The spleen Flashcards
location of spleen
left hypochondriac region
relations of spleen
visceral surface in contact with stomach,left kidney and tail of pancreas
convex surface lies directly under diaphragm
is spleen easily palpated
no
weight of spleen
152-250g
length of spleen
5-13cm
when can spleen be seen?
when enlarged,it moves with respiration
accessory spleens
found in 10% of people.
usually a piece of tissue found at any site in the abdomen
when does spleen become palpable
if the size exceeds 14 cm
oxygenated blood enters spleen through
splenic artery
splenic artery gives off branches?
True. branches are called trabecular arteries which enter spleen to form central arterioles
central arterioles become?
cords which lack an endothelial lining leading to the formation of an open blood system
what structures line the cord formed by central arterioles
loose reticular connective tissue network lined by macrophages and fibroblasts
From the cords how does blood re enter circulation
by passing across endothelium of venus sinuses to splenic vein to general circulation
what is the red pulp
this is formed by the cords and venus sinuses
volume of red pulp
forms 75% of the spleen
function of the red pulp
monitors integrity of RBCs. Macrophages pick up old RBCs and destroy them
what surrounds central arterioles
White pulp, a core of lymphatic tissue similar to lymph nodes made up of B cells
The white pulp is equivalent to this zone in lymph noded
t zone
are all central arteriole to venous connection terminated?
No. a minority of them are closed in, presenting with continuous endothelial lining and circulation
Functions of spleen
Quality control of RBCs by destroying old ones
Destruction of blood borne pathogens
What is splenomegaly?
increase in size of spleen. remember above 14cm
How does one detect that there is splenomegaly
usually palpable under left costal margin and if exaggerated may be felt as far as right iliac fossa
moves with respiration
medial splenic notch may be palpable
causes of splenomegaly
hematological disorders
portal hypertension
storage diseases
infections
tropical diseases
systemic disorders
hematological causes of splenomegaly
sickle cell dx chronic myeloid leukemia chronic lymphocytic leukemia acute leukemia hairy cell leukemia polycythemia vera thalassemia major/ intermediate Malignant lymphoma hemolytic anemia primary myelofibrosis
portal hypertension causes of splenomegaly
liver cirrhosis
hepatic, portal, splenic artery thrombosis
Storage disease causes of splenomegaly
Gauchers disease
Niemann Picks disease
Histocytosis X
Infections that cause splenomegaly
ACUTE CHRONIC
septicemia Tuberculosis
bacterial endocarditis brucellosis
typhoid syphillis
infectious mononucleosis leshmaniasis
Schistosomiasis
Tropical causes of splenomegaly
Malaria
Systemic diseases that cause splenomegaly
Sarcoidosis Amyloidosis Collagen dx SLE rheumatoid arthritis systemic mastocytosis
What is hypersplenism?
A condition where the spleen is overactive and removes blood cells too quickly.
Presentation of hypersplenism
Anemia
Enlargement of spleen
reduction of one or more cell lines in peripheral circulation
Bone marrow hyperplasia
A normal cell has these amounts of cell lines
5% or 50-70mls of RBC
50% of marginating neutrophils
30% of platelet mass
A hypersplenic spleen has these amount of cell lines
40% of red cell mass
90% of platelets
Why will hypersplenism present with anemia
This is due to hoarding of RBCs in the spleen leading to low counts in peripheral blood film
Many diseases that cause hypersplenism associated with
diseases that cause splenomegaly
Is hypersplenism a major disease?
NO. It is just a clinical sign and a sign of underlying dx
Treatment of hypersplenism
Treat underlying dx
Splenectomy in cases of severe anemia. Benefits should outweigh risk
What is hyposplenism?
A reduction in splenic function as a result of various medical conditions. It does a poor job of filtering out old RBCs
Why do sickle cell anemia patients present with hyposplenism?
There is functional asplenia after 1 year of age - splenic tissue present but doesnt work well
There is anatomical asplenia after 6-8 yrs due to autoinfarction of spleen. Blockage of blood supply to the spleen causes hypoxia and subsequently necrosis
Congenital absence of spleen is
rare
can occur due to transposition of organ
Malformation of heart and lungs
Atrophy of the spleen seen at what age
Old age, around 65 yrs
Danger for hyposplenic patients
Increased susceptibility to infections especially in infants and sickle cell anaemia.
Common infections that affect hyposplenic patients
S. Pneumoniae
H. Influenza type B
N. Meningitides
Malaria and
Infections caused by bites ( more common in those who have had splenectomy)
Causes of hyposplenism
Splenectomy Sickle cell Anaemia Splenic arterial thrombosis Amyloidosis Adult gluten induced entropathy Essential thrombocytopenia
Red blood cell film features in hyposplenism
Howell Jolly bodies Acanthocytosis Irregularly contracted cells Pappenhaumer bodies Target cells Iron granules
White blood cell blood film features in hyposplenism
Mild lymphocytosis
Monocytosis
Platelets blood film count in hyposplenism
Thrombocytosis. 30% of platelets that was supposed to be in spleen present in circulation
How to prevent infection in Hyposplenic patients
Patients should be told about their susceptibility to infection and if possible shouls carry a card around
Prophylactic oral penicillin for life
Vaccination against pneumococcus, influenza, meningococcus etc
What drug will you give to patients allergic to penicillin
Erythromycin
High risk groups that should be given oral penicillin
Patients under 16
Patients above 50
Patients who have undergone splenectomy
Patients with a history of previous pneumococcal dx
