Splenic disorders, splenectomy and asplenia

• The spleen filters blood, clears damaged red cells and, most importantly for patient survival, responds to encapsulated bacteria. Losing splenic function is therefore not a minor issue.
• Asplenia (no working spleen) or hyposplenism (reduced function) can be surgical, congenital, or caused by disease such as sickle cell disease, coeliac disease or cirrhosis.
• The body's most feared consequence is overwhelming infection with encapsulated organisms, especially Streptococcus pneumoniae, with mortality reported as high as 50% without prevention. ^[3]
• Protection rests on three things together: vaccination (pneumococcal, meningococcal, Haemophilus influenzae type b, annual influenza), daily antibiotic prophylaxis in higher-risk periods, and education so that fever leads to immediate antibiotics and emergency care.
• Splenic injury is graded by the AAST 2018 Organ Injury Scale (grades 1 to 5). Haemodynamic status, not grade alone, decides whether the patient is observed, embolised, or taken to the operating theatre. ^[1][2]

By the end of this page you should be able to:

1. Explain what the spleen does and how splenic function is lost.
2. Recognise the causes of hyposplenism and asplenia, and identify them on a blood film.
3. State the main indications for splenectomy, and the timing of vaccination around elective surgery.
4. Grade a splenic injury on CT using the AAST 2018 scale and apply a trauma management algorithm.
5. Describe overwhelming post-splenectomy infection, its lifelong risk and emergency management.
6. Outline the current BSH and CDC/ACIP recommendations for vaccination and antibiotic prophylaxis in asplenic patients.
7. Adapt prevention to children, adults, pregnancy and low-resource settings.

The spleen has two working parts. The red pulp filters blood: macrophages there remove old or damaged red cells and phagocytose opsonised bacteria. The white pulp contains T cells, macrophages and naive B cells; when an antigen arrives, antigen-presenting cells activate T cells, which drive B cells to become plasma cells producing first IgM then IgG. That B-cell response is the defence against encapsulated bacteria. ^[3] Because the spleen also clears infected or damaged red cells, it protects against intra-erythrocytic parasites such as malaria and Babesia. ^[3]

A person can lose splenic function in two ways. Anatomic asplenia means the spleen is absent or removed (surgery, congenital absence, auto-infarction in sickle cell disease). Functional hyposplenism (also called functional asplenia when severe) means a spleen is present but does not work: red pulp macrophage function or white pulp immune response is impaired. ^[8] The clinical risk is the same in both, which is why the term asplenia is often used for either.

Hyposplenism is under-diagnosed. A normal-sized or even enlarged spleen can be non-functional (for example in coeliac disease or cirrhosis). ^[11]

Anatomic (surgical or congenital):

• Trauma: splenectomy after splenic injury is the most common cause in young adults.
• Therapeutic splenectomy: immune thrombocytopenia, autoimmune haemolytic anaemia, hereditary spherocytosis, thalassaemia, portal hypertension/splenomegaly, splenic cysts or tumours, hypersplenism. ^[10]
• Congenital asplenia syndromes: isolated congenital asplenia, heterotaxy (ivemark) syndrome.
• Auto-splenectomy: repeated splenic infarction in sickle cell disease leaves a fibrotic remnant.

Functional hyposplenism:

• Haematological: sickle cell disease and other haemoglobinopathies, thalassaemia, essential thrombocythaemia.
• Immunological: antiphospholipid syndrome, severe coeliac disease (probably the most common cause with liver disease), inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus.
• Liver disease: cirrhosis with portal hypertension; acute alcohol misuse can also impair splenic function briefly.
• Oncology: chronic graft-versus-host disease after allogeneic haematopoietic stem cell transplant, lymphoma infiltration, splenic irradiation.
• Vascular: splenic artery or vein thrombosis, splenic infarct.
• Infiltrative: amyloidosis, sarcoidosis, thorium dioxide (historical). ^[11][8]

Howell-Jolly bodies (small round nuclear remnants in red cells) on a peripheral blood film are the classic clue. Their presence indicates a degree of hyposplenism severe enough to matter for overwhelming post-splenectomy sepsis. ^[11] A full blood count often shows mild thrombocytosis and leucocytosis; pitted red cells and target cells may be seen. A liver-spleen radionuclide scan shows absent or reduced splenic uptake, and can distinguish a small functioning remnant from none. ^[11]

Note that Howell-Jolly bodies can be absent in mild hyposplenism and can appear in other conditions (myelodysplasia, haemolysis). If the blood film is equivocal but the clinical context suggests hyposplenism, a liver-spleen scan (or labelled heat-damaged red cell scan, the most sensitive test) confirms it. ^[11]

These fall into trauma, haematological/oncological disease, and other conditions. Many historical indications have shrunk because medical therapy has improved.

Trauma:

• Penetrating splenic injury with haemodynamic instability, or blunt injury that cannot be managed non-operatively and is not suitable for angioembolisation.
• Non-operative management (observation with or without splenic artery embolisation) is now the standard for most blunt splenic injuries in stable patients. ^[1][2]

Haematological and immunological (elective):

• Immune thrombocytopenia refractory to medical therapy.
• Autoimmune haemolytic anaemia refractory to medical therapy.
• Hereditary spherocytosis and other haemolytic anaemias with significant symptoms.
• Thalassaemia major with hypersplenism.
• Splenomegaly causing pressure symptoms or severe hypersplenism (cytopenias) not controlled otherwise.

Oncological and infiltrative:

• Staging or treatment of lymphoma (now uncommon; splenectomy for diagnosis is rare).
• Hairy cell leukaemia (used in the past; now mainly medical therapy).
• Splenic primary tumours or cysts; massive splenomegaly causing symptoms.
• Hypersplenism from portal hypertension (usually shunt or transplant preferred).

Other:

• Splenic artery aneurysm.
• Splenic abscess or infarct not responding.
• Congenital or functional asplenia does not need surgery; it needs the preventive package below.

Partial splenectomy is used when possible, especially in children and in haematological disease, to preserve immunological function while controlling haemolysis. Evidence that partial splenectomy changes the benefit-risk balance compared with total splenectomy is limited; the choice is individualised. ^[3]

Damage is graded by imaging (CT, and angiography), operative findings, or pathology, whichever gives the highest grade. The 2018 revision added vascular injury (pseudoaneurysm, arteriovenous fistula, active bleeding) to the scale. ^[1] Vascular imaging in both arterial and portal venous phases is recommended to detect these injuries. ^[1]

If several grade I or II injuries are present, advance one grade, up to grade III. ^[1]

Haemodynamic status decides everything. The WSES classification combines the AAST grade with stability: minor (stable grades I-II), moderate (stable grades III-V), severe (unstable, any grade). ^[2] Low-grade injuries in stable patients are managed non-operatively; high-grade stable injuries may need splenic artery embolisation; unstable patients go to theatre. ^[2]

Children with blunt splenic injury are managed non-operatively whenever possible, in dedicated paediatric trauma centres. ^[2]

Two practical points follow from the guidelines. Angioembolisation is often attempted before splenectomy in stable patients with high-grade injuries, because preserving splenic tissue preserves immune function. ^[2] VTE prophylaxis is generally withheld initially in high-grade injuries, then started once bleeding has stopped. ^[2]

Splenectomy may be open or laparoscopic. The laparoscopic approach is now standard for elective disease; open surgery is used in trauma and when massive splenomegaly makes laparoscopy unsafe. ^[10]

Perioperative points:

• Vaccinate before surgery when it is planned: ideally at least 2 weeks before splenectomy, because immunogenicity is reduced after splenectomy or during chemotherapy. ^{[11] [3]}
• If surgery is emergent and vaccines were not given, start the course about 2 weeks after splenectomy. ^[3]
• Prophylactic antibiotics around the operation follow local surgical prophylaxis guidance.
• Asplenic patients who need sinus or airway surgery later should have presumptive antibiotics before the procedure. ^[3]

Surgical complications include reactive thrombocytosis and a hypercoagulable state with risk of portal and splenic vein thrombosis, subphrenic abscess, pancreatic fistula when the tail of the pancreas is injured, and injury to the pancreas or stomach.

Overwhelming post-splenectomy infection (OPSI) is the syndrome of rapid, often fulminant sepsis caused by encapsulated bacteria in a person without splenic function. S. pneumoniae is the most common cause; Neisseria meningitidis, H. influenzae type b, Capnocytophaga canimorsus (from dog bites), Babesia and Plasmodia also occur. ^[3][8] Mortality without prevention has been reported as high as 50%. ^[3]

Risk magnitude:

• Children after splenectomy: about 1.8 to 3 cases of sepsis per 100 person-years, highest in children under 3 years. ^[3]
• Adults: about 11 to 14 cases per 100 person-years, higher again in adults aged 60 or over. ^[3]
• The risk is highest in the first 1 to 3 years after splenectomy but is lifelong; infection has been reported decades later, up to 50 years after surgery. ^[3]
• Underlying disease matters: thalassaemia, sickle cell disease and malignancy as the reason for splenectomy carry higher sepsis risk. ^[3]
• Partial splenectomy reduces but may not remove this risk.

Presentation is fever, chills, rigors, vomiting or diarrhoea that can progress within hours to sepsis, shock and purpura fulminans. ^[3] Any febrile asplenic patient should be treated as OPSI until proven otherwise.

This is the core of long-term care. Three standards underpin it: the British Society for Haematology guideline of 2024, ^[4] current CDC/ACIP guidance, ^[5][6] and the Apply-to-your-setting principle that local epidemiology and antimicrobial resistance patterns matter. ^[4]

Vaccinate as early as possible, ideally at least 2 weeks before elective splenectomy; if that window is missed, start about 2 weeks after surgery. ^[11][3] Conjugate vaccines are preferred for priming because they give higher opsonophagocytic antibody titres and polysaccharide vaccines can cause hyporesponsiveness. ^[3]

The BSH 2024 guideline states that immunisations should include pneumococcus, meningococcus and influenza, and that Hib is part of the infant schedule and is no longer required for older hyposplenic patients. ^[4] The CDC/ACIP list for asplenia adds pneumococcal, meningococcal, Hib and influenza. ^[5]

Important timing rules:

• MenACWY-D and PCV13 must not be given together in asplenia: give PCV13 first, then MenACWY-D 4 weeks later. ^[7]
• If MenACWY-CRM (Menveo) is used, simultaneous administration with PCV13 and Tdap is acceptable. ^[7]
• MenB products are not interchangeable within a series; use one brand throughout. ^[3]
• Add a conjugate vaccine before the polysaccharide one whenever possible. ^[3]

The common regimens and the duration controversy are summarised below. Evidence for prophylaxis comes mainly from the sickle cell literature, where penicillin reduced pneumococcal infection by 50 to 63% in children aged 5 years or under. ^[3] Failures of both vaccination and prophylaxis are well documented. ^[3]

Duration:

• US and Australian practice: 1 to 3 years after splenectomy, or until age 5 in children, and lifelong in immunocompromised patients or after an episode of sepsis. ^[3]
• UK (BSH) practice: prophylaxis for children under 16, adults over 50, and patients with inadequate serological response to pneumococcal vaccination; decisions are individualised. ^[3][4]
• BSH 2024 notes that antibiotic prophylaxis remains key because vaccines do not cover all pneumococcal serotypes or all meningococcal strains. ^[4]

• Give every asplenic patient a supply of antibiotics to take at the first sign of fever, then attend the emergency department immediately. ^[3]
• Teach patients and families that fever, chills, rigors, vomiting or diarrhoea can progress within hours to shock. ^[3]
• Recommend a medical alert bracelet or card stating asplenia, allergies, current prophylaxis and vaccination history, and emergency contact. ^[3][11]
• Label the patient record. Tell new clinicians and dentists. ^[11]
• Preprocedural prophylaxis for sinus or airway procedures: amoxicillin 2 g 30-60 minutes before the procedure in adults (also corroborated by dental endocarditis prophylaxis regimens; amoxicillin 2 g 30-60 minutes before). ^[3]
• Animal bites (especially dogs): Capnocytophaga and Pasteurella risk; give presumptive antibiotics even if asymptomatic. ^[3][9]
• Travellers: counsel about malaria and babesiosis prophylaxis and awareness; mosquito and tick precautions. ^[3][8]
• Annual influenza vaccination of patient and household members reduces secondary bacterial infection. ^[3]

Dedicated teams or clinics for patients with asplenia improve vaccination rates and reduce sepsis; quality of care is often poor without them. ^[3] Spleen registries (as in Australia) reduce infection. ^[3][8]

• Thrombosis: portal and splenic vein thrombosis after splenectomy, especially with myeloproliferative disease or thalassaemia; reactive thrombocytosis.
• Pulmonary hypertension has been reported in asplenic patients. ^[3]
• VTE risk is also higher in asplenic patients with haemoglobinopathies. ^[8]
• Thromboprophylaxis policies after splenic injury are covered by trauma guidelines. ^[2]

Children:

• Highest sepsis incidence, especially under 3 years; lifelong risk remains but early years are the most dangerous. ^[3]
• Manage conservatively where possible; partial splenectomy preferred when feasible. ^[3][2]
• Follow paediatric vaccine schedules with extra doses as listed. ^[3][5]
• Antibiotic prophylaxis usually continues at least 2 years and often longer. ^[11]

Pregnancy:

• Splenectomy during pregnancy is avoided except for trauma; if unavoidable, vaccinate beforehand if possible.
• Vaccines recommended in pregnancy include inactivated influenza and (where indicated) pneumococcal; live vaccines are avoided.
• Iron and folate support as usual. ^[10]
• Asplenic women are not at increased infection risk in pregnancy per se, but their underlying disease may modify management. ^[11]

Immunocompromised:

• Lifelong antibiotic prophylaxis is advised, and conjugate-based vaccine schedules, because response to polysaccharide vaccines is poor. ^[3]
• Recombinant zoster vaccine is recommended routinely for adults aged 50 or over; asplenia alone does not increase zoster risk. ^[3]

Low-resource settings:

• The preventive package is cheap relative to the cost of OPSI. Check the peripheral blood film (or request it) for Howell-Jolly bodies when hyposplenism is suspected. ^[11]
• PCV, Hib and MenACWY are often available through national immunisation programmes; advocate for their delivery to at-risk patients.
• Oral penicillin prophylaxis and a written emergency plan cost little and save lives.
• In malaria-endemic areas, asplenic patients are at higher risk of severe malaria; strict bite prevention and prompt treatment are essential. ^[8]
• When trauma occurs without CT, clinical judgement and haemodynamic status guide laparotomy, and every attempt should be made to preserve splenic tissue.

• The spleen is the main defence against encapsulated bacteria; losing that function is lifelong and dangerous.
• Asplenia and hyposplenism may be surgical, congenital, haematological, immunological, hepatic or vascular in origin. ^[8][11]
• Howell-Jolly bodies on a blood film are the bedside clue to functional hyposplenism. ^[11]
• Indications for splenectomy have narrowed as medical therapy has improved; trauma with instability, and refractory haematological disease, remain the main ones. ^[10]
• Splenic injuries are graded by the AAST 2018 Organ Injury Scale; haemodynamics, not grade alone, determines management. ^[1][2]
• Non-operative management of blunt splenic trauma is standard for stable patients; embolisation preserves function. ^[2]
• OPSI mortality approaches 50% without prevention, and the risk is highest in the first 1-3 years but lifelong. ^[3]
• Sepsis incidence after splenectomy is about 1.8-3 per 100 person-years in children and 11-14 per 100 person-years in adults, with higher rates in adults aged 60 or over. ^[3]
• Vaccinate at least 2 weeks before elective splenectomy, or 2 weeks after; the package includes PCV13 then PPSV23, MenACWY, MenB, Hib (in children) and annual inactivated influenza. ^[3][5][6]
• BSH 2024 states Hib is part of the infant schedule and not required for older hyposplenic patients; antibiotic prophylaxis is still key. ^[4]
• Daily penicillin or amoxicillin prophylaxis is used for higher-risk periods, with duration varying between 1-3 years (US/Australia) and UK practice for children under 16 and adults over 50. ^[3][4]
• Every patient needs an emergency antibiotic supply, education, and a medical alert marker. ^[3][11]
• Dedicated asplenia services and registries improve outcomes. ^[3][8]
• Partial splenectomy preserves function and is preferred where it achieves the surgical goal. ^[2][3]
• In low-resource settings the blood film, cheap antibiotics and a written plan are the highest-value interventions. ^[11]

Surgical sepsis and intra-abdominal infection; initial trauma assessment and primary survey; thoracic trauma; secondary survey and penetrating trauma; head and spinal injury in trauma; haemolytic anaemias; sickle cell disease; immune thrombocytopenia; vaccines and immunisation in general; anticoagulant and antithrombotic drugs (thromboprophylaxis after injury).