High Risk/Low Prevalence: Asplenia

Asplenia is not just prior splenectomy; functional asplenia and hyposplenia carry real risk for overwhelming infection, thrombosis, and pulmonary hypertension. In the ED, the dangerous miss is early sepsis that looks viral at first, especially in patients with sickle cell disease or other chronic conditions that blunt splenic function.

Recognizing Asplenia in the ED

• Anatomic versus functional loss: Asplenia includes surgical absence of the spleen and a present-but-nonfunctioning spleen, with sickle cell disease as the classic functional example by early childhood.
• Hyposplenia disease associations: Reduced splenic function shows up across chronic liver disease, HIV, malignancy, thalassemia, celiac disease, lupus, and other inflammatory disorders, so the risk extends well beyond splenectomy.
• Peripheral smear clues: Howell-Jolly bodies are the classic bedside clue when history is unclear, and characteristic RBC membrane pits also point toward hyposplenism.
• Bedside identification tools: If the patient cannot give the history, ultrasound can confirm presence or absence of a spleen while the smear helps flag impaired function. We get into the practical recognition pitfalls in the episode.

Infection Risk and OPSI

• Encapsulated organism vulnerability: The spleen is the key organ for clearing encapsulated bacteria, making Streptococcus pneumoniae the headline pathogen along with H. influenzae and Neisseria.
• High-stakes infection burden: Asplenic patients have a 2- to 3-fold increase in infection, sepsis, and mortality, and a first infection predicts markedly higher risk of another in the next few years.
• OPSI early presentation: Overwhelming post-splenectomy infection often starts like gastroenteritis or a viral syndrome, then can progress to shock, ARDS, and DIC within hours.
• Sepsis-first treatment mindset: Treat suspected OPSI like neutropenic sepsis or septic shock, with immediate broad-spectrum antibiotics and aggressive resuscitation rather than watchful waiting.
• Steroid consideration in shock: Refractory hypotension in these patients should raise concern for adrenal insufficiency, with stress-dose steroids as a reasonable adjunct when fluids and pressors are not enough.

Prevention and Long-Term Complications

• Core vaccine strategy: Pneumococcal, meningococcal, and Haemophilus influenzae type b vaccination are foundational prevention measures for anatomic and functional asplenia.
• Antibiotic prophylaxis role: Penicillin or amoxicillin is standard prophylaxis after splenectomy, and some high-risk patients need extended or lifelong coverage.
• Standby antibiotic plans: Many patients carry emergency antibiotics for fever, rigors, or chills, a practical detail that matters when symptoms begin far from care. We cover the real-world counseling nuances in the chapter.
• Thrombotic complication burden: Asplenia increases risk of arterial and venous thrombosis, including DVT, PE, stroke, MI, and portal vein thrombosis, especially in the months after splenectomy.
• Pulmonary hypertension signal: Pulmonary hypertension is an underrecognized complication marked by dyspnea, fatigue, chest pain, syncope, or edema, and ED management hinges on avoiding hypoxia, hypotension, and unnecessary intubation.

References:

1. Long B, et al. Complications in the adult asplenic patient: A review for the emergency clinician. Am J Emerg Med. 2021 Jun;44:452-457. PMID: 32247651.