🏥 High-Yield Points: Gallbladder & Pancreas

🫀 GALLBLADDER

Anatomy

• Pear-shaped sac: 7–10 cm long, capacity 30–50 mL; when obstructed can distend to 300 mL
• Divided into: fundus (most smooth muscle), body (most elastic tissue), infundibulum, neck
• Hartmann's pouch — mucosal outpouching at the neck; gallstones commonly lodge here
• Calot's triangle (hepatocystic triangle): bounded by cystic duct, common hepatic duct, and inferior liver margin — safe dissection here is the key to laparoscopic cholecystectomy
• Cantlie's line — vertical plane from gallbladder fossa to IVC; divides liver into right and left lobes
• Cystic artery (usually from right hepatic artery) is the main blood supply; anomalies are common — critical to identify before clipping

Physiology

• Fasting: 80% of hepatic bile stored in the gallbladder
• Gallbladder mucosa = greatest absorptive power per unit area of any structure in the body — concentrates bile 10-fold
• Mucosal cells secrete mucus glycoproteins (protect mucosa + "white bile" in hydrops) and H⁺ ions (acidification prevents calcium salt precipitation → prevents stone formation)
• CCK (from duodenal enteroendocrine cells) stimulates gallbladder to empty 50–70% of its contents within 30–40 min after a meal
• Vagus nerve = stimulates contraction; splanchnic sympathetics = inhibitory
• Anticholinergic drugs (e.g. atropine) → gallbladder relaxation; Cholinergic drugs (nicotine, caffeine) → contraction
• Motilin mediates phase II MMC-related fasting gallbladder emptying

Gallstone Disease

• Most common GI indication for surgery in the Western world
• Types:
  • Cholesterol stones (~80%) — require: cholesterol supersaturation + nucleation + impaired motility
  • Pigment stones — Black (hemolysis, cirrhosis, ileal disease) vs. Brown (biliary infection/stasis)
• Risk factors (5 F's): Fat, Female, Forty, Fertile, Fair (+ Family history, rapid weight loss, TPN, Crohn's disease, ileal resection)
• Natural history: 80% of gallstones are asymptomatic — only 2–3% develop symptoms per year
• Biliary colic: RUQ/epigastric pain, post-fatty meal, lasting 15 min to 6 h — resolves spontaneously; pain > 24 h → suspect impacted stone or acute cholecystitis
• Investigation of choice: Abdominal ultrasound (sensitivity >95% for stones >2 mm)
• Treatment: Laparoscopic cholecystectomy is the gold standard; ~90% rendered symptom-free

Acute Cholecystitis

• Caused by obstruction of cystic duct by stone (~90% calculous; 10% acalculous)
• Murphy's sign — inspiratory arrest on RUQ palpation
• Charcot's triad (ascending cholangitis): fever/rigors, jaundice, RUQ pain
• Reynolds' pentad (severe cholangitis): Charcot's triad + hypotension + altered consciousness
• Tokyo Guidelines severity grading used for acute cholangitis and cholecystitis
• Mirizzi syndrome — extrinsic common hepatic duct obstruction by stone in cystic duct/Hartmann's pouch
• Treatment: Early laparoscopic cholecystectomy (within 72 h) preferred; broad-spectrum antibiotics
• Acalculous cholecystitis: ICU patients, post-major surgery/trauma/burns/TPN; 10% of all acute cholecystitis; higher mortality (~30%); treat with percutaneous cholecystostomy if unfit for surgery (90% respond)

Gallbladder Pathology — High Yield

Choledochal (Biliary) Cysts

• Incidence: 1:100,000–1:150,000 (Western); up to 1:1000 (East Asia)
• Female : Male = 3–8 : 1

• 90% have anomalous pancreaticobiliary duct junction (long common channel >1.5 cm) → reflux of pancreatic juice into biliary tract → inflammation + cyst

• Classic triad: Abdominal pain + jaundice + palpable mass (seen in <50%)
• Todani classification: Type I (most common, fusiform CBD dilation), Type IV (most common in adults, multiple intra + extrahepatic), Type V (Caroli's disease — intrahepatic only)
• Risk of malignancy (cholangiocarcinoma) increases with age → surgical excision is mandatory

Carcinoma of the Gallbladder

• 6th most common GI malignancy in Western countries
• Female : Male = 2–6 : 1; peak incidence: 7th decade
• Median survival: ~6 months; 5-year survival: 5% overall; >80% if incidentally found T1 tumor
• Risk factors:
  • Gallstones (present in 85% of cases; but <3% of stone patients develop cancer)
  • Stones >3 cm → 10-fold increased risk
  • Gallbladder polyps >10 mm
  • Porcelain gallbladder (~10% risk)
  • Anomalous pancreaticobiliary junction, PSC, carcinogens (azotoluene, nitrosamines)
• Pathology: 80–90% adenocarcinoma
• Staging (T-stage) drives management:
  • T1a (lamina propria only) → cholecystectomy alone sufficient
  • T1b (muscularis) → simple cholecystectomy may be sufficient
  • T2+ → re-resection with 2 cm liver margin + portal lymphadenectomy
  • T3/T4 → consider resection if R0 possible

Primary Sclerosing Cholangitis (PSC)

• Strong association with IBD (especially UC) — present in 70–80% of PSC cases
• ERCP/"beaded" appearance on cholangiography (multifocal strictures)
• High risk of cholangiocarcinoma (10–30% lifetime risk)
• Definitive treatment: Liver transplantation

🫁 PANCREAS

Anatomy & Embryology

• Ventral pancreatic bud → head and uncinate process; dorsal bud → body, tail, and most of the head
• Pancreas divisum (failure of fusion of ventral + dorsal ducts, ~7% of population) — most common congenital pancreatic anomaly; associated with recurrent pancreatitis
• Annular pancreas — ring of pancreatic tissue surrounding the duodenum → duodenal obstruction
• Ectopic (heterotopic) pancreas — most common in stomach, duodenum, jejunum

Physiology

• Secretes 500–800 mL/day of alkaline pancreatic juice
• Amylase: Only pancreatic enzyme secreted in its active form; hydrolyzes starch → glucose, maltose, maltotriose, dextrins
• Proteolytic enzymes secreted as proenzymes: Trypsinogen → Trypsin (by enterokinase from duodenal mucosa); trypsin then activates all other proteases
• SPINK1 (PSTI) — trypsinogen inhibitor in acinar cells; mutations cause familial pancreatitis
• CCK (from duodenal I-cells) + Secretin (from duodenal S-cells in response to acid) → stimulate pancreatic enzyme + bicarbonate secretion
• CATT mnemonic for secretin: Secretin → Secretes biCArbonaTE, inhibits gastric motility

Acute Pancreatitis

• Two most common causes: Gallstones (~40%) + Alcohol (~35%)
• Other causes: Hypertriglyceridemia (Type I, V), hypercalcemia, drugs (thiazides, furosemide, estrogens, steroids, propofol), ERCP, trauma, infections (mumps), hereditary mutations (PRSS1, SPINK1, CFTR)
• Pathophysiology: Premature intra-acinar trypsinogen activation → autodigestion → inflammatory cascade → cytokine release → SIRS → MOF
• Diagnosis: Clinical + amylase/lipase >3× ULN (lipase more sensitive/specific) ± CT if needed
• Severity scoring (Ranson's criteria — at admission):
  • Age >55, WBC >16,000, Glucose >200 mg/dL, LDH >350 IU/L, AST >250 IU/L
  • At 48h: Hct fall >10%, BUN rise >5, Ca²⁺ <8, PaO₂ <60, Base deficit >4, Fluid sequestration >6L
  • Score ≥3 = severe pancreatitis
• CT Severity Index (CTSI) = Balthazar score + necrosis score; score ≥7 = severe
• Revised Atlanta Classification (2012):
  • Mild = no organ failure, no local complications
  • Moderately severe = transient organ failure (<48h) or local complications
  • Severe = persistent organ failure (>48h)
• Local complications:
  • Acute peripancreatic fluid collection (APFC) — first 4 weeks, no wall
  • Pseudocyst — >4 weeks, well-defined wall, homogeneous
  • Acute Necrotic Collection (ANC) — <4 weeks, heterogeneous
  • Walled-off necrosis (WON) — >4 weeks, thick wall
• Infected necrosis: Suspect if fever + clinical deterioration after week 1; CT-guided FNA for diagnosis; management: "step-up" approach — percutaneous/endoscopic drainage first, then minimally invasive necrosectomy (VARD, endoscopic) if needed; open surgery reserved as last resort
• Gallstone pancreatitis: Early ERCP + sphincterotomy if cholangitis or biliary obstruction; cholecystectomy during same admission (or within 2 weeks) to prevent recurrence
• Diabetes: Develops in ~23% of patients after acute pancreatitis (vs. 4–9% general population); screen at follow-up

Chronic Pancreatitis

• Most common cause: Alcohol (70–80% of cases)
• Other causes: Tropical (nutritional), hereditary (PRSS1 gain-of-function mutation), autoimmune, idiopathic (SPINK1, CFTR mutations)
• Pathology: Irreversible parenchymal fibrosis + ductal strictures + calcifications
• Classic triad: Epigastric pain radiating to back + steatorrhea + diabetes
• Steatorrhea only occurs when >90% of exocrine function lost
• Exocrine insufficiency: Fecal elastase-1 — <100 μg/g = pancreatic exocrine insufficiency; >200 = normal
• ERCP = most sensitive test for ductal changes (Cambridge Classification)
• EUS = best for parenchymal changes and early disease
• CT reliable when calcification/duct dilation present; chain-of-lakes pattern = dilated duct with strictures
• "Double duct sign" on ERCP — simultaneous dilation of CBD + pancreatic duct = red flag for pancreatic head carcinoma
• Surgery indications: Intractable pain, biliary/duodenal obstruction, suspicion of malignancy
  • Puestow procedure (lateral pancreaticojejunostomy) — dilated duct (>7 mm)
  • Whipple's (pancreaticoduodenectomy) — head disease, suspected malignancy
  • Frey procedure — combination of head coring + lateral PJ

Pancreatic Carcinoma

• Most common type: Ductal adenocarcinoma (~90%)
• Location: Head (70%), body (20%), tail (10%)
• 5-year survival: Overall ~10%; resectable: ~20–25%
• Risk factors: Smoking (RR 2–3), chronic pancreatitis, T2DM, obesity, hereditary syndromes (BRCA2, Lynch, FAMMM, Peutz-Jeghers), familial pancreatitis (PRSS1)
• Molecular mutations: KRAS (>90%), CDKN2A (p16), TP53, SMAD4/DPC4
• Clinical features:
  • Head → painless progressive jaundice + Courvoisier's sign (palpable non-tender GB)
  • Body/tail → back pain, late presentation, weight loss
  • New-onset DM in elderly → screen for pancreatic cancer
• Courvoisier's law: Palpable non-tender gallbladder + jaundice = NOT gallstones (GB is fibrosed in longstanding stone disease); more likely malignancy
• Imaging: CECT (pancreas protocol) = investigation of choice; CA 19-9 (elevated but not diagnostic alone)
• Resectability criteria:
  • No distant metastases
  • No involvement of SMA, celiac axis, aorta, IVC
  • Portal/SMV involvement: borderline resectable
• Surgery: Whipple's procedure (pancreaticoduodenectomy) for head lesions; distal pancreatectomy ± splenectomy for body/tail
• Most common complication of Whipple's: Delayed gastric emptying; most dangerous: pancreatic fistula/leak
• Adjuvant chemotherapy (gemcitabine ± nab-paclitaxel or FOLFIRINOX) improves survival

Pancreatic Cystic Lesions

Endocrine Tumors (Islet Cell/Neuroendocrine Tumors)

Sources: Schwartz's Principles of Surgery, 11th Ed. (Chapters 32 & 33) | Sabiston Textbook of Surgery — equivalent coverage to Bailey & Love's Short Practice of Surgery. Bailey & Love is not directly available in the library but these texts cover identical surgical curricula.