A pessary is a flexible silicone device that is inserted into the vaginal canal and used to support the pelvic organs. Pelvic organ prolapse, and specifically uterine prolapse, is the most common reason for patients to use a pessary. However, stress urinary incontinence, prolapsed bladder rectocele or retroverted uterus can also benefit from the support of a pessary.
Most medical imaging is not affected by the presence of a pessary, but transvaginal ultrasound is an exception. However, pessary ultrasound images can still be taken with a few adjustments to the exam and patient preparation.
Navigating Around a Pessary
Transvaginal ultrasound is the only type of ultrasound exam that will encounter a pessary in a significant way. Transabdominal ultrasound will be only minimally affected by the presence of a pessary, as the device can cause some shadowing within the vaginal canal and over the cervix. Typically, patients are requested to remove a pessary prior to the ultrasound exam to allow for a full and complete assessment of the pelvic organs. Yet, should one have to remain in place for a particular reason, the exam can still be completed with a reasonable degree of thoroughness.
If a transvaginal ultrasound is being performed to add more information to a complete pelvic assessment, it may be more important to remove the pessary due to the device's shape, size and location. Its presence within the vagina prevents the transvaginal transducer from being placed in the ideal location within the upper vaginal fornices, as the pessary usually occupies that space. The material the pessary is composed of will also cause shadowing over portions of the cervix, uterus and even adnexa and ovaries, resulting in an incomplete assessment.
Modifications for Better Pessary Ultrasound Images
Fortunately, most pessaries are easily removed. However, when a patient is unable or advised not to remove a pessary, some studies have demonstrated that it is still possible to image the areas around the device with a modification to the transvaginal ultrasound technique. Research published in Ultrasoud in Obstretrics and Gynecology reports that good visualization of the cervix can be achieved by placing the transvaginal transducer between the posterior vaginal wall and the pessary, where it is just touching the external os of the cervix. This allows for a window through the center of the pessary that reduces the shadowing artifact.
This is still a limited field of view, and it will not allow examination of other pelvic organs. Other techniques must often be attempted as well. A translabial ultrasound approach can also be used for assessment of the more inferior parts of the pelvis, such as the vaginal canal, the cervix and the pelvic floor, but it will not allow a sonographer to adequately visualize the uterus or ovaries.
When a patient with a pessary requires a pelvic ultrasound exam, ideally they will remove the pessary before the appointment. If a patient cannot remove their pessary, begin with the transabdominal approach for visualization of the more superior pelvic organs (the uterus, ovaries and adnexa) and then proceed to the transvaginal and translabial approaches for assessment of the more inferior pelvic organs (vagina, cervix and pelvic floor).
The Future of Ultrasound for Pessaries
With the changes restricting the sale and distribution of vaginal mesh in the United States, the United Kingdom, France, New Zealand and several other countries, more patients may be referred for a pessary. Some may consult an OB/GYN to discuss issues with the vaginal mesh or having it removed. Ultrasound can be used to evaluate these patients and determine the extent of injury from past mesh use as well as to fit them for a pessary. Clinical ultrasound trials for pessary fit have used 3D translabial imaging of the vagina at various distension volumes to find the best possible pessary size and shape. This may allow for more accurate fitting of pessaries.
Clinicians have many options for completing a thorough assessment of the pelvis for patients who utilize a pessary. Reliance on pessary ultrasound images and pessary images may be on the rise as more patients take advantage of this nonsurgical option for the safe and effective treatment of pelvic organ prolapse.
