Characterizing levator-ani muscle stiffness pre- and post-childbirth in European and Polynesian women in New Zealand: a pilot study.

INTRODUCTION: The influence of levator-ani muscles on second-stage labor is poorly understood. The ability of these muscles to stretch without damage may affect birth outcomes, but little is known about material properties, effects of pregnancy and/or ethnicity on levator-ani stiffness. There are strong associations between muscle damage and subsequent pelvic floor disorders. This study aimed to quantify levator-ani muscle stiffness during the third trimester of pregnancy and postpartum in European and Polynesian women. Associations between stiffness, obstetric variables, and the risk of intrapartum levator-ani injury (avulsion) were investigated. MATERIAL AND METHODS: This was a prospective observational pilot study. A total of 167 (106 European and 61 Polynesian) nulliparous women were recruited antenatally; 129 returned postnatally. Participants were assessed between 36 and 38 weeks' gestation and three to five months postpartum. Assessments included pelvic floor ultrasound, elastometry testing, and validated questionnaires on pelvic floor function. Logistic regression, Student t-, Chi-square and Mann-Whitney tests were used as appropriate. RESULTS: There are significant differences between antenatal and postnatal muscle stiffness measurements (p < 0.01). Stiffness was significantly higher in the European cohort (p = 0.03). There were more avulsion injuries in European (20%) than in Polynesian (9%) women. There were no significant differences in antenatal stiffness between women with and without avulsion, but change in stiffness (antenatal to postnatal) was significantly less in the avulsion group. There were no associations between stiffness, and other obstetric variables, epidural anesthesia seemed protective (p = 0.03). CONCLUSIONS: Quantification of levator-ani muscle stiffness is feasible. Muscle stiffness is significantly different before and after birth.

Clinical evaluation of a high-fidelity wireless intravaginal pressure sensor.

INTRODUCTION AND HYPOTHESIS: A wireless intravaginal pressure sensor (IVPS) has been developed to quantify abdominal pressure (P(abd)) changes during exercise and activities of daily living to guide post-operative advice given to women. In this pilot study, we aimed to compare IVPS performance, comfort, retention, and acceptability to a standard fluid-filled intrarectal pressure catheter currently used to measure P(abd) during routine urodynamics. METHODS: A Life-Tech 3-mm urodynamic intrarectal catheter and IVPS were inserted concurrently in volunteers attending a urodynamics clinic. The IVPS was positioned above the levator plate and the intrarectal catheter positioned in routine fashion well above the anal sphincter. Routine urodynamics was undertaken, with women asked to perform star jumps if coughing or Valsalva did not invoke leakage. Subjects rated device comfort using a visual analogue scale (0-10). Repeated measures Bland-Altman analysis determined level of agreement (LOA) between the two devices for peak pressures for each activity. RESULTS: Twenty-seven women were recruited, 67% of the participants preferred the IVPS, 18% the intrarectal catheter, while 15% had no preference. Mean comfort score was 0.9 ± 1.7 and 2.1 ± 2.6 (p = 0.049) for the IVPS and intrarectal catheter respectively. Bland-Altman analysis demonstrated minimal bias for cough and Valsalva, however LOA were wide. Differences were more prominent during star jumps where rapid dynamic pressure changes occurred. CONCLUSIONS: The IVPS had a higher comfort score and was well retained. The LOA between the two systems was moderate, but the high sampling rate and lower susceptibility to motion artefacts of the IVPS may provide more accurate information that will be important clinically.