Chapter 3 The Digestive System 117 Upper Gastrointestinal Series An upper gastrointestinal (UGI) series is a radio- graphic (X-ray) examination of the upper GI tract, which includes the esophagus, stomach, and duode- num (Figure 3.12). The patient drinks a milkshake-like mixture containing barium, a chemical element that serves as a contrast agent. The barium allows radio- graphic imaging of body organs and vessels that could not otherwise be seen on an X-ray. The barium mixture is flavored to make it more palatable to the patient. During a UGI series, a radiologist views and records images as the barium flows through the esoph- agus and stomach. If the imaging procedure stops at the stomach, it is referred to as a barium swallow. If the entire small intestine also needs to be examined, the radiologist continues to record images of the duo- denum, jejunum, and ileum until the barium reaches the beginning of the large intestine at the ileocecal valve. This valve prevents the backflow of waste from the large intestine into the small intestine. This diag- nostic procedure is known as an upper GI and small bowel series. Gastric Bypass Surgery Gastric bypass surgery is a type of weight-loss surgery that limits food con- sumption by reducing the size of the stom- ach (Figure 3.13). In addition to limiting the amount of food that can be consumed in one sitting, this surgery reduces the absorption of nutrients from food. Gastric bypass and other weight-loss surgeries are performed when diet and exercise methods alone have been ineffective or when obesity causes serious health problems. Typically, gastric bypass surgery is per- formed with a laparoscope (LĂP-ă-rō-skōp) inserted through small incisions made in the abdomen. The laparoscope is linked to a video monitor, which enables the surgeon to see and operate inside the abdomen without having to make large incisions. Compared to open surgery, laparoscopy (lăp-ă-RŎS-kō-pē) involves a shorter hospitalization period and faster recovery. Santibhavank P/Shutterstock.com Figure 3.12 This upper gastrointestinal (UGI) study of an adult female shows a close-up of the stomach and duodenum. Figure 3.13 Gastric bypass surgery limits food consumption by reducing the size of the stomach. Before surgery After surgery Jejunum Jejunum Duodenum (bypassed) Duodenum Stomach Stomach (bypassed)