Importance of transient myometrial contractions in diagnosis of adenomyosis and congenital uterine anomalies

Uterine contractions may affect the thickness and features of the myometrial wall as well as the shape of the uterine cavity. The transient nature of these changes can be appreciated during real-time two-dimensional ultrasound examination and should always be borne in mind when analyzing static three-dimensional ultrasound (3D-US) volumes or magnetic resonance images, as well as during hysteroscopic investigation, due to the short duration of assessment. Myometrial contractions may result in erroneous image interpretation and, thus, incorrect diagnosis1. This is particularly relevant in the assessment of adenomyosis2 and in the classification of congenital uterine anomalies3-6. Uterine contractions might temporarily generate some features that are characteristic of adenomyosis, particularly asymmetry of the uterine wall thickness, reported by the Morphological Uterus Sonographic Assessment (MUSA) criteria2, but also other diagnostic features such as globular appearance and/or enlarged uterus. Figure 1a shows a uterus with a thickened, heterogeneous posterior wall with fan-shaped shadowing. The image in Figure 1b, which was taken 10 min later in the same patient, shows a normal posterior wall and a temporarily thickened anterior wall. Both images show physiological changes of a normal uterus but could lead to an incorrect diagnosis of adenomyosis. Figure 2a is a rendered 3D-US mid-coronal image of a uterus that would be classified as T-shaped uterus according to the Congenital Uterine Malformation by Experts (CUME) criteria3. However, a second volume of this uterus, which was taken 15 min later, demonstrates its normality (Figure 2b). Assessment of the uterus presented in Figure 3a would most likely classify it as partially septate; however, the image of the same uterus acquired 30 min later shows a normal uterine cavity (Figure 3b). In the latter case, both a transient myometrial contraction and a section artifact are likely to have caused the discrepancy. We believe it is important to rule out the effect of myometrial contractions before diagnosing adenomyosis and uterine anomalies. A simple strategy would be to repeat the image acquisition after at least 30 min when adenomyosis and/or uterine anomalies are suspected on the initial scan. Confirmation of the transient nature of the anomaly may save women needless anxiety and interventions. Further studies using 3D-US should evaluate and quantify the impact of transient myometrial contractions on the misdiagnosis of adenomyosis and congenital uterine anomalies.