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Asplenia describes the absence of normal splenic function, whether due to surgical removal, congenital absence, or functional impairment associated with systemic disease. The spleen serves as a key extramedullary lymphoid organ responsible for filtration of senescent erythrocytes, clearance of opsonized bacteria, and generation of immunoglobulin M-mediated immune responses. Loss of splenic function disrupts innate and adaptive immunity, thereby impairing clearance of encapsulated organisms such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. Increased susceptibility to overwhelming postsplenectomy infection represents a life-threatening complication characterized by the rapid onset of sepsis and high mortality. Additional consequences include altered hematologic parameters, increased risk of thromboembolism, and vulnerability to parasitic infections. Recognition of anatomic or functional asplenia requires careful clinical assessment, review of medical history, and appropriate laboratory or imaging evaluation to guide preventive and therapeutic strategies. This educational activity equips the participant with a detailed understanding of infection pathophysiology, diagnostic considerations, and risk stratification in patients with asplenia. Emphasis is placed on evidence-based prevention strategies, including immunization schedules, antimicrobial prophylaxis, and patient education regarding early signs of infection. Early detection and prompt management of febrile illness receive focused attention to reduce morbidity and mortality. Clinical decision-making is strengthened through discussion of guideline-directed care and real-world application. Collaboration within an interprofessional healthcare team enhances patient outcomes by integrating expertise from clinicians, pharmacists, nurses, and public health professionals. Objectives: Identify patients with anatomic or functional asplenia who are at increased risk for severe infection and related complications. Screen patients with asplenia for infectious risk factors, vaccination status, and early signs of infection. Implement evidence-based vaccination schedules and preventive strategies before and after splenectomy. Collaborate with interprofessional healthcare team members to optimize prevention, monitoring, and management of patients with asplenia.

Screen patients with asplenia for infectious risk factors, vaccination status, and early signs of infection. Implement evidence-based vaccination schedules and preventive strategies before and after splenectomy. Collaborate with interprofessional healthcare team members to optimize prevention, monitoring, and management of patients with asplenia. Access free multiple choice questions on this topic.

Asplenia refers to the absence of normal splenic function and may be anatomic or functional secondary to various disease states. The spleen, a major extramedullary lymphoid organ in the left upper quadrant, is typically nonpalpable and averages 10.6 by 5.2 cm, with size varying by sex and race (eg, larger in men and in White individuals than in women or Black individuals).[1] Palpability or radiographic enlargement should prompt evaluation for inherited or acquired causes of splenomegaly. Patients receiving splenic irradiation, particularly 40 Gy or greater, are also at increased risk for developing hypo or asplenia.[2] Functionally, the spleen filters senescent red blood cells, mounts immune responses to infectious pathogens (particularly encapsulated organisms), and supports extramedullary hematopoiesis.[3] The spleen's 2 distinct regions, white pulp and red pulp, mediate these roles: the white pulp generates antigen-specific antibodies, while the red pulp, composed of sinusoids and the cords of Bilroth, filters blood and removes aged cells and circulating microorganisms.[4][5] As the body's largest blood-filtering organ, the spleen plays a central role in the broader lymphatic system, which includes the lymph nodes, thymus, tonsils, and appendix. Asplenia may result from damage to the white pulp, red pulp, or both, and can arise from disease-related injury, infection, or direct toxic insults.[3] Understanding its etiologies and complications is essential as asplenia significantly increases susceptibility to encapsulated bacteria. Infections with Neisseria meningitides or Streptococcal pneumoniae, and other pathogens can rapidly become life-threatening, and asplenic patients have a reported 200-fold higher risk of death from septicemia than individuals with normal splenic function.[6] Numerous case reports describe fatal outcomes, including pneumococcal meningitis, following splenectomy for refractory immune thrombocytopenia.[7]

Infections with Neisseria meningitides or Streptococcal pneumoniae, and other pathogens can rapidly become life-threatening, and asplenic patients have a reported 200-fold higher risk of death from septicemia than individuals with normal splenic function.[6] Numerous case reports describe fatal outcomes, including pneumococcal meningitis, following splenectomy for refractory immune thrombocytopenia.[7] Mortality in invasive infections remains high at approximately 69% in meningitis, 64% in septicemia, and 7% in purpura fulminans.[6] Invasive group A streptococcal infections, including endocarditis with cardiac rupture, have also been reported.[8] Emerging data from the COVID-19 pandemic indicate that aspenic patients experience higher rates of hospitalization, though not necessarily increased mortality.[9] These findings highlight the importance of vigilant monitoring and timely vaccination in this high-risk population.

Asplenia may be congenital, acquired, or functional despite the spleen's anatomic presence. Acquired asplenia most commonly results from trauma or surgical removal. Historically, trauma has been the leading indication for splenectomy.[10] In one retrospective review, the results showed traumatic injury accounted for 41.5% of splenectomies, while hematologic malignancies and cytopenias each accounted for 15.4%.[11] A range of benign and malignant hematologic disorders may necessitate splenectomy, including hereditary spherocytosis, sickle cell disease, thalassemia major or intermedia, refractory immune thrombocytopenia, myeloproliferative disorders such as myelofibrosis with symptomatic splenomegaly, autoimmune hemolytic anemias, lymphoproliferative disorders, and, rarely, thrombotic thrombocytopenic purpura.[4] Congenital asplenia may occur in isolation or as part of rare syndromes such as Ivemark syndrome, a form of heterotaxy characterized by splenic hypoplasia or absence, complex congenital heart defects, and abnormal thoracoabdominal organ arrangement.[12] Beyond the common causes of asplenia, numerous additional etiologies have been reported across multiple organ systems. These include the following: Gastrointestinal disorders: celiac disease, Whipple disease, and inflammatory bowel diseases [13] Infectious diseases: HIV and other acquired immunodeficiency states [13] Hepatic disorders: Alcoholic liver disease, cirrhosis, portal hypertension, and hepatorenal syndrome [13] Rheumatologic conditions: Systemic lupus erythematosus [4] Chronic graft-versus-host disease: Rare cases reported [14]

Following splenectomy, the risk of vascular thrombosis varies by underlying disease. Younger individuals face a greater risk of infection, with the highest incidence of complications occurring within the first 2 postoperative years.[15] The epidemiology of asplenia varies by underlying etiology. Nearly all patients with sickle cell anemia (hemoglobin [Hgb] SS disease) develop functional asplenia and are at high risk for overwhelming infection.[13][16] Other hemoglobinopathies, such as HgbSC disease, may also lead to splenomegaly, splenectomy, or progressive splenic dysfunction. Additional conditions associated with reduced splenic function include celiac disease (prevalence 33%–76%), Whipple disease (47%), and alcoholic liver disease (37%–100%).[13] Remark syndrome is rare, occurring in approximately 1 in 10,000 to 40,000 cases.[6]

The pathophysiology of asplenia varies with the underlying disease and comorbid conditions. In many benign hematologic disorders, functional asplenia results from recurrent hypersequestration of RBCs, causing splenic enlargement followed by progressive atrophy. Severe atrophy, or autosplenectomy, is characteristic of sickle cell anemia, particularly in patients with HgbSS disease.[13] In contrast, hematologic malignancies may lead to asplenia through direct infiltration of malignant cells into the splenic parenchyma. Several gastrointestinal disorders can lead to functional asplenia. In hepatic dysfunction or failure, disruption of normal hepatic circulation, such as in portal hypertension, may contribute to splenic hypofunction. Alcohol use can also exert direct toxic effects on splenic tissue.[13] In celiac disease, excessive lymphocyte loss through the inflamed intestinal mucosa leads to reticuloendothelial atrophy and subsequent functional asplenia.[13]

Histologically, splenic atrophy is characterized by degeneration of the white pulp, including reduced periarteriolar lymphatic sheaths, follicles, germinal centers, and marginal zones. The red pulp shows diminished hematopoietic elements. Cytologic markers of asplenia include Howell–Jolly bodies and pitted RBCs on peripheral smear, along with nonspecific findings such as monocytosis, lymphocytosis, or thrombocytosis.[17] The presence of “pocked” or highly vacuolated erythrocytes in high proportions, sometimes exceeding 80%, is considered a highly sensitive indicator of hypo- or asplenia.[18]

Patients with asplenia can be asymptomatic or present with nonspecific symptoms such as malaise, fatigue, fever, or encephalopathy. On physical examination, a normal spleen is not palpable, and in functional asplenia or autosplenectomy, chronic atrophy typically renders the spleen nonpalpable. When enlarged, it can generally be palpated below the costophrenic border on deep inspiration. Clinical presentations often reflect underlying infection. Severe infections with S pneumoniae, Haemophilus influenzae, and N meningitides are most common, and assessment for nuchal rigidity is essential in febrile individuals. Pneumococcal meningitis is notably more severe in this population, with mortality up to 4 times higher and poor outcomes more than 6 times more likely compared with other bacterial meningitides.[7] Aslepnic patients are also at increased risk for infections such as malaria (Plasmodium falciparum), babesiosis, and Capnocytophaga canimorsus.[19][20]

Peripheral blood smear evaluation may reveal Howell-Jolly bodies, nuclear remnants within RBCs, which are a key clue to congenital or functional asplenia. To confirm clinical findings and assess splenic anatomy, multiple imaging modalities may be used, including abdominal ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and splenic scintigraphy.[6] Ultrasound, CT, and MRI can further characterize congenital or vascular abnormalities. Spleen scintigraphy, which uses a technetium-99m–labeled radiocolloid taken up by splenic tissue, demonstrates absent uptake in patients with asplenia.

Patients with asplenia are at markedly increased risk for severe bacterial infections, particularly those caused by encapsulated organisms. Accordingly, preventive strategies, early detection, and prompt management have become central to care in this population. S pneumoniae is the most common pathogen, with one study reporting infection rates of up to 87% in patients with asplenia.[21] To reduce morbidity, all patients with asplenia, regardless of the cause, should receive appropriate vaccinations against encapsulated bacteria. Immunization is recommended before and after splenectomy, and individuals with functional asplenia or autosplenectomy should follow the same comprehensive vaccination schedule. Before planned splenectomy, patients should receive the pneumococcal conjugate vaccine (PCV13) at least 8 weeks prior, followed by the pneumococcal polysaccharide vaccine (PPSV23), the Haemophilus influenzae type b conjugate vaccine (Hib), and the quadrivalent meningococcal conjugate vaccine at least 14 days before surgery.[7] Continued booster doses for pneumococcal and meningococcal vaccines are also recommended.[19] Vaccination should continue in the postoperative period. Five years after splenectomy, patients should receive a repeat dose of PPSV-23, with an additional dose recommended at age 65. The meningococcal conjugate vaccine should be administered every 5 years.[22] In patients with acquired immunodeficiency, assessment of vaccine titers may help determine immune status. Annual influenza vaccination is also advised. Prophylactic penicillin is recommended for children with asplenia, such as those with sickle cell disease, until age 5, but is not routinely recommended for adults.[23] Adults with asplenia should, however, have immediate access to antibiotics from their healthcare provider, as delays in treatment can be life-threatening.[7] Individuals aged 50 and older should receive the recombinant zoster vaccine, and COVID-19 vaccination is strongly recommended.[9][19]

Prophylactic penicillin is recommended for children with asplenia, such as those with sickle cell disease, until age 5, but is not routinely recommended for adults.[23] Adults with asplenia should, however, have immediate access to antibiotics from their healthcare provider, as delays in treatment can be life-threatening.[7] Individuals aged 50 and older should receive the recombinant zoster vaccine, and COVID-19 vaccination is strongly recommended.[9][19] Overwhelming post-splenectomy infection occurs most frequently in children younger than 16 years, reflecting immune immaturity.[13] Patients with asplenia presenting with signs of infection should receive immediate broad-spectrum antibiotics pending identification of the causative microorganism. According to the Surviving Sepsis Campaign guidelines, antimicrobial therapy should be initiated within 1 hour of suspected sepsis to reduce adverse outcomes.[23] Prompt intravenous fluid resuscitation is essential, with escalation to vasopressors for hemodynamic support as needed. Mechanical ventilation may be required in cases of respiratory failure. Emerging resistance to beta-lactam and macrolide antibiotics has been reported.[16] Despite optimal management, mortality from overwhelming sepsis in asplenic patients remains high, approaching 40% to 50%.

The differential diagnosis of asplenia includes hyposplenia, which shares many clinical features and may precede progressive functional decline or autosplenectomy. Unlike asplenia, hyposplenia may be reversible with treatment of the underlying condition. For example, in patients with celiac disease, improved disease control can restore normal splenic function.

The prognosis of asplenia is poor if unrecognized, as affected patients face a substantially increased risk of severe infection in the absence of appropriate vaccination. Vaccination and, in selected cases, antibiotic prophylaxis are key management strategies, particularly for individuals with asplenia and concomitant immunodeficiency.[13] Patients who remain unimmunized are at high risk of severe bacterial infection, sepsis, septic shock, and death. Fatal infections may occur despite optimal medical care. Accordingly, patient and caregiver education is essential. In patients with asplenia, early recognition of infection and prompt communication with healthcare providers are critical, as delays in treatment can be life-threatening.[16]

The most common and serious complication in patients with asplenia is overwhelming post-splenectomy infection (OPSI). Asplenia confers increased susceptibility to infections caused by encapsulated organisms, most notably S pneumoniae. OPSI is characterized by rapid-onset, massive bacteremia, often without an identifiable primary source, a brief prodromal phase, and progression to septic shock that may be complicated by disseminated intravascular coagulation. Mortality rates of 60% to 70% have been reported in inadequately treated cases.[13] In the normal spleen, the red pulp filters blood and removes senescent erythrocytes through phagocytosis, providing defense against intraerythrocytic parasites.[24] Loss of this function predisposes patients with asplenia to parasitic infections, including babesiosis and malaria. The white pulp contains organized T- and B-cell compartments that support adaptive immunity and antibody production, including a significant population of memory B cells, which are essential for humoral immune responses.[24] The absence of memory B cells in individuals with asplenia contributes to more severe infections. Additionally, the spleen serves as a reservoir for noncirculating, undifferentiated monocytes within the red pulp, which are mobilized in response to myocardial injury and contribute to tissue repair. Splenectomy eliminates this monocyte reserve, potentially impairing wound healing.[25] Beyond its immunologic functions, the spleen contributes to vascular homeostasis, and asplenia has been associated with thrombotic complications. Vascular events have been reported most frequently in patients with hematologic disorders such as beta thalassemia, in whom thrombotic events occur in approximately 1.65%.[26] Increased rates of stroke, myocardial infarction, and coronary artery disease have also been observed.[27] These complications are thought to arise from chronic inflammation and endothelial dysfunction, leading to platelet activation and thrombosis.[24]

Beyond its immunologic functions, the spleen contributes to vascular homeostasis, and asplenia has been associated with thrombotic complications. Vascular events have been reported most frequently in patients with hematologic disorders such as beta thalassemia, in whom thrombotic events occur in approximately 1.65%.[26] Increased rates of stroke, myocardial infarction, and coronary artery disease have also been observed.[27] These complications are thought to arise from chronic inflammation and endothelial dysfunction, leading to platelet activation and thrombosis.[24] Asplenia is also associated with pulmonary hypertension, likely related to an increased thrombotic risk. The reported incidence ranges from 8% to 11.5% and is substantially higher in patients with hemoglobinopathies, reaching up to 30% in those with sickle cell disease or beta thalassemia.[24][28] Additional severe complications include adrenal hemorrhage, known as Waterhouse–Friderichsen syndrome, and purpura fulminans.[29] Both conditions require a high index of clinical suspicion, as early recognition and prompt management are essential to reduce morbidity and mortality.

The primary goal in caring for patients with asplenia is comprehensive preventive care. Patients should be educated about the heightened risk of severe infection, which may result in premature death, and the importance of adherence to preventive strategies. Vaccination remains central to risk reduction, with patients advised to stay up to date on pneumococcal, meningococcal, Hib, and influenza immunizations. Prophylactic antibiotics, most commonly penicillin or amoxicillin, are recommended in selected clinical settings, particularly for young children with asplenia and immunocompromised adults.[7] Patient education on appropriate antibiotic use is essential. Additionally, individuals with asplenia traveling to regions endemic for intraerythrocytic parasites, such as malaria or babesiosis, should receive counseling on the increased risk of infection, with region-specific antiparasitic prophylaxis considered when appropriate.

Key facts to keep in mind about asplenia include the following: Absence of normal splenic function can be anatomic or functional. Common causes include splenectomy, trauma, congenital absence, and functional loss in sickle cell disease. Nearly all patients with sickle cell anemia develop functional asplenia. The spleen removes encapsulated bacteria and senescent RBCs. Loss of splenic function increases the risk of overwhelming post-splenectomy infection. The most common pathogens are S pneumoniae, Hib, and N meningitidis. Other vital organisms include Capnocytophaga canimorsus, Babesia, Plasmodium falciparum, and Salmonella. Fever in patients with asplenia is a medical emergency. Overwhelming post-splenectomy infection has a rapid onset and high mortality. Peripheral smear may show Howell-Jolly bodies and pitted RBCs. Thrombocytosis and monocytosis may be present. Vaccinations are critical and include pneumococcal, meningococcal, Hib, and annual influenza vaccines. Vaccines should be given before a splenectomy when possible. Booster doses are required for pneumococcal and meningococcal vaccines. Children with asplenia receive prophylactic penicillin until age 5. Adults should have immediate access to antibiotics for febrile illness. Antibiotics should be started within 1 hour if sepsis is suspected. Patients with asplenia are at increased risk of parasitic infections such as malaria and babesiosis. Noninfectious complications include thrombosis, pulmonary hypertension, stroke, and myocardial infarction. The risk of infection is highest in children and during the first 2 years after splenectomy.

The most common indications for splenectomy are traumatic, neoplastic, and hematologic conditions.[30] Given the spleen’s critical role in immune function, surgical management has increasingly emphasized splenic preservation in trauma patients. Nonoperative approaches, including angiographic embolization, are now more frequently employed and have contributed to a decline in surgical splenectomy for splenic injury.[31] Recognition of the spleen as a vital organ underscores its importance, as maintaining splenic function reduces the risk of infectious and thromboembolic complications. In patients with hematologic disorders who develop functional asplenia or undergo autosplenectomy, vaccination status should remain up to date and be reassessed at each follow-up visit. Ongoing patient education and clear communication are essential components of optimal care.