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General Surgery
Pancreas Surgical Anatomy
Built from Skandalakis' Surgical Anatomy: The Embryologic and Anatomic Basis of Modern Surgery
What’s inside
8 sections · 198 slides
Overview
- Deep retroperitoneal position, with no peritoneum over the posterior surface No other abdominal organ is surrounded by so many structures at once Duodenum, stomach, spleen, left adrenal, transverse mesocolon and colon, left kidney, right ureter, jejunum Enzyme-rich secretion digests suture material — Whipple's success in 1940 rested partly on silk Halsted first removed the pancreatic head and part of the duodenum for ampullary cancer in 1898 Sir Andrew Watt Kay, 1978: "For me, the tiger country is removal of the pancreas"
- Surgical warning from R.J. Baker
- Rufus of Ephesus coined "pankreas" (all flesh) around A.D. 100 Claude Bernard demonstrated the digestive enzymes in 1850 — the gland acquired a function Halsted 1898: first successful removal of the pancreatic head with duodenum for ampullary cancer Two-stage resections followed in the United States and elsewhere Whipple 1940: the one-stage pancreatoduodenectomy The full chronology follows in the reference table
- Anatomic and Surgical History of the Pancreas
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
- Anatomic and Surgical History of the Pancreas (continued)
Embryology and congenital anomalies
- Timetable of pancreatic development
- Ventral primordium: terminal part of the duct of Wirsung, part of the uncinate process and head Dorsal primordium: remainder of the uncinate process and head, plus the whole body and tail After fusion the principal ducts anastomose Proximal duct of Wirsung joins the common bile duct, perhaps on day 32 — contributing to the ampulla of Vater Distal duct of the dorsal pancreas persists as most of the main duct Duct of Santorini is the proximal part of the dorsal duct
- Embryogenesis of the pancreatic ducts
- Two endodermal populations: one forms ducts and acini, the other forms islet cells Ducts and acini form first; islet primordia bud off the ducts as soon as they exist Endocrine and exocrine components awaken functionally at about 10 to 12 weeks Insulin secretion is taking place around the fifth month Parenchymal cells also give rise to glucagon- and somatostatin-secreting cells Polak et al.: mesenchyme drives endocrine differentiation and epithelial proliferation
- Only two events truly matter: rotation and fusion of the primordia Malrotation of the ventral primordium in the fifth week produces an anular pancreas Fusion in the seventh week determines the ductal pattern, and several variants are normal Around the sixth week the pancreas lies within the dorsal mesentery Ansa pancreatica: classically a loop between inferior branches of the dorsal and ventral ducts Suda et al. instead observed fusion of an inferior dorsal branch with the ventral duct
- Ontogeny of the Gastrointestinal Peptides
- Ontogeny of the Gastrointestinal Peptides (continued)
- Congenital Anomalies of the Pancreas
- Failure of the anlagen to fuse: Wirsung and Santorini drain separately, also called isolated ventral pancreas On ERCP in about 12% of patients with pancreatitis, but only 3% of those having pancreatography for other reasons The disparity suggests predisposition; attacks may follow stenosis or obstruction of one or both ducts Stenting may relieve symptoms in chronic pancreatitis Procedure of choice: sphincteroplasty of both ducts with cholecystectomy, to avoid the formation of stones Neblett and O'Neill: more distal ductal obstruction or ductal ectasia may benefit from pancreaticojejunostomy
- A thin flat band of normal pancreatic tissue encircling the second part of the duodenum The band continues into the head of the pancreas on either side It may be partly or wholly free of the duodenum, or may penetrate the duodenal muscularis The ring contains a large duct that usually enters the main pancreatic duct Occasionally that duct enters the duodenum independently Duodenal stenosis at the level of the ring is typical
- Anular pancreas encircling the second part of the duodenum
- Obstruction present before birth is frequently accompanied by hydramnios Half of patients have no symptoms until adulthood Adults present with signs of duodenal obstruction Procedure of choice: duodenoduodenostomy, first proposed by Gross and Chisholm Alternative: duodenojejunostomy Bypass the ring — do not divide it
- Boyden, 1926: gallbladder duplications in cats where the accessory organ arose from the ventral pancreatic bud He suggested some human duplications might be of this type Wrenn and Favara reported a human pancreatic gallbladder; Boyden confirmed it Pancreatic tissue within the wall of an otherwise normal gallbladder does not imply ventral bud origin Ectopic pancreas is common in stomach, duodenal or ileal wall, Meckel's diverticulum and umbilicus Less common: colon, appendix, gallbladder, omentum or mesentery, bronchoesophageal fistula
- Chief sites of heterotopic pancreatic tissue
- Most ectopic pancreatic tissue is functional Islet tissue is often present in gastric and duodenal heterotopia, usually absent elsewhere Accessory duodenal pancreas: lobules of normal pancreas in the submucosa beneath the muscularis externa Feldman and Weinberg found duodenal pancreatic tissue in 13.7% of 410 necropsy specimens Pearson: heterotopic tissue in as many as 2% of autopsies if carefully sought About 6% of Meckel's diverticula contain pancreatic tissue
- Increasingly recognised cause of pyloric obstruction and disrupted peristalsis May produce peptic ulceration or a neoplasm Ravitch: an ulcerated nodule in stomach or duodenum causes ulcer-like symptoms relieved by removal Rosai: in a patient with heterotopic pancreas, acute pancreatitis also inflames the heterotopic foci Asymptomatic deposits are frequently incidental findings
- Tuncel et al. reported head and part of the body lying intraperitoneally Peritoneum covered the gland within the omental bursa, except the tail The anterior layer of the hepatogastric ligament turned over the hepatoduodenal ligament It continued behind the head with the peritoneum forming the posterior wall of the epiploic foramen of Winslow Peritoneum also covered part of the posterior surface of the body, forming a recess behind the pancreas A rarity, but it converts a fixed organ into a mobile one
- Gastrinoma: benign or malignant tumour located primarily in the pancreas Causes Zollinger-Ellison syndrome — acid and pepsin supersecretion by parietal and chief cells of the fundus Named for the researchers who linked islet cell tumour, hormone hypersecretion and severe clinical disease Stabile: their work "served as the defining moment for the entire field of gastrointestinal endocrinology" Passaro et al. propose some gastrinomas arise from ventral pancreatic bud stem cells Those stem cells disperse and are enveloped by lymphoid tissue and duodenal wall
- Boundaries of the gastrinoma triangle
- Stabile et al.: about 90% of gastrinomas lie within the gastrinoma triangle Triangle boundaries: cystic duct; junction of 2nd and 3rd parts of duodenum; junction of pancreatic neck and body Townsend and Thompson: head to body to tail distribution of 4:1:4 Fewer than 25% of patients have a single tumour Two pancreatic areas are affected in 30% of patients 20% have tumour in all three areas
- Pathology, Location, and Extent of Tumor in Patients with Zollinger-Ellison Syndrome
- Pathology, Location, and Extent of Tumor in Patients with Zollinger-Ellison Syndrome (continued)
- Surgery is the procedure of choice for gastrinoma, benign or malignant Kisker et al.: intraoperative ultrasonography with pancreatic and duodenal exploration detected 96% Proye et al.: include intraoperative gastrin measurement Norton et al.: resection of localised liver gastrinoma gives a cure rate similar to extrahepatic disease Jordan: duodenal gastrinoma with nodal metastases is still curable A gastrinoma may arise in a lymph node and be cured by removing that node
- Gastrinoma compared with insulinoma
- Insulinoma syndrome is overproduction of insulin from a beta-cell tumour of the islets After preoperative localisation, surgery is the treatment of choice Kuzin et al.: intraoperative ultrasonography plus selective celiac arteriography with arterial stimulated venous sampling Boukhman et al.: intraoperative ultrasonography more sensitive than preoperative ultrasound or any other study Hashimoto and Walsh: exploration plus intraoperative ultrasonography identified more than 90% of insulinomas Where technically feasible, enucleation is curative with low morbidity
- Distribution of Neuroendocrine Tumors
- Distribution of Neuroendocrine Tumors (continued)
- MEN I and metastases are not contraindications — operate aggressively Results of operation were similar with and without MEN I Gastrinomas not found at operation are likely to be small duodenal gastrinomas Parietal cell vagotomy is recommended after operation if residual tumour is suspected Insulinomas are best treated by enucleation, except in MEN I or microadenomatosis Otherwise Whipple operation, or distal pancreatectomy with enucleation of tumour in the remnant
- Body and tail derive from the dorsal anlage and lie, with the spleen, in the dorsal mesogastrium They share blood supply — left gastric and splenic arteries — with the proximal stomach They also share lymphatic drainage with the proximal stomach Head derives from the ventral anlage and lies in the mesoduodenum Head shares its supply — pancreaticoduodenal and gastroduodenal arteries — with duodenum, distal CBD, distal stomach En bloc resection follows the mesentery of origin, not the organ boundary
- En bloc resection fields of the proximal and distal stomach
Topography, relations and the parts of the pancreas
- Anterior relationships of the pancreas
- Bare areas of the duodenum
- Posterior relationships of the pancreas
- Proximity to so many organs makes the pancreas prone to local invasion by carcinoma Z'graggen et al. reported metastasis to the pancreas from carcinoma of the kidney and lung Isolated metastases may be amenable to palliation and even long-term survival with resection Pancreatic cancer is equally likely to invade adjacent organs Direct invasion and metastatic sites are tabulated separately in this topic
- Organ Directly Invaded (at Autopsy) by Pancreas Duct Cancer (75 Patients)
- Sites of Metastases from Carcinoma of the Pancreas as Seen at Autopsy
- Sites of Metastases from Carcinoma of the Pancreas as Seen at Autopsy (continued)
- Lies transversely in the retroperitoneal sac, between the duodenum on the right and the spleen on the left Related to the omental bursa above, the transverse mesocolon anteriorly, the greater sac below For all practical purposes the pancreas is a fixed organ The tail is the exception — it is relatively mobile Osler: "the abdominal area of romance where the head of the pancreas lies folded in the arms of the duodenum" Busnardo et al. described two anatomicosurgical segments from 30 corrosion casts
- Busnardo et al. found two segments, analogous to segmentation in liver, spleen and kidney Right segment: cephalocervical, comprising caput and cervix Left segment: corporocaudate, comprising corpus and cauda The two are separated by a poorly vascularised, pauci-arterial area They are connected by the main pancreatic duct and often by a small artery That artery is usually the inferior pancreatic artery, the left terminal branch of the dorsal pancreatic artery
- Arteries surrounding the pancreas and the intersegmental plane
- Anatomicosurgical segments of the pancreas
- The five parts of the pancreas
- Flattened, with an anterior and a posterior surface Anterior surface is adjacent to the pylorus and the transverse colon Anterior pancreaticoduodenal arcade runs on the ventral surface, parallel to the duodenal curvature Posterior pancreaticoduodenal arcade is a major entity on the posterior surface Posteriorly close to hilum and medial border of the right kidney and the right renal vessels Also to the inferior vena cava, the right crus of the diaphragm and the right gonadal vein
- Relations of the common bile duct to the pancreatic head
- "Hooklike" extension of the head, highly variable in size and shape Passes downward and slightly to the left from the principal part of the head Continues behind the superior mesenteric vessels and in front of the aorta and inferior vena cava In sagittal section it lies between aorta and SMA, left renal vein above and duodenum below May be absent, or may completely encircle the superior mesenteric vessels Skandalakis: present in 18 of 20 fresh cadaver dissections
- Sagittal section through the neck of the pancreas
- Extension of the uncinate process under the mesenteric vessels
- If the process is well developed, section the neck from the front to avoid injuring the vessels Short vessels from the superior mesenteric artery and vein supply the process and must be carefully ligated A ligament of the uncinate process may attach it densely to the superior mesenteric artery Pancreatitis or cancer makes that fixation even more adherent An anomalous right hepatic artery may pass through the process Because the aorta lies behind, pancreatic carcinoma there can be inseparable from the aorta
- Defined as the site where the superior mesenteric vessels pass and the portal vein begins, dorsal to the gland 1.5 to 2.0 cm long, partially covered anteriorly by the pylorus Gastroduodenal artery passes to the right of the neck It gives origin to the anterior superior pancreaticoduodenal artery Posterior to the neck, the portal vein forms from the superior mesenteric and splenic veins Careful elevation of the neck and ligation of any anterior tributaries are necessary
- Near the inferior margin: terminations of the inferior pancreaticoduodenal and right gastroepiploic veins These drain into the superior mesenteric, the splenic vein, or the portal vein proper The inferior mesenteric vein drains with roughly equal frequency into splenic, SMV, or the portal confluence Portal vein receives the posterior superior pancreaticoduodenal, right gastric, left gastric and pyloric veins An anomalous vein entering the anterior surface is fairly common Bleeding here makes it difficult to evaluate structures lying beneath the neck
- Anterior surface covered by the double peritoneal layer of the omental bursa separating stomach from pancreas Omental tuberosity: a blunt upward projection contacting the lesser curvature at the lesser omentum attachment Transverse mesocolon divides into two leaves — superior over the anterior surface, inferior below the gland The middle colic artery emerges from beneath the pancreas to run between those leaves Posteriorly: aorta, origin of the SMA, left crus, left kidney and its vessels, left adrenal, splenic vein Small pancreatic veins entering the splenic vein must be ligated to preserve vein and spleen
- Relatively mobile, unlike the rest of the gland Its tip reaches the hilum of the spleen in 50% of cases Contained with the splenic artery and origin of the splenic vein between two layers of the splenorenal ligament Outer layer of the splenorenal ligament is the posterior layer of the gastrosplenic ligament Careless division of that ligament may injure the short gastric vessels The splenorenal ligament is almost avascular, but digital manipulation should stop at the pedicle
- Relations of the tail of the pancreas to the splenic hilum
- The tail of the pancreas is contiguous with the superior pole of the left kidney Acute inflammation exudes activated enzymes, particularly trypsin, into the peripancreatic space This produces an inflammatory change in the left kidney, similar to interstitial nephritis Explains left costovertebral angle tenderness (Murphy punch) and trace to 1+ albuminuria The right kidney is shielded by the interposed inferior vena cava and duodenum In necrotising pancreatitis, left perirenal fat is often necrotic and needs extensive debridement
Pancreatic ducts, papilla and the vaterian apparatus
- Arises in the tail; main and accessory ducts lie anterior to the major pancreatic vessels Through tail and body it lies midway between superior and inferior margins, slightly posterior Crosses the vertebral column between T12 and L2 — at L1 in more than half of persons In tail and body, 15 to 20 short tributaries enter at right angles, superior and inferior alternating On reaching the head the duct turns caudad and posterior At the major papilla it turns horizontally to join the caudal surface of the CBD, usually at L2
- Characteristically slightly superior to the midpoint of the gland in the superoinferior plane Classically at the junction of the superior one third and inferior two thirds, viewed from the front Depth from the anterior surface is far more variable — anterior third, middle, or towards the posterior surface Needle aspiration of a normal duct through the anterior surface usually fails without intraoperative ultrasound An obstructed duct may be palpable as a groove or "soft spot" in the midportion That finding is common in head carcinoma and in strictures with chronic pancreatitis
- Drainage of the main duct in the head after filleting
- May drain the anterosuperior head, into the duodenum at the minor papilla or into the main duct Usual pattern: accessory duct smaller than Wirsung, opening at the minor papilla In about 10% there is no connection at all between accessory and main duct There is no minor papilla in 30% In some with a minor papilla the terminal accessory duct is too small to pass any quantity of fluid Three papillae have been reported; Baldwin found a loop in the main duct in 3 of 76 specimens
- Degrees of suppression of the accessory pancreatic duct
- Degrees of suppression of the main pancreatic duct
- Relations of the bile duct, duct of Wirsung and duct of Santorini
- Rare variations of the pancreatic ducts
- ERCP made duct length, diameter and capacity clinically important Greatest diameter is in the head, just before the duct enters the duodenal wall, tapering towards the tail Like the bile duct, the pancreatic duct is constricted within the duodenal wall Baker: 1.0 to 2.5 mL of contrast fills a normal duct Kasugai et al.: 2 to 3 mL fills the main duct in life; 7 to 10 mL fills branches and smaller ducts Trapnell and Howard: 0.5 to 1.0 mL sufficient in autopsy specimens
- Reported length of the main pancreatic duct
- Reported diameter of the main pancreatic duct
- Both the volume of dye and the pressure of injection are elements of concern Injecting 5.0 mL or more visualises branches and smaller ducts — and sometimes ruptures them The resulting post-endoscopic pancreatitis can be necrotising, with always-serious consequences An experienced endoscopist injects at very low pressure, filling but not overdistending the ducts Chronic pancreatitis: large ducts, distal strictures, and fibrosis make the gland less susceptible to damage Yamaguchi et al.: MRCP is complementary to ERCP but has limitations in surgical application
- The literature confuses the two terms The so-called papilla of Vater should be called the major duodenal papilla It is a nipple-like projection of duodenal mucosa The distal end of the ampulla passes through it into the duodenum The ampulla of Vater (hepatopancreatic) is the union of the pancreaticobiliary ducts Vater described it in 1720, but Bidloo of The Hague illustrated it in 1685
- On the posteromedial wall of the second part of the duodenum, 7 to 10 cm from the pylorus Rarely it lies in the third part of the duodenum On endoscopy, right of the vertebral column at L2 in 75% to 85% of bodies examined Reported at L3 in 57% of autopsy specimens Found where a longitudinal mucosal fold or frenulum meets a transverse fold to form a T No such arrangement marks the site of the minor papilla
- T arrangement of duodenal mucosal folds at the major papilla
- The papilla of Vater may not be obvious Too much traction can erase the mucosal folds It may be covered by one of the transverse folds Dowdy et al.: the papilla was "prominent" and easily found in 60% of specimens If the T is not apparent and the papilla cannot be palpated, probe the CBD from above A duodenal diverticulum near the papilla may confuse surgeon or endoscopist
- A dilatation of the common pancreaticobiliary channel adjacent to the papilla, below the ductal junction If a septum extends as far as the duodenal orifice, no ampulla exists Michels collected 2500 specimens from 25 investigators: an ampulla was present in 64% Ampulla defined as present when the septal edge does not reach the tip of the papilla Rienhoff and Pickrell: septal edge to papillary tip 1 to 14 mm, 75% being 5 mm or less A true ampulla with dilatation is present in about 75% of type 1, and absent in types 2 and 3
- Bile duct and pancreatic duct relations at the duodenal papilla
- The vascular topography of the ampulla has never been defined well enough to prevent post-procedure bleeding Advised incision: at 10 to 11 o'clock, approximately 5 to 8 mm long Little is known about the safe depth of incision Vessels responsible for bleeding: the retroduodenal artery and an anomalous right hepatic artery from the SMA Both lie between the distal CBD and the duodenum Palpate behind the ampulla during open sphincteroplasty — pulsation means an anomalous artery
- Frequency distribution of the blood supply of the ampulla of Vater
- Arterial blood supply of the papilla
- Retroduodenal artery: a branch of the gastroduodenal artery or, variably, of the PSPD artery Lies very near the superior border of the duodenum, anterior to the lower CBD Its ascending branches travel upward along the CBD Descending branches from the cystic and right hepatic arteries supply the lower CBD Their anastomosis forms the 3 o'clock and 9 o'clock vessels of Northover and Terblanche Retroportal artery: from SMA or celiac axis; joins the right hepatic artery behind the CBD in 20%
- Anastomosis between PSPD and PIPD arteries lies close to the ampulla, but its exact site is uncertain Kimura and Nagai: an arcade forms between PSPD and PIPD in 88% of cases ASPD runs 1.5 cm below the ampulla before turning posteriorly to meet the AIPD Kimura: a named artery leaves the PSPD and runs along the right side of the CBD to the papilla Biazotto: bleeding at papillotomy is limited because thick veins lie in the body and base of the papilla Small veins draining into duodenal submucosa at the apex explain diffuse, low-intensity bleeding
- Several sphincters of smooth muscle around the intramural CBD, the main pancreatic duct, and the ampulla Separate embryonic origin from duodenal musculature, and functions separately Total length of the complex ranges from 6 mm to as much as 30 mm Length depends on the obliquity of the ducts' path through the duodenal wall The sphincter may extend beyond the duodenal wall into the pancreatic portion of the bile duct That extension matters when sphincterotomy is performed
- Four components of the sphincter of Boyden
- Oddi defined his sphincter in 1887 as a sphincter of the hepatopancreatic ampulla; its motility is debated Shibata et al.: possible sphincter of Oddi dysfunction after proximal duodenal transection, not gastric Marks et al. (canine): Botox into the sphincter reduces CBD pressures, an alternative to biliary stenting Minor papilla lies about 2 cm cranial and slightly anterior to the major papilla, and lacks the T folds Baldwin found it in all of 100 specimens; Dowdy et al. found none in 18 of 100 The gastroduodenal artery, anterior to the accessory duct and minor papilla, is the landmark
Arterial and venous supply
- The vascular system is complex and non-typical, with several different patterns Blood comes from branches of the celiac trunk and of the superior mesenteric artery Van Damme: "The most important pancreatic artery is the splenic artery" Variations are common — differing textbook illustrations are all correct for some patients Foregut (celiac trunk) and midgut (SMA) both contribute, matching the embryology of duodenum and pancreas All major arteries lie posterior to the ducts
- Formation of a pancreaticoduodenal arcade
- Usually arises from the splenic artery near its origin from the celiac trunk, at the level of the neck Also arises rather commonly from the celiac trunk or the common hepatic artery Right branch supplies the head and usually joins the posterior arcade; may anastomose with the ASPD One or two left branches pass through body and tail, connecting with splenic artery branches At the tip of the tail it connects with the splenic or left gastroepiploic artery Left and right branches lie in a groove on the inferior margin, forming the transverse (inferior) pancreatic artery
- Gastroduodenal artery is one of two terminal branches of the common hepatic artery Soon after origin it gives the supraduodenal, retroduodenal and PSPD arteries Supraduodenal and retroduodenal arteries may instead be branches of the PSPD It ends by dividing into right gastroepiploic and ASPD arteries ASPD lies on the anterior surface of the head and gives eight to ten branches to pancreas and duodenum Its main stem anastomoses richly with the AIPD at the lower margin of the head
- AIPD arises from the SMA at or above the inferior margin of the pancreatic neck It may form a common trunk with the posterior inferior artery One or both may arise from the first or second jejunal branches of the SMA A posterior inferior artery may arise from an aberrant right hepatic artery springing from the SMA Ligating the jejunal branch endangers the blood supply to the fourth part of the duodenum The posterior arcade runs further from the duodenum and passes behind the intrapancreatic CBD
- Major arterial supply of the pancreas, anterior view
- Major arterial supply of the pancreas, posterior view
- Named arteries of the pancreas
- Artery for the neck arises from celiac divisional branches or from the SMA, and runs behind the neck Its right branch reaches the anterior head as the prepancreatic artery in 76% of specimens Its left branch forms the transverse pancreatic artery Artery for the body arises from the splenic artery; more than one in 37% of specimens Arteries for the tail: more than one in 68%; from splenic (21%), left gastroepiploic (20%), splenogastroepiploic trunk (50%) Recurrent tail branches injured at splenectomy may cause post-splenectomy pancreatitis
- Splenic artery runs left along the posterior surface of body and tail, looping above and below the upper margin Its course becomes more tortuous with age Great pancreatic artery of Von Haller (pancreatica magna) arises from the splenic near the body-tail junction It commonly anastomoses with the inferior pancreatic artery Caudal pancreatic artery arises from the distal splenic, the left gastroepiploic, or a splenic hilar branch It supplies accessory splenic tissue at the hilum when present
- Configurations of blood supply to the distal pancreas
- Always look for an anomalous hepatic artery before a pancreatic resection Aberrant arteries may be accessory to, or replace, the normal hepatic arteries An anomalous common hepatic artery arises from the SMA in 2.0% to 4.5% of persons It may pass through the head of the pancreas and then behind the portal vein Michels: an aberrant right hepatic artery from the SMA in 26% of bodies; it may give off the IPD arteries Anomalous left hepatic artery in 27%, most commonly from the left gastric artery
- Variations of the hepatic arteries
- Anomalous middle colic artery traversing the pancreatic head
- Veins parallel the arteries and lie superficial to them; both lie posterior to the ducts in body and tail Drainage is to portal, splenic, and superior and inferior mesenteric veins Four pancreaticoduodenal veins form arcades draining the head and the duodenum ASPD vein joins the right gastroepiploic vein, which receives a colic vein to form the gastrocolic vein That trunk drains into the superior mesenteric vein; PSPD vein enters the portal vein above the gland Anterior and posterior inferior pancreaticoduodenal veins enter the SMV together or separately
- White: pancreatic tributaries do not enter the anterior surface of the portal or superior mesenteric veins That reduces the risk of bleeding when incising the neck of the pancreas Silen warned that superior pancreatoduodenal and gastrocolic veins may enter anteriorly in some patients Baden, after more than 100 Whipple procedures, never saw a pancreatic vein enter the anterior side Identify and divide the gastrocolic trunk before proceeding cephalad on the anterior aspect of the SMV Anterior and posterior inferior pancreaticoduodenal veins usually enter together on the dorsal aspect of the SMV
- Left pancreas drains into two channels: splenic vein above, transverse (inferior) pancreatic vein below A smaller superior pancreatic vein can sometimes be identified The splenic vein receives 3 to 13 short pancreatic tributaries Inferior mesenteric vein ends in the splenic vein in about 38%; left gastric vein similarly in 17% Portal vein forms behind the neck from superior mesenteric and splenic veins It lies in front of the inferior vena cava, with the CBD on the right and the common hepatic artery on the left
- Venous drainage of the pancreas, anterior view
- Venous drainage of the pancreas, posterior view
- Rarely the portal vein lies anterior to the pancreas and duodenum This is persistence of the preduodenal rather than the postduodenal plexus of the embryonic vitelline veins Inadvertent section of this vessel could be fatal Often associated with anular pancreas, malrotation and biliary tract anomalies Rare at any age and extremely rare in adults — Ishizaki et al. reported 11 cases Other reported anomalies: pulmonary vein joining the portal vein, and congenital portal stricture
- Embryonic origin of the preduodenal portal vein
- Anomalies of the portal vein
- Selective celiac angiogram
- Selective superior mesenteric angiogram
Bertelli's account of the arterial supply
- Supply comes mainly from the celiac and superior mesenteric arteries, or from their major branches Eight main arteries arise, with various patterns of origin Described topographically: head, then neck and body, then tail Variations in number, incidence, site of origin and even course are marked Irregularity is greatest in the distal segment, body and tail Statistical surveys diverge strikingly, and it is not yet possible to say which is most correct
- Previously called the retroduodenal artery — a confusing name also used for other small duodenal arteries Considered a constant artery; calibre ranges from barely detectable angiographically to 3 mm In about 70-80% it arises within the first 2 cm of the gastroduodenal artery, usually from its posterior aspect Spiral descending course: crosses in front of the CBD, turns round its right side, recrosses behind it It then anastomoses with the posterior inferior pancreaticoduodenal artery In more than 20% it arises from non-conventional sources, mainly the hepatic artery or its branches
- ASPD is almost constant and usually larger than the PSPD In more than 90% it arises from the gastroduodenal artery as a terminal branch, behind the first part of duodenum It may lie in front of the duodenum, on the surface of the head, or buried in the parenchyma At the papilla it may be separated from the choledochus by only 1 mm of pancreatic parenchyma It usually turns backward over the posterior surface of the uncinate process to meet the AIPD AIPD is the smallest of the pancreaticoduodenal arteries; in 90% it ends by anastomosing with the ASPD
- AIPD and PIPD arise from the bifurcation of the IPD artery in 60-70% of cases The IPD arises directly from the SMA as its first right collateral branch With an accessory right hepatic artery present, it becomes the second right collateral branch Reported incidence of that pattern ranges from 4% to 47%, depending on the author It may arise through a common trunk with the first jejunal artery — the pancreaticoduodenojejunal trunk The IPD crosses behind the superior mesenteric vein, in contact with the posterior face of the uncinate process
- Right branch of the dorsal pancreatic artery crosses the anterior head, forming the prepancreatic (Kirk's) arcade It joins a small artery from the gastroduodenal, right gastroepiploic or, less often, the ASPD The arcade has been reported in 75% to 93% of cases DP, PM and TP arteries supply neck, body and sometimes tail — any one may become dominant In some patients a single artery supplies the entire distal pancreas A dominant TP artery crossing the line of Whipple resection is a vascular hazard
- DP artery, Haller's arteria pancreatica suprema, is the largest pancreatic vessel — calibre up to 1 cm Present in 80-98% of cases; it divides as an inverted T near the neck-body junction at the lower border Right terminal branch runs behind the SMV and forms the prepancreatic arcade; left branch is the TP artery PM artery arises from the splenic, typically the middle third; incidence 64-98%, calibre averages 2 mm PM may be double (33-54%) or triple (3%); it anastomoses with the TP in 90% of cases TP artery is present in about 90%; "long-type" in about 30%, supplying the head as well as body and tail
- Tail supplied by one or more caudal pancreatic arteries and by distal extremities of the arteries of the body CP arteries reported in 66% to 95% of cases; considered constant by many investigators Single in 32-36%, two in 46%, three in 8-20%, four in 2% They run downward or transversely to the right depending on origin In most cases they enter the gland from the anterior face of the tail In 33% they are the sole supply of the tail, with no anastomosis with the arteries of the body
- Common patterns of pancreatic arterial blood supply
- Angiographic patterns of supply to the pancreatic head
- Dominant short-type transverse pancreatic artery
- Dorsal pancreatic artery and its terminal branches
- Head drainage is arranged in two venous arcades, superficial to the homonymous arterial arcades Anterior arcade: ASPD vein drains to right gastroepiploic vein, then to SMV via the gastrocolic trunk AIPD vein follows its artery behind the uncinate process, joining the uppermost jejunal vein It usually reaches the jejunal vein via a common trunk with the PIPD vein PSPD vein is the largest venous trunk of the pancreatic head In 40% the PSPD vein leaves its artery at the superior edge and crosses behind the choledochus
Lymphatic drainage and nerve supply
- Drainage is centrifugal — to whichever surrounding nodes are nearest No standard nodal terminology exists, though Evans and Ochsner proposed one No attempt to demarcate specific drainage areas has gained wide acceptance Studies of Cubilla et al. provide the basis for most recent work Vessels arise in a rich perilobular interanastomosing network Channels run on the surface and in interlobular spaces alongside the blood vessels
- Superior nodes: from the anterior and posterior superior half, to suprapancreatic nodes on the upper border Some superior lymphatics end in the gastropancreatic fold or in the hepatic chain Inferior nodes: from the lower half of head and body, to nodes along the inferior border Inferior drainage may extend to superior mesenteric and left lateroaortic nodes, rarely direct to a lumbar trunk Anterior nodes: two trunks on the front of the head to infrapyloric and anterior pancreatoduodenal nodes Posterior nodes: to posterior pancreaticoduodenal, CBD, right lateroaortic and SMA-origin nodes
- Splenic lymphatics originate from the tail of the pancreas They drain to nodes at the splenic hilum and in the splenophrenic ligament Also to the inferior and superior nodes of the tail of the pancreas A few channels end in nodes superior and inferior to the body Anterior trunks may also reach mesenteric nodes at the root of the transverse mesocolon Intraductal papillary mucinous tumours: main duct and branch duct subtypes behave differently
- Lymphatic drainage and nodal metastasis of the pancreas
- Nomenclature of perigastric and peripancreatic lymph nodes
- Anatomic Distribution of Peripancreatic Lymph Nodes in Resected Specimens
- Anatomic Distribution of Peripancreatic Lymph Nodes in Resected Specimens (continued)
- Operative Procedures for Carcinoma of the Head of the Pancreas Region
- Lymph Node Involvement in Patients with Carcinoma of the Head of the Pancreas Region
- Lymph Node Involvement in Patients with Carcinoma of the Head of the Pancreas Region (continued)
- Sympathetic supply through the splanchnic nerves; parasympathetic through the vagus Nerves generally follow the blood vessels to their destinations Together they may constitute the "pancreatic nerve" of Holst Both divisions give efferent fibres to vessel walls, the pancreatic duct and the acini Both also carry visceral afferent (pain) fibres The distribution of those afferents within the pancreas is not well understood
- Autonomic nerve supply of the pancreas
- Preganglionic fibres from the greater and lesser thoracic splanchnic nerves Greater splanchnic: preganglionic efferents from T5 to T9 or T10; lesser: T9-T10 or T10-T11 The least splanchnic nerve may contribute some fibres Fibres pierce the diaphragmatic crura to reach the celiac and superior mesenteric ganglia Postganglionic fibres accompany celiac and superior mesenteric arterial branches to the pancreas Afferent cell bodies lie in dorsal root ganglia at the same spinal levels as the preganglionic fibres
- Innervation via the celiac division of the posterior vagal trunk Efferents are preganglionic axons from the dorsal motor nucleus of the vagus Preganglionic vagal fibres synapse with terminal ganglion cells within the pancreas Postganglionic fibres terminate at pancreatic islet cells Almost 90% of vagal fibres are sensory — stretch, chemoreceptors, osmoreceptors, thermoreceptors Grundy: fewer than 10% of vagal fibres are autonomic efferents
- The severity of pancreatic pain is not easily explained anatomically Drapiewski: nerves are invaded by tumour in 84% of cases Bockman et al.: the perineurium is damaged Frey and Bockman: inflammatory cells concentrate around nerves and ganglia in chronic pancreatitis Ductal hypertension also produces pain Widdison et al. speculate on a compartment syndrome from raised tissue and ductal pressure
- Sympathectomy and vagotomy have both been used for pancreatitis and pancreatic carcinoma Howard: sympathectomy has not proven a good procedure for palliation Mallet-Guy, father of left splanchnicectomy, reported good or perfect results in 83% of his patients Stone and Chauvin: left transthoracic splanchnicectomy with bilateral vagotomy controls chronic alcoholic pancreatitis pain Cuschieri et al.: bilateral endoscopic splanchnicectomy via a posterior thoracoscopic approach Flanigan and Kraft: 40 mL of 5% phenol in almond oil, or 75% alcohol, into celiac plexus and splanchnic nerves
Histology, physiology and pancreatitis
- Islets of Langerhans constitute only 2% of the pancreatic mass Cell types: A (alpha), B (beta), D (delta) and F or PP (pancreatic polypeptide) A secretes glucagon; B secretes insulin D secretes somatostatin, which inhibits insulin and glucagon F secretes pancreatic polypeptide, which inhibits pancreatic exocrine secretion The gland is poorly encapsulated — a very thin connective tissue, with no peritoneum posteriorly
- B and D cells are evenly distributed throughout the gland Islets in the uncinate process are rich in F cells and poor in A cells Islets in body and tail are rich in A cells and poor in F cells No islets are present in parenchyma derived from the ventral diverticulum of the duodenum That ventral territory gives rise to the terminal duct of Wirsung, the uncinate process and part of the head
- Acinar cells, ducts and ductules make up 80% to 90% of the pancreatic mass An acinus is a collection of acinar cells secreting digestive enzymes, pancreatic fluid and electrolytes All acinar secretion drains through the ductal network to the duodenum via major and minor papillae Vagal stimulation augments exocrine secretion; the sympathetic system perhaps inhibits it The pancreas secretes 500 to 800 mL per day of alkaline fluid That fluid contains bicarbonate and enzymes including amylase, lipase and trypsinogen
- Ranson tabulated routine laboratory findings in 100 patients with acute pancreatitis He compared them against 100 patients with other acute abdominal emergencies The comparison is what gives the findings discriminating value Aetiological factors are multiple and are tabulated separately Lad et al. reported recurrent pancreatitis secondary to a duodenal duplication cyst Nakamura et al.: pancreaticobiliary maljunction may cause recurrent pancreatitis
- Routine Laboratory Findings in 100 Patients with Acute Pancreatitis versus Those in 100 Patients with Other Acute Abdominal Emergencies
- Routine Laboratory Findings in 100 Patients with Acute Pancreatitis versus Those in 100 Patients with Other Acute Abdominal Emergencies (continued)
- Routine Laboratory Findings in 100 Patients with Acute Pancreatitis versus Those in 100 Patients with Other Acute Abdominal Emergencies (continued)
- Etiologic Factors of Acute Pancreatitis
- Etiologic Factors of Acute Pancreatitis (continued)
- Etiologic Factors of Acute Pancreatitis (continued)
- Bounded anteriorly by posterior parietal peritoneum, posteriorly by transversalis fascia Extends from the pelvic brim below to the diaphragm above Contains adrenals, kidneys, ureters, parts of duodenum, pancreas, IVC, aorta, portal vein, ascending and descending colon In horizontal cross section it is C-shaped, following the lumbar curvature So pancreas and duodenal loop lie anterior to spleen, kidneys and posterior liver Meyers divided the region into three compartments by well-defined fascial planes
- The three extraperitoneal compartments
- Perirenal space is often said to have no continuity across the midline, though debate continues Posterior fascial layers fuse with psoas or quadratus lumborum fascia medially Renal fascia fuse anteriorly with the connective tissue around the great vessels, behind pancreas and duodenum Where continuity does occur, it appears at the level of the hila and inferior poles of the kidneys Posterior pararenal space is demarcated by fusion of transversalis fascia with muscle fascia medially It contains no organs but may communicate with preperitoneal fat of the anterolateral abdominal wall
- The three extraperitoneal compartments
- The three extraperitoneal spaces in cross section
- Structures of the three extraperitoneal spaces on the left
- Extravasation pathways depend on which part of the gland is involved Drainage from the head runs downward and to the right, meeting the ascending colon Extravasation from the tail runs left, meeting the left colon, spleen and left kidney The spaces around the kidneys are the first to be occupied Extravasation may travel craniad to the neck, mediastinum or lesser sac It may enter the root of the small bowel mesentery, or pass transperitoneally to the most dependent part
- Route to the posterior pararenal space
- Fluid collection in the right anterior pararenal compartment
- Anterior pararenal haemorrhage from a splenic artery aneurysm
- Pancreatic extravasation into the posterior pararenal compartment
- Pathways of pancreatic extravasation
- At the height of an attack, inflammation does not respect fascial planes; residual exudate may then be confined Fluid may rupture into a hollow viscus such as duodenum or transverse colon, or into the peritoneal cavity Continuity of the spaces allows extension to the thorax above and the scrotum below Also into the left retroperitoneal space, perihepatic and peripancreatic spaces, transverse mesocolon, gastrocolic omentum Jaffe et al.: 12 cases dissecting into the mediastinum — six through the aortic hiatus, six through the esophageal hiatus Extravasations eventually arrest and form a pseudocyst, or later an abscess
- Peritoneal spaces and reflections of the abdomen
- Schoenberg et al.: pancreatic abscess is a localised collection of pus within a capsule or pseudocapsule Septic (infected) necrosis is a diffuse bacterial inflammation of necrotic pancreatic and peripancreatic tissue Surgery is the treatment of choice for both conditions Baril et al.: percutaneous catheter drainage first for culture-positive collections or abscesses Seifert et al.: transgastric endoscopic debridement of infected necrosis, a less traumatic alternative Sakorafas et al.: totally necrotic parenchyma carries a poor prognosis; peripancreatic necrosis alone, better
- Uomo et al.: severe biliary pancreatitis with sterile necrosis often loses main duct integrity That loss is not an absolute indication for surgical intervention Bosscha et al.: open management of the abdomen with planned reoperation for fulminant acute pancreatitis Weber and Keller: distal pancreatectomy and pancreaticojejunostomy for childhood chronic pancreatitis DuBay et al. favour the modified Puestow procedure — longitudinal pancreaticojejunostomy Takase et al.: apoptotic renal tubular cell death occurs in severe acute pancreatitis
- Treatment protocol for biliary pancreatitis
- Ventral anlage gives the terminal duct of Wirsung, part of the head and uncinate; dorsal gives everything else Fusion failure gives pancreas divisum; malrotation gives anular pancreas The uncinate process lies behind the SMA and in front of the aorta — divide the neck from the front Both pancreaticoduodenal arcades are always present, and they supply the duodenum too An aberrant right hepatic artery from the SMA is present in about 26% — look for it before every resection Pancreatic fluid follows the anterior pararenal space, and can reach mediastinum, flank or scrotum
- References
- References (continued)
- Skandalakis' Surgical Anatomy: The Embryologic and Anatomic Basis of Modern Surgery
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