Exam 3: Lecture 15 - Surgery of the Liver Flashcards
1
Q
What does hepatectomy/total hepatectomy mean
A
removal of the entire liver
2
Q
what does partial hepatectomy mean
A
removal of a portion of the liver
3
Q
what does lobectomy mean
A
often used to refer to removal of a single (or multiple) liver lobes without performing a total hepatectomy
4
Q
Hypoalbuminemia below what value may be associated with delayed wound healing
A
< 2g/dl
5
Q
describe coagulopathies as a preoperative concern
A
- preop eval of clotting function esp mucosal bleeding time is warranted
- fresh whole blood transfusions may reduce intraoperative hemorrhage in selected patients
6
Q
below what hematocrit are animals considered clinically hypoxic or weak
A
hematocrit below 20%
7
Q
what should we do if a patient is anemic and has a hematocrit below 20% prior to sx
A
given preoperative blood transfusions
8
Q
what are some other preoperative concerns for a liver surgery
A
- potassium abnormalities
- anorexia
- hypoglycemia
- massive ascites
9
Q
what should we do for patients with severe hepatic encephalopathy prior to surgery
A
- controlled protein diet
- antibiotics
- cleansing enemas
- fluids
- lactulose
10
Q
T/F: aerobic and anaerobic bacteria normally reside in the liver
A
true!!
11
Q
T/F: The normal bacteria in the liver does not usually proliferate with hepatic ischemia or hypoxia
A
false! it may proliferate
12
Q
when are prophylactic abx warranted with liver surgery
A
in patients with severe hepatic disease that are undergoing hepatic sx (other than a biopsy)
13
Q
Is the portal system low pressure or high pressure
A
low pressure
14
Q
is the arterial system high or low pressure
A
high pressure
15
Q
what does the portal vein drain an also supply
A
drains: stomach, pancreas, spleen
supplies: 4/5th of the blood that enters the liver
16
Q
what do proper hepatic arteries supply
A
the remainder of the afferent blood supply
17
Q
why should we use caution when dissecting around the pylorus
A
to avoid damage to the common bile duct
18
Q
when should we take a liver biopsy
A
in patients with clinical signs of hepatic disease or clinically normal animals with lab abnormalities/imaging changes consistent with hepatic disease
19
Q
what are the 6 techniques of a liver biopsy
A
- percutaneous and fine needle
- laparoscopic
- guillotine method
- guillotine by interlocking loops
- punch
- partial lobectomy
20
Q
how can we obtain a percutaneous liver biopsy
A
- tru-cut biopsy
- large bore needle
- automated biopsy device
21
Q
what is important to remember about percutaneous core liver biopsies
A
- need 2-3 samples that are 2cm long
- generally taken from only left lateral lobe
- must take extreme care to ensure core biopsy needle doesn’t pass through needle
22
Q
why should we take core liver biopsies from the left lateral lobe
A
minimize chance of lacerating the bile ducts or gall bladder (both are on right side)
23
Q
T/F: false-negative results are more common than false-positive results for a percutaneous liver biopsy
A
true!
24
Q
how do we do the guillotine method for liver biopsies
A
- place a loop of suture around the protruding margin of a liver lobe
- pull ligature tight and allow it to crush through hepatic parenchyma before tying
- using a sharp blade to cut tissue approx 5mm distal to ligature
- as an alternative, place several overlapping guillotine sutures around the margin of the lesion and excise it
25
what is the minimum size for a punch biopsy of the livef
6mm minimum
26
what type of biopsy is shown in this picture
punch biopsy
27
how do we do a partial lobectomy
1. determine line of separation between normal and hepatic parenchyma that needs to be removed
2. sharply incise liver capsule along the site
3. bluntly fracture the liver and expose the parenchymal vessels
4. ligate large vessels and electrocoagulate small bldders
28
what technique for a biopsy is being shown here
partial lobectomy
29
what is another name for portosystemic shunts
portosystemic vascular anomalies
30
what are portosystemic shunts
anomalous vessels that allow normal portal blood draining from the stomach, intestines, pancreas, and spleen to pass directly into systemic circulation WITHOUT passing through liver first
31
what is a portocaval shunt
technically refers to a specific type of vascular anomaly
32
what are extrahepatic shunts
vascular anomalies located outside the hepatic parenchyma
33
what is a CEPSSs
congenital extrahepatic portosystemic shunts (aquired)
34
what are IHPSSs
congenital intrahepatic portosystemic shunts (located in the liver)
35
what is another name for hepatic microvascular dysplasia
portal vein hypoplasia
36
what is hepatic microvascular dysplasia
small or absent intrahepatic portal vessels and portal arteriolar hyperplasia associated with microscopic shunting of blood through the liver without a macroscopic portosystemic shunt
37
what are the broad general categories for shunts
1. congenital or acquired
2. intrahepatic or extrahepatic
38
T/F: congenital extrahepatic shunts typically are single anomalous vessels that allow abnormal blood flow from portal vein directly to systemic circulation
TRUE!
39
CEPSS account for nearly ____% of single shunts in dogs
63%
40
can CEPSS occur in dogs and cats
yes!!
41
T/F: cats most commonly have a large single vessel that empties directly into the pre-hepatic vena cava
true!
42
how can atypical CEPSS connections in cats flow
1. renal vein
2. phrenicoabdominal vein
3. azygos vein
4. internal thoracic vein
43
T/F: Intrahepatic portosystemic shunts are usually acquired
FALSE! usually congenital
44
why do singular intrahepatic portosystemic shunts occur
because the ductus venosus fails to close after birth
45
T/F: acquired extrahepatic shunts are typically multiple and represent about 20% of all canine PSSs
true!
46
when are multiple extrahepatic shunts most common
with chronic, severe hepatic disease
47
T/F: hepatic microvascular dysplasia is non-surgical
true!
48
what are the 3 good to know things about PSS
1. small breed dogs are more likely to have extrahepatic shunts and large breeds are more likely to have intrahepatic shunts
2. consider congenital PSS in any young animal with a prolonged response to anesthesia agents
3. nuclear scintigraphy, a useful non-invasive screening tool for diagnosing congenital or acquired shunts
49
what is important about medical management of shunts
1. sx appears to be treatment of choice
2. medical management in patients with congenital PSS have about a 48% mortality rate
50
what type of shunt is a surgical candidate and what is the goal of sx
only patients with congenital PSS are surgical candidates
goal of sx is to ID and occulde/attenuate the abnormal vessel
51
what are the 3 types of surgical occlusion or attenuation in PSSs
1. ameroid constrictor
2. cellophane banding
3. ligation
52
what are these
Ameroid constrictors
53
describe characteristics of ameroid constrictors
1. initial shunt constriction is affected by swelling of hygroscopic material that makes up inner portion of the device
2. additional shunt occlusion occurs as fibrosis develops around vessel
3. complete occlusion of the vessel may not occur
4. vascular occlusion may occur owing to thrombus formation in some dogs
54
describe the characteristics of cellophane banding
1. fold 10cm by 1.2cm wide strip of cellophane longitudinally to form a 3-layer strip that is approx 4mm wide
2. causes an initial acute inflammatory response followed by a chronic low-grade FB tissue rxn
3. vascular attenuation may be slower and less complete with cellophane bands than with ameroid constrictors
55
T/F: Ligation of shunts often lead to portal hypertension which may be fatal
TRUE!! Important
56
how do we measure portal pressures
1. use jejunal vessel (vein)
2. obtain baseline pressure (normal is 8-13 cm H2O)
3. increase of 10cm H2O over baseline or exceeding 20-23cm H2O means ligation should be abandoned for attenuation
4. observe for splanchnic congestion for 5-10 mins after placing ligature or attenuating
57
what are the 3 good to now things about sx options
1. if you find multiple shunts in an animal, biopsy liver
2. ameroid should fit on vessel without compromising the lumen
3. warn owners that ligation if IHPSS is difficult because these shunts are often hard to ID at time of sx
58
T/F: Cavitary hepatic lesions are usually cysts or abscesses
true
59
sometimes the hepatic cysts or abscesses are large ___1___ lesions such as ___2__ and __3____
1. neoplastic lesions
2. hemangiomas
3. adenomas cavitate
60
T/F: Hepatic abscesses are closed, fluid-filled sacs lined by secretory epithelium
FALSE! Those are hepatic cysts. Abscesses are localized collections of pus in the hepatic parenchyma
61
T/F: hepatic abscesses are rare in dogs and cats and are usually associated with extrahepatic infection
TRUE
62
hepatic cysts are usually ________ findings
incidental
63
T/F: in rare cases hepatic cysts become large enough to interfere with the function of adjacent organs
true!!
64
A __1___ hepatic cyst may be noted or ____2__ cysts may be present in the same of different lobes
1. single
2. several
65
why should we eval the kidneys in cats with hepatic cysts
they may also have cystic disease
66
how do we treat cavitary hepatic lesions
generally with a partial hepatectomy
67
what should we do if there is a hepatic lesion and we cant do a hepatectomy
the cyst can be omentalized
68
what are the 4 goals of omentalization
1. ID a segment of the omentum that will extend into the cyst cavity
2. remove as much of the wall of the cyst as possible
3. spread the omentum over the remaining cyst and adjacent liver
4. tack it gently in place to the remaining cyst capsule
69
what are the 5 types of epithelial hepatic neoplasia
1. hepatocellular carcinoma
2. hepatocellular adenoma
3. cholangiocellular carcinoma
4. cholangiocellular adenoma
5. hepatic carcinoids
70
what are the 4 types of mesenchymal hepatic neoplasia
1. hemangiosarcoma
2. fibrosarcoma
3. extraskeletal osteosarcoma
4. leiomyosarcoma
71
T/F: if the tumor is localized to a single lobe or confined to the gall bladder, surgical resection is still not curative
FALSE! it may be curative
72
how does a hepatic lobe torsion occur
when a liver lobe twists on its axis, it creates venous obstruction, causing increased hydrostatic pressure, ascites, and thrombosis leading to liver lobe necrosis
73
what are the 6 characteristics of hepatic lobe torsion
1. occurs when a lobe twists around its axis
2. rare in dogs and cats
3. torsion of the left lateral or medial lobe appears to be most common
4. in most animals cause is unknown
5. congenital absence or traumatic rupture of hepatic ligs is general suspected
6. no breed or sex predisposition
74
how do we treat hepatic lobe torsions
surgical resection
75
what can hepatic lobe torsions look like on histologic evaluation
devitalized mass may appear similar in appearance to a hepatic tumor
