Procedures · Chest, abdomen and GI2 min read5-question check
Barium study positions
Anterior obliques open the colic flexure nearest the receptor; posterior obliques open the far one.
Esophagus
For an esophagram, the RAO position is preferred, rotated about 35 to 40 degrees. It places the esophagus between the vertebrae and the heart, so it is not hidden by either. Center at T5 or T6, about 2 to 3 inches below the jugular notch. A lateral and an AP or PA are often added.
Stomach and duodenum
For the stomach and duodenum, gravity decides where barium and air go. In the RAO, about 45 degrees for a sthenic patient, barium fills the pylorus, duodenal bulb, and C-loop. In the PA, barium fills the body and pylorus, with air in the fundus. In the LPO, also about 45 degrees, air fills the bulb and pylorus for a double-contrast look, and barium pools in the fundus. The right lateral shows the retrogastric space and the duodenal bulb and C-loop in profile. Most stomach projections are centered around L1 to L2 for sthenic patients, higher for hypersthenic patients and lower for asthenic patients.
Barium enema
For a barium enema, the PA or AP shows the entire colon. Anterior obliques open the flexure closest to the receptor, and posterior obliques open the flexure farthest away. So the RAO opens the hepatic flexure and shows the ascending colon and sigmoid. The LAO opens the splenic flexure and descending colon. The LPO opens the hepatic flexure and shows the ascending colon and rectosigmoid. The RPO opens the splenic flexure and descending colon. A lateral rectum, centered at the level of the ASIS, shows the rectum and rectosigmoid.
Decubitus with air
In a double-contrast barium enema, decubitus projections with a horizontal beam show air-filled walls on the side up. In the right lateral decubitus, the right side is down, so air fills the medial wall of the ascending colon and the lateral wall of the descending colon. The left lateral decubitus shows the lateral ascending and medial descending walls.
Clinical Example
During a barium enema, the radiologist asks for a view to open the splenic flexure. You turn the patient into an LAO, about 40 degrees, with the left anterior side on the table. The splenic flexure opens clearly.
Common Mistakes
- Using an LAO for the esophagus instead of the preferred RAO.
- Mixing up RAO and LPO for the duodenum: RAO shows barium, LPO shows air.
- Using an LPO to open the splenic flexure; posterior obliques open the far side.
- Using a vertical beam for decubitus images, which hides air-fluid levels.
Why It Matters
Correct positions show disease without repeat fluoroscopy and extra dose. The registry asks which position opens a flexure or fills a part with barium or air.
Key Relationships
- Esophagus: RAO 35 to 40 degrees, between the spine and heart
- Stomach RAO: barium in the duodenal bulb; LPO: air in the bulb
- Colon: anterior obliques open the near flexure; posterior obliques open the far flexure
- Decubitus double contrast: side up fills with air