title: Perineal body anatomy seen by three-dimensional endovaginal ultrasound of asymptomatic nulliparae.
abstract: OBJECTIVE
  The perineal body (PB) plays an important role in supporting the pelvic floor and the posterior vaginal wall, but its attachments and relationships are still debated. This study aimed to assess the normal anatomy of the PB using high-resolution three-dimensional endovaginal ultrasound (3D-EVUS) in asymptomatic nulliparae.
  
  
  METHODS
  To validate the identification of perineal structures, 3D-EVUS was initially performed on nulliparous cadavers. Fresh frozen pelves were prepared and echogenic structures thought to be the PB, the external anal sphincter, the superficial and deep transverse perineii, pubovaginalis, puboperinealis, puboanalis, puborectalis and iliococcygeus muscles were tagged with biopsy needles, and marked with indigo carmine dye for localization during dissection. In the second part of the study, consecutive asymptomatic nulliparae were prospectively imaged with the same ultrasound modality. Interrater reproducibility was assessed off-line from stored 3D US volumes using a standardized technique.
  
  
  RESULTS
  Five fresh frozen pelves and 44 asymptomatic nulliparae were assessed with 3D-EVUS. The PB was seen as an ovoid structure of mixed echogenicity between the rectum and vagina. It appeared to be divided into a superficial level, in contact with the external anal sphincter, the bulbospongiousus and the superficial transverse perineii muscle and a deep level, in contact with puboperinealis and puboanalis muscles. Interobserver repeatability was excellent for the measurements of PB height [intraclass correlation coefficient (ICC) 0.927], PB depth (ICC 0.969) and PB width (ICC 0.932).
  
  
  CONCLUSIONS
  The PB is divided into two levels with different anatomical relationships with the pelvic floor muscles. 3D-EVUS yields reproducible assessment of this complex structure.
authors.affiliation: Department of Colorectal Surgery, Digestive Disease Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates.
authors.forename: G A
authors.initials: GA
authors.lastname: Santoro
authors.affiliation: Section of Female Pelvic Medicine and Reconstructive Surgery, Division of Obstetric and Gynecology, Health Sciences Center, University of Oklahoma, Oklahoma City, Oklahoma, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Shobeiri
authors.affiliation: Academic Department of Surgery, St Vincent's Hospital Clinical School, Sydney, New South Wales, Australia.
authors.forename: P P
authors.initials: PP
authors.lastname: Petros
authors.affiliation: CIBERehd, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Zapater
authors.affiliation: Department of Paediatric Radiology, Medical University of Lublin, Lublin, Poland.
authors.forename: A P
authors.initials: AP
authors.lastname: Wieczorek
mesh_terms: D000328:Adult; D002102:Cadaver; D019160:Endosonography / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015588:Observer Variation; D010298:Parity; D010502:Perineum / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D011247:Pregnancy; D015203:Reproducibility of Results; D014621:Vagina / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Anal sphincter; pelvic floor; perineal body; three-dimensional ultrasound