GI tract overview

the gastrointestinal tract/alimentary canal consists of the:

• mouth

• pharynx

• esophagus

• stomach

• small intestines

• colon

what is the route of the GI tract?

mouth → pharynx → esophagus (travels through the esophageal hiatus) → stomach (GEJ is where the esophagus and stomach join) → small intestines (duodenum, jejunum, ileum) → cecum → colon (ascending, transverse, descending) → sigmoid colon → rectum → anus

ascending colon

after the cecum, it travels superiorly toward the liver, within the right side of the abdomen

transverse colon

• beginning marked by a bend in the colon, the hepatic flexure/right colic flexure

• travels across the abdomen

descending colon

• beginning marked by a bend, the splenic flexure/left colic flexure, located inferior to the spleen

• located within the left side of the abdomen

is the GI tract intraperitoneal or retroperitoneal?

• most parts are intraperitoneal

• duodenum, ascending, and descending colon are retroperitoneal

indications for a sono of the GI tract include:

• hypertrophic pyloric stenosis (HPS)

• intussusception

• acute appendicitis

what transducer is used for GI tract exams?

most often a high-frequency linear array but some studies may require a curved-array

the alternating echogenicites of the bowel wall layers should produce what type of sonographic appearance?

a “target” or “bull’s-eye” appearance

pyloric sphincter

a muscle that controls the emptying of the contents of the stomach into the duodenum

where is the appendix located?

at the level of the ileocecal valve, connected to the cecum

what are the 5 layers of the gut and what are their echogenicites on sono?

• superficial mucosa (innermost layer) → echogenic

• deep mucosa → hypoechoic

• submucosa (muscularis propria interface) → echogenic

• muscularis propria → hypoechoic

• serosa (outermost layer) → echogenic

normal bowel should be compressible and have:

observable peristalsis

normal small bowel wall thickness:

1.5-3 mm in thickness

small bowel distention measurement is defined as:

2.5 cm or greater from outer to outer wall

normal nondistended colon wall thickness:

4- 9 mm

colon distention is defined as the diameter of a segment that:

exceeds 6 cm

color doppler of normal bowel will show:

little to no color