Liver and biliary system Flashcards
According to Piegols 2020 in Vet Surg, catheterization of the common bile duct during cholecystectomy resulted in an increased risk of what?
Pancreatitis (no difference between retrograde and normograde catheterization)
According to Putterman 2021 in Vet Surg were patients undergoing normograde or retrograde catheterization of the common bile duct during surgery for GM more likely to experience post-operative complications? Was there any impact on survival?
Retrograde catheterization was associated with an increased risk of post-operative complications, but no difference in survival.
According to Simpson 2021 in Vet Surg, what was the major indication for cholecystectomy in cats? What was the post-operative mortality rate and most common complication?
Cholelithiasis was the most common indication. The perioperative mortality rate was 22%, and the most common complication was vomiting.
In a study by Dickerson 2022 in Vet Surg, what was the most common organism cultured in cases of hepatic abscessation? What was the perioperative complication rate and MST?
E coli was the most commonly cultured bacteria.
Perioperative complications occurred in 1/3 of cases, and MST was 638 days. Pre-operative septic peritonitis was common.
In a study by Takagi 2022 in Vet Surg, what was the median number of hepatic veins draining the left lateral liver lobe?
3 vessels.
Additionally, median of 2 vessels reported draining the right lateral. Remaining lobes had a median of 1 vessel, with variable drainage patterns (e.g. quadrate lobe either drained directly to CVC, indirectly via the LHV or following merger with the vessel from the right medial lobe).
In a study by Hernon 2023 in Vet Surg, did normograde flushing of the common bile duct during cholecystectomy for GBM result in improvements in clinical outcome or biochemical parameters as compared to not flushing?
No - there was no observed benefit to flushing vs. not flushing of the CBD.
In a study by Moore 2023 in Vet Surg, what were the 4 factors associated with risk of post-operative complications following liver lobectomy? What were 2 factors associated with intra-operative complications?
Post-operative complications (29%) were less likely if the lobectomy was performed by a specialist, with a TA stapling device, and in heavier dogs. Complications were more likely if the incision extended into the thorax.
Intraoperative complications (11%) were 19 times more likely if a TA stapling device was not used, and for right divisional as compared to left sided lobectomies.
In a study by Bergen 2024 in Vet Surg, what was the median time of balloon expandable stent patency in cats and dogs following placement for EHBO?
Cats: 446 days
Dogs: 650 days
In a study by Parlier 2024 in Vet Surg, how much did portal pressures increase per mmHg of insufflation pressures?
7% increase per mmHg of insufflation.
(increased by 100% at 10mmHg, and 175% at 14mmHg).
In a study by Cleary 2023 in JAVMA, was the 2- and 12-month survival improved in dogs with EHBO secondary to pancreatitis with surgical or medical management?
Surgical management associated with improved survival (95% of surgical patients survived, compared to 57% of medically managed patients). Most surgically managed patients had cholecystoenterostomies performed.
In a study by Reist 2023 In JAVMA, what percentage of patients with hemoabdomen secondary to ruptured liver mass were diagnosed with hepatocellular carcinoma or benign disease? What was MST for patients with hepatocellular carcinoma, benign masses, and hemangiosarcoma? What were 3 prognostics factors for survival?
64% of patients had either a hepatocellular carcinoma or benign disease.
The MST for patients with hepatocellular carcinoma was 897 days (36% of patients), benign was 905 days (28% of cases), and hemangiosarcoma was 45 days (26% of cases).
Three factors associated with survival were presence of anemia, whether a transfusion was given, and ALT (increased ALT led to increased survival).
In a study by Ullal 2023 in JAVMA, what were 2 factors associated with increased risk of non-survival in dogs undergoing cholecystectomy? What was the overall survival to discharge?
Increasing age and decreased intraoperative blood pressure (<65mmHg) were associated with non-survival.
The overall survival was 76%.
In a study by Dean 2020 in JSAP what was the complication rate attributable to diaphragmotomy during hepatobiliary surgery?
25% - none of these complications required surgical intervention.
In a study by Hattersley 2020 in JSAP, did the presence of intraoperative hypotension affect survival in patients undergoing cholecystectomy? What 2 other factors were associated with survival?
No - intraoperative hypotension did not affect survival.
Ileus and pancreatitis were found to significantly impact mortality.
In a study by Frieson 2021 in JSAP, what was the mortality rate for patients undergoing elective and non-elective cholecystectomies? What was the overall complication rate? What post-operative complication showed a much higher incidence in patients undergoing retrograde flushing of the CBD, compared to normograde or no flushing?
Mortality rate for elective surgery was 6%, and 23% for non-elective.
Complication rate was 50% for both elective and non-elective procedures.
Post-operative hyperthermia occurred in 35% of dogs undergoing retrograde flushing, as compared to 4% with normograde and 7% with no flushing.
What technique for gallbladder dissection was described for laparoscopic cholecystectomy by Kondo 2023 in JSAP?
Subserosal technique. 90% dissection successful in 80% of dogs, with conversion required in 9%.
In a study by Villm 2022 in VRU, what was the incidence of gallbladder sludge in cats undergoing abdominal ultrasound?
44% - no correlation with clinical signs or clinicopathologic variables.
According to Jang 2023 in VRU, increase opacity of the gallbladder on thoracic ventrodorsal radiograph is suggestive of what disease?
Presence of gallbladder sediment or sludge balls.
In a study by Murakami 2023 in VRU, renomegaly was most pronounced in which shunt morphology?
1) Intrahepatic
2) Extrahepatic portoazygous
3) EH portocaval
4) EH portophrenic
Intrahepatic, then portocaval. Renomegaly was present in 87% of cases but was uncommon in dogs with portoazygous shunts.
In a study by Chan 2024 in VRU, what was the overall MST for patients undergoing stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma? What was was the median tumour diameter treated, and what was the median percentage of planning v. liver volume?
MST was 164 days.
The median tumour diameter was 5.5 cm, and the median percentage of planning v. liver volume was 27%.
In a study by Burke 2023 in JVECC, what were the 3 most common presenting clinical signs in dogs with hepatic abscessation? What was the most commonly cultured organism? What was the overall survival to discharge? What factors was associated with decreased odds of survival?
Lethargy, hyporexia and vomiting were the three most common clinical signs. Elevated liver enzymes frequently reported on biochem.
E. coli was the most commonly cultured organism. Hepatic neoplasia underlying abscess formation was found in 10/47 dogs.
Overall survival to discharge was 71%. The majority (41/49) dogs underwent surgical intervention.
Multifocal abscessation was associated with decreased odds of survival.
In a study by Allan 2021 in JVIM, what was the median survival time of dogs with cholelithiasis undergoing either medical or surgical management?
457 days
In a study by Griffin 2021 in JVIM, what percentage of cats undergoing choledochal stenting survived to discharge? In what percentage of cats did EHBO reoccur? What was the MST of cats that survived to discharge?
78% of cats survived to discharge.
Recurrence of EHBO was documented in 39% of cats, and was associated with cholelithiasis.
MST was 931 days.
In a study by Jaffey 2022 in JVIM, what were 2 independent predictors of death in dogs undergoing cholecystectomy for gallbladder mucocele?
Increasing age, and intraoperative blood pressure nadir.
Increasing developmental stage of GM on imaging was associated with an increase in the likelihood of clinical signs (see image).
In a study by Couture 2024 in JVIM, what 3 hematologic abnormalities were more common in dogs with IHPSS compared to EHPSS?
Anemia, microcytosis, hypochromia. Gastrointestinal signs were also more common.
In a study by Jablonski 2024 in JVIM, what liver histologic findings were common in dogs with gallbladder mucocele (3)? Which of these was associated with survival?
Hepatic fibrosis, portal inflammation, biliary hyperplasia.
The presence of hepatic fibrosis was associated with decreased survival.
In a study by Torres 2024 in JVIM, what cut-off value for hyperbilirubinemia was associated with a higher likelihood of biliary obstruction in cats?
> 3.86 mg/dL (>66 umol/L).
In a study by Brunet 2023 in JVIM, what two factors increased the chance of clinical signs related to cholelithiasis in cats? What was negatively associated with survival?
Choleliths in multiple locations and obstructive disease were associated with clinical signs (41% of cases were asymptomatic).
Biliary obstruction was negatively associated with survival. 74% of cats with choleliths survived to discharge.
Concurrent hepatobiliary disease was common (83% of cases).
In a study by Brunori 2023 in JVIM, dogs developing hypernatremia within 6-hours of cholecystectomy had how much higher odds of non-survival?
8 times.
All dogs with a peak sodium >160 mEq/L did not survive.
In a study by Kawamura 2023 in JVIM, what was the MST for dogs undergoing transcatheter arterial embolization for hepatocellular masses? What two factors were associated with reduced survival?
MST 419 days.
History of intraabdominal hemorrhage and increased pre-embolization tumour volume/body weight were negatively associated with survival.
The major complications were tumour lysis syndrome (1 dog), and tumour necrosis (1 dog) - both resulted in death.
How many triangular ligaments of the liver are there?
Three: left, right medial and right lateral. The right lateral is more substantial than the right medial.
Describe the anatomy of the liver.
What percentage of blood volume and oxygen supply do the portal and hepatic arteries provide to the liver?
Portal: 80% blood volume, 50% oxygen.
Hepatic: 20% blood volume, 50% oxygen.
At the level of the porta hepatis how many branches does the hepatic artery divide into?
2-5
At the level of the porta hepatis how many branches does the portal vein divide into?
Two in dogs (left and right), three in cats (left, central, right).
Which part of the portal vascular system is absent in cats?
The gastroduodenal vein.
How many hepatic veins are there?
6-8 (the left drains most cranially, the right most caudally).
What is the number of hepatic ducts in dogs?
2-8
Is the pancreatic or accessory pancreatic duct the larger excretory duct in the dog?
The accessory which enters at the minor duodenal papilla.
How does the anatomy of the bile and pancreatic ducts differ in the cat as compared to the dog?
- Only 20% of cats have an accessory pancreatic duct, which is smaller than the pancreatic duct.
- The bile duct and pancreatic duct conjoin before entering the duodenum (which may explain the frequent concurrence of pancreatic and hepatobiliary disease in cats).
What are the primary functions of the liver?
Synthesis and clearance of plasma proteins, maintenance of carbohydrate and lipid metabolism, coagulation factors, immune function (reticuloendothelial system), GI health (bile production, gastrin), storage organ, clearance organ for toxic metabolites.
How much of the functional liver capacity has to be lost before hypoalbuminemia or hypoglycemia is observed?
70%
Which coagulation factors are not produced in the liver?
vWF and factor VIII (produced in the vascular endothelium).
Which coagulation factors are vitamin K dependent?
II, VII, IX and X.
Which cells of the hepatic reticuloendothelial are responsible for phagocytosis?
Kupffer cells, which are hepatic macrophages distributed throughout the sinusoids.
What is the composition of bile?
Bile acids, bilirubin, cholesterol, phospholipids, water, bicarbonate, and other ions.
What is the function of bile salts in the small intestine?
Aid in the digestion of fat, bind endotoxin.
They are formed by the conjugation of bile acids with taurine (dogs and cats) or glycine (dogs).
What percentage of bilirubin is reabsorbed from the intestine?
10%
What hormone is responsible for gallbladder contraction?
Cholecystokinin.
What percentage liver resection is tolerated in dogs?
65-70%.
>84% results in mortality due to portal hypertension.
Following hepatectomy what is responsible for regeneration of the remaining liver?
Portal blood flow increases to the remaining liver which causes hypertrophy and hyperplasia of the hepatocytes (peaking within 3-days, and complete by 6-days). Cytokines, growth factors, vasoregulators and hormones may also play a role.
What factors result in impeded hepatic regeneration?
Biliary obstruction, diabetes mellitus due to reductions in insulin (a potent hepatotrophic factor), malnutrition, male gender, older age.
How does blunt trauma result in traumatic biliary tract rupture?
Common bile duct and hepatic ducts most commonly affected. A short wide cystic duct and compression of the gallbladder results in rapid filling of the CBD, combined with cranial traction force on the liver with avulsion of structures from the relatively immobile duodenum.
What are the most common causes of EHBO in dogs and cats?
Dogs: Pancreatitis, neoplasia, mucocele, cholangitis, cholelithiasis.
Cats: pancreatitis, cholangiohepatitis, cholecystitis (+/- cholelithiasis), neoplasia.
What are common sequelae of EHBO?
Hypotension (often refractory to vasopressor agents), decreased myocardial contractility, acute renal failure, coagulopathies, GI hemorrhage, delayed wound healing.
These are largely thought to be secondary to the absence of bile salts in the GI, bacterial overgrowth and systemic endotoxemia.
What are the most common causes of bile peritonitis in dogs?
Trauma, necrotizing cholecystitis, ruptured GM mucocele. Leakage from an upper GI perforation can also occur.
What are the effects of bile in the peritoneal cavity?
Inflammation, hemolysis, tissue necrosis, fluid shifting and hypovolemic shock. Concurrent infection markedly worsens the prognosis.
What percentage of feline and canine choleliths are radioopaque?
Canine: 50%
Feline: 80%
What is the normal size of the canine and feline CBD?
3-4mm.
Following administration of cholecystokinin what percentage of the gallbladder should be emptied in normal dogs?
40%
Following injection of technetium-99m, passage into the intestines is expected within what time frame?
<3 hours. Longer may indicate EHBO.
What are some hepatobiliary imaging techniques?
Radiography, ultrasonography (+/- contrast enhanced microbubbles), scintigraphy, CT/MRI, endoscopic retrograde cholangiopancreatography.
What bacteria are commonly cultured from the liver of patients with hepatobiliary disease?
Enterococcus, e.coli, clostridium, bacteroides (enteric bacteria).
Are dogs or cats more likely to have single isolates on culture of the liver?
Cats (83% v. 50%). Cats also more likely to culture positive (14% v. 5%).
Are biliary or hepatic culture results collected at the time of surgery more likely to be positive?
Biliary (30% v. 7% for hepatic). No patients had negative bile and positive hepatic cultures concurrently.
What are some suggested protocols for antimicrobial prophylaxis in patients undergoing liver surgery?
(1) fluoroquinolone, penicillin, and metronidazole; (2) fluoroquinolone and amoxicillin-clavulanate; or (3) fluoroquinolone and clindamycin
What are some intra-operative methods to control capsular hemorrhage of the liver?
Pressure, surgical clips or staples, hemostatic agents (oxidised regenerated cellulose, gelatin sponge, cyanoacrylate, fibrin sealants), vascular occlusion techniques.
What are some methods of vascular occlusion that can be performed in instances of extensive liver hemorrhage?
- Control of CVP (<5 cmH2O)
- Control of liver inflow:
a. Pringle manoeuvre. Tolerated for 20 minutes.
b. Hepatic artery ligation if bleeding from a tumour (tumours receive 95% of their blood from the hepatic artery). Concurrent prophylactic cholecystectomy should be considered. - Occlusion of inflow and outflow: simultaneous occlusion of the suprahepatic and infrahepatic caudal vena cava with concurrent inflow occlusion.
Why does severe hepatic bleeding sometimes persist despite the Pringle maneouvre?
1) Incorrect finger placement (not occluding the gastroduodenal vein).
2) Back bleeding from the gastroduodenal artery.
3) Back bleeding from hepatic veins.
What is a potential complication associated with use of ultrasound guided automatic biopsy needles for liver biopsy collection?
Vagotonic shock (particularly in cats)
How many portal triads are ideally obtained with liver biopsy?
3-12
What are some methods of liver biopsy?
- FNA: easy but unreliable.
- Needle biopsy: 6% major complication rate, 60% accurate (same as punch and cup biopsy forceps).
- Transjugular: reduced risk of hemorrhage. Liver capsule penetration occurred in 64% of canine patients.
- Open: suture fracture, guillotine, punch (should be limited to 50% depth to prevent damage to hepatic vein branches), 5mm cup biopsy forcep, ultrasonic scalpel, bipolar vessel sealer.
- Laparoscopic (low morbidity [2%] and conversion [4%]): cup biopsy, pretied loop ligature, extracorporeal loop assembly.
For what size lesions was use of a pretied encircling ligating loop (Surgitie) safe for partial hepatic lobectomies?
<8cm hepatic lesions.
What are some surgical methods of partial liver lobectomy?
Blunt dissection with individual vessel sealing by cautery, Ligaclip, or ligation; vessel sealing devices; thoracoabdominal staplers or encircling suture devices
Skeletonization and surgical clip technique associated with greater blood loss in one study.
What are some surgical methods of complete liver lobectomy?
Blunt dissection and suture ligation (may be beneficial when tumours encroach on the hilus preventing stapler placement), surgical stapling equipment, vessel sealing devices with ligation of larger vessels.
Encircling suture devices might be used for left lateral or right lateral liver lobes in small dogs and cats, but not recommended as sole method of vessel attenuation due to risk of hemorrhage.
What are the relative volumes of the liver lobes of the dog?
Right lateral and caudate: 28%
Right medial and quadrate: 28%
Left lateral and medial: 44%
What could be considered in instances of excessive intraoperative portal pressure following hepatic resection?
Creation of a porto-caval shunt.
Alternatively, if a large hepatectomy is planned, prior embolization or ligation of the portal vein branch supplying the lobe to be resected may allow for more aggressive hepatectomy.
What are some causes of mortality following liver lobe resection?
Hemorrhage, liver failure, portal hypertension.
By how much are intratumoral chemotherapeutic concentrations increased using chemoembolization techniques?
10- to 50-fold
What are some reported complications of transarterial embolization or chemoembolization for treatment of liver tumours?
Non-target embolization, hepatic infarction or abscessation, postembolization syndrome (malaise, fever, pain).
Above what level of serum bilirubin concentration is icterus evident?
1.5 - 2.0 mg/dL
What level of bilirubin in the peritoneal fluid helps to confirm bile peritonitis?
> 2 x serum
If there are concerns over coagulation parameters in a dog undergoing hepatic surgery, what treatments may be administered?
Vitamin K (ideally three doses pre-operatively), fresh frozen plasma administration.
In what percentage of cases with bile peritonitis is bacterial infection reported?
58-61%
When might choledochoduodenostomy be considered?
If the gallbladder is too diseased to perform a cholecystoenterostomy and there is extrahepatic bile duct obstruction.
Generally ill-advised due to the size of the CBD, but may be possible if distended due to disease.
How is closure of a cholecystotomy incision performed?
Simple continuous inverting pattern.
Rarely indicated.
What are some indications for laparoscopic cholecystectomy?
Uncomplicated gallbladder mucocele and symptomatic cholelithiasis not associated with EHBO, gallbladder rupture, or choledocholithiasis.
Is cholocystoduodenostomy or cholocystojejunostomy preferred?
Cholocystoduodenostomy as it provides normal passage of bile into the duodenum, which helps to prevent gastric ulceration through control of gastric acid secretion.
How long should the stoma for cholocystoduodenostomy be?
> 2.5 cm to prevent retention of intestinal chyme and subsequent ascending cholangiohepatitis.
What are some complications associated with cholocystoduodenostomy?
Hemorrhage, incisional dehiscence, stricture of the stoma, ascending cholangitis, gastric ulceration.
What is shown in the attached image?
A human polyethylene choledochal stent. Proximal and distal flaps prevent migration and preclude the need for suturing.
What are the most common indications for choledochal stenting?
Temporary obstructions such as those caused by pancreatitis or cholangiohepatitis. May also be used to support repair of a ruptured CBD.
What are the two methods by which choledochal stents can be placed?
Open, endoscopic retrograde placement.
Stents are ideally removed after 2-4 months if the obstruction has resolved to prevent ascending cholangitis or obstruction secondary to the stent.
What are two methods of cholecystostomy tube placement?
Open placement using a locking pigtail or foley catheter (through the apex of the gallbladder and right body wall), laparoscopic assisted.
How long should cholecystostomy tubes be maintained for?
Ideally 3-4 weeks to allow complete stoma formation.
When might a choledochotomy be performed?
If a cholelith cannot be flushed retrograde back into the gallbladder. Ideally avoided if possible due to high risk of dehiscence.
If a cholelith is lodged at the papilla a sphincterotomy might be appropriate.
What was the most common bacteria identified in hepatic abscessation?
E.coli, although multiple isolates were common.
What are some treatment options for hepatic abscessation in dogs?
Systemic antimicrobials alone, ultrasound guided drainage +/- alcoholization, surgical resection.
What are some differences between hepatic abscessation in cats and dogs?
Liver enzyme elevations less predictable in cats, focal abscessation less common (with multiple macroabscessation or microabscessation common), focal abscesses exclusively affected the right liver lobes in cats, cats had a worse prognosis and were often septic (71%).
What is the common signalment for dogs with liver lobe torsion?
Middle aged to older large breed dogs.
Which liver lobe is most commonly torsed in instances of liver lobe torsion?
Left lateral.
Doppler ultrasonography is useful to confirmed the diagnosis.
What is the treatment for liver lobe torsion?
Lobectomy, considered a surgical emergency. Prognosis is excellent.
What is the underlying lesion for gallbladder mucocele?
Cystic mucosal hyperplasia. Hypersecretion of mucus leads to accumulation of thick, gelatinous bile.
What are some proposed causes of gallbladder mucocele?
- Genetic deficiencies (ABCB4 gene).
- Underlying cholestasis.
- Endocrinopathies (dogs with hypoT 3 x as likely, hyperA 29 x as likely).
What is the sensitivity of ultrasound for biliary rupture?
86%, however may be lack of correlation.
In what percentage gallbladder mucocele cases is rupture identified?
23-60%
What are the most common bacterial isolates in cases of gallbladder mucocele?
E.coli, enterococcus.
Aerobes and anaerobes identified in 3-75%, and 0-25% of samples respectively.
What percentage of dogs with GM mucocele have concurrent EHBO?
30%
What are the reported mortality rates of dogs undergoing cholecystectomy for biliary mucocele?
21-28%
What are some post-operative complications following cholecystectomy for GB mucocele?
Leakage of bile, pancreatitis, reobstruction of the CBD.
What is the most common composition of choleliths in dogs and cats?
Dogs: calcium carbonate, calcium bilirubinate.
Cats: calcium carbonate.
What factors are thought to contribute to the formation of choleliths?
Cholestasis and/or infection (E.coli, streptococcus, enterococcus, Klebsiella most frequently cultured).
Is medical dissolution typically effective in cases of cholelithiasis?
No, surgical removal generally required (cholecystectomy preferred).
What was the postoperative mortality rate patients undergoing surgery for cholelithiasis?
20%
What are the four general types of hepatobiliary tumour?
Hepatocellular, cholangiocellular, neuroendocrine, mesenchymal.
Metastatic tumours are more common than primary tumours.
What is the most common primary liver tumour in dogs?
Hepatocellular carcinoma (50-70% of nonhematopoietic tumours).
Three forms; massive (61%), nodular (29%), diffuse (10%).
Which liver lobe does the massive form of hepatocellular carcinoma most frequently involve?
Left lobe (67% of cases).
Is metastasis more common with the massive, nodular or diffuse forms of hepatocellular carcinoma?
Nodular and diffuse (93%), compared to massive (36%).
Most commonly to the lymph nodes, lungs, and peritoneum.
What is the median survival time for massive hepatocellular carcinoma in dogs following resection?
1460 days
No recurrence observed despite incomplete margins in 9.5% of cases.
What was associated with a poorer prognosis for surgical resection of hepatocellular carcinoma?
Right sided tumours
What percentage of canine hepatocellular tumours are benign?
30% (benign adenomas)
What is the most common primary hepatic neoplasm in cats?
Cholangiocellular neoplasms.
Biliary cystadenomas (good prognosis) are twice as common as bile duct carcinomas (poor prognosis, 67% rate of metastatic disease).
What forms of cholangiocellular carcinoma are described in dogs?
Massive (50%), nodular (28-50%), diffuse (22%). Majority (~90% are intrahepatic). Metastasis present in 88% of cases.
What is the prognosis for neuroendocrine tumours of the liver?
Poor for both dogs and cats. Normally diffuse disease and metastasis common.
What is the most common metastatic tumour to the liver?
Lymphoma
