Inter-rater reliability of assessment of levator ani muscle strength and attachment to the pubic bone in nulliparous women

Objectives The modified Oxford scale (MOS) has been found previously to have poor inter-rater reliability, whereas digital assessment of levator ani muscle (LAM) attachment to the pubic bone has been shown to have acceptable reliability. Our aim was to evaluate inter-rater reliability of the validated MOS and to develop a reliable classification system for digital assessment of LAM attachment, correlating this to findings on transperineal ultrasound (TPUS) examination. Methods Evaluation of the MOS by palpation was performed in nulliparous women by two investigators. LAM attachment was evaluated using digital palpation, for which a novel classification system was developed with four grades based on the position of the attachment and presence of discernible muscle. Findings were compared with those on TPUS examination. Inter-rater reliability was assessed using Cohen's kappa statistic. Results Twenty-five nulliparous women were examined. There was agreement in MOS scores between the investigators in 64% of women (n=16), with a kappa of 0.66 (indicating substantial agreement). There was agreement in palpation of LAM attachment using the new grading system in 96% of women (n=24), with a kappa of 0.90 (indicating almost perfect agreement). TPUS examination did not show LAM avulsion in any woman, with the exception of one with a partial avulsion. Conclusion 4">In this group of nulliparous patients, there was substantial agreement between the two investigators in evaluation of the MOS and there was good agreement between grades of LAM attachment using the new classification system, which correlated with findings on TPUS examination. It therefore appears that these results are reproducible in nulliparous women and the techniques can be readily learned and reliably incorporated into clinical practice and research after appropriate training. Further research is required to establish clinical utility of the grading system for LAM attachment in postpartum women and in women with symptomatic pelvic organ prolapse. Copyright (c) 2013 ISUOG. Published by John Wiley & Sons Ltd.