What imaging study is first-line for diagnosing abnormal uterine bleeding?

Transvaginal ultrasound is the first-line imaging study for diagnosing abnormal uterine bleeding due to its effectiveness in visualizing the uterus and surrounding structures in detail. This method allows for the assessment of the endometrial lining, detection of uterine abnormalities such as fibroids, polyps, or endometrial hyperplasia, and can be performed with minimal discomfort for the patient. Moreover, it provides real-time images and is readily available in many clinical settings, making it a practical choice.

In contrast, other imaging modalities such as CT scans and MRIs, while useful in certain contexts, are not routinely employed for initial evaluation of abnormal uterine bleeding. CT scans expose patients to radiation and are more suited for assessing complex cases rather than routine evaluations. MRIs, although very detailed, are more expensive and less accessible compared to transvaginal ultrasound. X-rays are generally not appropriate for this type of evaluation, as they do not provide adequate imaging of the soft tissues involved in uterine pathology. Thus, transvaginal ultrasound stands out as the most suitable option for initial diagnosis in cases of abnormal uterine bleeding.