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Topic

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Middle Colic Vein

The middle colic vein is the primary venous drainage vessel of the transverse colon, running within the transverse mesocolon and accompanying the middle colic artery. It is typically a major tributary of the superior mesenteric vein (SMV), although variations exist.

It plays a key role in mesenteric venous return and serves as an important anatomical landmark during right hemicolectomy, central mesenteric dissection, oncologic lymphadenectomy, and pancreaticobiliary procedures. Because of its variable branching pattern, precise radiologic understanding is essential for operative planning.

Synonyms

  • Vena colica media

  • Transverse mesocolon vein

Origin, Course, and Drainage

Origin:

  • Formed by venous tributaries draining the proximal and distal transverse colon within the transverse mesocolon

Course:

  • Runs centrally within the transverse mesocolon, parallel to the middle colic artery

  • Travels toward the root of the mesentery at the anterior surface of the pancreas

Drainage:

  • Typically drains directly into the superior mesenteric vein (SMV)

  • Common variations:

    • Drains into a common trunk with the right colic vein

    • May join the gastrocolic trunk of Henle (confluence with right gastroepiploic vein, anterior superior pancreaticoduodenal vein, and right colic vein)

Relations

  • Anteriorly: Transverse colon, greater omentum

  • Posteriorly: Head and neck of the pancreas, SMV

  • Superiorly: Stomach and gastrocolic ligament

  • Inferiorly: Jejunal loops and small bowel mesentery

  • Medially: SMA and SMV trunk

  • Laterally: Hepatic flexure and splenic flexure venous branches

Function

  • Drains venous blood from the entire transverse colon

  • Contributes to the portal venous system via the SMV

  • Plays a key role in nutrient absorption, venous return, and metabolic transport from the midgut-derived colon

  • Serves as a surgical vascular landmark during colectomies and pancreatic surgery

Clinical Significance

  • Important landmark in right and extended right hemicolectomy

  • May be involved in mesenteric venous thrombosis

  • Variants influence surgical complexity in:

    • Colon cancer resections

    • Pancreaticoduodenectomy

    • Gastrocolic trunk dissection

  • Recognizing drainage pattern helps avoid injury to Henle’s trunk and SMV during surgery

MRI Appearance

T1-weighted images:

  • Vein demonstrates flow void (dark intraluminal signal) due to fast-flowing blood

  • Surrounding mesenteric fat appears bright, outlining the vessel

  • Smooth vessel wall with no intrinsic T1 hyperintensity

T2-weighted images:

  • Flowing blood remains dark, maintaining the flow void appearance

  • Vessel lumen clearly contrasted against bright mesenteric fat planes

  • Walls appear as thin low-signal margins

STIR:

  • Blood flow void remains dark

  • Fat suppression accentuates the vessel’s course through the transverse mesocolon

  • Clear visualization of venous outline due to dark lumen against suppressed background

T1 Fat-Saturated Post-Contrast:

  • Vein shows strong homogeneous enhancement as it fills during the venous phase

  • Vessel wall may appear slightly brighter but uniform

  • Enhancing SMV and its branches show clear continuity with the middle colic vein

CT Appearance

Non-Contrast CT:

  • Appears as a soft-tissue density tubular structure adjacent to the middle colic artery

  • Hard to distinguish from surrounding soft tissue without contrast

  • Mesenteric fat enhances visualization of the vein course

Post-Contrast CT (Portal Venous Phase):

  • Middle colic vein becomes brightly contrast-filled, well visualized against mesenteric fat

  • Clearly delineates drainage into the SMV or gastrocolic trunk of Henle

  • Allows confirmation of anatomic variants and branching patterns

MRI image

Middle Colic Vein MRI coronal image-img-00000-00000

MRI image

Middle Colic Vein mri coronal