Contrast Studies of the Gastrointestinal Tract: Normal Patterns

GIT CONTRASTED NORMAL PATTERN

1. Esophagram (Barium Swallow or Upper GI Contrast Study)

A contrast-enhanced examination of the gastrointestinal tract (GIT) is performed to evaluate structural and functional abnormalities.

• Indications:
• Dysphagia (difficulty swallowing)
• Odynophagia (painful swallowing)
• Suspected esophageal stricture or web
• Gastroesophageal reflux disease (GERD)
• Hiatal hernia
• Esophageal motility disorders (e.g., achalasia)
• Esophageal perforation (use water-soluble contrast)
• Foreign body localization

Pre/post-operative evaluation

OESOPHAGUS

ANATOMY OF THE OESOPHAGUS

The oesophagus (plural: oesophagi or oesophaguses) is a muscular tube that conveys food and fluids from the pharynx to the stomach. It forms part of the upper gastrointestinal tract.

The esophagus is 23-37 cm long with a diameter of 1-2 cm and is divided into three parts:

cervical: continuous with the hypopharynx, commences at the lower border of cricoid cartilage (at level of C5/6) or cricopharyngeus muscle thoracic: from superior thoracic aperture (T1) to the esophageal hiatus (T10) in the diaphragm which covers the inferior thoracic aperture abdominal: from esophageal hiatus and is continuous with the cardia of the stomach at the gastro-esophageal junction

RELATION

The cervical esophagus begins at the upper esophageal sphincter, which is formed by the cricopharyngeus muscle.

The esophagus then descends to the left of the midline through the neck and superior mediastinum, returning to the midline at T5, before coursing to the left of the midline once more, in the posterior mediastinum. The distal thoracic esophagus then curves anteriorly to pass through the diaphragm into the abdominal cavity.

The lower esophageal sphincter, a specialized region of the circular muscle of the distal esophagus, manifests itself radiographically as the phrenic ampulla (a.k.a. esophageal vestibule), a 2-4 cm long dilatation between the A-ring and B-ring.

phrenic ampulla is seen radiographically as a globular structure above the diaphragm and below the tubular oesophagus.

Phrenic ampulla, A and B-rings

The phrenic ampulla (also known as the esophageal vestibule) is the region between the A-ring and B-ring of the distal esophagus. The gastro-esophageal junction is below the ampulla (and gastric folds should not enter the region of the ampulla) The ampulla is more prominent in some patients than in others, but it is a normal finding and should not be confused with a sliding hiatal hernia or an esophageal web.

Three normal narrow esophageal segments (oesophageal constrictions) should not be confused with pathology:

• The narrowest segment is at C5/C6 at the level of the cricoid cartilage
• Due to the aortic arch at the T4/5 level

At the esophageal hiatus at the T10/11 level

Radiological features of Esophagus

• Appearance: A smooth, narrow, tubular structure from the pharynx to the stomach.

On Barium Swallow:

• Shows a uniform/symmetrical, smooth mucosal outline.
• The cervical esophagus is slightly wider.

Normal peristalsis moves contrast smoothly.

The gastroesophageal junction (GEJ) appears as a Z-line(A zig-zag mucosal border where the oesophageal mucosa transitions to the gastric mucosa).

Extrinsic Indentations: There are three normal anatomical indentations where the esophagus is compressed by:

• The aortic arch
• The left main bronchus
• The left atrium

Forming notch or a deep recesses

2. Upper GI Series (Stomach and Duodenum)

• Indications:
• Epigastric pain
• Suspected peptic ulcer disease
• Gastric outlet obstruction
• Vomiting of unknown cause
• Gastrointestinal bleeding (when endoscopy is unavailable)
• Mal-rotation or volvulus (especially in pediatrics)
• Suspected mass or tumor

Evaluation of post-surgical anatomy

Stomach

STOMACH

One common radiologic procedure of the GI tract is an “upper GI,” in which barium sulfate flows from the esophagus and into the stomach and small bowel.

Once the barium reaches the stomach, the evaluation of the stomach contour, position, and rugae and the peristaltic changes occurring as the stomach fills and empties.

Contrast Studies of the Gastrointestinal Tract: Normal Patterns

In many instances, a gas-producing substance (carbon dioxide crystals) is used with barium sulfate to produce a double-contrast examination.

The purpose is to expand the stomach and promote coating of the stomach mucosa.

Stomach

• Appearance: A J-shaped or crescentic organ with a rugal fold pattern.

On Barium Meal:

• Fundus: Fills first and appears as a rounded area under the left hemidiaphragm.
• Body and Antrum: Display smooth peristaltic waves.
• Rugae (mucosal folds) are longitudinal and prominent folds, especially in the body.

Pyloric canal appears as a narrow outflow tract into the duodenum.

Small Bowel Follow-Through (SBFT) / Enteroclysis

• Indications:
• Chronic diarrhea
• Malabsorption syndromes
• Inflammatory bowel disease (e.g., Crohn’s disease)
• Obscure gastrointestinal bleeding
• Suspected small bowel obstruction or stricture
• Evaluation of fistulas

Post-surgical complications (e.g., adhesions)

Small intestine

Small Bowel (Duodenum, Jejunum, Ileum)

On Small Bowel Follow-Through:

Duodenum: C-shaped loop surrounding the pancreatic head; smooth mucosa with a fixed position.

Jejunum: Located in the left upper quadrant; displays a “feathery” or “stacked coin” appearance due to prominent valvulae conniventes.

Ileum: In the lower abdomen/pelvis, has smoother and thinner folds compared to jejunum.

4. Barium Enema (Lower GI Study)

• Indications:
• Chronic constipation
• Rectal bleeding
• Change in bowel habits
• Suspected colonic obstruction (water-soluble contrast if perforation is suspected)
• Evaluation of colonic masses or polyps

Inflammatory bowel disease (e.g., ulcerative colitis)

LARGE BOWEL

The lower GI tract is examined by administering a barium enema through the rectum.

This examination demonstrate abnormalities of the large bowel and intraluminal neoplasm's.

The barium enema is performed in a single-contrast fashion with only barium or as a double-contrast study using barium sulfate in combination with a negative contrast agent.

Contrast Studies of the Gastrointestinal Tract: Normal Patterns

The negative contrast agent distends the lumen, allowing improved visualization of the mucosal lining, especially small polyps and intraluminal tumors.

After evacuation of the barium sulfate mixture, the radiographer will obtain a “postevacuation” radiograph to visualize colon contraction and to demonstrate the mucosa.

Large Bowel (Colon)

On Barium Enema:

Haustral folds are spaced more widely and do not traverse the full lumen.

Normal path: Cecum → Ascending colon → Transverse colon → Descending colon → Sigmoid colon.

• Cecum appears bulbous and in the right lower quadrant.

Sigmoid colon is tortuous but maintains a smooth mucosal pattern.

Rectum and Anus

• On Contrast Enema or Defecography:
• Rectum: Straight with smooth mucosa; has three normal transverse folds (Houston valves).
• Anal canal: Appears as a short, narrow terminal segment with a tapered end.

Anorectal angle may be assessed during defecography.

General Indications for Any GIT Contrast Study

• Structural anomalies (congenital or acquired)
• Functional disorders (motility issues)
• Post-trauma assessment
• Preoperative planning

Postoperative complications (e.g., leaks, strictures)