Anatomy, embryology, pathophysiology

  • The pelvic floor consists of the levator ani, the pelvic sphincters, and fascia that support the rectum, bladder and urethra, as well as the vagina, cervix, and uterus in females and the prostate in males.

  • These organs are divided into three compartments in females: anterior (bladder and urethra), middle (uterus, cervix, and vagina), and posterior (rectum and anus). In males, there is no middle compartment.

  • Pelvic floor dysfunction is a broad term that includes dysfunction of any of the three compartments, including urinary incontinence, anal incontinence, defecation dysfunction, and pelvic organ prolapse.

  • The risk of having at least one pelvic floor dysfunction in women of reproductive age is estimated to be at least 24% and as high as 46%, affecting a much smaller proportion of men.

  • Approximately 10% of women undergo surgery for pelvic floor dysfunction.

  • Fluoroscopic defecography (FDG) and magnetic resonance defecography (MDG), involving real-time relaxation of the levator ani and evacuation, contribute additional findings to physical examination in up to 65% of cases.

Techniques

Fluoroscopic defecography

FDG allows dynamic imaging of the pelvic floor and involves contrast opacification of the rectum and vagina with or without contrast opacification of the bladder and small bowel. Imaging is performed on a radiolucent commode and is therefore considered more physiological than other described techniques.

Magnetic resonance defecography

MDG offers similar benefits to FDG and provides additional anatomic information regarding the pelvic organs because of its high image contrast and triplanar imaging protocol; this allows easy identification of the pelvic organs, including the bladder, urethra, prostate, uterus, vagina, rectum, and anus and demonstration of their subsequent movement during defecatory maneuvers. MDG’s lack of radiation makes it the preferred imaging modality in younger patients. Open MRIs can also enable physiologic defecation positioning.

Translabial pelvic floor ultrasound

A relatively new, less established modality for the evaluation of pelvic floor disease in females, with high reported accuracy. This technique will not be covered in this chapter.

Protocols

Protocol considerations

Protocols for optimal evaluation of suspected pelvic floor dysfunction aim to image two or three compartments, depending on the gender and imaging protocol. Study of the pelvic floor involves dynamic imaging during provocatory maneuvers, including Kegel maneuvers, straining, and evacuation. Before any procedure, a detailed questionnaire inquiring about symptoms is important to reveal any previously unsolicited details that may be helpful in the diagnostic workup.

Suggested fluoroscopic defocography protocol

Organ and landmark opacification

  • Perineum: tape a 1.3 cm Barium tablet in the perineum for both landmark and size reference for magnification correction.

  • Proximal bowel: administer dilute oral contrast 45 minutes before the procedure to better identify peritoneoceles, omentoceles, and enteroceles.

  • Anterior compartment (optional): in the supine position, at least 30 mL cystographic contrast is administered into the bladder through a Foley catheter.

  • Middle compartment: at least 20 mL high density barium mixed with ultrasound gel is vaginally administered either by the patient or by an operator via a Foley catheter in the supine position.

  • Posterior compartment: 200 mL of barium paste injected by hand via a large plastic syringe.

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