Pelvic Ultrasound in Abnormal Uterine Bleeding Evaluation

Introduction to Pelvic Ultrasound

The American College of Obstetricians and Gynecologists recommends pelvic ultrasound as the first-line imaging study for patients with abnormal uterine bleeding before initiating oral contraceptives, as it provides a comprehensive evaluation of the uterus and adnexa, identifying structural causes including polyps, adenomyosis, leiomyomas, and endometrial hyperplasia/malignancy 1
Combined transabdominal and transvaginal ultrasound is critical because starting OCPs without imaging risks missing serious pathology that would be temporarily suppressed by hormonal contraception, delaying diagnosis of conditions like endometrial cancer or significant structural lesions 1

The Centers for Disease Control and Prevention recommends that hormonal testing such as FSH and LH does not contribute substantially to safe oral contraceptive initiation, classifying these tests as "Class C" (not contributing substantially to safe contraceptive use) in the U.S. Selected Practice Recommendations 1
The Society of Obstetricians and Gynaecologists of Canada indicates that endometrial biopsy is not the first test—it is indicated based on age and ultrasound findings, and its need is guided by ultrasound findings, particularly for women ≥35 years or younger women with risk factors for endometrial cancer 1, 2

The American College of Obstetricians and Gynecologists suggests obtaining pelvic ultrasound first (transvaginal and transabdominal with Doppler) to assess endometrial thickness and architecture, identify structural lesions, and evaluate for masses, and then considering endometrial biopsy if patient is ≥35 years old, has risk factors for endometrial cancer, or ultrasound shows focal endometrial abnormality or thickened endometrium 1, 2
The American Academy of Pediatrics states that a speculum or bimanual examination is considered unnecessary before prescribing oral contraceptive pills, but ultrasound remains essential to exclude structural pathology before masking symptoms with hormonal therapy 4, 1