How does adenomyosis differ from retained products of conception (RPOC) on pelvic ultrasound?

From the Guidelines

Adenomyosis and retained products of conception (RPOC) can be differentiated on pelvic ultrasound based on their distinct appearances, with adenomyosis typically showing a diffusely enlarged uterus with heterogeneous myometrium and RPOC appearing as heterogeneous material within the endometrial cavity. The key differences in ultrasound findings between adenomyosis and RPOC are crucial for guiding management, as adenomyosis is a chronic condition requiring long-term management, whereas RPOC may require surgical evacuation to prevent complications such as hemorrhage or infection 1. Some of the key ultrasound features of adenomyosis include:

• A diffusely enlarged uterus with heterogeneous myometrium
• Small myometrial cysts
• Poor definition of the endometrial-myometrial border
• Hyperechoic islands or linear striations extending from the endometrium into the myometrium In contrast, RPOC typically appears as:
• Heterogeneous material within the endometrial cavity
• Internal vascularity on color Doppler imaging
• An irregular, echogenic mass in the endometrial cavity with blood flow on Doppler The location of the abnormality (myometrial versus endometrial cavity) and the patient's clinical history (recent pregnancy versus chronic symptoms) are crucial factors in distinguishing these conditions on ultrasound 1. It is essential to note that while ultrasound is helpful in differentiating adenomyosis from RPOC, the clinical context and correlation with other diagnostic findings, such as beta-hCG levels, are also important for making an accurate diagnosis 1. In clinical practice, a combined transvaginal and transabdominal approach is the primary modality of choice for investigating late postpartum hemorrhage, as RPOC with or without endometritis is one of the major causes of secondary or late postpartum hemorrhage 1. Therefore, a thorough ultrasound evaluation, taking into account the patient's clinical history and other diagnostic findings, is essential for accurately differentiating adenomyosis from RPOC and guiding appropriate management.

From the Research

Ultrasound Characteristics of Adenomyosis and Retained Products of Conception

• Adenomyosis is characterized by the invasion of endometrial glands and stroma within the myometrium, which can be visualized on pelvic ultrasound as a heterogeneous or hypoechoic area within the uterine myometrium 2, 3.
• Retained products of conception (RPOC) appear as a hyperechogenic vascularized area within the uterine cavity on pelvic ultrasound, which can be implanted over a focal area of adenomyosis 4.
• The ultrasound characteristics of adenomyosis and RPOC can be distinguished by the location and appearance of the lesions, with adenomyosis typically appearing as a diffuse or focal area of heterogeneous echotexture within the myometrium, and RPOC appearing as a discrete hyperechogenic area within the uterine cavity.

Differential Diagnosis on Pelvic Ultrasound

• Adenomyosis can be misdiagnosed as multiple uterine leiomyomata or endometrial thickening on sonography, highlighting the importance of careful evaluation of the ultrasound characteristics of the lesions 5.
• RPOC can be distinguished from adenomyosis by the presence of a discrete hyperechogenic area within the uterine cavity, which is not typically seen in adenomyosis.
• The use of additional imaging modalities, such as magnetic resonance imaging (MRI), can help to confirm the diagnosis and distinguish between adenomyosis and RPOC 2, 5.

Clinical Implications of Accurate Diagnosis

• Accurate diagnosis of adenomyosis and RPOC is essential for guiding therapeutic management and preventing long-term complications, such as intrauterine adhesions and Asherman syndrome 4.
• The diagnosis of adenomyosis can have significant implications for reproductive health, including an increased risk of infertility, miscarriage, and obstetric complications 3, 6.
• The distinction between adenomyosis and RPOC on pelvic ultrasound can inform the choice of treatment, with hysteroscopic removal of RPOC being a feasible and safe management option 4.