The pubococcygeal line (PCL) is a reference line for the pelvic floor on imaging studies and helps detect and grade pelvic floor prolapse in defaecography studies.
Measurement
The pubococcygeal line is defined as one that connects the inferior border of the symphysis pubis (anterior margin) to the final coccygeal joint (posterior margin) on 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.
Interpretation
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 categorised as showing mild, moderate or severe descent according to the "rule of 3s":
0-3 cm: mild
3-6 cm: moderate
>6 cm: severe