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Presacral fascia

The presacral fascia is a connective tissue layer covering the anterior surface of the sacrum and extending laterally over the sacral foramina. It forms part of the parietal pelvic fascia and contributes to the boundaries of the presacral (retrorectal) space. The fascia encloses the presacral venous plexus, lymphatics, and autonomic nerves, making it highly relevant in rectal surgery and pelvic imaging.

Synonyms

  • Parietal pelvic fascia (sacral portion)

  • Pre-sacral connective tissue layer

  • Sacral parietal fascia

Location and Boundaries

  • Anteriorly: Retrorectal space (separating it from the mesorectal fascia and rectum)

  • Posteriorly: Anterior surface of the sacrum and coccyx

  • Laterally: Continuous with the pelvic sidewall fascia and periosteum of sacral foramina

  • Superiorly: Continuous with endopelvic fascia near the pelvic brim

  • Inferiorly: Blends with fascia around the coccyx and pelvic floor

Relations

  • Covers the anterior sacrum and coccyx

  • Encloses the presacral venous plexus and sacral lymphatics

  • Related to sacral nerve roots as they exit through sacral foramina

  • Lies posterior to the retrorectal (presacral) space, anterior to sacrum

Function

  • Provides a fascial covering for sacral bone and venous plexus

  • Forms part of the posterior boundary of the retrorectal space

  • Protects and encloses venous and lymphatic structures

  • Provides a surgical landmark during rectal mobilization

Clinical Significance

  • Rectal surgery: Important landmark in total mesorectal excision (TME) to avoid presacral venous injury

  • Hemorrhage: Injury to presacral venous plexus can cause severe bleeding

  • Pathology: May be displaced or infiltrated by retrorectal tumors (e.g., chordoma, tailgut cyst, dermoid)

  • Abscesses/collections: May accumulate in the retrorectal space posterior to presacral fascia

MRI Appearance

T1-weighted images:

  • Fascia appears as a thin, dark line covering sacrum

  • No fluid: Retrorectal space filled with bright fat

  • Fat: Hyperintense, outlining sacrum and rectum

  • Blood/proteinaceous material: Hyperintense if present

T2-weighted images:

  • Fascia remains a thin, dark line

  • No fluid: Retrorectal space shows bright fat

  • Fluid collections or abscess: Appear bright

  • Tumors/cysts: Bright or heterogeneous signal masses

STIR (Short Tau Inversion Recovery):

  • Fascia is dark

  • Fat signal suppressed (appears dark)

  • Fluid, edema, or inflammation appears bright

T1 Fat-Sat Post-Contrast:

  • Fascia itself does not enhance

  • Fat: Suppressed and dark

  • Abscess: Rim enhancement

  • Tumors: Heterogeneous or nodular enhancement

CT Appearance

Non-Contrast CT:

  • Fascia is not individually visualized; anterior sacrum appears covered by soft tissue density

  • Fat: Retrorectal space shows low attenuation fat

  • No fluid: Clear fat space

  • Collections/tumors: Appear as soft tissue or fluid density masses

Post-Contrast CT:

  • Fascia not separately enhanced

  • Abscess: Rim enhancement with central low density

  • Tumor infiltration: Irregular soft tissue, heterogeneous enhancement

  • Fat: Low attenuation unless obscured by stranding

MRI images

MRI images

presacral fascia MRI AXIAL anatomy image-img-00000-00000

MRI images

presacral fascia MRI axial anatomy image-img-00000-00000