Assessment of pelvic organ descent by use of functional cine-MRI: which reference line should be used?

So far there is no agreement between clinical and radiological measurements and reference points for the quantification of pelvic organ descent in women. The aim of this study was to find out which of three reference lines on functional cine-magnetic resonance imaging (MRI) correlates best with the respective clinical diagnoses.

We retrospectively evaluated the functional cine-MRI studies of 41 asymptomatic volunteers. Our golden standard was the results of the clinical examination using the International Continence Society (ICS)-score. On MRI, we measured the distance of the bladder-neck, distal edge of cervix/posterior fornix, and the most ventrocaudal point of the ventral rectal wall, respectively, to the pubococcygeal line (PCL), the horizontal tangent of the inferior rim of the pubic bone, and the line drawn through the long axis of the pubic bone. The results were correlated with the respective clinical findings using descriptive analysis alone.

The volunteers either showed a Stage 0 (16 cases), Stage I (12 cases), or a Stage II (13 cases) organ descent on clinical examination with 10 women (24.4%) having a pathological ICS-score in the anterior, 15 women (36.1%) in the superior, and 4 women (9.8%) in the posterior compartment. On functional MRI the best correlation with the clinical results was achieved using the PCL for the anterior compartment (22.0%), the PCL with an offset of +3 cm for the superior (36.6%), and the hymenal line (HL) for the posterior compartment (9.8%).

Organ descent on functional cine-MRI cannot be described using only one reference line. In order to optimize clinical exploitation of functional MRI of the pelvic floor a consensus regarding imaging protocols and evaluation criteria should be aimed for.