P.S. - This Not-So-Sick Looking Patient May Be Septic

The Gist:  Exercise caution in febrile asplenic patients because these folks are at an increased risk of post-splenectomy sepsis (PSS), particular encapsulated organisms and red blood cell (RBC)-based parasites.  Sepsis may present differently in these patients - maintain a high index of suspicion.  For a good case-based podcast review, check out the Splenectomy-Sepsis lecture (Episode 26) from UC-Irvine.  

This isn't crazily, common.  Do I really need to care?
Somewhere between a hematology lecture and my surgical rotation, I became enraptured with the spleen.  A typically unassuming organ, the spleen bridges innate immunity with adaptive immunity, houses 30% of RBCs, and cleanses the dregs of our cells.  

• It turns out that despite the fact that patients are benefited by splenectomy, there are very important, preventable complications from our patients.  PSS is likely the most feared of these complications and is decreasing in frequency due to the utilization of prophylactic vaccines.  However, these patients become sick very quickly and may present with an atypical picture.  Furthermore, this may occur in young, otherwise healthy looking folks who can compensate (aka not your typical sepsis picture). 
• Variable numbers of  asplenic patients aren't aware that they're at increased risk for infection - including up to 84% in a 2000 publication (2) and 50% in a 2008 paper (3).  Thus, the patient may not disclose that they've had a splenectomy.  In these patients, history can be crucial.
• Check for splenectomy scar
• Ask about travel, tick exposure, vaccination status, sick contacts.

Clues that a patient may be asplenic:

• Hemoglobinopathy (sickle cell anemia, thalassemia) 
• Left sided abdominal surgical scar due to:
• Hemolytic anemia (e.g. hereditary spherocytosis)
• Trauma. Note:  S/P blunt trauma - sepsis may be less common due to the presence of accessory spleens
• Assorted other causes: thrombocytopenia, hypersplenism, malignancy

So, how do they present?

• PSS is most common in the first few post-splenectomy years but can occur for decades after splenectomy.
• Fever and rigors are the most common signs.  
• Headache and gastrointestinal complaints (diarrhea) can be manifestations of severe pneumooccal infections and may be mistaken for gastroenteritis
• Disseminated Intravascular Coagulation

Suspect Organisms

• Encapsulated bacteria (due to the production of IgM memory B cells, specially located within the spleen):   Streptococcus pneumoniae, Haemophilus influenza, and Neisseria meningitidis.  Also,  Capnocytophaga canimorsus from dog bites.
• Parasites:  
• Malaria (Think travel to endemic areas like S.Asia, sub-Saharan Africa, etc)
• Babesiosis - tick borne illness, especially in NY/CT/MA and s/p RBC transfusion 
• Ehrlichiosis - tick borne illness in the Southeast/mid-Atlantic US (1)
• Virus:  Cytomegalovirus

Patients with PSS deteriorate quickly, what should I do?

• If they're septic, naturally follow the sepsis protocol.
• Patient looks sick with a questionable/unknown vaccine history?  Give empiric antibiotics.
• Ceftriaxone Adults: 2 g IV q12 to 24 hours, Children: 50 mg/kg IV q12 hours (1)
• Vancomycin if S.pneumoniae penicillin resistance suspected:  Adults: 1 to 1.5 g IV q12 hours, Children: 30 mg/kg IV q12 hours (1)
• Thinking babesiosis?
• IV clindamycin and oral quinine or IV atovaquone and IV azithromycin
• Have a high index of suspicion for meningitis, so have a low threshold to do an LP if warranted.

Pretty sure my patient really does just have the flu/gastroenteritis/etc, what do I do now?

• It's recommended that asplenic patients receive prophylactic antibiotics at the onset of febrile illnesses, although this recommendation is not evidenced based.  For example, British guidelines recommend  Amoxicillin prophylaxis through adulthood.  
• Those with adequate primary care physician coverage receive vaccines against pneumococcus, meningococcus, and haemophilus but even these are not fool proof (interestingly, over-vaccination with pneumococcal vaccine actually has a counterproductive effect on the immune system).
• Educate. Even if they have something minor, let them know when to return to the doctor.

References:

1.  Pasternack, M.  Clinical features and management of sepsis in the asplenic patient.  

2.  Di Sabatino A; Carsetti R; Corazza, G. Post-splenectomy and hyposplenic states. The Lancet378. 9785 (Jul 2-Jul 8, 2011): 86-97.

3.  Wilkes, A, Wills, V, Smith S.  Patient knowledge of the risk of post-splenectomy sepsis.  ANZ Journal of Surgery. Volume 78, Issue 10, pages 867-870, October 2008.