title: Changes in the mean echogenicity and area of the puborectalis muscle during pregnancy and postpartum.
abstract: OBJECTIVE
  Three-dimensional (3D) and four-dimensional (4D) volume transperineal ultrasound imaging is increasingly used to assess changes in the dimensions of the pelvic floor during pregnancy and after delivery. Little is known with regard to the area of the puborectalis muscle and its structural changes. Echogenicity measurement, a parameter that provides information on the structure of muscles, is increasingly used in orthopaedics and neuromuscular disease evaluation. This study is aimed at assessing the changes in the mean echogenicity of the puborectalis muscle (MEP) and the puborectalis muscle area (PMA) during first pregnancy and after childbirth.
  
  
  METHODS
  The MEP and PMA of 254 women during first pregnancy were measured at 12 and 36 weeks' gestation and 6 months postpartum. To determine the effect of child-birth on MEP and PMA, the results at 6 months postpartum were separately analysed for vaginal deliveries, operative vaginal deliveries (ventouse) and caesarean section deliveries. Mean differences in MEP and PMA were analysed using ANOVA statistics.
  
  
  RESULTS
  The MEP at 6 months postpartum was, independent of manoeuvre, significantly (p < 0.001) lower than MEP values during pregnancy. After caesarean delivery, the PMA was significantly smaller at maximum pelvic floor contraction than PMA after vaginal delivery (p = 0.003) or operative vaginal delivery (p = 0.002).
  
  
  CONCLUSIONS
  Our study indicates that structural changes in the puborectalis muscle during and after pregnancy, as measured by MEP, occur and can be analysed. In addition, the mode of delivery affects the area of the puborectalis during contraction after delivery. For true volume analysis, as part of an assessment of contractility of the puborectalis muscle we will need 3D volume analysis.
authors.affiliation: Department of Reproductive Medicine and Gynecology, University Medical Center, PO box 85500, 3508 GA, Utrecht, Netherlands. a.t.m.grob-3@umcutrecht.nl.|MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands. a.t.m.grob-3@umcutrecht.nl.
authors.forename: Anique T M
authors.initials: AT
authors.lastname: Grob
authors.affiliation: Department of Reproductive Medicine and Gynecology, University Medical Center, PO box 85500, 3508 GA, Utrecht, Netherlands.
authors.forename: Mariella I J
authors.initials: MI
authors.lastname: Withagen
authors.affiliation: Department of Reproductive Medicine and Gynecology, University Medical Center, PO box 85500, 3508 GA, Utrecht, Netherlands.
authors.forename: Maria K
authors.initials: MK
authors.lastname: van de Waarsenburg
authors.affiliation: Department of Reproductive Medicine and Gynecology, University Medical Center, PO box 85500, 3508 GA, Utrecht, Netherlands.
authors.forename: Karlijn J
authors.initials: KJ
authors.lastname: Schweitzer
authors.affiliation: Department of Reproductive Medicine and Gynecology, University Medical Center, PO box 85500, 3508 GA, Utrecht, Netherlands.
authors.forename: Carl H
authors.initials: CH
authors.lastname: van der Vaart
mesh_terms: D000328:Adult; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D017773:Pelvic Floor / Q000000981:diagnostic imaging*; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D012016:Reference Values; D016216:Ultrasonography, Prenatal
keywords: 3D/4D ultrasound; Area; Echogenicity; Pelvic floor