Decidualized adenomyosis during pregnancy and post delivery: three cases of magnetic resonance imaging findings

Pregnancy is associated with reduced progression of symptomatic adenomyosis: a retrospective pilot study

BACKGROUND

Adenomyosis is a common gynecological disease in women of reproductive age and causes various symptoms such as dysmenorrhea and heavy menstrual bleeding. However, the influence of pregnancy on the progression of adenomyosis remains unclear. The insight into whether the size of adenomyosis is increased, decreased, or unchanged during pregnancy is also undetermined. The current study aimed to evaluate the influence of pregnancy in patients with symptomatic adenomyosis.

METHODS

This study retrospectively enrolled patients diagnosed with adenomyosis by magnetic resonance imaging between 2015 and 2022 at The University of Tokyo Hospital. Uterine size changes were evaluated by two imaging examinations. In the pregnancy group, the patients did not receive any hormonal and surgical treatments, except cesarean section, but experienced pregnancy and delivery between the first and second imaging examinations. In the control group (nonpregnancy group), the patients experienced neither hormonal and surgical treatments nor pregnancy from at least 1 year before the first imaging to the second imaging. The enlargement rate of the uterine size per year (percentage) was calculated by the uterine volume changes (cm3) divided by the interval (years) between two imaging examinations. The enlargement rate of the uterine size per year was compared between the pregnancy group and the control group.

RESULTS

Thirteen and 11 patients with symptomatic adenomyosis were included in the pregnancy group and in the control group, respectively. The pregnancy group had a lower enlargement rate per year than the control group (mean ± SE: -7.4% ± 3.6% vs. 48.0% ± 18.5%, P < 0.001), indicating that the size of the uterus with adenomyosis did not change in the pregnancy group.

CONCLUSIONS

Pregnancy is associated with reduced progression of symptomatic adenomyosis.

Adenomyosis in Pregnancy: Diagnostic Pearls and Pitfalls

Adenomyosis is a common benign uterine disorder in which ectopic endometrial glands extend into the myometrium. Adenomyosis is increasingly diagnosed in young women, affecting 20%-35% of women of reproductive age. Features of adenomyosis can be seen with either US or MRI, especially with newer imaging technology. With advances in reproductive endocrinology as well as a trend toward later maternal age, adenomyosis is increasingly noted during pregnancy, often while performing imaging for other reasons. Hormonal changes during pregnancy alter the appearance of adenomyosis, which includes diffuse, focal, and cystic adenomyosis. Recognizing these imaging changes in pregnancy proves essential for accurately diagnosing adenomyosis as a benign condition, as it mimics serious placental and myometrial abnormalities. Using a lower-frequency US transducer or MRI can be helpful in distinguishing among these entities. Describing the location of adenomyosis in relationship to the site of placentation is also important. Diagnosing adenomyosis is crucial because it can be associated with poor pregnancy outcomes, including spontaneous abortion, preterm birth, and fetal growth restriction. Adenomyosis is also a risk factor for preeclampsia. Intramural ectopic pregnancy is a rare but serious condition that can mimic cystic adenomyosis, and comparison with prepregnancy images can help differentiate the two conditions. The authors review the unique imaging characteristics of adenomyosis in pregnancy, focusing on accurate diagnosis of an underrecognized benign condition that can mimic myometrial and placental pathologic conditions.^©RSNA, 2021.

Uterine adenomyosis with extensive glandular proliferation: case series of a rare imaging variant

PURPOSE

We aimed to investigate the clinical and magnetic resonance imaging (MRI) characteristics of uterine adenomyosis, in which there is an extensive area of high signal intensity in the myometrium on T2-weighted MRI.

METHODS

This retrospective radiographic study reviewed a case series of six patients (mean age, 36 years) with adenomyosis. These patients were selected because, unlike in classical adenomyosis, T2-weighted images showed a larger area of high signal intensity than that of low signal intensity in the myometrium. The morphology of the myometrial lesions, patterns of contrast enhancement (n=4), intramyometrial hemorrhaging, diffusion restriction (n=5), endometrial lesions, and imaging findings after treatment (n=3) were evaluated on MRI.

RESULTS

The patients' clinical symptoms included vaginal bleeding and severe anemia. Four were administered hormonal therapy, one underwent hysterectomy, and one underwent enucleation. On T2-weighted images, all showed endometrial thickening and a high signal intensity area in the myometrium that was divided up by a mesh of low signal intensity bands, with an appearance reminiscent of a fish caught in a net. Other findings included gradual centripetal enhancement with contrast defects in multicystic areas (4/4), an intramyometrial hemorrhage (1/6), and increased diffusion (5/5). Following hormonal therapy, the uteruses decreased in size and were similar to those of classical adenomyosis on MRI (3/3). The lesions were diagnosed as adenomyosis with a proliferation of adenomyotic glandular tissue and a proliferative endometrial polyp.

CONCLUSION

This case series suggests that there is a subgroup of uterine adenomyosis that shows a characteristic "fish-in-a-net" appearance on T2-weighted images.

Symptoms and classification of uterine adenomyosis, including the place of hysteroscopy in diagnosis

Where histology used the presence of glands and/or stroma in the myometrium as pathognomonic for adenomyosis, imaging uses the appearance of the myometrium, the presence of striations, related to the presence of endometrial tissue within the myometrium, the presence of intramyometrial cystic structures and the size and asymmetry of the uterus to identify adenomyosis. Preliminary reports show a good correlation between the features detected by imaging and the histological findings. Symptoms associated with adenomyosis are abnormal uterine bleeding, pelvic pain (dysmenorrhea, chronic pelvic pain, dyspareunia), and impaired reproduction. However a high incidence of existing comorbidity like fibroids and endometriosis makes it difficult to attribute a specific pathognomonic symptom to adenomyosis. Heterogeneity in the reported pregnancy rates after assisted reproduction is due to the use of different ovarian stimulation protocols and absence of a correct description of the adenomyotic pathology. Current efforts to classify the disease contributed a lot in elucidated the potential characteristics that a classification system should be relied on. The need for a comprehensive, user friendly, and clear categorization of adenomyosis including the pattern, location, histological variants, and the myometrial zone seems to be an urgent need. With the uterus as a possible unifying link between adenomyosis and endometriosis, exploration of the uterus should not only be restricted to the hysteroscopic exploration of the uterine cavity but in a fusion with ultrasound.

Adenomyosis: a life-cycle approach

The life-cycle approach to endometriosis highlighted unexpected features of the condition; the same approach was therefore applied to gain insight into the clinical features of adenomyosis and to draw a comparison with endometriosis. This is possible today thanks to new imaging techniques enabling non-invasive diagnosis of adenomyosis. The specificity and sensitivity of magnetic resonance imaging and transvaginal ultrasound remain uncertain. Unlike endometriosis, little information is available on the presence of classic adenomyosis in adolescents, except for rare cystic forms that may not represent the true disease. Adenomyosis is most likely to affect adult women, although most reported incidences are still based on post-hysterectomy studies, and are affected by diligence in histopathologic diagnosis and the adopted cut-off point. The traditionally accepted associations of adult adenomyosis, such as multiparity, a link to infertility and its effect on pregnancy are uncertain. Active adenomyosis has been found in pre- and peri-menopausal women and in postmenopausal women receiving tamoxifen. In conclusion, major diagnostic limitations and the systematic bias of hysterectomy make it difficult to draw firm conclusions from existing evidence. In addition, no information is available on the natural history of adenomyosis and no study has systematically evaluated its existence in adolescents.

Adenomyosis in pregnancy mimicking morbidly adherent placenta

The objective of this study was to illustrate a false-positive diagnosis of adherent placenta due to underlying adenomyosis. A 34-year-old woman was diagnosed for placenta previa totalis with adherent placenta at 33 weeks, based on the findings of loss of clear space or distinguishing outline separating the placenta and uterine wall, presence of intraplacental lacunae and densely atypical vessels in the lesion. Caesarean hysterectomy was performed at 35 weeks. Pathological findings revealed placenta previa totalis with adenomyosis beneath the placenta at the lower segment, with no adherent placenta. In conclusion, this report underlines the importance of possible false-positive test of prenatal ultrasound and MRI findings of adherent placenta caused by underlying adenomyosis which could obliterate the outline distinguishing the placenta and myometrium and atypical vessels secondary to decidualisation and hypervascularity from pregnancy. This case may probably encourage physician to beware of false-positive test of adherent placenta due to adenomyosis.