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Topic

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Rectovesical pouch

The rectovesical pouch is the most dependent peritoneal space in the male pelvis. It lies between the urinary bladder and the rectum, extending inferiorly between these organs. As a peritoneal recess, it serves as an important site where fluid, pus, blood, or pathological collections may accumulate. It is the male anatomical counterpart of the rectouterine pouch (pouch of Douglas) in females.

Synonyms

  • Rectovesical recess

  • Male pelvic cul-de-sac

  • Rectovesical peritoneal pouch

Location and Boundaries

  • Anteriorly: Posterior surface of the urinary bladder and seminal vesicles

  • Posteriorly: Anterior surface of the rectum

  • Superiorly: Peritoneal reflection from bladder to rectum

  • Inferiorly: Extends downward between bladder base and rectum to the level of the seminal vesicles and prostate

Relations

  • Anterior: Urinary bladder, seminal vesicles, prostate (inferiorly)

  • Posterior: Rectum

  • Superior: Peritoneal cavity

  • Inferior: Urogenital diaphragm and perineum

Function

  • Acts as a potential peritoneal space in the male pelvis

  • Serves as a dependent site for peritoneal fluid accumulation (ascites, blood, pus)

  • Provides surgical access in transperitoneal approaches

  • Important anatomical landmark in pelvic imaging

Clinical Significance

  • Pathological collections: Site for fluid accumulation in trauma (hemoperitoneum), infection (pelvic abscess, peritonitis), or malignancy (peritoneal carcinomatosis)

  • Urological relevance: May be invaded by bladder or rectal tumors

  • Surgical relevance: Must be recognized during pelvic and prostate surgeries

  • Imaging: Crucial in radiology for evaluating pelvic free fluid, abscesses, or tumor deposits

MRI Appearance

T1-weighted images:

  • No fluid: Appears as a potential space with thin low-signal peritoneal lining

  • Fluid: Simple fluid appears dark; blood or proteinaceous fluid appears bright

  • Fat: Bright signal outlining peritoneal recess

T2-weighted images:

  • No fluid: Not visualized except for a faint peritoneal line

  • Fluid: Simple fluid appears bright; hemorrhage may vary in signal intensity

  • Fat: Bright signal adjacent to pouch

STIR (Short Tau Inversion Recovery):

  • No fluid: Pouch is collapsed and indistinct

  • Fluid: Bright hyperintense signal

  • Fat: Suppressed, appearing dark, highlighting fluid or pathology

T1 Fat-Sat Post-Contrast:

  • Normal pouch: Minimal peritoneal enhancement

  • Pathology: Tumor deposits, peritonitis, or endometriotic implants (rare in males) show nodular or rim enhancement

  • Abscess: Rim enhancement with central non-enhancing component

3D T2 SPACE / CISS:

  • Pouch margins defined by intermediate peritoneal lining

  • Fluid: Hyperintense relative to muscle, making recess well-delineated

  • Fat: Very bright, contrasting with darker peritoneal lining and intermediate rectum/bladder walls

CT Appearance

Non-Contrast CT:

  • No fluid: Pouch not visible, only a potential space between bladder and rectum

  • Fluid: Simple fluid appears as low-attenuation collection; blood appears denser

  • Fat: Low attenuation outlining the peritoneal reflection

Post-Contrast CT:

  • Normal pouch: No significant enhancement

  • Pathology: Enhancing nodules or soft tissue thickening in peritoneal metastases

  • Abscess: Rim-enhancing collection with central low attenuation

  • Inflammation: Fat stranding around pouch

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