Pubococcygeal line

Last revised by Dr Daniel J Bell on 05 May 2022

The pubococcygeal line (PCL) is a reference line for the pelvic floor on imaging studies and helps detect and grade pelvic floor prolapse in defecography studies. It is defined as a line that joins the inferior border of the symphysis pubis to the final coccygeal joint and it is drawn in a midline sagittal image.

On the image subjectively assessed as showing the greatest degree of pelvic organ descent, perpendicular lines are drawn from the PCL to the bladder neck, anterior cervical lip or vaginal apex if there has been a hysterectomy, and anterior aspect of the anorectal junction, to assess the degree of descent of the anterior, middle and posterior pelvic compartments respectively.

From the anterior and middle compartments, 1 cm is subtracted from the measured distance between the PCL and the organ-specific reference points, to allow for normal downward movement of the organs during straining 5. From the posterior compartment measurement, 3 cm is subtracted from the measured distance between the PCL and the anorectal junction. The resulting measurements are categorized as showing mild, moderate or severe descent according to the rule of 3s:

  • 0-3 cm: mild
  • 3-6 cm: moderate
  • >6 cm: severe

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Cases and figures

  • Figure 1
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  • Figure 2: example of measurements
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  • Levator ani imaging (3D transperineal ultrasound)
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