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Apex of urinary bladder

The apex of the urinary bladder is the anterior-most point of the bladder, located just behind the upper part of the pubic symphysis. It represents the point where the median umbilical ligament (remnant of the urachus) is attached. This region is clinically significant as it serves as a landmark in pelvic surgery, imaging, and can be a pathway for urachal abnormalities.

Synonyms

  • Bladder apex

  • Dome of bladder (anterior apex)

  • Urachal attachment of bladder

Location and Boundaries

  • Anteriorly: Related to the posterior surface of the pubic symphysis

  • Superiorly: Continuous with the superior surface of the bladder

  • Posteriorly: Related to the bladder body and dome

  • Inferiorly: In continuity with the bladder neck and anterior wall

  • Externally: Marks the attachment site of the median umbilical ligament (urachus) extending toward the umbilicus

Relations

  • Anterior: Retropubic space (space of Retzius) and pubic symphysis

  • Superior: Peritoneum covering the bladder dome

  • Posterior: Body of urinary bladder

  • Superiorly and externally: Median umbilical ligament (fibrous remnant of urachus)

Function

  • Provides the anterior attachment for the median umbilical ligament (urachus)

  • Contributes to the dome shape of the bladder during filling

  • Serves as a surgical and radiological landmark for bladder orientation

Clinical Significance

  • Urachal remnants: Cysts, sinuses, or fistulas may arise from the urachus attached at the apex

  • Surgical relevance: Used as a landmark in bladder and pelvic surgery, including urachal resection

  • Trauma: Bladder dome and apex are common sites of rupture in blunt abdominal trauma

  • Tumors: Urachal carcinoma often arises from the bladder apex

  • Imaging: Apex helps distinguish bladder dome contour in pelvic imaging and cystography

MRI Appearance

T1-weighted images:

  • No fluid: Bladder wall at the apex shows low signal intensity as a thin line

  • With fluid: Urine inside bladder is low signal intensity

  • Fat: Retropubic fat anterior to apex appears bright

T2-weighted images:

  • No fluid: Apex wall remains low signal intensity

  • With fluid: Urine inside bladder appears bright

  • Fat: Retropubic fat shows intermediate-to-bright signal intensity

STIR (Short Tau Inversion Recovery):

  • No fluid: Apex wall appears dark

  • With fluid: Urine shows bright hyperintensity

  • Fat: Fat signal is suppressed and appears dark

T1 Fat-Sat Post-Contrast:

  • Normal: Apex wall shows mild thin uniform enhancement

  • Pathology (urachal carcinoma, inflammation, abscess): Enhances focally, heterogeneously, or with rim pattern depending on etiology

  • Fat: Suppressed and appears dark

CT Appearance

Non-Contrast CT:

  • No fluid: Apex appears as part of bladder wall with soft tissue density

  • With fluid: Urine shows water density (0–20 HU)

  • Fat: Retropubic fat anterior to apex shows low attenuation

Post-Contrast CT:

  • Normal: Apex wall enhances mildly and evenly

  • Inflammation/tumor: Appears as focal thickening or enhancing lesion at apex

  • Abscess or necrosis: May show rim enhancement with central low attenuation

  • Fat: Retropubic fat remains low attenuation, may show stranding in infection or trauma

MRI image

Apex of urinary bladder mri sag anatomy image-img-00000-00000

MRI image

Apex of urinary bladder mri sag anatomy image-img-00000-00000

CT image

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CT image

Apex of urinary bladder ct coronal anatomy image-img-00000-00000