Basics of Surgery of the Pancreas

1. Surgical Anatomy

• Head - lies within the C-loop of the duodenum; the uncinate process projects posterior to the superior mesenteric vessels
• Neck - overlies the superior mesenteric vein (SMV) and portal vein confluence
• Body - crosses the spine at L1-L2
• Tail - extends to the splenic hilum

• The portal vein forms behind the neck of the pancreas from the confluence of the SMV and splenic vein
• The superior mesenteric artery (SMA) lies just left of the SMV
• The common bile duct runs through or behind the head of the pancreas before joining the pancreatic duct at the ampulla of Vater
• The gastroduodenal artery (GDA) descends anterior to the pancreatic head

2. Surgical Exposure of the Pancreas

Anterior Exposure

Posterior Exposure

• Kocher maneuver - incises the peritoneum lateral to the duodenum and sweeps the duodenum and pancreatic head medially to expose the inferior vena cava and aorta behind the head. The duodenum and pancreatic head are mobilized to the level of the left renal vein.
• Medial rotation of the spleen - for the body and tail, the white line of Toldt along the left colon is mobilized, splenic attachments to the diaphragm and colon are divided, allowing the spleen and distal pancreas to be rotated medially.

3. Major Pancreatic Operations

3a. Pancreaticoduodenectomy (Whipple Procedure)

1. Define the infrapancreatic SMV - Enter the lesser sac, incise the visceral peritoneum along the inferior border of the pancreas, expose the SMV and its junction with the middle colic vein.
2. Mobilize the duodenum and pancreatic head - Kocher maneuver to the level of the left renal vein; dividing the posterior peritoneum facilitates later SMA dissection.
3. Portal dissection - Identify the common hepatic artery, remove the hepatic artery lymph node, perform cholecystectomy top-down, and divide the common hepatic duct above the cystic duct confluence.
4. Divide the stomach or duodenum - Standard Whipple: divide the antrum. Pylorus-preserving Whipple (PPPD): divide the duodenum 2 cm distal to the pylorus.
5. Divide the pancreatic neck - Pass a tunnel posterior to the pancreatic neck over the SMV/portal vein and divide the neck with electrocautery or a stapler.
6. Divide the uncinate process - Separate the uncinate from the SMA using a systematic SMA-first approach; the SMA margin is the most common site of positive resection margins.

• Pancreaticojejunostomy or pancreaticogastrostomy for the pancreatic remnant
• Hepaticojejunostomy for the bile duct
• Gastrojejunostomy (antecolic preferred over retrocolic to reduce delayed gastric emptying)

Diagnostic laparoscopy before laparotomy is recommended - approximately 10% of patients will have small metastatic deposits not seen on preoperative imaging.

3b. Distal Pancreatectomy

• Posterior exposure via medial rotation of the spleen from retroperitoneal attachments
• Isolate and ligate the splenic artery and vein individually where possible
• If hemodynamically unstable (trauma), fire a linear cutting stapler across the splenic vessels, then a second fire across the pancreas
• Oversew the transected pancreatic stump with overlapping 3-0 absorbable U-stitch sutures; oversew the duct if visible
• Wide external drainage of the pancreatic bed (high leak rate with soft gland)

3c. Total Pancreatectomy

4. Pancreatic Pathology Requiring Surgery

4a. Pancreatic Ductal Adenocarcinoma (PDAC)

• 5-year survival ~10% - most patients present with unresectable disease
• Key biomarker: CA 19-9 (sensitivity and specificity ~80%); pre-op levels correlate with resectability
• Resectability criteria (NCCN):
  • Resectable - no arterial involvement, less than 180° contact with SMV/portal vein
  • Borderline resectable - limited arterial contact or >180° venous contact; neoadjuvant therapy first
  • Locally advanced/unresectable - >180° arterial involvement
• Chemotherapy regimens: FOLFIRINOX or Gemcitabine + nab-paclitaxel
• Germline testing recommended (BRCA1/2, PALB2, etc.) - implications for PARP inhibitor therapy

4b. Intraductal Papillary Mucinous Neoplasm (IPMN)

• Main duct dilation >10 mm
• Obstructive jaundice with cystic lesion in the head
• Enhanced solid component within cyst (mural nodule)

4c. Pancreatic Neuroendocrine Tumors (PNETs)

• Account for 3% of pancreatic malignancies
• Can be functional (insulinoma, gastrinoma, glucagonoma, VIPoma) or non-functional
• WHO grading based on Ki-67 index and mitotic rate
• Chromogranin-A (CHGA) is the principal biomarker
• Associated with hereditary syndromes: MEN1 (most common), VHL, neurofibromatosis type 1, tuberous sclerosis

4d. Mucinous Cystic Neoplasm (MCN)

• Almost exclusively in women (>95%); located in body/tail
• Do not communicate with the main pancreatic duct (distinguishes from IPMN)
• Have "ovarian stroma" histologically
• All MCNs should be resected (distal pancreatectomy) due to malignant potential

4e. Autoimmune Pancreatitis (AIP)

• Type I AIP: Elevated serum IgG4, lymphoplasmacytic sclerosing pancreatitis - responds dramatically to glucocorticoids
• Type II AIP: IgG4 normal, idiopathic duct-centric pancreatitis - also steroid-responsive
• A steroid trial (prednisolone 40 mg/day x 2 weeks) can confirm AIP and avoid unnecessary Whipple resection

5. Pancreatic Trauma

AAST Grading of Pancreatic Injuries

• Grade I/II - Contusion or laceration without duct injury - manage conservatively with closed suction drainage
• Grade III - Distal transection or laceration with duct injury - distal pancreatectomy
• Grade IV/V - Proximal ductal injury or severe disruption of the pancreatic head

• MRCP is the preferred non-invasive method to assess ductal integrity
• Intraoperative: direct inspection, methylene blue injection, intraoperative ERCP
• Findings suggesting duct disruption: complete transection, laceration >50% of pancreatic diameter, severe maceration

6. Pancreatic Fistula (Key Post-op Complication)

• Biochemical leak (Grade A) - drain amylase >3x upper limit of normal on POD3 with no clinical impact
• Grade B - clinical impact requiring change in management (prolonged drainage, antibiotics, endoscopic/radiologic intervention)
• Grade C - life-threatening, requires reoperation

Summary

1. Safe vascular dissection around the SMV/portal vein/SMA
2. Prevention and management of pancreatic fistula
3. Patient selection (resectable vs. borderline resectable disease)
4. Distinguishing malignant from benign or premalignant conditions (especially IPMN and AIP)