Short gastrics and splenic artery are end arteries

  Splenic vein is posterior and inferior to the splenic artery

  Spleen serves as an antigen-processing center for macrophages

  Is the largest producer of IgM

  85% red pulp – acts as a filter for aged or damaged RBCs

•  Pitting – removal of abnormalities in RBC membrane

•  Howell–Jolly bodies – nuclear remnants

•  Heinz bodies – hemoglobin

•  Culling – removal of less deformable RBCs

  15% white pulp – immunologic function; contains lymphocytes and macrophages

•  Major site of bacterial clearance that lacks preexisting antibodies

•  Site of removal of poorly opsonized bacteria, particles, and cellular debris

•  Antigen processing occurs with interaction between macrophages and helper T cells

  Tuftsin – an opsonin; facilitates phagocytosis → produced in spleen

  Properdin – activates alternate complement pathway → produced in spleen

  Hematopoiesis – occurs in spleen before birth and in conditions such as myeloid dysplasia

  Spleen serves as a reservoir for platelets

  Accessory spleen (20%) – most commonly found at splenic hilum

  Indication for splenectomy – idiopathic thrombocytopenic purpura (ITP) far greater than for thrombotic thrombocytopenic purpura (TTP)

  ITP most common nontraumatic condition requiring splenectomy

IDIOPATHIC THROMBOCYTOPENIC PURPURA (ITP)

  This can occur from many etiologies – drugs, viruses, etc.

  Caused by anti-platelet antibodies (IgG) – bind platelets; results in decreased platelets

  Petechiae, gingival bleeding, bruising, soft tissue ecchymosis

  Spleen is normal

  In children < 10 years, ITP usually resolves spontaneously (avoid splenectomy in children)

  Tx: steroids (primary therapy); gammaglobulin if steroid resistant

  Splenectomy indicated for those who fail steroids removes IgG production and source of phagocytosis; 80% respond after splenectomy

  Give platelets 1 hour before surgery

THROMBOTIC THROMBOCYTOPENIC PURPURA (TTP)

  Associated with medical reactions, infections, inflammation, autoimmune disease

  Loss of platelet inhibition – leads to thrombosis and infarction, profound thrombocytopenia

  Purpura, fever, mental status changes, renal dysfunction, hematuria, hemolytic anemia

  80% respond to medical therapy

  Tx: plasmapheresis (primary); immunosuppression

  Death most commonly due to intracerebral hemorrhage or acute renal failure

  Splenectomy rarely indicated

POST-SPLENECTOMY SEPSIS SYNDROME (PSSS)

  0.1% risk after splenectomy; ↑ risk in children

  S. pneumoniae (#1), H. influenzae, N. meningitidis – most common

  Secondary to specific lack of immunity (immunoglobulin, IgM) to capsulated bacteria

  Highest in patients with splenectomy for hemolytic disorders or malignancy

  Children also have ↑ risk of mortality after developing PSSS

  Try to wait until at least 5 years old before performing splenectomy → allows antibody formation; child can get fully immunized

  Most episodes occur within 2 years of splenectomy

  Children < 10 years should be given prophylactic antibiotics for 6 months (controversial)

  Vaccines needed before splenectomy – Pneumococcus, Meningococcus, H. influenzae

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