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Topic

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Pyloric canal

The pyloric canal is the distal portion of the stomach, measuring about 2–3 cm in length, and connects the pyloric antrum to the pyloric orifice at the duodenum. It is a tubular structure surrounded by a thickened circular layer of smooth muscle that forms the pyloric sphincter, regulating gastric emptying. The mucosa of the pyloric canal is arranged into folds, which may become prominent in conditions such as hypertrophic pyloric stenosis. The pyloric canal plays a central role in the controlled passage of gastric contents into the duodenum and prevents duodenogastric reflux.

Synonyms

  • Canalus pyloricus

  • Gastric outlet canal

  • Distal gastric canal

Function

  • Regulates emptying of stomach contents into the duodenum

  • Prevents duodenogastric reflux

  • Coordinates with pyloric sphincter contractions for digestive control

  • Provides a site of clinical importance in pyloric stenosis and gastric outlet obstruction

Arterial Supply

  • Supplied by the right gastric artery (branch of the common hepatic artery)

  • Additional supply from the right gastroepiploic artery

  • Anastomoses with branches from the gastroduodenal artery

Venous Drainage

  • Drains via the right gastric vein and right gastroepiploic vein

  • Both empty into the portal venous system

Nerve Supply

  • Parasympathetic innervation from the vagus nerve (CN X) → stimulates peristalsis and relaxation of sphincter

  • Sympathetic innervation from the celiac plexus → inhibits motility and tightens sphincter tone

MRI Appearance

T1-weighted images:

  • Wall shows intermediate to low signal intensity

  • Lumen contains variable contents (fluid = low signal, air = signal void)

  • Muscle thickening in pathology (e.g., pyloric stenosis, tumor) appears as low signal concentric thickening

T2-weighted images:

  • Wall is low to intermediate signal, lumen fluid appears bright hyperintense

  • Hypertrophy, inflammation, or tumors cause asymmetric or concentric thickening with altered signal

  • Useful for identifying gastric outlet obstruction or infiltrative disease

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of edema, inflammation, or neoplastic infiltration

  • Pathological changes appear hyperintense, normal smooth muscle wall remains low signal

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal canal wall enhances homogeneously

  • Malignancy shows irregular, asymmetric enhancement

  • Inflammatory changes demonstrate diffuse mural enhancement

CT Appearance

Non-contrast CT:

  • Seen as a tubular soft tissue structure between antrum and duodenum

  • Wall normally thin; thickened in pyloric stenosis or carcinoma

  • Lumen may contain air (black) or fluid (soft tissue density)

Contrast-enhanced CT (CECT):

  • Wall enhances homogeneously in normal state

  • Gastric carcinoma: irregular thickening with heterogeneous enhancement

  • Hypertrophic pyloric stenosis: concentric thickening of canal wall with narrowed lumen (“string sign”)

  • Useful for evaluating gastric outlet obstruction, mass lesions, or postoperative anatomy

MRI images

Pyloric canal anatomy MRI axial image -img-00000-00000

MRI images

Pyloric canal anatomy MRI CORONAL image -img-00000-00000

CT image

Pyloric canal anatomy CT axial image -img-00000-00000