Fiser Chapter 34 SPLEEN Flashcards Preview

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Flashcards in Fiser Chapter 34 SPLEEN Deck (28):
1

Splenic arteries

Splenic and short gastrics (end arteries), left gastroepiploic

2

Splenic vein location

Posterior and inferior to splenic artery
Goes into portal vein

3

Speen function

Reservoir for platelets

Ag-processing center for macrophages

Largest producer of IgM

Red pulp (85%): filter for aged or damaged RBCs

White pulp (15%): immunologic, contains lymphocytes and macrophages

Hematopoiesis before birth and in myeloid dysplasia

4

Red pulp

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

5

White pulp

Immunologic function; contains lymphocytes and macrophages

Major site of bacterial clearance that lacks preexisting Abs

Site of removal of poorly opsonized bacteria, particles, debris

Ag processing occurs with interaction between macrophages and helper T cells

6

Tuftsin

An opsonin that facilitates phagocytosis and is produced in spleen

7

Properdin

Activates alternate complement pathway, produced in spleen

8

Accessory spleen most commonly found where

Splenic hilum
Occurs in 20%

9

Splenectomy indications

Trauma
ITP >> TTP
Hypersplenism
Hereditary spherocytosis
Pyruvate kinase deficiency
G6PD deficiency (sometimes)
Beta thalassemia (if splenomegaly)
Warm antibody-type acquired immune hemolytic anemia
Lymphomas
Splenic sarcoidosis
Felty's syndrome
Splenectomy
Splenic cysts

10

ITP pathophysiology

Anti-platelet IgG binds platelets

Petechiae, gingival bleeding, bruising, soft tissue ecchymosis

Normal spleen

Tx: steroids, gammaglobulin if steroid resistant, splenectomy for those who fail steroids

11

How does splenectomy help ITP?

Removes IgG production and source of phagocytosis

Give platelets 1 hour before surgery

80% response; Avoid splenectomy in children < 10 years, will usually resolve spontaneously; At least wait until 5 so they have Ab's

12

TTP pathophysiology

Loss of platelet inhibition leads to thrombosis and infarction -> profound thrombocytopenia

Purpura, fever, AMS, renal dysfunction, hematuria, hemolytic anemia

Tx: Plasmapheresis; immunosuppression; 80% respond to medical tx; splenectomy RARELY indicated

Death from intracerebral hemorrhage or ARF

13

Risk of post-splenectomy sepsis syndrome

Most episodes occur within 2 years after splenectomy
0.1%
Children have higher risk and mortality
Higher in hemolytic disorders or malignancy

14

Post-splenectomy sepsis syndrome bacteria

SHiN: S pneumonia, H influenza, N meningitides

15

Post-splenectomy sepsis syndrome pathophysiology

Lack of IgM to capsulated bacteria

16

Vaccines needed before splenectomy

Pneumococcus
Meningococcus
H influenza

17

Hypersplenism definition

-Decreased circulating cell count of erythrocytes and/or platelets and/or leukocytes
-Normal compensatory hematopoietic response in BM
-Correction of cytopenia by splenectomy
+/- Splenomegaly

18

Spherocytosis

-Most common congenital hemolytic anemia requiring splenectomy
-Spectrin deficit (membrane protein) deforms RBCs and leads to splenic sequestration (hypersplenism)
-Causes pigmented stones, anemia, reticulocytosis, jaundice, splenomegaly
-Tx: Splenectomy and Cholecystectomy; curative

19

Elliptocytosis

Similar to but less common that spherocytosis
-Spectrin and protein 4.1 deficit (membrane protein)

20

Pyruvate kinase deficiency

Altered glucose metabolism
--> congenital hemolytic anemia
--> RBC survival enhanced by splenectomy

Most common congenital hemolytic anemia NOT involving membrane protein that requires splenectomy

21

G6PD deficiency

Splenectomy usually not required

22

Causes of spontaneous splenic rupture

Mononucleosis
Malaria
Sepsis
Sarcoid
Leukemia
Polycythemia vera

23

What is splenosis

Splenic implants
Usually related to trauma

24

Results of splenectomy/hyposplenism

Howell-Jolly bodies (nuclear fragments)
Heinz bodies (Hgb deposits)
Pappenheimer bodies (iron deposits)
Target cells
Spur cells (acanthocytes)
Transient thrombocytosis
Transient leukocytosis
Persistent lymphocytosis
Persistent monocytosis

25

Most common cause of splenic artery or splenic vein thrombosis?

Pancreatitis

26

Postsplenectomy changes in blood

Increased RBCs
Increased WBCs
Increased platelets: if > 1 x 10^6, give ASA

27

Most common splenic tumors

Benign: Hemangioma (most common overall)
Malignant: Non-Hodgkin's lymphoma

28

Guidelines for prevention of ppostplenic sepsis

-If possible vaccinate with polyvalent pneumococcal vaccine at least 10-14 days prior to splenectomy

-If urgent, wait at least 14 days postop to vaccinate

-Also meningococcal and H influenza vaccine for high-risk patients (immunosuppressed of children <10yo)

-Abx ppx for children <5yo

-Early Abx for initial signs of infection

-MedicAlert bracelet