title: Transabdominal ultrasound measurement of pelvic floor muscle activity when activated directly or via a transversus abdominis muscle contraction.
abstract: OBJECTIVE
  The purpose of the present study was to compare the effectiveness of instruction to contract the pelvic floor muscles (PFM), the transversus abdominis (TrA), and the TrA + PFM visualized as displacement of the pelvic floor by ultrasound.
  
  
  METHODS
  Twenty female physical therapists, mean age 41.1 years (range 26-56) participated in the study. A 3.5 MHz 35 mm curved linear array ultrasound transducer (Dornier Medtech) was placed in the mid-sagittal plane immediately suprapubically, angled at 15-30 degrees from the vertical depending on subcutaneous fat and anatomical variations, to image the pelvic floor. Six trials of three maneuvers in random order were performed: contraction of PFM, TrA, and TrA + PFM.
  
  
  RESULTS
  In spite of correct contractions assessed by palpation and clinical observation, one subject demonstrated a downward movement of the pelvic floor during PFM contraction on ultrasound. Six subjects (30%) showed a downward movement during a TrA- contraction, and two during the combined TrA + PFM contraction. Instruction to contract PFM produced significantly greater mean displacement: 11.2 mm (95% CI 7.2-15.3) than TrA 4.3 mm (95% CI -0.2-8.8), P < 0.01, and combination: 8.5 mm (95% CI 5.2-12), P = 0.04. Hence, instruction of PFM contraction produced a 61.6% greater displacement of the pelvic floor in the correct direction than a TrA contraction.
  
  
  CONCLUSIONS
  It is concluded that ultrasound is a more valid method than palpation and clinical observation to assess PFM function, and that instruction to contract the PFM produces a significantly more effective pelvic floor muscle contraction than instruction to perform a TrA contraction.
authors.affiliation: The Norwegian University of Sport and Physical Education, Ullevål Stadion, Oslo, Norway. Kari.bo@nih.no
authors.forename: Kari
authors.initials: K
authors.lastname: Bø
authors.forename: Margaret
authors.initials: M
authors.lastname: Sherburn
authors.forename: Trevor
authors.initials: T
authors.lastname: Allen
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging*; D000009:Abdominal Muscles / Q000000981:diagnostic imaging* / Q000502:physiology; D000328:Adult; D005260:Female; D006801:Humans; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D010173:Palpation; D017773:Pelvic Floor / Q000000981:diagnostic imaging*; D014463:Ultrasonography