What comes to mind when I say ovarian torsion and ultrasound? I suspect most physicians would think of something along the lines of no flow or decreased flow. Compared with its male counterpart, the testicular torsion, the diagnosis of adnexal torsion can be difficult.
Fortunately, we don't see this problem often. The prevalence of adnexal torsion is estimated at 2.7 percent to 3.0 percent. (J Ultrasound Med 2011;30:1205.) I've seen far fewer cases in my practice of more than 10 years, so it's not surprising that there might be some uncertainty in the diagnosis.
Traditionally, adnexal torsion is described as sudden onset, severe, localized to one side of the lower abdomen or pelvis, and it is often associated with nausea and vomiting. Ultrasound has been the preferred initial diagnostic modality secondary to its ability to evaluate morphologic characteristics of the adnexa while simultaneously assessing the arterial and venous flow. There is more and more push to integrate bedside ultrasound into the care of patients in the ED, so more physicians may consider taking a look at the adnexa in patients with presentations concerning for torsion.
To put it bluntly, however, Doppler is confusing and intimidating, leading a lot of physicians to avoid bedside ultrasound. Even when interpreting a “formal” ultrasound, the diagnosis of adnexal torsion is fraught with potential pitfalls.
Many articles have looked at the ultrasound signs of adnexal torsion and sought to develop a consensus. One of the most recent review articles from 2014 found that making the diagnosis utilizing Doppler flow was not straightforward. (J Minim Invasive Gynecol 2014;21:196.) One of the articles they reviewed found that 60 percent of surgically proven cases of torsion continued to demonstrate arterial flow with Doppler. As with testicular torsion, venous flow is typically compromised first due to the decreased resistance of the veins to external pressure. This venous disruption results in edema of the ovary and movement of the follicles to the periphery. In contrast, lack of arterial flow is considered to be a late sign and may be predictive of viability of the ovary. Frustratingly, some cases of adnexal torsion may even demonstrate the appearance of normal blood flow due to either intermittent detorsion or the fact that the adnexa is served by a dual blood supply.
Clinical suspicion remains paramount when considering a potential case of adnexal torsion. EPs must remain vigilant and avoid being quick to rule it out based on the presence of flow alone. Looking for additional signs, specifically ovarian enlargement, an ovarian mass (point of torsion), free fluid in the cul-de-sac, and movement of the follicles to the periphery increases the sensitivity of the ultrasound and ensures that this uncommon surgical emergency is not missed.
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