The state of pelvic floor muscle dynamometry: A scoping review

To discuss the advantages and limitation of the different pelvic floor muscle (PFM) dynamometers available, both in research and industry, and to present the extent of variation between them in terms of structure, functioning, psychometric properties, and assessment procedures.

We identified relevant studies from four databases (MEDLINE, Compendex, Web of Science, and Derwent Innovations Index) up to December 2020 using terms related to dynamometry and PFM. In addition, we conducted a hand search of the bibliographies of all relevant reports. Peer-reviewed papers, conference proceedings, patents and user's manuals for commercial dynamometers were included and assessed by two independent reviewers.

One hundred and one records were included and 23 PFM dynamometers from 15 research groups were identified. From these, 20 were considered as clinical dynamometers (meant for research settings) and three as personal dynamometers (developed by the industry). Overall, significant heterogeneity was found in their structure and functioning, which limits development of normative data for PFM force in women. Further research is needed to assess the psychometric properties of PFM dynamometers and to standardize assessment procedures.

This review points up to the heterogeneity of existing dynamometers and methods of assessing PFM function. It highlights the need to better document their design and assessment protocol methods. Additionally, this review recommends standards for new dynamometers to allow the establishment of normalized data.