Consensus definitions and interpretation templates for dynamic ultrasound imaging of defecatory pelvic floor disorders

See “editorial” on page 169. The Pelvic Floor Disorders Consortium (PFDC) is a multidisciplinary organization of colorectal surgeons, urogynecologists, urologists, gynecologists, gastroenterologists, radiologists, physiotherapists, and other advanced care practitioners. Specialists from these fields are all dedicated to diagnosing and managing patients with pelvic floor conditions but approach evaluation and treatment of such patients with their unique perspectives given differences in their training. The PFDC was formed to enable collaboration between these specialties in developing and evaluating educational programs, creating clinical guidelines and algorithms, and promoting high-quality care for this unique patient population. The recommendations included in this document represent the work of the PFDC Working Group on Ultrasound in Imaging of Defecatory Disorders of the Pelvic Floor (members listed alphabetically in Table 1). The objective was to generate inclusive, rather than prescriptive, guidance for all practitioners interested in considering pelvic floor ultrasound imaging in their assessment of defecatory pelvic floor disorders. TABLE 1. - Members of the workgroup on the use of dynamic ultrasound in the evaluation of defecatory pelvic floor disorders Name and degree Affiliation City, state, country Amy Halverson, M.D. Department of Surgery, Northwestern Memorial Hospital and Feinberg School of Medicine Chicago, IL, USA Jonia Alshiek, M.D.1 Urogynecology Unit, Hillel Yaffe Medical Center, Technion Medical School Technion Medical School, Hadera, Israel Hina Arif-Tiwari, M.D. Department of Medical Imaging, College of Medicine, University of Arizona. Phoenix, AZ, USA Liliana Bordeianou, M.D. Section of Colorectal Surgery, Massachusetts General Hospital Pelvic Floor Disorders Center, Harvard Medical School Boston, MA, USA Shuqing Ding, Ph.D. Department of Surgery, Northwestern Health Sciences University Bloomington, MN, USA Andrea Ferrara, M.D. Department Colorectal Surgery, Colon & Rectal Surgery Clinic of Orlando Orlando, FL, USA Linda Ferrari, M.D. Pelvic floor unit. St. Thomas’ Hospital London, UK Giuseppe Gagliardi, M.D. Department of Colorectal Surgery, University of Illinois Chicago, IL, USA Phyllis Glanc, M.D. Department of Medical Imaging, Sunnybrook Health Sciences Center Toronto, ON, Canada Gaurav Khatri, M.D. Department of Radiology, University of Texas Southwestern Medical Center Dallas, TX, USA S. Abbas Shobeiri, M.D. Department of Obstetrics and Gynecology, Inova Health System Fairfax, VA, USA Lieschen H. Quiroz Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center Oklahoma City, OK, USA Ari Steiner, M.D. Department of Radiology, South Nassau Community Hospital Oceanside, NY, USA David Sheyn, M.D. Department of OBGYN, University Hospitals Cleveland, OH, USA Joanne Favuzza, M.D. Department of Surgery, Boston Medical Center Boston, MA, USA Sergio Larach, M.D. Department of Surgery, Digestive and Liver Center of Florida Orlando, FL, USA Anders Mellgren, M.D. Department of Surgery, University of Illinois Chicago, IL, USA Yara Lima de Mendonca, M.D. Colorectal Surgery, Hospital Municipal Ronaldo Gazolla and University of Exeter Rio de Janeiro, Brazil, and Exeter, UK Miles Murphy, M.D. Division of Urogynecology, Department of OB–GYN, Abington—Jefferson Health Abington, PA, USA Sthela Murad-Regadas, M.D. Department of Surgery, School of Medicine of the Federal University of Ceará Fortaleza, Brazil Lucia Oliveira, M.D. Department of Anorectal Physiology, Policinica General do Rio de Janeiro Rio de Janeiro, Brazil Ghazaleh Rostaminia, M.D. Department of Obstetrics and Gynecology, Northshore Hospital Chicago, IL, USA Milena Weinstein, M.D. Department of Obstetrics and Gynecology, Massachusetts General Hospital Boston, MA, USA Steven Wexner, M.D. Department of Surgery, Cleveland Clinic Florida Weston, FL, USA STATEMENT OF THE PROBLEM Dynamic pelvic floor ultrasound (PFUS) has been shown to be an effective and relatively inexpensive method for evaluating pelvic organs, including the urethra, bladder, vagina, cervix and uterus, anal canal, rectum, and other pelvic floor structures, such as the levator ani muscles. PFUS can be performed using transperineal/introital, endovaginal, or endoanal/endorectal approaches. There is considerable evidence for the use of PFUS imaging to quantify pelvic floor disorders. Still, there is significant variation across disciplines regarding the degree of utilization of PFUS for such indications and the preferred choice of specific PFUS technique.1–4 Also, there is variability in the definitions of pathology described on PFUS between specialists, which results in more significant variability in how different physicians and specialties interpret and use findings seen on PFUS. These factors create challenges for health care providers in their efforts to counsel patients and effectively communicate and cooperate between specialities. Patients with pelvic floor disorders often have recurrent or multifactorial symptomatology, which may require care from multiple disciplines. Furthermore, many health care providers may be concurrently managing different aspects of pelvic floor dysfunction in the same patient in parallel. Lack of coordination and communication in imaging terminology can create misunderstandings and confusion for health care providers and patients. The American Institute of Ultrasound in Medicine and the International Urogynecologic Association generated a practice parameter guideline that made one of the first attempts at standardization of the language in the field of pelvic floor ultrasonography.5 However, the document had limited reference to defecatory pelvic floor disorders. Thus, this effort was undertaken with the explicit goal of inviting and including representatives from all relevant clinical specialties for whom PFUS holds clinical significance. This document aims to create a universal set of recommendations for a minimum common language for PFUS interpretation and reporting of defecatory pelvic floor disorders, with relevance across disciplines and all PFUS modalities. METHODOLOGY This document was developed by the Pelvic Floor Disorders Consortium (PFDC) Working Group on Ultrasound Imaging of Defecatory Disorders and created under the guidance of the American Society of Colon and Rectal Surgeons (ASCRS). The PFDC comprises clinicians with demonstrated expertise in the care and treatment of patients with pelvic floor conditions. The Working Group was created by enlisting PFDC volunteers. Invitation criteria included leadership in pelvic floor disorders with academic scholarship and a history of crossdisciplinary collaboration. Members of the working group participated in at least 2 group preliminary phone calls and researched an assigned topic. Each topic had at least 2 members assigned, always from different specialties. Each pair identified the literature on a relevant topic and performed a systematic review of the literature using a specified format. These systematic reviews involved an organized search of MEDLINE, PubMed, Embase, and the Cochrane Database of Collected Reviews performed up to April 1, 2019. Retrieved publications were limited to the English language, but no limits on the year of publication were applied. The search terms included “fecal incontinence,” “urinary incontinence,” “constipation,” “lower urinary tract symptoms in men and women,” and “pelvic floor disorders in men and women.” The search strategies used “dynamic ultrasound,” “pelvic organ prolapse,” “obstructed defecation,” “anal incontinence,” “pelvic pain,” “dyspareunia,” “obstetric injury,” “OASIS” (obstetric anal sphincter injuries), “anal sphincter injury,” “pelvic floor ultrasound,” “translabial ultrasound,” “transperineal ultrasound,” “endoanal ultrasound,” “endorectal ultrasound,” “transvaginal ultrasound,” “echodefecography,” “enterocele,” “internal intussusception,” “rectocele,” “sigmoidocele,” “perineal descent,” “levator ani tears,” “levator ani avulsion,” “levator injury,” “pelvic floor dysfunction,” and “rectal prolapse” as primary search terms. Directed searches of the embedded references from the primary articles were also sometimes performed. Criteria for inclusion of references included articles that described original descriptions of relevant ultrasound measurements or clinically relevant literature describing the use of ultrasound imaging in clinical practice. The workgroup presented its preliminary research to the consortium at large for further discussion. Pelvic Floor Consortium Expert Meeting The Pelvic Floor Consortium Expert Meeting convened on June 2, 2019, in Cleveland, Ohio. It included 126 in-person (or online) participants from the United States, Europe, Asia, England, and Canada. These experts belonged to several subspecialties (colorectal surgery, gastroenterology, urogynecology, urology, physiotherapy, and radiology). They included members of numerous professional societies involved in the diagnosis and treatment of pelvic floor disorders. The event was also audited by formal representatives from the ASCRS, the Society of Abdominal Radiology (SAR), the American Urogynecologic Society, the International Urogynecological Association (IUGA), and the Society of Gynecologic Surgeons. The meeting was funded by the ASCRS. The participants at the expert consortium meeting analyzed the proposed sonographic techniques and definitions for each of the conditions reviewed in this statement, ultimately offering consensus recommendations for the technique and interpretation of PFUS as well as a standardized and clinically relevant synoptic reporting template. The group labeled this final template as the “Ultrasound Interpretation Template for the Initial Measurement of Patient-Reported Defecatory Pelvic Floor Complaints,” or “Ultrasound-IMPACT” (see Supplement 1 at https://links.lww.com/DCR/C46). For a recommendation to make it into the Ultrasound-IMPACT template, expert consensus was required. Expert consensus was defined as >70% agreement among the voting participants. A subsequent committee meeting was then held to summarize these statements while keeping the expert consensus panel discussion directives in mind. In summary, this work is not meant to be an exhaustive description or pictorial essay of all disease processes found on PFUS imaging. Rather, this article sought to identify areas of consensus across disciplines so that a common language can be used to achieve the shared goal of caring for patients with defecatory pelvic floor disorders. Areas where consensus was not achieved remain potential topics for research to help further standardize best practices in the future and across all relevant disciplines. Final Review Once the document was finalized, the proposed recommendations were presented for review by the ASCRS Pelvic Floor Disorders Steering Committee. This Steering Committee is directed to develop clinical practice recommendations on colorectal pelvic floor disorders based on the best available evidence. The ASCRS Steering Committee edited the document and sent it to the ASCRS Executive Committee for final approval for publication. Similar reviews and endorsements were also given by the American Urogynecologic Society Publications Committee and Board of Directors, the SAR Board of Directors and SAR Disease Focused Panel on Pelvic Floor Dysfunction, the ICS Board of Directors, and the Executive Board of the Society of Gynecologic Surgeons. In addition, the document was reviewed by the IUGA Board of Directors. In accordance with the IUGA policy, the IUGA Board of Directors distributed the document for review by its entire membership and subsequently endorsed the document. Before submission of the document for publication, a rereview of the relevant literature was performed to include articles published between April 1, 2019, and March 1, 2021, and to assure that key new works pertaining to topics of defecatory pelvic floor disorders were also considered. RECOMMENDATIONS Overview of Techniques Many forms of dynamic ultrasound imaging exist, each with its advantages. Choice of the technique used may depend on the specific indication and the available expertise of the sonographer and interpreting physician (degree of consensus: 100%). Dynamic PFUS has 3 commonly used modalities: endoanal/endorectal (aPFUS), transperineal/introital (pPFUS), and endovaginal (vPFUS). Regardless of modality, these studies can be performed in a radiology department or an office setting, depending on the available level of sonographic expertise and appropriate equipment. Advantages of ultrasound evaluation include good patient tolerance, lack of radiation exposure, and the ability to decide on a case-by-case basis to perform ultrasound imaging as appropriate. It is essential to ensure that the imaging clinician, whether in-office or in the radiology department, has undergone specific training to provide quality imaging and interpretation of the examination.6 An appropriate transducer can be placed gently on the perineum or between the labia and the anus during ultrasound imaging. For the average patient, the examination is not painful. Following the acquisition of static images, a dynamic ultrasound video (cine loop) can be performed by instructing the patient to perform a strain/Valsalva maneuver and, in some cases, to attempt to empty ultrasound gel from the rectum to simulate defecation. Recommended ultrasound imaging protocols typically involve both dynamic 2-dimensional (2D) and 3-dimensional (3D) volume acquisitions using aPFUS (Fig. 1A), pPFUS (Figs. 1B and C), or vPFUS (Fig. 1D) techniques. Each modality conveys complementary information and may be used on the basis of the specific clinical indication. Physicians using ultrasound imaging may have various transducers and varying degrees of skill sets for different ultrasound assessment portions.FIGURE 1.: Examples of PFUS modalities. A, Endoanal/endorectal PFUS. The transducer is inserted in the anal canal to a depth of 5–6 cm. B, pPFUS using a 2D/3D curvilinear transducer. The probe tip is gently placed between the labia. C, pPFUS using an end-fire endocavitary probe. The transducer tip is gently placed between the labia and perineum. pPFUS also is commonly performed using a curved 3D probe placed along the labia. D, Endovaginal PFUS using a 2D/3D automatic transducer inserted 5–6 cm in the vagina to the level of the bladder-urethra junction. 2D = 2-dimensional; 3D = 3-dimensional; PFUS = pelvic floor ultrasound; pPFUS = transperineal/introital PFUS.For further discussion, the terminology we use when referencing these techniques is described in the following paragraphs. Dynamic aPFUS Traditionally, aPFUS is performed using an ultrasound scanner with a 7- to 10-MHz rotating transducer (focal range, 3–45 mm), providing a 360° axial view of the anal canal (Fig. 1A). The patient is usually scanned in either the left lateral or the dorsal lithotomy position depending on local preferences. Images are acquired at rest, during contraction of the pelvic floor muscles, and during a strain/Valsalva maneuver. For 2D imaging, the transducer is placed into the anal canal, and circumferential images of the top, middle, and distal anal canal are acquired. Characterization of the perineal body and the distance from the anal canal to the vagina is measured. For 3D volumetric imaging, the tip of the transducer is placed in the cephalad part of the anal canal. The transducer automatically acquires 3D volumetric data through the full length of the anal canal, which can be rendered into axial, sagittal, coronal, or additional oblique planes if needed for image analysis. After the transducer is inserted up to 6 cm above the anal verge, various additional maneuvers may be performed to evaluate the levator plate, the anal sphincter complex, and the surrounding structures. This dynamic variant of aPFUS (also sometimes called “echodefecography”) involves insertion of ultrasound gel into the rectum after rectal cleansing with an enema. This is then followed by an evacuation maneuver, which further enhances the dynamic evaluation of the pelvic floor in defecatory dysfunction conditions.7 Dynamic pPFUS Traditionally, operators have performed transperineal ultrasound with a 2- to 6-MHz curved array transducer (Fig. 1B) or 6- to 9-MHz end-fire transducer (Fig. 1C) with 3D/4-dimensional capabilities to image the pelvic floor. Images are acquired at rest and during contraction and strain/Valsalva maneuvers. Sometimes a patient is asked to defecate ultrasound gel during the examination. Images are obtained by placing a covered transducer between the labia minora and the perineum, typically beginning in a midsagittal position.8 The imaging starts with assessing the pelvic floor hiatus in a 2D midsagittal plane of the pelvic floor structures, including, from anterior to posterior, the following structures: pubic symphysis, urethra, bladder, vagina, anorectum, and levator plate. The levator plate is defined as the echogenic tissue in the midline posterior to the anorectal junction. Visualization is easier if the bladder contains a small volume of urine, and the rectum may remain empty or can be gently filled with a small amount of gel.9,10 Synthetic graft components are visualized with various ultrasound techniques, and ultrasound imaging is considered one of the primary modalities for this purpose, in particular for those with a suburethral component such as midurethral slings. Following static images, cineloops are acquired at rest in the sagittal plane from right to left to include the obturator muscles. The key dynamic maneuver is acquired in the sagittal midline plane while the patient performs a sustained maximum pelvic floor strain/Valsalva maneuver. Many practitioners will add a pelvic floor contraction dynamic sequence to aid in determining which patients may benefit from pelvic floor physiotherapy. The dynamic strain/Valsalva technique is useful to visualize rectouterine pouch hernias, internal rectal intussusception, or rectoceles. 3D volume acquisitions enable multiplanar reformats in the coronal, axial, and sagittal planes, plus the rendered 3D view. The rendered 3D view and the axial multiplanar reformats are beneficial in determining the integrity of the levator ani muscles at their insertions and identifying levator ani avulsion. As the imaging quality of 3D systems improves, studies are progressively demonstrating a good correlation between aPFUS and pPFUS of the anal sphincter complex, particularly for OASIS, with sensitivity improving with expertise.11,12 The technique has become one of the more common pelvic floor imaging modalities because of its availability.13 Dynamic vPFUS A vPFUS is performed using a side-fire transducer that obtains either axial or radial images of the pelvic floor. If performed with the same transducer used for aPFUS (Fig. 1D), vPFUS should be performed before aPFUS to avoid the introduction of rectal contents into the vagina after aPFUS. In addition to static images, dynamic evaluation of the pelvic floor can be achieved by instructing the patient to contract the pelvic floor muscles and then perform strain/Valsalva maneuvers while capturing cineloops of the bladder, rectum, anorectal angle flattening, and levator plate movement. Although the vPFUS transducer supports the vaginal apex and may reduce posterior vaginal prolapse (rectocele), rectal movement and persistent rectal intussusception may still be visualized. Rectouterine pouch hernias are visualized infrequently with vPFUS; these may be best pictured with pPFUS because of the nonobstructive nature of that approach. Once the dynamic images are obtained, the 3D volume may also be obtained to assess the integrity of levator ani musculature (LAM). vPFUS modality may also be used for discrimination between subdivisions of the LAM that may be injured (puborectalis, puboanalis, pubococcygeus/iliococcygeus), particularly in women after delivery.14 IMAGING OF SPHINCTER ANATOMY 1. Although all forms of ultrasound imaging mentioned in this document may visualize anal sphincter anatomy, the criterion standard in ultrasound imaging of anal sphincter integrity is the aPFUS technique (degree of consensus: 94%). Fecal incontinence is a common condition with a profound and disabling impact on the quality of life. Understanding the anal sphincter anatomy may be helpful when choosing treatment for this condition. Ultrasound imaging is a relatively inexpensive examination that offers additional information regarding sphincter integrity and augments regular physical examination.15–18 All forms of ultrasound imaging described above can visualize a typical anal sphincter complex, but aPFUS is considered the validated reference standard in evaluating anal sphincter anatomy (Fig. 2) and identifying defects. Performing pPFUS and vPFUS with conventional ultrasound transducers can also be useful in identifying sphincter normality for clinical purposes, but they are less detailed and have lower sensitivity.19 During the past decade, there has been a flurry of publications demonstrating the utility of pPFUS for the assessment of the anal complex.11 If there is any doubt about the integrity of the anal sphincter or pathology by pPFUS or vPFUS, the findings need to be further investigated with aPFUS. Using aPFUS, a clinician can identify the anal canal’s distinct muscular layers: the innermost anal mucosa, the internal sphincter (upper and middle anal canal), the longitudinal muscles, the intersphincteric space (upper and middle anal canal), and the outer striated sling-like levator plate muscles (puborectalis and pubococcygeus in the upper anal canal) or the striated external sphincter (middle and lower anal canal).20–23 Its findings have been correlated with symptoms of both fecal incontinence and anorectal physiology findings.18,24 As with all PFUS techniques, aPFUS is associated with a learning curve, and specialized instruction/teaching are recommended for optimal technique and interpretation of the examination.6,25 In the absence of aPFUS capability, both pPFUS and vPFUS have good test accuracy and can be used as a screening tool to identify sphincter complex abnormalities with subsequent referral to specialists as necessary.26–28 With rising expertise and technological improvements in pPFUS and vPFUS, some literature suggests possible equivalency of these modalities to aPFUS.29 An MRI for detailed anatomic evaluation may be of value in the absence of access to aPFUS.FIGURE 2.: Examples of anal sphincter anatomy in side-by-side images of the anal canal as obtained during aPFUS. The “A” column shows the axial view obtained with the aPFUS transducer. The “B” column shows the patient’s right midsagittal view at the same level. The level of images in column A is denoted by the green line in column B. The midsagittal structures are outlined in panel B. A, Inferior or low anal canal with superficial EAS. B, Midanal canal with the main part of EAS and IAS. C, Upper midanal canal with the U-shaped configuration of EAS where the EAS is incomplete anteriorly. D, Upper anal canal with PR and IAS. E, Upper anal canal with PC fibers. aPFUS = endoanal/endorectal pelvic floor ultrasound; AR = anorectum; EAS = external anal sphincter; IAS = internal anal sphincter; L = left; LP = levator plate; P = posterior; PC = pubococcygeus; PR = puborectalis; R = right; V = vagina. 2. When an anal sphincter injury is suspected, complete characterization of the injury requires both a description of the degree of injury to the internal and external anal sphincter (EAS) and information about the size of the perineal body and the length of the mentioned injury in relationship to the length of the entire anal sphincter (degree of consensus: 90%). Obstetric anal sphincter injury is a common cause of fecal incontinence.30,31 Severe obstetric lesions occur after 1% to 5% of natural births, and endoanal ultrasonography can show hidden defects in at least a third of women after their first birth.32–34 However, some of these findings may not have clinical significance: in a study of 908 patients, a false positive OASIS rate of 7% was demonstrated.31 Other mechanisms of anal sphincter injury, such as anorectal procedures and anorectal pathology, can also result in anal incontinence. In a study of 123 anorectal surgery patients, subsequent lesions of the EAS and internal anal sphincter (IAS) were identified in 21% of cases.34 PFUS is helpful for the identification and quantification of OASIS injuries and for recognition of IAS defects.35 These injuries have a pathognomonic appearance on aPFUS (Fig. 3). IAS tears usually appear as relatively hyperechoic defects in the hypoechoic muscle, and EAS tears appear as relatively hypoechoic defects in the hyperechoic circular wall of the anal musculature. In general, EAS defects are found more frequently in the midanal canal in the anterior quadrant in females.36 For the visualization of sphincter injuries, 3D aPFUS has higher intraobserver reliability than 2D aPFUS (98% for 3D versus 88% for 2D).37FIGURE 3.: Demonstration of midanal canal anal sphincter defects as visualized on aPFUS, axial view. A, Angle of the EAS defect. B, Angle of the IAS defect. aPFUS = endoanal/endorectal pelvic floor ultrasound; EAS = external anal sphincter; IAS = internal anal sphincter.Important caveats in imaging include the following: 1) identification of the puborectalis muscles immediately cephalad to the anal sphincter; 2) differentiation of an anterior external sphincter injury versus a short anal sphincter in a female in the middle anal canal; 3) recognition that the distal anal canal only contains external sphincter; and 4) and a thinned out perineal body may be a sign of middle anal sphincter injury. The operator should carefully measure the degree of separation between the IAS and EAS and the specific level at which this separation is present. Further comments should be made as to whether this is a combined lesion of the IAS and EAS (see Video 1 at https://links.lww.com/DCR/C117). The number of defects and the extent of the defect circumferentially (radial angle in degrees or hours of the clock) and longitudinally (proximal, distal, or full length) should also be reported. In addition, 3D PFUS allows measurement of length, thickness, and angle of sphincter defect in multiple imaging planes. Other forms of PFUS can also provide this information when performed by appropriately trained sonographers and interpreting physicians. 3. Complete imaging of sphincter anatomy should also include a description of the levator ani muscle anatomy with a detailed measurement of the size of the levator hiatus (degree of consensus: 83%) and a description of the presence/absence of concomitant levator ani muscle injury (degree of consensus: 94%). Various types of injury to the LAM are common after vaginal birth and may be associated with pelvic organ prolapse.38,39 The LAM includes the puborectalis, pubococcygeus, iliococcygeus, puboperinealis, and puboanalis muscles40 (Fig. 4). The pubococcygeus/iliococcygeus, puboperinealis, and puboanalis muscles are clearly seen by vPFUS.1 Data from women who have fecal incontinence of unknown cause suggest that women with obstructive defecatory symptoms have a wider rectum and more descent of the levator plate, regardless of the stage of prolapse or the severity of rectocele.41,42 Many women with visible anal sphincter tears may have coexisting LAM disruption or dysfunction, and these women may have worsened outcomes following traditional surgical procedures such as overlapping sphincteroplasty repairs, presumably because levator dysfunction can be associated with pudendal nerve injury during LAM overdistention43,44 or avulsion.26,45 Thus, a careful concurrent characterization of LAM to further stratify OASIS patients may be clinically helpful.31,46FIGURE 4.: Levator ani anatomy demonstrated via vPFUS, axial view. A, The levator hiatus in the plane of minimal hiatal dimension. The levator ani muscle subdivisions are colored on the patient’s left for easy recognition. B, Same image in render mode may help appreciate scarring, although none is present in this image. A = anterior; AR = anorectum; L = left; PA = puboanalis; PC = pubococcygeus; PR = puborectalis; Pr = posterior; PS = pubic symphysis; R = right; U = urethra; V = vagina; vPFUS = endovaginal pelvic floor ultrasound.The LAM complex compresses and closes the pelvic outlet and provides support for the pelvic organs.42 A laxity or defect in the LAM is associated with the widening of the plane of minimum dimension or enlargement of the circumference of the urogenital hiatus.43,47 The minimum distance between the pubic symphysis and the posterior aspect of the anorectal junction at the level of the levator plate is termed the plane of minimum dimension, sometimes also referred to as minimal anatomic levator hiatus (Fig. 5). The plane of minimum dimension is located at the most caudal level of the LAM, at which the puborectalis muscle overlaps with pubococcygeus/iliococcygeal fibers posterior to the anorectum and creates the levator plate.48,49 The levator plate represents the junction of the LAM complex in the posterior midline at the level of the anorectal junction. LAM deficiency represents atrophy and global loss of the muscles. It is different from detachment or avulsion of the muscle from its origin at the pubic bone (Fig. 6), which can lead to distortion and/or downward displacement affecting the muscle and the functions of the pelvic organs.43,50 To evaluate the pelvic floor with vPFUS, as with other PFUS techniques, ultrasound imaging always starts with 2D dynamic pPFUS to asse