Hepatobiliary surgeries

Overview

  • Course Name: VMS 5649

  • Focus: Advanced curriculum on small animal surgical procedures specifically targeting the hepatobiliary system, encompassing both diagnostic and therapeutic interventions for various conditions affecting the liver and bile ducts.

Objectives

  • Surgical Anatomy of the Liver: Comprehensively identify and describe the gross and microscopic divisions, vascular supply, innervation, and specific anatomical components of the canine and feline liver, understanding their clinical relevance during surgery.

  • Trauma to the Liver: Discuss common causes of liver trauma (e.g., blunt force, penetrating injuries), accurately diagnose hemoabdomen using clinical signs and diagnostic imaging, and differentiate between indications for conservative management (e.g., stable patient, minor hemorrhage) versus immediate surgical intervention (e.g., ongoing significant hemorrhage, unstable patient).

  • Pringle Maneuver: Explain the precise technique involving the occlusion of the hepatoduodenal ligament, its primary purpose (reducing blood flow to the liver to control hemorrhage or allow for surgical manipulation), and specific indications for its use during liver surgery.

  • Liver Biopsy Techniques: Discuss various biopsy methods, including fine needle aspirate (FNA), Tru-Cut/core needle biopsy, open wedge biopsy, guillotine technique, and laparoscopic approaches, along with their respective advantages, disadvantages, and contraindications (e.g., coagulopathy).

  • Liver Lobectomies: Clearly differentiate between partial (removal of a portion of a lobe) and complete lobectomies (removal of an entire lobe), understanding the surgical techniques, and assessing the associated morbidity implications (e.g., blood loss, potential for liver insufficiency).

  • Extrahepatic Biliary Tree: Understand the detailed anatomy of the extrahepatic biliary system, including the gallbladder, cystic duct, common bile duct, and pancreatic ducts, as well as the terminology and steps involved in surgical procedures performed on these structures.

  • Biliary Mucoceles: Cover the complex etiology (e.g., gallbladder dysmotility, excessive mucus production, breed predispositions), diverse clinical signs (e.g., vomiting, icterus, abdominal pain), diagnostic modalities (e.g., ultrasonography, laboratory findings), and various treatment options, discussing the implications of medical management versus surgical management (cholecystectomy).

  • Cholecystectomy Indications: Provide clear justification for performing a cholecystectomy (gallbladder removal), outlining specific medical conditions (e.g., necrotizing cholecystitis, biliary mucocele) that necessitate the procedure, along with required pre-operative steps (e.g., coagulation profile, antibiotics).

  • Cholecystectomy Complications: Identify potential post-operative issues arising from the procedure, such as bile leakage leading to peritonitis, hemorrhage, and infection.

  • Biliary Obstruction: Differentiate between intraluminal (e.g., gallstones, inspissated bile, neoplasia within the duct lumen) and extraluminal obstructions (e.g., pancreatic mass, duodenal stricture compressing the duct) and outline appropriate surgical management strategies for each type.

  • Biliary Diversion: Understand various surgical options (e.g., cholecystoduodenostomy) to bypass an obstructed or injured common bile duct, and recognize their respective potential complications (e.g., ascending cholangiohepatitis).

  • Bile Peritonitis: Detail diagnosis methods, including abdominocentesis and biochemical analysis of effusion fluid, and critically differentiate between sterile and infected bile peritonitis regarding prognosis and treatment.

Surgical Anatomy of the Liver

  • Divisions of the Liver: The canine and feline liver is composed of distinct lobes, each with specific anatomical features:

    • Quadrate Lobe: Located between the left and right medial lobes, cranial to the porta hepatis.

    • Left Medial Lobe: A central lobe of the left division.

    • Central Division Lobe: Often not distinctly named in some anatomical texts, but functionally part of the central area.

    • Left Division: Comprises the Left Medial Lobe and Left Lateral Lobe.

    • Right Division: Consists of the Right Medial Lobe and Right Lateral Lobe.

    • Caudate Lobe: Located dorsally, and contains two processes:

    • Caudate Process: Adjacent to the right kidney.

    • Papillary Process: Located near the lesser omentum.

    Understanding these divisions is crucial for precise surgical planning and reporting.

  • Major Vessels:

    • Caudal Vena Cava: Runs along the dorsal aspect of the liver, receiving hepatic veins directly.

    • Common Hepatic Artery: Branches off the celiac artery, supplying oxygenated blood to the liver parenchyma and biliary tree.

    • Portal Vein: Formed by the confluence of the splenic, cranial mesenteric, and caudal mesenteric veins, it carries nutrient-rich, deoxygenated blood from the gastrointestinal tract, pancreas, and spleen to the liver for processing. These vessels form the porta hepatis, a critical anatomical landmark for surgical approaches.

Hepatobiliary Diseases

  • Hepatic Diseases: A range of conditions affecting the liver parenchyma:

    • Obstruction: Often involves intrahepatic bile ducts or major hepatic veins.

    • Trauma: Direct injury to liver tissue, leading to hemorrhage or necrosis.

    • Neoplasia: Primary liver tumors (e.g., hepatocellular carcinoma) or metastatic lesions.

    • Liver Lobe Torsion: Rare but severe condition where a liver lobe twists, compromising its blood supply.

    • Cysts: Fluid-filled sacs, congenital or acquired.

    • Abscesses: Localized collections of pus within the liver, typically bacterial.

    • Vascular Malformations:

    • Portosystemic shunts (PSS): Abnormal vessels connecting the portal venous system to the systemic circulation, bypassing the liver.

    • Hepatic microvascular dysplasia: Microscopic shunts within the liver, often leading to similar clinical signs as PSS.

    • Hepatic veno-occlusive disease: Obstruction of small hepatic veins.

    • Non-cirrhotic portal hypertension: Elevated portal pressure without cirrhosis.

    • Idiopathic portal hypertension: Portal hypertension of unknown cause.

    • Arteriovenous (A-V) fistula: Abnormal connection between an artery and a vein within the liver.

  • Biliary Diseases: Conditions primarily affecting the gallbladder and bile ducts:

    • Cholecystitis: Inflammation of the gallbladder, acute or chronic.

    • Biliary Mucoceles: Excessive mucus accumulation within the gallbladder, leading to distension and potential rupture.

    • Biliary Obstruction: Blockage of bile flow from the liver to the duodenum.

    • Trauma: Injury to the gallbladder or bile ducts.

    • Neoplasia: Tumors affecting the gallbladder or bile ducts.

    • Cholelithiasis: Presence of gallstones within the gallbladder or bile ducts.

Liver Trauma

  • Causes of Trauma: Direct physical forces or penetrating injuries:

    • Blunt Trauma: Often results from vehicular accidents, falls, or direct blows to the abdomen, causing contusions, hematomas, or lacerations.

    • Liver Fractures: Severe blunt trauma can lead to parenchymal fractures.

    • Penetrating Wounds: Caused by objects such as gunshot, arrows, or animal bites, resulting in direct damage to liver tissue and vessels.

  • Clinical Signs: Blood loss symptoms are often acute and pronounced, including pallor of mucous membranes, tachycardia, weak pulses, and hypotension, indicative of hypovolemic shock. Abdominal pain and distension may also be apparent.

Diagnosis and Management of Liver Trauma

  • Hemoabdomen Management: Critical for stabilizing the patient and addressing hemorrhage:

    • Conservative Management: Effective for many cases of minor hemoabdomen where hemorrhage is not ongoing or self-limiting.

    • Low flow fluid resuscitation with constant monitoring of vital signs (heart rate, respiratory rate, blood pressure), packed cell volume (PCV), and total solids (TS).

    • Obtain peritoneal fluid via abdominocentesis or diagnostic peritoneal lavage (DPL); large volumes (often defined as >5mL/kg) of blood-tinged or pure blood fluid that does not clot, or consistently declining PCV values in a 24-hour period strongly suggest the need for surgical intervention.

    • Surgical Management: Primarily indicated when conservative measures fail, and hemorrhage is persistent or life-threatening.

    • Indicated by decreasing peripheral packed cell volume (PCV) despite fluid resuscitation, signs of ongoing shock, or evidence of expanding hemoabdomen.

    • Surgical repair involves:

      • Ligating severed vessels: Careful identification and ligation of actively bleeding hepatic arteries or veins.

      • Partial hepatectomy: Removal of severely damaged or devitalized liver tissue.

      • Employ Pringle maneuver for improved outcomes: Temporarily occluding the hepatoduodenal ligament to reduce hepatic blood flow during major liver resections or repair.

    • Pringle Maneuver: Technique used to occlude hepatic blood flow (via clamping the hepatic artery and portal vein) to facilitate repair of liver injuries or during complex resections. It is generally well-tolerated for up to 15-20 minutes in dogs.

    • Greater likelihood of surgical intervention needed for injuries close to the hilus, due to the density of major vessels and bile ducts.

Hepatobiliary Surgery Procedures

  • Hepatic Procedures: Surgeries directly on the liver parenchyma:

    • Biopsy: Collection of liver tissue for histopathological examination, essential for diagnosis of diffuse liver diseases or identification of tumor type.

    • Partial Lobectomy: Removal of a portion of a liver lobe.

    • Complete Lobectomy: Removal of an entire liver lobe.

  • Biliary Surgery: Procedures involving the gallbladder and bile ducts:

    • Cholecystotomy/Cholecystectomy: Incision into the gallbladder for stone removal or drainage (cholecystotomy), or complete surgical removal of the gallbladder (cholecystectomy).

    • Bile Duct Exploration/Reconstruction: Surgical opening and examination of bile ducts for obstructions, or repair/re-routing of damaged ducts.

    • Biliary Diversion; includes procedures to reroute bile flow when the common bile duct is obstructed or irreparable:

    • Cholecystoduodenostomy: Anastomosis of the gallbladder to the duodenum.

    • Cholecystojejunostomy: Anastomosis of the gallbladder to the jejunum.

    • Choledochoenterostomy: Anastomosis of the common bile duct to the small intestine (duodenum or jejunum).

Liver Biopsy Techniques

  • Types: Various methods tailored to the patient's condition and the suspected pathology:

    • Fine Needle Aspirate (often non-diagnostic): Simple, minimally invasive, but often only yields cytology and may not provide sufficient diagnostic material for definitive diagnosis of various liver diseases or grading of neoplasia.

    • Tru-Cut Needles (image guided): Core biopsy needles provide a tissue sample, typically guided by ultrasound, improving accuracy and reducing complications.

    • Open Techniques: Performed during laparotomy, allowing direct visualization and precise sampling:

    • Skin Biopsy Punch: Can be used to obtain small biopsy samples from the liver edge.

    • Guillotine Technique: Involves placing a suture around a small pedicle of liver tissue and ligating it, then excising the tissue distal to the ligature. Provides a wedge-shaped sample.

    • Laparoscopic Procedures: Minimally invasive approach with quicker recovery times.

    • Cup Biopsy Forceps: Used to grasp and excise small pieces of superficial liver tissue.

    • Tru-Cut Needles: Advanced laparoscopically for accurate core biopsies.

    • Pre-formed loop sutures in Guillotine technique: Allows for laparoscopic application of the guillotine method for larger samples.

  • Laparoscopic Biopsy: Techniques and instruments used outlined and visual details provided in the course material, emphasizing precision guided by endoscopic visualization.

Partial Lobectomy

  • Indications for Partial Lobectomy: The removal of a segment of a liver lobe is performed for a variety of localized conditions:

    • Biopsy: To obtain a large, representative tissue sample for definitive diagnosis when smaller biopsies are insufficient.

    • Neoplasia: Excision of localized primary or metastatic tumors involving only a portion of a lobe.

    • Trauma: Removal of devitalized or severely hemorrhaging portions of a liver lobe that cannot be repaired.

    • Abscess: Excision of localized liver abscesses.

    • Cysts: Removal of symptomatic or enlarging liver cysts.

  • Suture Techniques: Methods for achieving hemostasis and closing the transected liver parenchyma:

    • Overlapping Sutures: Various patterns such as mattress sutures or continuous interlocking sutures can be used to control bleeding from the cut surface.

    • Stapling Technique involving Thoracoabdominal Stapler (TA 55 PREMIUM (TM) 3.5 Loading Unit): These staplers utilize multiple rows of titanium staples to simultaneously transect tissue and achieve hemostasis and biliostasis.

    • Underlines staple sizes and their applications: Different staple leg lengths (e.g., 3.5 mm, 4.8 mm) are chosen based on tissue thickness to ensure proper tissue compression and hemostasis.

Surgery of the Extrahepatic Biliary System

  • Procedures Defined: Terminology and execution of common biliary surgeries:

    • Cholecystotomy: Surgical incision into the gallbladder, typically for removal of gallstones, flushing, or obtaining bile samples for culture. It is less commonly performed than a cholecystectomy due to risk of leakage.

    • Cholecystectomy: Complete surgical removal of the gallbladder. This is the definitive treatment for many gallbladder diseases, such as mucoceles, necrotizing cholecystitis, and some tumors.

    • Choledochotomy: Surgical incision into the common bile duct, usually performed to remove obstructions like choledocholiths or inspissated bile, or to explore the duct lumen.

    • Cholecystoduodenostomy: Surgical creation of a permanent communication (anastomosis) between the gallbladder and the duodenum, diverting bile flow directly into the small intestine, bypassing an obstructed common bile duct.

Biliary Mucoceles

  • Etiopathogenesis: The precise cause is complex and often multifactorial:

    • Unclear, involves:

    • Hyperplasia of mucus-secreting cells: An increase in the number of goblet cells lining the gallbladder, leading to excessive mucus production.

    • Excessive mucus secretion: Abnormally high production of thick, gelatinous mucus.

    • Altered gallbladder motility: Impaired contraction and emptying of the gallbladder, leading to bile stasis.

    • Inspissated bile accumulation leading to potential rupture: The combination of thick mucus and stagnant bile forms a dense, semi-solid material that distends the gallbladder and increases pressure, predisposing it to rupture.

    • Clinical features noted in 50% of cases grossly and more than 70% histologically, possibly associated with cholecystitis: Suggests that inflammation of the gallbladder (cholecystitis) is often present concurrently with or precedes mucocele formation.

Signalment & Clinical Signs

  • Demographics:

    • Older dogs (average age 9 years), predominantly small and medium breeds (Shelties, Cocker Spaniels, Shetland Sheepdogs, Miniature Schnauzers) have a higher predisposition.

  • Clinical Signs: Can be acute or chronic and subtle:

    • None: Approximately 23% of cases may be asymptomatic or incidental findings on imaging.

    • Vomiting: Reported in 70% of affected dogs, often intractable.

    • Anorexia: Affects 65% of dogs, indicating systemic illness.

    • Lethargy: Present in 65% of dogs, a non-specific sign of illness.

    • Polyuria/Polydipsia (PU/PD): Occurs in 27% of cases, potentially related to secondary effects on renal function or systemic inflammatory response.

    • Diarrhea: Seen in 12.5% of dogs.

Physical Examination & Laboratory Data

  • Examination Findings: Key findings on physical exam include:

    • Abdominal Pain: Ranging from mild discomfort to severe acute pain upon palpation of the cranial abdomen.

    • Icterus: Yellow discoloration of mucous membranes, sclera, and skin, indicating hyperbilirubinemia due to cholestasis or biliary obstruction.

    • Fever (>102.7°F [39.3°C]): Indicative of systemic inflammation or infection, particularly if concurrent cholecystitis or peritonitis is present.

  • Biochemical Abnormalities: Liver enzymes and bilirubin are commonly elevated:

    • Elevated Alkaline Phosphatase (ALP): A common indicator of cholestasis or drug induction.

    • Elevated Alanine Aminotransferase (ALT): Suggests hepatocellular damage.

    • Elevated gamma-Glutamyl Transferase (GGT): Also an indicator of cholestasis, often increasing in conjunction with ALP.

    • Increased Total Bilirubin: Indicates impaired bile flow or severe liver dysfunction.

Diagnostic Imaging

  • Methods: Imaging is crucial for confirming a mucocele and assessing its severity:

    • Survey Radiographs: May show hepatomegaly or a gas pattern suggestive of emphysematous cholecystitis, but are often non-diagnostic for mucoceles themselves.

    • Ultrasonography: The most sensitive and specific diagnostic tool for biliary mucoceles.

    • Indicators include enlarged gallbladder with immobile echogenic bile; characteristic striated or stellate patterns known as "Kiwi sign" (due to the layered appearance of the mucus).

    • Recent studies indicate variable sensitivity in identifying gallbladder rupture during assessment, so the absence of a rupture on ultrasound does not definitively rule it out. Other signs such as pericholecystic fluid, hyperechoic fat, and free abdominal fluid should be evaluated.

Treatment Options for Biliary Mucoceles

  • Medical Management: Reserved for specific cases where surgery is not immediately indicated.

    • Only if asymptomatic or incidental finding; involves choleretics (e.g., ursodeoxycholic acid) to promote bile flow, liver protectants, and monitoring of progression with serial ultrasounds.

  • Cholecystectomy: The treatment of choice for symptomatic mucoceles or those with risk of rupture.

    • Surgical removal of the gallbladder.

    • Confirm patency of bile duct: After cholecystectomy, it's crucial to ensure the common bile duct is patent by passing a catheter or flushing saline to avoid iatrogenic obstruction.

    • Culture bile if not on antibiotics: Intraoperative bile samples should always be collected for bacterial culture and sensitivity testing, especially if there are signs of infection, to guide antibiotic therapy.

Indications for Cholecystectomy

  • Medical conditions warranting cholecystectomy include:

    • Necrotizing cholecystitis: Severe inflammation leading to gallbladder wall necrosis.

    • Chronic cholecystitis: Persistent inflammation that has not responded to medical therapy.

    • Biliary mucocele: Symptomatic mucoceles or those at high risk of rupture.

    • Cholelithiasis: Symptomatic gallstones or those causing obstruction.

    • Neoplasia: Tumors originating in or involving the gallbladder.

    • Trauma: Irreparable injury to the gallbladder.

Complications of Cholecystectomy

  • Potential issues include: Post-operative complications can be serious and require prompt recognition and intervention.

    • Bile Peritonitis: The most significant and life-threatening complication, resulting from bile leakage into the abdominal cavity.

    • Due to failure to ligate cystic duct adequately: The cystic duct must be securely ligated or stapled to prevent leakage.

    • Failure to recognize and ligate smaller accessory bile ducts entering cystic duct: Small, often overlooked ducts can be a source of leakage.

    • Bleeding related to failure to ligate cystic artery: Inadequate ligation of the cystic artery can lead to significant hemorrhage.

Biliary Obstruction Management

  • Types of Obstruction: Understanding the location and cause is crucial for choosing the correct surgical approach.

    • Intraluminal: Obstruction originating from within the lumen of the bile duct.

    • Includes diseases such as inflammatory disease or presence of choleliths/choledocholiths (gallstones within the bile ducts), neoplasia (tumors growing within the duct), or inspissated bile and parasites (e.g., liver flukes).

    • Extraluminal: Obstruction caused by compression from outside the bile duct.

    • Commonly linked to pancreatic or duodenal diseases, such as pancreatitis, pancreatic neoplasia (e.g., adenocarcinoma), or duodenal masses/strictures.

  • Choledochotomy: Surgical incision into the dilated common bile duct.

    • Used for incisions into dilated common bile duct; applicable for choledocholithiasis and biliary sludge cases; allows for removal of obstructions and flushing of the duct.

Bile Duct Stenting

  • Intended for relieving obstructions caused by extraluminal compression (e.g., inoperable pancreatic tumors) by providing a passageway for bile flow.

  • Involves placing and suturing a catheter (stent) into the bile duct for temporary relief of obstruction, often as a palliative measure.

Biliary Diversion Procedures

  • Indicative for irreparable obstructions or injuries to common bile duct when direct repair is not feasible or likely to fail.

    • Includes:

    • Cholecystoenterostomy: A general term for creating an anastomosis between the gallbladder and any part of the intestine.

    • Cholecystoduodenostomy: Anastomosis of the gallbladder to the duodenum (most common).

    • Cholecystojejunostomy: Anastomosis of the gallbladder to the jejunum.

Complications of Biliary Diversion

  • Possible Complications:

    • Leakage (particularly cats): Anastomotic breakdown or leakage of bile from the surgical site is a severe complication, especially critical in cats where the common bile duct shares a common opening with the pancreatic duct, making pancreatic complications common. Correlates with high morbidity and mortality rates, often due to underlying conditions and severe inflammatory responses.

    • Chronic vomiting in dogs: Associated with ascending infections (bacteria from the intestine ascending into the biliary tree), or bleeding at the stoma site from the surgically created anastomosis.

Bile Peritonitis

  • Etiologies include trauma (e.g., to the gallbladder or bile ducts), spontaneous rupture of bile duct (e.g., secondary to a mucocele or obstruction), or iatrogenic causes (e.g., surgical error during cholecystectomy).

  • Diagnosis: Acute abdominal pain, vomiting, lethargy, and potentially rapid progression to septic shock.

    • Based on abdominal effusion assessment comparing fluid and serum bilirubin levels; positive if fluid bilirubin concentration is >=2 times the serum bilirubin concentration. This ratio is a strong indicator of bile leakage.

    • Diagnostic procedures such as abdominocentesis, ultrasound-guided aspiration, or diagnostic peritoneal lavage (DPL) are utilized to obtain fluid for analysis.

  • Prognosis: Highly dependent on whether the bile is sterile or infected.

    • Sterile bile results in chemical peritonitis
      —generally well-tolerated with good prognosis if underlying cause is resolved and the leaked bile is removed and source sealed. The irritation is primarily from bile acids.

    • Infected bile leads to septic peritonitis
      —prognosis is guarded to poor with elevated morbidity and mortality due to the combined effects of bacterial infection and bile irritation. This constitutes a severe surgical emergency.