Association between ICS POP-Q coordinates and translabial ultrasound findings: implications for definition of 'normal pelvic organ support'

Objectives Female pelvic organ prolapse is quantified on clinical examination using the pelvic organ prolapse quantification system of the International Continence Society (ICS POP-Q). Pelvic organ descent on ultrasound is strongly associated with symptoms of prolapse, but associations between clinical and ultrasound findings remain unclear. This study was designed to compare clinical examination and imaging findings, especially regarding cut-offs for the distinction between normal pelvic organ support and prolapse. Methods This was a retrospective study using 839 archived datasets of women referred to a tertiary urogynecological center for symptoms of lower urinary tract and pelvic floor dysfunction between June 2011 and May 2013. The main outcome measures were the maximum downward displacement of the anterior vaginal wall (point Ba), the cervix (point C) and the posterior vaginal wall (point Bp), the length of the genital hiatus (Gh) and the length of the perineal body (Pb), as defined by the ICS POP-Q; explanatory parameters were measures of pelvic organ descent on translabial ultrasound, ascertained by offline volume data analysis at a later date, by an operator blinded to all other data. Results Full datasets were available for 825 women. On clinical examination, 646 (78.3%) were found to have prolapse of at least POP-Q Stage 2. All coordinates on clinical examination were strongly associated with the ultrasound measurements of pelvic organ descent (P < 0.001). These relationships were almost linear, especially for the anterior compartment. Conclusions There is a near linear relationship between sonographic and clinical measures of prolapse. Previously proposed cut-offs to define 'significant prolapse' on ultrasound and POP-Q (Ba >= -0.5 and cystocele >= 10 mm below the symphysis pubis, C >= -5 and uterine position of 15mm above the symphysis pubis, Bp >= -0.5 and rectocele >= 15mm below the symphysis pubis) are plausible and mutually consistent. Copyright (C) 2015 ISUOG. Published by John Wiley & Sons Ltd.