Chapter 29 – Pancreas




Abstract






  • The pancreas lies transversely in the retroperitoneum, at the L1–L2 vertebral level, between the duodenum and the hilum of the spleen.
  • The head of the pancreas lies over the inferior vena cava (IVC), right renal hilum, and the left renal vein at its junction with the IVC.
  • The uncinate process extends to the left and wraps from around the superior mesenteric vessels. It is in close proximity to the inferior pancreaticoduodenal artery.
  • The neck of the pancreas lies over the superior mesenteric vessels and the proximal portal vein. The space between the neck and the superior mesenteric vessels is avascular and allows blunt dissection without bleeding. The area to either side of the midline is vascular and should be avoided.
  • The body of the pancreas lies over the suprarenal aorta and the left renal vessels. It is intimately related to the splenic artery and vein.
  • The major pancreatic duct (Wirsung) traverses the entire length of the pancreas and drains into the ampulla of Vater, approximately 8 cm below the pylorus. The lesser duct of Santorini branches off the superior aspect of the major duct, at the level of the neck of the pancreas, and drains separately into the duodenum, approximately 2–3 cm proximal to the ampulla of Vater.
  • The pancreas receives its blood supply from both the celiac artery and the superior mesenteric artery.

    • The head of the pancreas and the proximal part of the duodenum receive their blood supply from the anterior and posterior pancreaticoduodenal arcades. These arcades lie on the surface of the pancreas, close to the duodenal loop. Any attempts to separate the two organs results in ischemia of the duodenum.
    • The body and tail of the pancreas receive their blood supply mainly from the splenic artery. The splenic artery originates from the celiac artery and courses to the left along the superior border of the pancreas. It follows a tortuous route, with parts of it looping above and below the superior border of the pancreas. It gives numerous small and short branches to the body and tail of the pancreas.
    • The splenic vein courses from left to right, superiorly and posteriorly to the upper border of the pancreas, inferiorly to the splenic artery. It is not tortuous like the artery. It joins the superior mesenteric vein, at a right angle, behind the neck of the pancreas, to form the portal vein. The inferior mesenteric vein crosses behind the body of the pancreas and drains into the splenic vein.

  • The portal vein is formed by the junction of the superior mesenteric and splenic veins, in front of the inferior vena cava and behind the neck of the pancreas.
  • The common bile duct (CBD) courses posterior to the first part of the duodenum, in front of the portal vein, continues behind the head of the pancreas, often partially covered by pancreatic tissue, and drains into the ampulla of Vater, in the second part of the duodenum.





Chapter 29 Pancreas


Demetrios Demetriades , Emilie Joos , and George C. Velmahos



Surgical Anatomy




  • The pancreas lies transversely in the retroperitoneum, at the L1–L2 vertebral level, between the duodenum and the hilum of the spleen.



  • The head of the pancreas lies over the inferior vena cava (IVC), right renal hilum, and the left renal vein at its junction with the IVC.



  • The uncinate process extends to the left and wraps from around the superior mesenteric vessels. It is in close proximity to the inferior pancreaticoduodenal artery.



  • The neck of the pancreas lies over the superior mesenteric vessels and the proximal portal vein. The space between the neck and the superior mesenteric vessels is avascular and allows blunt dissection without bleeding. The area to either side of the midline is vascular and should be avoided.



  • The body of the pancreas lies over the suprarenal aorta and the left renal vessels. It is intimately related to the splenic artery and vein.



  • The major pancreatic duct (Wirsung) traverses the entire length of the pancreas and drains into the ampulla of Vater, approximately 8 cm below the pylorus. The lesser duct of Santorini branches off the superior aspect of the major duct, at the level of the neck of the pancreas, and drains separately into the duodenum, approximately 2–3 cm proximal to the ampulla of Vater.



  • The pancreas receives its blood supply from both the celiac artery and the superior mesenteric artery.




    • The head of the pancreas and the proximal part of the duodenum receive their blood supply from the anterior and posterior pancreaticoduodenal arcades. These arcades lie on the surface of the pancreas, close to the duodenal loop. Any attempts to separate the two organs results in ischemia of the duodenum.



    • The body and tail of the pancreas receive their blood supply mainly from the splenic artery. The splenic artery originates from the celiac artery and courses to the left along the superior border of the pancreas. It follows a tortuous route, with parts of it looping above and below the superior border of the pancreas. It gives numerous small and short branches to the body and tail of the pancreas.



    • The splenic vein courses from left to right, superiorly and posteriorly to the upper border of the pancreas, inferiorly to the splenic artery. It is not tortuous like the artery. It joins the superior mesenteric vein, at a right angle, behind the neck of the pancreas, to form the portal vein. The inferior mesenteric vein crosses behind the body of the pancreas and drains into the splenic vein.




  • The portal vein is formed by the junction of the superior mesenteric and splenic veins, in front of the inferior vena cava and behind the neck of the pancreas.



  • The common bile duct (CBD) courses posterior to the first part of the duodenum, in front of the portal vein, continues behind the head of the pancreas, often partially covered by pancreatic tissue, and drains into the ampulla of Vater, in the second part of the duodenum.



General Principles




  • The management of pancreatic trauma is determined by the presence or absence of pancreatic duct injury. Patients with pancreatic contusions or lacerations without duct involvement may be managed nonoperatively. If these injuries are discovered during the operation, drainage with closed suction drain is usually sufficient. Conversely, almost all patients with pancreatic duct transection require operative management and pancreatic resection.



  • The pancreas is surgically divided into a distal and proximal part. The distal pancreas consists of all pancreatic tissue (body and tail) to the left of the superior mesenteric vessels. The proximal pancreas is composed of all pancreatic tissue (head and neck) to the right of the superior mesenteric vessels.




    • In distal pancreatic injuries involving the pancreatic duct, a distal pancreatectomy is the procedure of choice. A spleen-preserving distal pancreatectomy can be considered in stable patients. However, in the presence of severe associated injuries or hemodynamic instability, a distal pancreatecomy with splenectomy should be performed because it is a much faster and easier procedure.



    • Distal pancreatecomy rarely results in permanent diabetes or pancreatic exocrine insufficiency. Hyperglycemia may be observed in the early postoperative period, but it usually resolves spontaneously.



    • For injuries involving the head of the pancreas, if the integrity of the duct cannot be confirmed, pancreatic drainage alone should be considered. Postoperative evaluation of the integrity of the pancreatic duct should be performed by CT scan or magnetic resonance cholangiopancreatography (MRCP) and, in selected cases, with endoscopic retrograde cholangiopancreatography (ERCP). Radical resections should be avoided because of the associated high morbidity and mortality.



    • Freeing of the lateral aspect of the head of the pancreas from the duodenum results in ischemia of the duodenum and it should never be done.



    • Pancreaticoduodenectomy should rarely be considered because of its complexity and the associated high morbidity and mortality. It should be considered primarily in cases with severe combined pancreaticoduodenal trauma.



    • In cases with pancreatic injury selected for nonoperative management, evaluation by means of ERCP or MRCP is important in order to assess the integrity of the pancreatic duct. In addition, for selected cases with partial pancreatic duct injury, ERCP can be used for therapeutic stent placement.




  • Missed pancreatic injuries with ductal involvement may result in complications such as pancreatitis, pancreatic ascites, pancreatic pseudocyst, abscess, or erosion of the adjacent vessels with life-threatening bleeding.



  • Pancreatic injuries without ductal involvement rarely cause significant problems and do not require operation.





Figure 29.1 Surgical anatomy of the pancreas. The head of the pancreas and the proximal part of the duodenum share blood supply from the anterior and posterior pancreaticoduodenal arcades. SMA, superior mesenteric artery; SMV, superior mesenteric vein.



Special Surgical Instruments




  • Standard exploratory laparotomy tray can be used for this approach



  • Self-retaining Bookwalter or Omni-flex retractor can greatly facilitate surgical exposure



  • Headlamp

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Sep 4, 2020 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 29 – Pancreas
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