Chapter 15: Pelvic Imaging

The clinical evaluation of pelvic floor disorders hinges on patient history and physical examination. Standardized systems for the clinical assessment of pelvic organ prolapse, such as the Baden–Walker Halfway System¹ or the Pelvic Organ Prolapse Quantification (POP-Q) System,² enable clinicians to reliably and reproducibly describe the extent of prolapse in each vaginal compartment.^3,4 However, the underlying defects that contribute to the symptomatology of pelvic floor disorders often elude visual inspection in the office. The organ lying behind each prolapsed vaginal segment varies^5,6 and important defects in the levator ani musculature cannot be visualized.^7,8 Pelvic floor clinicians and researchers abandoned the terms “cystocele” or “rectocele” in favor of anterior vaginal wall or posterior vaginal wall prolapse to reflect clinicians’ inability to reliably determine the organ lacking support behind the prolapsed vaginal wall.

Multiple studies report high rates of reoperation for pelvic floor disorders after initial pelvic floor surgery.⁹ Some experts believe that the unacceptably high reoperation rate for pelvic floor disorders may result from patients receiving an operation that is not tailored to the specific anatomic defects that lead to their symptomatology. Clinicians have used various techniques and maneuvers on physical examination to precisely identify each anatomic defect that may be responsible for a patient’s pelvic floor dysfunction.^10,11 In 1976 Richardson et al. described a technique of supporting the lateral vaginal fornices with ring forceps to differentiate midline defects, which would persist despite fornix support, from lateral detachments of the paravaginal connective tissue from the arcus tendineus fascia pelvis.¹⁰ Similarly, pelvic floor surgeons describe identifying rectovaginal septal defects¹² and levator ani defects during office examination. The straining q-tip test aims to discern stress urinary incontinence due to urethral hypermobility from intrinsic sphincter deficiency; and the dovetail sign is interpreted as an indication of anal sphincter disruption or dysfunction.

Despite attempts to uncover the specific defects responsible for pelvic floor dysfunction on physical examination, the pathophysiology of pelvic organ prolapse and urinary incontinence remains poorly understood. In an attempt to understand the underlying etiology of pelvic floor disorders, researchers have turned to static and dynamic imaging of pelvic soft tissues and viscera. The advantages, limitations, and clinical applications of pelvic imaging modalities will be discussed in this chapter.

CYSTOURETHROGRAPHY

Cystourethrography is a simple, inexpensive imaging modality that can be performed as a series of still images or can be used with fluoroscopy to obtain dynamic images. Because it employs plain radiography, it requires relatively small doses of ionizing radiation.¹³ To perform the test, a catheter is inserted into the bladder and used for instillation of contrast media.

Cystourethrography is used to diagnose urethral obstruction, such as from a tight sling, urethral fracture, or avulsion following trauma, especially if there is extravasation of contrast material outside of the urethra or bladder neck (Figure 15-1...