Splenic disorders Flashcards
Where does splenic artery arise from?
celiac artery
What does splenic artery divide into?
into approx. 25 small hilar arteries which enter the spleen on its concave surface
What does the splenic vein drain into?
portal vein
What are the important branches of the splenic artery/ vein serving?
- left limb of pancreas
- greater curvature of stomach (left gastroepiploic)
- fundus of stomach (short gastrics)
Can dogs and cats normally survive without a spleen?
yes - much easier than humans
List 5 functions of the spleen
- RBC maintenance
- iron metabolism
- blood reservoir
- haematopoiesis
- immune functions
explain the RBC maintenance of spleen
1 filtration of blood
2 phagocytosis
3 remodelling RBCs
4 removal of intra-erythrocytic inclusions (e.g. heinz bodies)
Outline iron metabolism and the spleen
significant iron stores result from continuous removal of old or damaged RBCs from circulation
Outline spleen as a blood reservoir
cats and dogs store 10-20% blood volume in the spleen, ready for acute blood loss/ haemolysis or during strenuous exercise
Outline spleen and haematopoiesis
spleen can resume haemopoietic functions in adult animals when the BM is unable to carry out its normal haemopoietic role
What does the spleen do immunologically
major site for clearance of microorganisms and providing immune response. protects against septicaemia. occurs in the white pulp
What occurs in the red pulp of the spleen?
RB maintenance
Fe metabolism
Blood reservoir
Haematopoiesis
How can a total splenectomy be performed?
2 methods
- ) Large ventral midline. Remove spleen at tail end and double ligate and transect all the hilar vessels. At head of spleen, try and preserve the short gastric vessels and trasect the gastrosplenic ligament.
- ) Quicker method. Ligate the short gastric vessels, left gastroepiploic a + v and the splenic a+ v distal to the branch supplying the pancreas. May be impossible if lots of adhesions or ruptured splenic mass or if anatomy is distorted because of splenic torsion of GDV.
- ) Real life = usually a mix of the two
Indications - total splenectomy
if neoplasia is known or suspected
Indications - partial splenectomy
localised, benign disease (and 100% sure of this)
Method - partial splenectomy
hilar vessels to diseased portion of spleen to be resected are ligated and transected. after a few minutes this will cause a clear demarcation b/w ischaemic and normal spleen which is used as a guideline for resection. Then either:
- ) squeeze the splenic tissue along the demarcation line towards the end to be removed and place forceps on the flattened portion (non-crushing intestinal forceps = Doyen). Divide spleen b/w forceps and reove diseased portion. Place 2 rows of mattress sutures in a continuous overlapping pattern next to the forceps and close the cut end of the spleen using a continuous suture pattern of fine absorbable suture.
- ) use a stapling device (linear stapler) but make sure there is sufficient tissue for the size of staple. This can reduce surgical time.
What are the main perioperative considerations for splenectomy?
- ECG monitoring
- Coagulation tests (PT, APTT)
- Abdominal retractors and suction
- Examine entire abdomen
- Haemostatic forceps adn swabsu
- Measure blood in suction bottle
- Gastropexy (breeds at increased risk of GDV but this is not evidenced)
- Monitor vital parameters and PCV/TP regularly
Why are coagulation tests necessary for splenectomy?
recommended for animals with intra-abdominal haemorrhage not thought to be due to trauma since DIC can occur with neoplastic splenic lesions and splenic otrsion
How much does 1ml of blood weigh?
1.3 grams
What are the 2 commonest complications of splenectomy?
haemorrhage and cardiac arrhythmias
What are the complications of splenectomy?
- Haemorrhage (technical failure or DIC)
- Cardiac arrhythmias
- Ischaemic pancreatitis and gastritis
- possible increased risk of infection (probably only significant in immunosuppressed animals)
- previous infection with haemoparasites (babesia, ehrlichia, mycoplasma) may become evident
How should you manage cardiac arrhythmias due to splenectomy?
- ECG monitoring (before, during, after surgery)
- preoperative stabilisation with fluids
- antidysrhythmic meds if necessary
What are the most common types of splenomegaly in dogs and cats?
- dogs = localised splenomegaly
- cats = diffuse splenomegaly
T/F: just because a spleen is palpable, does not necessarily imply it is abnormal and not all enlarged spleens are palpable (especially if abdominal effusion is present)
True
Causes - localised splenomegaly
NON-NEOPLASTIC: haematoma, abscess, nodular hyperplasia, infarction, cyst. (infarction occurs with multiple concurrent medical conditions so splenectomy is unlikely to be curative of all problems)
NEOPLASIA: Benign (haemangioma, leiomyoma, fibroma, lipoma) or malignant (HSA, fibrosarcoma, leiomyosarcoma, any other sarcoma)
Causes - diffuse splenomegaly
INFECTION: bacterial, fungal, viral, parasitic
CONGESTION: drugs (barbiturates), splenic torsion +/or GDV, right-sided CHF
NEOPLASIA: acute/chronic leukaemia, systemic MCT (esp cats), lyphima, multiple myeloma, malignant histiocytosis
IMTP: splenectomy only if refractory to tx with immunosuppressive drugs
When is FNA useful for splenomegaly?
Cases of diffuse splenomegaly (usually cats)
What happens if you FNA a localised haematoma or HSA?
FNA often produces blood
When is ultrasound useful for splenomegaly?
reliably diagnoses a splenic mass and can differentiate liver and splenic masses and evaluate the abdomen for possible metastatic diseases
Where do HSA metastasize to?
liver omentum mesentery brain right atrium subcutaneous tissue
T/F: 50% dogs with splenic HSA have concurrent right arial HSA
False - 25%
T/F: HSA is grossly indistinguishable from haemangioma or aematoma
True - separating these ddx may be challenging on histopathology
What diagnostics should you do with all animals with a splenic mass/
thoracic radiographs or CT to look for pulmonary mets
MST for dogs with HSA without metastases undergoing total splenectomy
3-12 weeks without chemotherapy
around 6 months with chemotherapy
What post-op chemotherapy might be used for dogs post-splenectomy for HSA?
various combinations of drugs including doxorubicin, cyclophosphamide and vincristine. RVC usually uses cyclophosphamide/ doxorubicin for 6 cycles
Causes - splenic trauma
RTA
fall from a height
overall uncommon
splenic laceration - penetrating or iatrogenic injury
Tx - splenic trauma
Surgical - not usually performed as haemorrhage either self-resolving or injuries are so severe that they are fatal before initiation before surgery
Tx - mild splenic laceration
suture of the splenic capsule and/or omentum sewn over the lesion
Tx - severe or persistent haemorrhage of spleen
ligation of splenic vessels involved followed by partial or total splenectomy as appropriate to deal with any ischaemia produced,
What is splenosis?
After rupture of the spleen, multiple small splenic nodules called splenosis may be seen throughout the abdomen.
- one type of ectopic splenic tissue
- acquired condition
- defined as autoimplantation of one or multiple focal deposits of splenic tissue in various compartments of the body
- abdominal: typically small, sessile (grow on serial/peritoneal surfaces) and multiple. Can grow quite sizeable. If isolated intrahepatically can cause serious diagnostic problems.
What fixes the head of the spleen to the abdomen?
gastrosplenic ligament
