Injuries to the pancreas and duodenum present a significant challenge, for a number of reasons. First, while their deep, central position affords the organs some degree of protection, their retroperitoneal location compromises the clinical detection of injury. This can lead to delays in diagnosis and treatment, which may result in morbidity and mortality.^{1,2,3,4,5,6,7} Second, even when managed promptly, anatomic and physiologic factors contribute to a disturbingly high incidence of complications. Third, the infrequency of these injuries has resulted in a lack of significant management experience—both of the primary injuries as well as the complications—among practicing trauma surgeons. Consequently, trauma to the pancreas and duodenum is associated with relatively poor outcomes that have not improved significantly over the past few decades, despite advances in trauma and critical care management (Tables 32-1 and 32-2).^{1,3,6,8,9,10,11,12,13,14,15,16,17,18,19}

Most early descriptions of duodenal and pancreatic injuries were isolated autopsy observations. The first known literature report of pancreatic trauma was published by Travers in 1827. By 1903, von Mikulicz-Radeck reported only 45 cases in the literature.²⁰ Of note, 72% of operated patients survived, a success rate that rivals modern-day results. Many of the recommendations from that early series still hold true today: thorough abdominal exploration, hemostasis, and drainage. Although military experience has shaped much of contemporary trauma management, a paucity of reports of injuries to the pancreas have emanated from wartime experiences. The first series of five patients from the American Civil War included one survivor, and a similar experience was described after World War I. World War II annals include 62 cases of pancreatic trauma, but only nine were reported from the Korean War. Virtually no reports of pancreatic or duodenal injuries are available from the Vietnam War experience except for two cases of pancreaticoduodenectomy.

The first account of successful surgical repair of a duodenal rupture was published by Herczel in 1896. In 1904, Summers²¹ cautioned about the difficulty in diagnosis of a retroperitoneal perforation of the duodenum from a gunshot wound, and may have been the first to describe the potential application of the pyloric exclusion procedure. The earliest reported series of traumatic duodenal ruptures was that of Berry and Giuseppi²² from 10 London hospitals. The authors described 29 patients with duodenal injuries, all of whom died; further, the authors cited only one known survivor of duodenal trauma to that point in time. From World War II, Cave²³ recorded 118 cases of duodenal injuries with a mortality of 56%, which is still the single largest military series of duodenal injuries.

Recent Historical Trends

Pancreaticoduodenal trauma remains uncommon, and few single institutions have extensive experience. Busy trauma centers such as Ben Taub, Grady Memorial, UT-Southwestern, L.A. County, Detroit Receiving, UT-Memphis, and Denver General Hospital reported just 10–20 duodenal and 10–20 pancreatic injuries per year in the 1960s–1980s.^{1,8,9,11,13,14,15,16,18,24,25} All of the patients in those series were diagnosed at laparotomy. In contrast, contemporary practice involves liberal imaging with high-resolution computed tomographic (CT) scanning, and as a result many occult low-grade injuries are identified. A recent analysis of the US Nationwide Inpatient Sample from 1998 to 2009 found that the incidence of pancreaticoduodenal injuries increased by 8% over the time period.²⁶ While the grade of injury was not documented, only 20% of patients underwent “pancreas-specific” surgical procedures. In the recent collective experience of trauma centers in New England, over 80% of pancreaticoduodenal injuries were grade I or II, and over 40% were managed nonoperatively.²⁷ Yet despite the increased detection of pancreaticoduodenal injuries, the total number is still low: 230 total patients in the 11-year experience of 11 New England trauma centers,²⁷ and only 2268 per year across the United States.²⁶ The current incidence of duodenal injuries is 0.2–0.3% of trauma admissions, and of pancreatic injuries is 0.004–0.6%.^6,13,28,29 From 2010 through 2014 at Denver Health Medical Center (DHMC), there were, on average, just 17 pancreatic or duodenal injuries per year (unpublished data). The incidence of pancreatic or duodenal injuries at DHMC was 2% following penetrating and 0.6% following blunt trauma. Duodenal and pancreatic injuries each occurred with a frequency of 1.2% following penetrating trauma; in contrast, blunt pancreatic injuries (0.5%) were more than twice as common as blunt duodenal injuries (0.2%). Whereas reports from the 1970s through 1990s^{1,3,6,8,9,10,11,12,13,14,15,16,17,18,19} contained a majority of penetrating trauma victims (see Tables 32-1 and 32-2), that trend has reversed due to decreasing urban violence over the past 20 years and liberal blunt trauma imaging. For example, the recent DHMC patient experience as described above (unpublished data) consists of 64% blunt trauma victims, and the Harborview Hospital experience is comprised of 71% blunt trauma patients.⁶ In the US Nationwide Inpatient Sample in 2009, only 25% of pancreaticoduodenal injuries were due to gunshot or stab wounds.²⁶

A survey of several large series over the last three decades of the 20th century demonstrates that gunshot victims have more than double the mortality rate compared with stab wound victims (see Tables 32-1 and 32-2).^{1,3,6,8,9,10,11,12,13,14,15,16,17,18,19} On the other hand, the overall mortality rate among penetrating and blunt trauma patients with pancreaticoduodenal injuries was the same, between 16% and 18%. Contemporary series with greater numbers of low-grade injuries report lower overall mortality, but it is still significant (ie, 12%).^26,27 Of note, the occurrence of combined pancreatic and duodenal injuries is associated with nearly double the mortality rate compared with that of either injury alone (Table 32-3).^{1,11,13,15,16,27}

It is important to recognize that the mortality is not typically attributed to the pancreaticoduodenal injury but rather to associated injuries and in particular major vascular injuries. The anatomic location of the pancreaticoduodenal axis, and its proximity to other vital structures, makes isolated injuries distinctly uncommon (Figs. 32-1 and 32-2). In virtually every large series, more than 90% of pancreatic and duodenal injuries are associated with injuries to other organs.^{1,8,9,11,12,13,14,15,18,19,30} On average, there are 2.5–4.6 associated injuries with each pancreatic or duodenal injury.^13,30 The common associated injuries and their frequencies are listed in Tables 32-4 and 32-5. Not surprisingly, complication rates are higher when there are associated injuries, and the mortality rate increases progressively with each associated injury.³¹ Collective analysis of 11 large trials reveals that 304 (68%) of 447 deaths occurred within the first 12–48 hours and were attributed to hemorrhagic shock or massive traumatic brain injury (Table 32-6).^{2,3,6,10,11,12,13,14,16,19,32,33} Moreover, the overall mortality attributed to the pancreatic or duodenal injuries is consistently fewer than 2%.

Predictors of survival include age, overall injury severity, indices of shock, and severe brain injury—but interestingly, not pancreatic or duodenal injury grade.^6,13,34 Late deaths in cases of pancreatic and duodenal trauma are most often ascribed to sepsis and multiple organ failure (MOF), often provoked by complications related to the original pancreatic or duodenal injury. This underscores the importance of early and prompt diagnosis. One quarter to one half of patients who survive initial operation can be expected to develop a complication.^6,27 Among those patients with a delay in the initial diagnosis of pancreaticoduodenal injury, morbidity and mortality rates are considerably higher.^{1,2,3,4,5,6,7}

The duodenum and pancreas are intimately associated with many vital structures in a deep and narrow region (see Figs. 32-1 and 32-2). The name duodenum is derived from duodenum digitorum (“space of 12 digits”), from the Latin duodeni (“12 each”)—so named by Greek physician Herophilus for its length, approximately 12 finger-breadths. It extends about 30 cm, from the pyloric ring to the ligament of Treitz. Classically the duodenum is divided into four portions: superior (first, or D1), descending (second, or D2), transverse (third, or D3), and ascending (fourth, or D4). The first portion of the duodenum extends from the pylorus to the common bile duct (CBD) and gastroduodenal artery. The second portion extends from that point to the ampulla of Vater. The third portion extends from the ampulla of Vater to the superior mesenteric artery (SMA) and vein (SMV), which emerge from posterior to the pancreas and descend anteriorly over the duodenum. The fourth portion extends from the SMA and SMV to the point where the duodenum emerges from the retroperitoneum to join the jejunum, just to the left of the second lumbar vertebra, at the ligament of Treitz. Thus, the duodenum is almost entirely a retroperitoneal structure, with the exception of the anterior half circumference of D1 and the most distal part of D4. The first portion, distal region of the third portion, and the fourth portion of the duodenum lie directly over the vertebral column. The psoas muscles, aorta, inferior vena cava, and right kidney complete the posterior boundaries of the duodenum. The liver and gallbladder overlie the first and second portions of the duodenum anteriorly; the second and third are bounded by the hepatic flexure and right transverse colon, and the fourth portion lies beneath the transverse colon, mesocolon, and stomach. The head of the pancreas is intimately associated within the C loop, or second portion.

The pancreas is divided into the head, contained within the duodenal C-loop; the neck, which is the narrowest portion and overlies the SMA and SMV; the body, which is rather triangular in cross section and which extends to the left across the vertebral column; and the tail, which extends into the splenic hilum. In blunt force trauma, the vertebral column may act as a fulcrum over which the pancreas may be transected. The root of the transverse mesocolon crosses the head anteriorly. Posteriorly, the head is separated from the body by the pancreatic incisure, where the superior mesenteric vessels lie. The uncinate process, a part of the head, extends to the left behind the SMA and SMV. The body of the pancreas extends laterally. The base of the transverse mesocolon is attached at the anterior margin, and is covered with peritoneum and forms the posterior wall of the omental bursa. The inferior surface of the pancreas is covered with peritoneum from the posterior mesocolon. The body of the pancreas rests on the aorta. The tail of the pancreas lies in front of the left kidney, in intimate proximity to the splenic flexure of the colon, often abutting the spleen via the lienorenal ligament. The splenic artery runs along the upper border of the gland, often crossing in front of the tail. The splenic vein lies in a groove behind the body and tail, usually on the inferior edge of the pancreas.

The blood supply of the pancreas and duodenum comes from the gastroduodenal, SMA, and splenic arteries. A network of vessels throughout the pancreas protects it from ischemia, but also contributes to vigorous bleeding following injury. The blood supply to the body and tail arises from the SMA and splenic arteries. The second portion of the duodenum has a unique blood supply that originates from both the gastroduodenal artery and the inferior pancreaticoduodenal artery, a branch of the SMA. Both of these vessels divide into anterior and posterior branches that are located on the edge of the head of the pancreas and anastomose with each other anteriorly and posteriorly. The second portion of the duodenum receives radial branches from these vessels that comprise its only blood supply. Consequently, if all of the pancreaticoduodenal vessels are injured by trauma, a pancreaticoduodenectomy will be necessary. The third portion of the duodenum receives its blood supply from the notoriously short mesentery of the SMA.

Although the arterial and venous supply as described is relatively constant, variations do exist and should be kept in mind during surgical exploration in this region. Origin of the common hepatic artery (5%) and a replaced right hepatic artery (15–20%) from the SMA are among the most frequent anomalous findings. In other instances, the right hepatic may arise from the aorta, gastroduodenal, or even left hepatic artery. In 4% of the population, the entire common or proper hepatic artery is aberrant, arising from the SMA, aorta, or left gastric artery. In addition, if the bifurcation of the proper hepatic artery is low, the right hepatic may lie in front of the CBD or cross in front of it as well as the cystic duct.

Surgeons dealing with injuries to the duodenum and pancreas should be particularly well versed with the anatomic positions of the CBD and pancreatic duct. The CBD descends from above to pass behind the first part of the duodenum, continuing downward on the posterior surface of the head of the pancreas where it is overlapped by lobules of pancreas obscuring its identification. In this region, the CBD curves to the right and joins with the main pancreatic duct of Wirsung prior to entering the posteromedial wall of the second part of the duodenum as the ampulla of Vater. The main pancreatic duct usually traverses the entire length of the gland and is located posteriorly slightly above a line halfway between the superior and inferior edges of the pancreas. The accessory duct of Santorini typically branches out from the main duct near the neck and empties separately into the duodenum about 2.5 cm proximal to the duodenal papilla. The CBD and main pancreatic duct may rarely enter the duodenum through separate openings. This is important to recognize when attempting cholangiopancreatography via the gallbladder or CBD.

Partially digested chyle from the stomach and the proteolytic and lipolytic secretions of the biliary tract and pancreas mix in the duodenum. The powerful digestive enzymes commonly found in this location include lipase, trypsin, amylase, elastase, and peptidases. Approximately 10 L of fluid from the stomach, bile duct, and pancreas passes through the duodenum in a day. Under normal conditions, the small intestine absorbs more than 80% of this fluid, but following injury, this high volume and enzymatically charged flow accounts for the disastrous consequences of a lateral duodenal fistula and associated derangements in water and electrolyte homeostasis.

The duodenum has several key roles in vitamin and mineral absorption as well as food processing. Vitamin B₁₂ malabsorption may result from extensive duodenal resection. The protein is hydrolyzed by pancreatic enzymes in the duodenum to allow free cobalamin (B₁₂) to bind to gastric parietal cell-derived intrinsic factor.

The duodenum is the main site for transcellular transport of calcium. A key step in transport is mediated by calbindin, a calcium binding protein produced by enterocytes. Regulation of calbindin synthesis appears to be the main mechanism facilitating vitamin D regulated calcium absorption.

The pancreas consists of both endocrine and exocrine cells. The endocrine cells are distributed throughout the substance of the gland, and the α-, β-, and δ-islet cells produce glucagon, insulin, and gastrin, respectively. The secretion of insulin and glucagon are responsive to blood glucose levels. Islet cell concentration is thought to be greater in the tail than the body and head of the gland, although it is generally held that normal hormonal balance may be maintained as long as approximately 10% of the gland remains after resection. Both duct and acinar cells of the pancreas secrete between 500 and 800 mL/d of clear, alkaline, isosmotic fluid. In addition, the acinar cells produce amylase, proteases, and lipases. Pancreatic amylase is secreted in its active form and serves to hydrolyze starch and glycogen to glucose, maltose, maltotriose, and dextrins. Proteolytic enzymes produced by these cells include trypsinogen, which is converted to trypsin in the duodenal mucosa by enterokinase. Pancreatic lipase is secreted in an active form and hydrolyzes triglycerides to monoglycerides and fatty acids. The acinar and duct cells also secrete the water and electrolytes found in pancreatic juice.

Bicarbonate secretion is directly related to the rate of pancreatic secretion; chloride secretion varies inversely with bicarbonate secretion so that the sum total of both remains constant. The hormone secretin, released from the duodenal mucosa, is the major stimulant for bicarbonate secretion, and serves to buffer the acidic fluid entering the duodenum from the stomach. Both endocrine and exocrine pancreatic functions are interdependent. Somatostatin, pancreatic polypeptides, and glucagons are all believed to have a role in inhibition of exocrine secretion. When pancreatic exocrine function is reduced to less than 10%, diarrhea and steatorrhea develop.

The approach to patients with abdominal trauma begins with an initial evaluation as described in the American College of Surgeons Advanced Trauma Life Support (ATLS) course.³⁵ Many pancreatic and duodenal injuries are the result of penetrating trauma, and the injury is usually discovered during exploratory laparotomy. The hemodynamically unstable patient requires little preoperative evaluation other than expeditious transport to the operating room. Prior to exploring patients with gunshot wounds, plain x-rays of the chest, abdomen, and pelvis should be obtained if possible; information regarding potential trajectory and involvement of more than one body cavity is invaluable. Blood typing is performed in anticipation of potential transfusion, and antibiotics are administered. It is critical that thorough exploration and examination of the pancreas and duodenum are performed during trauma laparotomy, particularly when there is retroperitoneal hematoma, bile staining, fat necrosis, or edema in the supramesocolic region.

Intraoperative evaluation of the duodenum and head of the pancreas begins with full mobilization achieved by the Kocher maneuver to the midline with coincident mobilization and medial rotation of the hepatic flexure of the colon. This provides exposure of the anterior and posterior surfaces of the second and third portions of the duodenum as well as the head and uncinate process of the pancreas. The distal CBD and third portion of the duodenum are exposed by dissection of the overlying peritoneal attachments and fascia. By detaching the hepatic flexure of the colon from the second portion of the duodenum, evaluation of potential injury to the mesenteric vessels may be assessed. Full medial rotation of the right colon, cecum, and terminal ileum will allow complete evaluation of associated hepatic or vascular injuries in the right upper and middle abdomen. Incision in the right side of the root of the transverse colon will allow reflection of the small bowel superiorly for further exposure of the third part of the duodenum. The body and tail of the pancreas are examined by division of the gastrocolic ligament and reflection of the stomach cephalad. Insertion of a curved retractor in the lesser sac allows full inspection of the anterior surface of the pancreas from the head to tail and from superior to inferior surfaces. In cases of active hemorrhage in the region of the neck of the pancreas suspected to originate from the superior mesenteric or portal vein behind the pancreas, the pancreas should be divided without hesitation. A stapling device will allow for rapid exposure of the injured vessel and hemorrhage control of the pancreas. Further exposure of the posterior surface of the pancreas is accomplished by division of the retroperitoneal attachments along the inferior border of the pancreas and retraction of the pancreas cephalad. Additional mobilization of the spleen and reflection of the spleen and tail of the pancreas from the left to the midline is a useful technique for further evaluation of the remaining areas of the pancreas. Most injuries sustained in penetrating trauma will be discovered with direct exploration. In many cases, the integrity of the main pancreatic duct remains in question. The importance of specific intraoperative assessment of the duct is in evolution (see below).