Adenomyosis and uterine stiffness: what is the chicken? Which is the egg?

Abstract

So just what is the relevance of adenomyosis anyway? Since it was first reported in 1860 (Rokitansky, 1860), adenomyosis has been variously described as a disease and a disorder, rare and common, and even a normal uterine anatomical variant (Weiss et al., 2009). Until the advent of imaging-based diagnosis, it was perceived to be a relatively uncommon condition and one largely confined to women in their fifth decade of life, the inevitable result of an insidious and invasive process that was destined to culminate in some combination of dysmenorrhea, heavy menstrual bleeding (HMB), a tender and symmetrically enlarged uterus, and, inevitably, a hysterectomy, at which time the diagnosis was typically confirmed. The picture began to change when both ultrasound and magnetic resonance imaging were demonstrated to be relatively sensitive and specific means by which adenomyosis could be diagnosed without the need for uterine extirpation (Champaneria et al., 2010). This non-invasive approach to diagnosis provided a lens through which adenomyosis could be seen in a different light. Unsurprisingly, there was an incomplete but evident relationship between suggestive imaging features and dysmenorrhea and HMB (Naftalin et al., 2014, 2016). Fertility was possibly compromised for reasons that ranged from dysfunctional sperm transport secondary to aberrant myometrial contractility (Kissler et al., 2006), to impaired endometrial receptivity (Munro, 2019). Eventually, evidence appeared linking adenomyosis to obstetrical disorders including fetal growth restriction, preterm labor, and peripartum hemorrhage (Nirgianakis et al., 2021). And then there was the revelation that adenomyosis features could be identified with high prevalence, even in 18- to 30-year olds with minimal or no symptoms (Pinzauti et al., 2015). This finding, if accurate, would challenge some of our notions of the pathogenesis of adenomyosis and would beg the question of what might be found if one could examine the uteri of even younger women and premenarchal girls. More recently, evaluation of women with adenomyosis with ultrasound-based elastography has demonstrated that increased uterine stiffness appears to be reflective of evolving fibrosis (Acar et al., 2016). In many instances, these observations seem at odds with our historical understanding of the pathogenesis and prevalence of adenomyosis, its impact on the uterus, and the variety of related clinical manifestations.