Evaluating the pancreas is part of the standard diagnostic ultrasound examination of the abdomen. As the pancreas lies in a midline retroperitoneal location behind hollow viscera, transabdominal ultrasound is often challenging. While CT, MRI, and EUS are perhaps preferred modes of imaging the pancreas, transabdominal ultrasound remains an indispensible tool as an initial examination, in a sense acting as a gateway to the more invasive and/or expensive modalities. Furthermore, ultrasound (in all its forms) is invaluable in image-guided procedures, where CT or MRI may prove to be unwieldy.
Clinical signs and symptoms that may warrant a focus on the pancreas include pain, weight loss, jaundice, diarrhea, bloating, or even new-onset diabetes. Pain due to pancreatic pathology usually presents as epigastric or left-sided abdominal pain that may radiate to the back. Weight loss, jaundice, and new-onset diabetes may herald malignancy in the pancreas. Ultrasound can help in distinguishing solid tumors (ductal adenocarcinoma and neuroendocrine tumors) from cystic tumors (serous and mucinous neoplasms, IPMNs, solid pseudopapillary tumors).
Signs of pancreatic insufficiency such as diarrhea or bloating can raise suspicion for chronic pancreatitis, particularly in the setting of alcoholism or gallstone disease. Sudden onset of characteristic midepigastric pain radiating to the back suggests acute pancreatitis. Ultrasound serves a particularly helpful role in this disease spectrum, in the diagnosis of acute disease, in follow-up of chronic pancreatitis and pseudocyst surveillance, and in image-guided procedures.
Figure 8-1 shows the basic anatomic position of the pancreas in the retroperitoneum, posterior to the stomach and lesser omentum. It courses transversely through the epigastrium at the level of the first or second lumbar vertebra. It is divided into four descriptive regions: the head, neck, body, and tail. Cradled in the C-loop of the duodenum, the head of the pancreas curves posteriorly and medially around the superior mesenteric vessels; this region adjacent to the superior mesenteric vessels is often termed the uncinate process. Anteriorly, the pancreas follows an angled path toward the left upper quadrant. Its thinner neck region is demarcated by where it courses anteriorly over the superior mesenteric and splenic vein confluence into the portal vein, continuing to become the more bulky body region. The tail refers to its most distal portion as it thins out toward the splenic hilum.
Schematic of pancreas anatomy. P = pancreas; D = duodenum; K = kidneys; S = spleen, and the asterisk (*) marks the superior mesenteric vein. (Reprinted with permission from Flay NW, Gorelick FS. Pancreas, anatomy. In: Johnson L, ed. Encyclopedia of Gastroenterology. New York;2004:25–29.)
The arterial supply of the pancreas derives from the celiac trunk and the superior mesenteric artery. A main branch of the celiac trunk, the splenic artery takes its well-recognized tortuous course toward the splenic hilum. As it transverses along the superior edge of the pancreas, the splenic artery gives off the dorsal pancreatic ...