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Superior rectal vein

The superior rectal vein is the main venous drainage vessel of the rectum and represents the continuation of the inferior mesenteric vein (IMV). It originates from the hemorrhoidal venous plexus surrounding the rectum and ascends in the mesorectum, draining blood from the mucosa and muscular wall of the rectum into the IMV, which then drains into the portal venous system.

Anatomically, the superior rectal vein communicates with the middle rectal veins (draining into the internal iliac system) and inferior rectal veins (draining into the internal pudendal vein → internal iliac system). These porto-systemic connections form the basis of anorectal varices and hemorrhoids, which can develop in portal hypertension.

Clinically, the superior rectal vein is important in colorectal surgery, portal hypertension assessment, and interventional procedures.

Synonyms

  • Superior hemorrhoidal vein

  • Rectal tributary of inferior mesenteric vein

Function

  • Primary venous drainage of the rectum into the portal system

  • Connects portal and systemic venous systems via rectal venous plexus

  • Plays a major role in hemorrhoid formation and anorectal varices in portal hypertension

Tributaries

  • Superior rectal venous plexus within the rectal wall

  • Communicates with middle and inferior rectal veins

MRI Appearance

T1-weighted images:

  • Vein appears as a flow void (black lumen) within the mesorectum

  • Surrounded by intermediate signal of rectal wall and fat

T2-weighted images:

  • Vein lumen seen as a signal void

  • Dilated veins in hemorrhoids or varices may show serpiginous hypointense structures around rectum

STIR:

  • Fat suppression highlights perivascular edema or congestion

  • Enlarged venous plexuses appear conspicuous against suppressed background

T1 Fat-Saturated (Pre-contrast):

  • Vein lumen may appear intermediate signal, standing out against suppressed mesorectal fat

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Enhances brightly and homogeneously during the venous phase

  • Demonstrates venous engorgement in portal hypertension or rectal varices

MRV (Magnetic Resonance Venography):

  • Provides non-invasive mapping of superior rectal venous drainage into IMV

  • Demonstrates communications with middle and inferior rectal veins

  • Useful in assessing portal hypertension, anorectal varices, or surgical planning

CT Appearance

CT Pre-Contrast:

  • Vein appears as linear soft-tissue density in mesorectum

  • Dilated venous plexus may appear as serpiginous densities around rectum

CT Post-Contrast:

  • Superior rectal vein enhances in venous phase, draining into IMV

  • Engorgement seen in portal hypertension with rectal varices

CTV (CT Venography):

  • Excellent for detailed mapping of rectal venous plexus and portal–systemic anastomoses

  • 3D reconstructions show superior rectal vein drainage into IMV and its communications

CT images

Superior rectal vein ct axial image 1

CT images

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MRI image

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CT image

superior rectal vein CT axial image 2

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superior rectal vein CT axial image 3

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MRI image

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MRI image

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