haemophilus influenzae type b vaccine if not completed, as above.
- Antimicrobial prophylaxis should be strongly considered in all children with asplenia/hyposplenia.
- Penicillin or amoxicillin is most commonly used; however, with increasing penicillin resistance, it may be replaced by amoxicillin-clavulanic acid, fluoroquinolones, or cefuroxime.
- Sickle cell patients have impaired splenic function at all stages and should receive antimicrobial prophylaxis.
Any patient with asplenia/hyposplenia with a febrile illness should be evaluated for systemic bacterial illness. Blood culture with broad-spectrum antibiotic coverage should be strongly considered.
- Patients should be counseled regarding the risk of bacterial infection and considerations in setting of febrile illness.
- MedicAlert bracelets/necklaces can be used to indicate splenic function and risk of sepsis.
- For asplenic or hyposplenic patients, risk of bacteremia is highest in younger children and in the years immediately following splenectomy.
- The most common pathogens causing bacteremia are the encapsulated organisms, Streptococcus pneumonia, Haemophilus influenzae, and Neisseria meningitidis.
- There is also an increased risk of infection with Babesia microti and Plasmodium falciparum (intraerythrocytic parasites) and Capnocytophaga canimorsus (via dog bites).
Generally, for patients <4 years, splenectomy is contraindicated because of the risk of developing bacterial infection.
- Centers for Disease Control and Prevention. Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine among children aged 6-18 years with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep. 2013;62(25):521–524. [PMID:23803961]
- Cohn AC, MacNeil JR, Clark TA, et al; Centers for Disease Control and Prevention. Prevention and control of meningococcal disease: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2013;62(RR-2):1–28. [PMID:23515099]
- Melles DC, de Marie S. Prevention of infections in hyposplenic and asplenic patients: an update. Neth J Med. 2004;62(2):45–52. [PMID:15127830]
- Rubin LG and, W Schaffner W. Clinical practice. Care of the asplenic patient. N Engl J Med. 2014;371(4):349–356. [PMID:25054718]
- Spelman D, Buttery J, Daley A, et al. Guidelines for the prevention of sepsis in asplenic and hyposplenic patients. Intern Med J. 2008;38(5):349–356. [PMID:18284463]
- 759.0 Anomalies of spleen
- V45.79 Other acquired absence of organ
- 289.59 Other diseases of spleen
- Q89.01 Asplenia (congenital)
- Z90.81 Acquired absence of spleen
- D73.89 Other diseases of spleen
- 93030006 Congenital absence of spleen (disorder)
- 23761004 Hyposplenism (disorder)
- Q: What should I do if my child has a fever?
- A: All patients with asplenia/hyposplenia should be evaluated for a serious bacterial infection and treated appropriately.
- Q: Are there any special times I need to worry about infections?
- A: Patients with asplenia/hyposplenia receiving dental work or GI endoscopy should be considered on a case-by-case basis. Antibiotic prophylaxis should be strongly considered in patients undergoing high-risk endoscopic procedures (i.e., sclerotherapy or stricture dilation).
Joseph A. Picoraro
Sarah S. Lusman
© Wolters Kluwer Health Lippincott Williams & Wilkins
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