Asplenia

The spleen is primarily responsible for the elimination of damaged erythrocytes and plays a central role in the opsonization and removal of encapsulated organisms from the bloodstream. Functional asplenia is the absence of normal spleen function and anatomical asplenia is the absence of the spleen itself. Anatomical asplenia is most commonly due to elective or emergency splenectomy, while functional asplenia is due to conditions that result in the loss of splenic function (e.g., multiple infarctions in sickle cell disease). Asplenia typically manifests with Howell-Jolly bodies on peripheral blood smears as well as neutrophilia and thrombocytosis. Patients with asplenia have a lifelong risk of fulminant, life-threatening infections. The prognosis for asplenic sepsis and overwhelming postsplenectomy sepsis is very poor. Preventive measures are vital and include immunization against encapsulated bacteria and early empiric antibiotic treatment for fever. Infections in asplenic or hyposplenic patients can quickly worsen and become an overwhelming postsplenectomy infection (OPSI), which requires immediate empiric antibiotic treatment, supportive care, and hospital admission.

• Acquired asplenia ^[1]
  • Anatomic asplenia: due to splenectomy, which may be indicated in
    • Thrombocytopenia (e.g., refractory idiopathic thrombocytopenic purpura)
    • Severe hemolytic anemias (e.g., spherocytosis)
    • Splenic rupture (e.g., from blunt abdominal trauma)
    • Hypersplenism with splenomegaly (See “Pathophysiology” in “Splenomegaly”)
  • Functional asplenia
    • Autosplenectomy: sickle cell anemia
    • Splenic infarction (splenic artery thrombosis)
    • Tumor infiltration
• Congenital asplenia: very rare ^[1]
  • Associated with other congenital disorders (e.g., congenital heart disease)
  • Isolated congenital asplenia affects 1:600,000 births.

Laboratory studies^[1][2]

• Peripheral blood smear
  • Pitted red blood cell count (criterion standard): limited availability
  • Howell-Jolly bodies
  • Target cells
• Complete blood count
  • Leukocytosis ^[3]
  • Reactive thrombocytosis: usually for the first weeks to months after splenectomy ^[4]

The lack of Howell-Jolly bodies in asplenic patients suggests an accessory spleen.

Imaging ^[1]

• Typically used as confirmatory testing for suspected anatomical asplenia (e.g., congenital asplenia) or other abnormalities (e.g., accessory spleen)
• Modalities: abdominal ultrasound, CT, MRI

Infection prevention

Immunization ^[1][5][6]

Patients with asplenia have more vaccination requirements compared to the general population.

• Recommended vaccines: Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b
  • S. pneumoniae vaccines: Pneumococcal conjugate and pneumococcal polysaccharide vaccines may be necessary (see "Immunization schedule by medical indication").
  • Meningococcal vaccines: Meningococcal conjugate (quadrivalent) and meningococcal B vaccines may be necessary (see "Immunization schedule by medical indication").
  • Hib vaccine: Dosing varies (see "Immunization schedule by medical indication").
• Timing of vaccination
  • Elective splenectomy: completion of vaccination course at least 14 days prior to the procedure
  • Emergency splenectomy: at least 14 days after the procedure
  • Functional asplenia: as soon as possible
• Consider the following annually:
  • Inactivated influenza vaccination
  • COVID vaccination ^[1]
• Consider daily antibiotic prophylaxis (e.g., with oral penicillin or amoxicillin) in all patients with asplenia.
  • There is limited data on the optimal duration of prophylaxis; some experts recommend the following:
    • Asplenic children: until at least 5 years of age
    • Following splenectomy: children > 5 years of age and adults for at least 1 year
  • Lifelong prophylaxis is recommended for patients who remain immunocompromised or have recovered from an episode of sepsis.
• Provide patients with an emergency oral antibiotic to be taken immediately in case of fever, e.g., amoxicillin/clavulanate (off-label). ^[7]
• Consider prophylactic amoxicillin for patients undergoing sinus surgery or airway procedures. ^[7]

Patient education ^[1][7]

• Closely monitor for clinical features of sepsis (e.g., fever) or nonspecific viral symptoms.
• Take emergency antibiotics and present to the emergency department immediately if symptoms arise.
• Consider carrying an identification card, bracelet, or necklace to inform providers that they have asplenia.
• Avoid dog and tick bites.
• Exercise caution when traveling to malaria-endemic areas.

Thrombosis prevention

• Indication: severe reactive thrombocytosis after splenectomy and risk factors for thrombosis (e.g., malignancy)
• Treatment
  • Low-dose heparin for at least 4 weeks
  • Optionally, acetylsalicylic acid (100 mg daily) for one year

• Immediately postsplenectomy: See "Postoperative complications."
• Increased risk of life-threatening infections and sepsis (see "Overwhelming postsplenectomy infection") that can continue for over 40 years after splenectomy^[1]
• Arterial and/or venous thrombosis
• Pulmonary hypertension

We list the most important complications. The selection is not exhaustive.

Background ^[2][8]

• Definition: a bacterial infection that develops into fulminant sepsis in individuals with asplenia
• Etiology: : typically infection with encapsulated bacteria (e.g., Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae)
• Epidemiology ^[9]
  • Incidence: 0.13 per 100 person-years among individuals with splenectomy
  • High mortality rates (50–70%)
• Pathophysiology
  • Normally, encapsulated pathogens are opsonized with antibodies and then phagocytosed by specialized macrophages in the spleen.
  • Individuals with asplenia do not have these specialized macrophages, allowing pathogens to spread and cause sepsis.

Asplenic individuals Have No Spleen: H. influenzae, N. meningitidis, and S. pneumonia are the pathogens that most commonly cause asplenic sepsis.

Clinical features ^[2][8][9]

• Patients may initially have nonspecific viral symptoms.
• Rapid deterioration within hours
• Isolated fever
• Signs of sepsis
• Signs of meningitis
• Signs of DIC
• Signs of acute respiratory distress syndrome

Initial management ^[2][8][9]

• Perform ABCDE survey.
• In patients without a known history of asplenia, check for indicators of possible asplenia (e.g., surgical scars, collateral history, rapid deterioration).
• Make a clinical diagnosis of OPSI.
• Obtain supportive diagnostics to assess for multisystem involvement and guide treatment.
• Initiate sepsis stabilization and treatment without delay.
  • Adults: See "Hour-1 bundle for sepsis."
  • Children: See "Hour-1 bundle for children with sepsis."
• Admit to hospital and consult critical care.

Maintain high suspicion for OPSI, as patients often initially present with nonspecific symptoms, and there is a high risk of misdiagnosis. ^[2]

Asplenic patients with fever require immediate empiric antibiotic therapy regardless of whether they have other symptoms.

Diagnostics ^[2][8][9]

• OPSI is a clinical diagnosis; maintain a high level of suspicion in asplenic patients with fever.
• Laboratory studies: to assess for multisystem involvement and guide treatment
  • Diagnostics for sepsis, including urinalysis, urine cultures, and blood cultures
  • Liver chemistries
  • Coagulation studies
• Chest x-ray to assess for pneumonia
• Consider diagnostics to confirm asplenia (e.g., peripheral blood smear, abdominal ultrasound) as indicated.

Ongoing management ^[2][8][9]

• Management of sepsis in adults
  • IV fluid resuscitation
  • Vasopressors for septic shock as indicated
  • Empiric antibiotic therapy for adults, e.g.:
    • Vancomycin ^[10]
    • PLUS ceftriaxone ^[11]
• Management of sepsis in children
  • Empiric antibiotic therapy for children with OPSI
    • Vancomycin (off-label) ^[12]
    • PLUS ceftriaxone (off-label) ^[12]
  • Fluid resuscitation for children with sepsis
• Consider the following if indicated:
  • Corticosteroids for suspected meningitis
  • Hydrocortisone for suspected adrenal insufficiency

Disposition

• All patients with asplenia should be admitted for further care. ^[13]
• Consider critical care admission for patients who require vasopressors, have signs of DIC, or otherwise require close monitoring.