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Perivesical (Prevesical) Fluid Collection
Molar Tooth Sign

General Considerations

  • Extraperitoneal pelvic fluid collections have been characterized as “molar-tooth” in appearance
  • The “crown” lies anterior to the urinary bladder between the umbilicovesical fascia and the transversalis fascia of the anterior abdominal wall
  • The bladder is displaced posteriorly
  • The “root” of the “tooth” extends posteriorly the fascia and the perineum or parietal pelvic fascia inferiorly
  • The bladder is frequently displaced from the midline, since the “roots” of the collection are usually asymmetrical
  • This compartment is continuous with the infrarenal extraperitoneal compartment
  • The prevesical space is also continuous with the rectus sheath, presacral space and the femoral sheath

Differential Diagnosis

  • Molar tooth sign is also applied to the appearance of the midbrain on axial CT with elongated superior cerebellar peduncles

molar tooth sign

From CT of Extraperitoneal Space: Normal Anatomy and Fluid Collections. Radiology, 1992

molar tooth sign

Large prevesical fluid collection. "Molar tooth sign." There is a Foley catheter in a collapsed urinary bladder which is displaced posteriorly and compressed lateral by a large prevesical fluid collection.



CT of Extraperitoneal Space: Normal Anatomy and Fluid Collections. M Korbkin; P Silverman, LE Quint and IR Francis.AJR 159:933-941, November 1992.


Extraperitoneal Paravesical Spaces: CT Delineation and US Correlation. YH Auh, WA Rubenstein, M Scneider, JM Reckler, JP Whalen and E Kazam. Radiology 1986: 159: 319-328.