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Sturm's Conoid

What it is

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The Optics of Astigmatism

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Components of the Conoid of Sturm

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The Circle of Least Confusion (CoLC)

• SE = (Sphere) + (Cylinder / 2)
• A spherical lens equal in power to the SE will move the entire conoid so the CoLC falls on the retina, giving the "best blur" - but not sharp vision
• The smaller the CoLC, the better the residual uncorrected vision
• To achieve true clear vision, the conoid must be collapsed to a single point on the retina - which requires a cylindrical (or toric) corrective lens

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Types of Astigmatism by Position of the Conoid Relative to the Retina

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Clinical Relevance

• Astigmatism is not correctable by accommodation - because accommodation changes lens curvature approximately equally in both meridians, it cannot selectively power up one meridian over the other
• Correction requires a cylindrical lens (or toric lens/implant) aligned to the axis of the flat meridian
• Surgical options (per Kanski's Clinical Ophthalmology) include limbal relaxing incisions/arcuate keratotomy, PRK/LASEK (up to 3D), LASIK (up to 5D), and toric intraocular lens implants
• The Maddox rod test, fan chart (clock dial), and Jackson cross-cylinder are clinical tools used to locate the axis of the conoid and determine the cylindrical correction needed

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Sturm's Conoid

Definition

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Formation

• The more curved (more powerful) meridian focuses light nearer to the lens → forms first focal line (perpendicular to this meridian)
• The flatter (less powerful) meridian focuses light farther from the lens → forms second focal line (perpendicular to the first)
• The spindle-shaped figure traced between these two focal lines is the conoid of Sturm

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Components (Label these if drawing a diagram)

First focal     Circle of      Second focal
    line      Least Confusion      line
     |               |               |
     ●━━━━━━━━━━━━━●━━━━━━━━━━━━━●
  (more powerful               (less powerful
    meridian)                    meridian)
        ←——— Focal Interval ———→

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Circle of Least Confusion

• Located midway between the two focal lines
• Corresponds to the spherical equivalent (SE) of the astigmatic error:

  SE = Sphere + (Cylinder ÷ 2)

• A spherical corrective lens equal to the SE moves the CoLC onto the retina → gives "best blur" (best uncorrected vision possible with a sphere alone)
• Not true sharp vision - the conoid must be fully collapsed to a point for that

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Clinical Significance

1. Astigmatism cannot be corrected by accommodation - accommodation increases lens power equally in all meridians
2. A cylindrical lens aligned to the flat meridian collapses the conoid to a single point on the retina
3. In mixed astigmatism, the retina lies within the focal interval (one focal line in front, one behind)
4. The CoLC concept explains why the spherical equivalent gives the "best sphere" prescription when full cylindrical correction is not given

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Types of Astigmatism (based on position of conoid relative to retina)

• Simple myopic - one focal line on retina, one in front
• Simple hyperopic - one focal line on retina, one behind
• Compound myopic - both focal lines in front of retina
• Compound hyperopic - both focal lines behind retina
• Mixed - one in front, one behind (retina cuts through the conoid)

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Acute Pancreatitis

Final Year MBBS Surgery - Long Answer / Short Note

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Definition

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Etiology (Causes) - Mnemonic: "I GET SMASHED"

Gallstones + alcohol = nearly 80% of all cases.

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Pathogenesis

1. Ductal obstruction (gallstone/biliary sludge impacting ampulla of Vater) → increased intraductal pressure → enzyme-rich interstitial fluid accumulation → fat necrosis → inflammatory cytokine release → edema and ischemia
2. Primary acinar cell injury (alcohol, hypertriglyceridemia, ischemia, drugs) → direct toxic effect → intracellular activation of enzymes
3. Defective intracellular transport → proenzymes co-packaged with lysosomal hydrolases → trypsin activation → lysosomal rupture

• Activates prekallikrein → kinin cascade
• Activates Factor XII (Hageman factor) → clotting + complement cascade
• Damages blood vessels → hemorrhage within pancreas

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Clinical Features

• Epigastric pain - sudden onset, severe, constant, radiating to the back (band-like/boring) - cardinal symptom
• Nausea and vomiting (does not relieve the pain - important!)
• Anorexia

• Tachycardia, hypotension (from third-spacing and hypovolemia)
• Fever
• Abdominal tenderness + guarding in the epigastrium
• Abdominal distension (paralytic ileus)
• Jaundice - if common bile duct compressed by gallstone or edematous pancreatic head

• Grey Turner's sign - ecchymosis (bluish discoloration) of the flanks (retroperitoneal hemorrhage tracking to flank)
• Cullen's sign - periumbilical ecchymosis (hemorrhage tracking along falciform ligament)

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Investigations

Blood Tests

Imaging

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Severity Assessment

Revised Atlanta Classification (2012)

Ranson's Criteria (most common exam question)

• Age >55 years
• WBC >16,000/mm³
• Blood glucose >200 mg/dL
• Serum LDH >350 IU/L
• AST >250 IU/L

• Hematocrit fall >10%
• BUN rise >5 mg/dL
• Serum Ca²⁺ <8 mg/dL
• PaO₂ <60 mmHg
• Base deficit >4 mEq/L
• Fluid sequestration >6 L

Score <3 = mild (mortality <1%) | Score ≥3 = severe | Score >6 = mortality ~50%

CT Severity Index (Balthazar score)

• Combines pancreatic inflammation score (0-4 points) + necrosis score (0-6 points)
• CTSI 0-3: mortality 3% | CTSI 4-6: mortality 6% | CTSI 7-10: mortality 17%

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Complications

• Pancreatic necrosis (sterile or infected)
• Pseudocyst (fluid collection enclosed by fibrous wall; develops after 4+ weeks)
• Pancreatic abscess
• Pancreatic fistula

• ARDS (most common pulmonary complication)
• Acute kidney injury
• Septic shock
• DIC
• Hypocalcemia / hypoglycemia
• Ileus

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Treatment

Conservative (cornerstone of management)

1. NPO (nil by mouth) - rests the pancreas
2. Aggressive IV fluid resuscitation - isotonic crystalloid (Ringer's lactate preferred); shock is the principal cause of death in the first 48h
3. Analgesia - Pethidine (meperidine) is the drug of choice; morphine is contraindicated (increases sphincter of Oddi tone)
4. NG tube - for persistent vomiting and to suppress pancreatic stimulation by removing gastric acid from the duodenum
5. Oxygen supplementation if PaO₂ <70 mmHg
6. Electrolyte correction - especially calcium, potassium
7. Monitoring - pulse, BP, urine output, CVP, ABG

Nutrition

• Mild AP: oral feeding restarted when pain subsides
• Severe AP: enteral nutrition via nasojejunal tube is preferred over TPN - maintains gut barrier, reduces infections

Antibiotics

• NOT routine; only for confirmed infected necrosis or sepsis (imipenem/meropenem)

ERCP

• Indicated within 24-72h in acute biliary pancreatitis with cholangitis or persistent biliary obstruction (not for uncomplicated gallstone pancreatitis)

Surgery / Intervention

• Cholecystectomy - done in the same admission (when recovered) for gallstone pancreatitis to prevent recurrence
• Necrosectomy (open or minimally invasive step-up approach) - for infected pancreatic necrosis not responding to antibiotics
• Drainage of pseudocyst if symptomatic/infected (endoscopic, radiological, or surgical)

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Key Exam Points to Remember

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Pancreatic Pseudocyst

Final Year MBBS Surgery - Short Note / Long Answer

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Definition

Key distinguishing feature: No epithelial lining (true cysts have epithelial lining)

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Etiology / Causes

1. Acute pancreatitis - most common; arises from an acute peripancreatic fluid collection (APFC) that fails to resolve
2. Chronic pancreatitis - especially alcoholic chronic pancreatitis (~25% develop pseudocysts)
3. Pancreatic trauma - duct disruption from blunt abdominal injury

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Pathogenesis

• Disruption or leakage from the main pancreatic duct or a side branch releases enzyme-rich pancreatic juice
• This fluid accumulates in the lesser sac or peripancreatic tissue
• Over 4-8 weeks, a fibrous/granulation tissue capsule forms around it
• More than 50-70% communicate with the main pancreatic duct
• The fibrotic reaction requires at least 4 weeks - a collection seen before 4 weeks is NOT yet a pseudocyst (it is an acute peripancreatic fluid collection / APFC)

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Incidence

• Occurs in 5-15% of patients with acute pancreatitis
• ~25% of patients with chronic pancreatitis
• Most common in the lesser sac (behind the stomach)
• Usually single; occasionally multiple

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Clinical Features

Symptoms

• Persistent epigastric pain - most common symptom (constant or colicky)
• Nausea and vomiting (gastric compression)
• Early satiety, weight loss
• Persistent elevation of serum amylase/lipase after an attack of pancreatitis should raise suspicion

Signs

• Palpable epigastric mass - rounded, smooth, non-tender (if uncomplicated); may be fluctuant
• Jaundice - if bile duct is compressed by a pseudocyst in the head of the pancreas
• Features of the underlying pancreatitis

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Investigations

Blood Tests

Imaging (KEY)

Cyst Fluid Analysis (to distinguish from cystic neoplasm)

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Natural History

• Up to 70% resolve spontaneously, particularly if:
  • Small (<4 cm)
  • Located in the tail
  • No ductal communication or obstruction
• Large (>6 cm), thick-walled, long-standing (>12 weeks), or those arising in chronic pancreatitis are less likely to resolve spontaneously
• Complications develop in 20-40% of cases

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Complications

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Treatment

Indications for Intervention

1. Symptomatic (pain, mass, vomiting, jaundice)
2. Complications develop (infection, hemorrhage, rupture)
3. Rapidly enlarging pseudocyst
4. Cannot be differentiated from a cystic neoplasm

Asymptomatic pseudocysts - observe conservatively; most will resolve

Wait for Maturation

• Intervene only after ≥4-6 weeks (wall must mature into firm fibrous tissue for safe anastomosis; earlier drainage leads to higher leak rates)

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Drainage Options

1. Endoscopic Drainage (First-line, preferred)

• EUS-guided transmural drainage (cystogastrostomy or cystoduodenostomy):
  • Puncture through posterior gastric or duodenal wall into cyst under EUS guidance
  • Double pigtail stent placed (one end in cyst, other in stomach lumen)
  • Success rate: 80-90%
  • For pseudocysts within 1 cm of stomach or duodenum
• Transpapillary drainage (via ERCP): for pseudocysts communicating with the main pancreatic duct in the head

2. Surgical Drainage (Gold standard, recurrence rate <5%)

• Cystogastrostomy - posterior wall of stomach sutured to anterior wall of cyst (for cysts adherent to posterior stomach wall) - most common surgical procedure
• Roux-en-Y Cystojejunostomy - most versatile; for cysts penetrating transverse mesocolon, paracolic gutters, or lesser sac
• Cystoduodenostomy - for cysts in the head adherent to the duodenum
• Can be open or laparoscopic

Internal drainage is always preferred over external drainage

3. Percutaneous Drainage - Generally AVOIDED

• High recurrence rate
• Risk of pancreaticocutaneous fistula (if duct communication present)
• Reserved only for infected pseudocyst causing sepsis (as a temporizing measure)

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Summary Table: Drainage Methods

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Exam High-Yield Points

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Cystogastrostomy - Short Note

What and Why

Works because: ~35% of pseudocysts lie in the lesser sac, directly fused against the posterior gastric wall - making the stomach the nearest and most natural drainage route.

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Steps of the Operation (Open Surgical)

STEP 1 — ANTERIOR GASTROTOMY
         ↓
STEP 2 — IDENTIFY BULGE in posterior gastric wall
         (confirm by needle aspiration → amylase-rich fluid)
         ↓
STEP 3 — INCISE POSTERIOR GASTRIC WALL + PSEUDOCYST WALL
         (electrocautery, 6-8 cm opening)
         ↓
STEP 4 — EVACUATE cyst contents + debris + send for cytology/biopsy
         ↓
STEP 5 — SUTURE anastomosis
         (locking running stitch, 2-0 absorbable monofilament,
          full thickness of posterior gastric wall + cyst wall)
         ↓
STEP 6 — CLOSE anterior gastrotomy in two layers

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Key Technical Points

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Endoscopic Cystogastrostomy (EUS-guided) - Modern Approach

EUS probe identifies pseudocyst through posterior gastric wall
        ↓
EUS-guided needle puncture through posterior gastric wall into cyst
        ↓
Guidewire coiled inside cyst cavity
        ↓
Tract dilated (balloon dilatation)
        ↓
Double-pigtail stent placed
  (one end in cyst, other end in stomach lumen)
        ↓
Cyst drains continuously into stomach → collapses over weeks

• Success rate: 80-90%
• No surgical incision needed
• Now considered first-line where available and cyst is within 1 cm of stomach wall

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Comparison: Open vs Endoscopic Cystogastrostomy

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One-Line Summary for Exam

Cystogastrostomy = surgical (or endoscopic) creation of a permanent opening between the posterior wall of the stomach and the anterior wall of an adherent pseudocyst, allowing the cyst to drain internally into the stomach lumen.

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Common Bile Duct (CBD) Stones - Choledocholithiasis

Final Year MBBS Surgery | SRB-style Answer

Note: SRB's Manual of Surgery is not available in this library. This answer follows the same structure and style as SRB, drawing from Sabiston, Bailey & Love, Schwartz, and Mulholland & Greenfield - all of which SRB references extensively.

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Definition

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Types of CBD Stones

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Signs and Symptoms

Asymptomatic

• Many stones are incidental findings on USG or intraoperative cholangiogram

Symptomatic - Clinical Features

1. Pain

• Right upper quadrant / epigastric biliary colic - colicky, radiating to back or right shoulder
• Pain is important distinguishing feature from malignant obstruction (which is usually painless)
• Onset is acute due to sudden ductal distension

2. Obstructive Jaundice

• Yellow discolouration of sclera and skin
• Dark urine (bilirubinuria - "tea-coloured")
• Pale/clay-coloured stools (absent bile pigments in stool)
• Pruritus (bile salt deposition in skin)
• Jaundice in CBD stone is typically painful, fluctuating (stone may intermittently shift) - distinguishes it from malignant obstruction (painless, progressive)

3. Fever / Rigors

• Suggests superimposed ascending cholangitis (bacterial infection of bile ducts)
• Fever with chills - due to bacteraemia

4. Charcot's Triad (Ascending Cholangitis)

Fever + Jaundice + Right upper quadrant pain

• Present in <50% of cholangitis cases
• Classic triad described by Jean Martin Charcot (1877)

5. Reynolds' Pentad (Severe/Suppurative Cholangitis)

Charcot's Triad + Hypotension + Altered mental status

• Indicates septic shock - ominous sign
• Mortality approaches 100% without immediate treatment

6. Other Features

• Nausea and vomiting
• Hepatomegaly (enlarged, tender liver due to back-pressure)
• Palpable gallbladder - usually NOT present with CBD stones (Courvoisier's Law: palpable gallbladder + jaundice = malignant obstruction, NOT stone; stone causes fibrosis/shrinkage of GB)
• Complications: acute pancreatitis (stone at ampulla), liver abscess

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Investigations

Blood Tests

Imaging

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ASGE Risk Stratification for CBD Stone

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Treatment

Principles

1. Clear the CBD of all stones
2. Treat/prevent cholangitis
3. Remove the gallbladder (cholecystectomy) to prevent recurrence

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A. Endoscopic Treatment - ERCP + Sphincterotomy (First-line)

1. ERCP performed under fluoroscopy
2. Endoscopic sphincterotomy (EST) - incision of the sphincter of Oddi
3. Stone extraction with Dormia basket or balloon catheter sweep
4. For large stones: mechanical lithotripsy (crushing within basket), or laser / electrohydraulic lithotripsy (EHL)
5. If duct cannot be cleared completely: biliary stent placed temporarily

• Clears duct in >75% in first attempt, >90% with repeat
• Followed by laparoscopic cholecystectomy in the same admission

• Cholangitis
• Ongoing biliary pancreatitis
• High operative risk patients

• Post-ERCP pancreatitis (most common)
• Haemorrhage (post-sphincterotomy)
• Perforation
• Cholangitis

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B. Surgical Treatment

1. Laparoscopic Common Bile Duct Exploration (LCBDE) + Cholecystectomy

• Performed at the same time as laparoscopic cholecystectomy
• Transcystic approach (for stones <8 mm): scope passed through cystic duct
• Choledochotomy approach (for stones >1 cm or CBD >1 cm diameter):
  • Longitudinal incision on anterior CBD (choledochotomy)
  • Stones extracted with Fogarty catheter, Dormia basket, or choledochoscope
  • CBD closed primarily if all stones cleared
  • Closed over a T-tube if concern for retained/recurrent stones

2. Open CBD Exploration

• ERCP fails
• Altered anatomy (previous Roux-en-Y bypass, duodenal diverticula)
• Large impacted stones / Mirizzi syndrome
• Biliary-enteric fistula

1. Kocher manoeuvre to expose CBD
2. Supraduodenal longitudinal choledochotomy between two stay sutures
3. Stone extraction with Fogarty catheter balloon, forceps, or rigid choledochoscope
4. T-tube placed if concern for residual stone / small duct

T-Tube (after choledochotomy)

T-tube placed in CBD after exploration
         ↓
Short limb in CBD lumen
Long limb exits through abdominal wall
         ↓
Postop Day 4-5: T-tube cholangiogram
(confirms duct clearance before capping tube)
         ↓
Retained stone found on cholangiogram?
→ Percutaneous extraction via T-tube tract (after 6 weeks)
         ↓
All clear: T-tube removed at 2-4 weeks

3. Biliary-Enteric Bypass (for recurrent/unresectable stones or distal stricture)

• Choledochoduodenostomy - anastomosis of CBD to duodenum
• Roux-en-Y hepaticojejunostomy - CBD to jejunum (when duodenum not accessible)
• Indicated for: multiple stones, recurrent stones with distal stricture, failed ERCP

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C. Management of Cholangitis (Complication)

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Summary of Treatment Algorithm

CBD Stone Suspected
        ↓
USG: Dilated CBD / stone seen?
        ↓
Risk Stratify (ASGE)
   ↓              ↓              ↓
High Risk      Moderate      Low Risk
ERCP first    MRCP/EUS       Lap Chole
                 ↓              + IOC
          CBD stone? → ERCP
                         ↓
               Stone cleared?
          YES → Lap Chole (same admission)
          NO  → Open CBDE / T-tube / Biliary bypass

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Key Exam Points

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Obstructive Jaundice

Final Year MBBS Surgery - Long Answer

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Definition

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Classification of Jaundice (Surgical Context)

Surgery deals primarily with post-hepatic (obstructive) jaundice

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Pathophysiology

Bile cannot enter duodenum
        ↓
Conjugated bilirubin regurgitates into blood
        ↓
Bilirubinaemia (conjugated/direct type)
        ↓
Filtered by kidney → Bilirubinuria (dark urine - "Coca-Cola urine")
        ↓
No bile pigments reach gut → Pale/clay-coloured stools
                              No urobilinogen in urine
        ↓
Bile salts accumulate in blood → Pruritus (bile salt skin deposits)
                                  Bradycardia (bile salt vagal effect)
        ↓
Absence of bile in gut → Malabsorption of fat-soluble vitamins (A, D, E, K)
                          ↓
                   Vitamin K deficiency → Impaired clotting (↑PT/INR) → Bleeding tendency
        ↓
Prolonged obstruction → Hepatocellular damage → Secondary biliary cirrhosis

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Causes of Obstructive Jaundice

Luminal (Within the Duct)

• CBD stones (choledocholithiasis) - most common benign cause
• Parasites (Ascaris, Clonorchis)
• Blood clots (haemobilia)

Mural (In the Wall of the Duct)

• Cholangiocarcinoma (bile duct cancer)
• Carcinoma of the ampulla of Vater (ampullary carcinoma)
• Benign biliary strictures (post-traumatic, post-cholecystectomy injury)
• Primary sclerosing cholangitis (PSC)
• Choledochal cyst
• Biliary atresia (in neonates)

Extrinsic Compression (Outside the Duct)

• Carcinoma of head of pancreas (most common malignant cause)
• Chronic pancreatitis / pseudocyst
• Enlarged lymph nodes (porta hepatis) - lymphoma, metastases
• Mirizzi syndrome (stone in Hartmann's pouch compressing CBD)
• Duodenal diverticulum

Mnemonic for Causes: "Stones, Strictures, Carcinomas"

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Clinical Features

Symptoms

1. Jaundice

• Yellow discolouration of skin, sclera, mucous membranes
• Fluctuating jaundice = CBD stone (stone may move)
• Progressive, deepening jaundice = malignancy (pancreatic/cholangiocarcinoma)

2. Dark Urine

• "Coca-Cola" or "tea-coloured" - conjugated bilirubin excreted by kidney
• Positive urine bilirubin test

3. Pale / Clay-Coloured Stools

• Absent bile pigments in stool (no stercobilinogen)

4. Pruritus (Itching)

• Due to bile salt deposition in skin; often severe and generalised
• May precede visible jaundice
• Scratch marks visible on skin

5. Pain

• Biliary colic / RUQ pain → suggests stone (painful obstructive jaundice)
• Painless, progressive jaundice → strongly suggests malignancy (pancreatic ca, cholangiocarcinoma)

6. Fever / Rigors

• Suggests ascending cholangitis (infection superimposed on obstruction)
• Charcot's Triad: Fever + Jaundice + RUQ pain = cholangitis

7. Weight Loss / Anorexia / Cachexia

• Suggests underlying malignancy

8. Nausea, Vomiting

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Signs

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Courvoisier's Law (High-Yield Exam Point)

"If the gallbladder is palpably enlarged in the presence of jaundice, the jaundice is unlikely to be due to a stone"

• Stone → chronic inflammation → fibrosed, shrunken, non-distensible gallbladder → NOT palpable
• Malignancy (Ca head pancreas) → slow progressive obstruction → distensible gallbladder → palpably enlarged, non-tender

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Investigations

Blood Tests

Key LFT Pattern in Obstructive Jaundice: High bilirubin (conjugated) + Markedly high ALP + Mildly raised AST/ALT

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Imaging

USG (first-line: dilated ducts? cause visible?)
        ↓
CECT (staging, vascular anatomy, resectability)
        ↓
MRCP (non-invasive biliary mapping)
        ↓
ERCP (if therapeutic intervention needed)
or PTC (if hilar block / ERCP failed)

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Treatment

A. Preoperative Preparation (Critical in Jaundice)

Surgery in jaundiced patients carries ~20% mortality - proper pre-op preparation is essential

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B. Definitive Treatment - Based on Cause

1. CBD Stones (Benign, most common)

• ERCP + Endoscopic Sphincterotomy + Stone extraction (first-line)
• Followed by laparoscopic cholecystectomy in the same admission
• If ERCP fails: Laparoscopic or Open CBD exploration (Choledochotomy ± T-tube)

2. Carcinoma Head of Pancreas (Malignant)

• Resectable: Whipple's operation (Pancreaticoduodenectomy)
  • En bloc removal of: head of pancreas + duodenum + distal CBD + gallbladder + part of stomach
• Unresectable / Palliative:
  • Endoscopic stenting (ERCP - plastic or metallic self-expanding stent) - biliary bypass
  • Surgical bypass: Choledochojejunostomy (CBD → jejunum) + Gastrojejunostomy
  • PTC with external or internal drain

3. Cholangiocarcinoma (Bile Duct Cancer)

• Hilar (Klatskin tumour): Resection of bile duct confluence + hepaticojejunostomy ± liver resection
• Distal CBD: Whipple's operation
• Palliative: Biliary stenting (ERCP or PTC); Photodynamic therapy

4. Ampullary Carcinoma

• Whipple's operation (best prognosis of periampullary cancers)

5. Benign Strictures (Post-op bile duct injury)

• Endoscopic balloon dilatation + stenting
• Surgical: Roux-en-Y hepaticojejunostomy (definitive)

6. Mirizzi Syndrome

• Cholecystectomy ± CBD repair

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C. Endoscopic / Percutaneous Palliation

• Plastic stent: cheaper, blocks after 3-4 months
• Self-expanding metal stent (SEMS): lasts longer (6-12 months); preferred for malignant obstruction with limited prognosis

• Used when ERCP not accessible (hilar block, altered anatomy)
• External drain or internal-external stent placed

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Complications of Untreated Obstructive Jaundice

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Differentiating Stone vs. Malignancy (Exam Favourite)

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Summary Box for Quick Revision

OBSTRUCTIVE JAUNDICE
        ↓
Conjugated bilirubin ↑ | ALP ↑↑↑ | GGT ↑ | AST/ALT mildly ↑
Dark urine | Pale stools | Pruritus | Coagulopathy
        ↓
Causes: Stones (painful, fluctuating)  vs  Malignancy (painless, progressive)
        ↓
Courvoisier's sign = palpable GB = malignancy
Charcot's triad = fever+jaundice+pain = cholangitis
Reynolds' pentad = Charcot's + shock + altered GCS = suppurative cholangitis
        ↓
Ix: USG → CECT → MRCP → ERCP/PTC
        ↓
Rx: Preop prep (Vit K, IV fluids, antibiotics)
    Stones → ERCP + Lap Chole
    Ca Pancreas resectable → Whipple's
    Ca Pancreas unresectable → Stenting / Bypass

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