What are the initial investigations for perimenopausal Abnormal Uterine Bleeding (AUB)?

Initial Investigations for Perimenopausal Abnormal Uterine Bleeding

Begin with combined transabdominal and transvaginal ultrasound with Doppler as your first-line imaging study, along with pregnancy testing in all reproductive-age women, and perform endometrial sampling in women with risk factors for endometrial cancer or failed medical management. 1

Immediate Assessment

• Check hemodynamic stability first – urgent evaluation is needed if bleeding saturates a large pad or tampon hourly for at least 4 hours 1
• Perform speculum examination to visualize the cervix and vagina, excluding cervical or vaginal sources of bleeding 1
• Conduct bimanual examination to assess uterine size, contour, mobility, and adnexal masses 1
• Palpate abdomen for enlarged uterus or masses 1

Essential Laboratory Tests

• Pregnancy test (β-hCG) – mandatory in all reproductive-age women with AUB 1
• Thyroid-stimulating hormone (TSH) – part of standard diagnostic workup 2, 1
• Prolactin levels – evaluate for hyperprolactinemia as a cause of ovulatory dysfunction 2, 1
• Hemoglobin and iron levels – assess for anemia in selected cases, particularly with heavy bleeding 3

First-Line Imaging

Combined transabdominal and transvaginal ultrasound with Doppler is the most appropriate initial imaging study for identifying structural causes including polyps, adenomyosis, leiomyomas, and endometrial hyperplasia/malignancy 1. This approach has several advantages:

• Transvaginal ultrasound serves as the primary modality for evaluating the endometrium and myometrium 1
• In perimenopausal women, an endometrial thickness <4 mm has nearly 100% negative predictive value for cancer 1
• Transabdominal imaging is useful for assessing other structural abnormalities when transvaginal approach is limited 2

Advanced Imaging When Indicated

Saline infusion sonohysterography (SIS) should be performed when initial ultrasound findings are unclear or suggest intracavitary lesions:

• Sensitivity of 96-100% and negative predictive value of 94-100% for uterine and endometrial pathology 2, 1
• Can distinguish between leiomyomas and endometrial polyps with 97% accuracy 1
• Confirms presence of intracavitary lesions and determines myometrial involvement with leiomyomas 2
• More accurate than transvaginal ultrasonography alone for endometrial assessment 2

Endometrial Sampling Indications

Perform endometrial biopsy in perimenopausal women with the following risk factors 1:

• Age and postmenopausal status
• Obesity, diabetes, hypertension
• Unopposed estrogen exposure
• Tamoxifen use
• Lynch syndrome or family history of endometrial cancer
• Endometrial thickness ≥4 mm on ultrasound
• Failed medical management

Important Caveat About Endometrial Biopsy

Endometrial biopsy is preferred over dilation and curettage because it is less invasive, safer, and lower cost 2. However, sensitivity can be affected by lesion type (focal vs. diffuse), lesion size, pathologic diagnosis, and whether uterine malformation is present 2. The combination of endometrial biopsy and transvaginal sonohysterography correlates with surgical findings >95% of the time, with sensitivity and specificity of 94% and 96% respectively 4.

When to Proceed to Hysteroscopy

Reserve hysteroscopy for cases where 2:

• Medical treatment has failed
• Imaging suggests focal lesions that may have been missed by endometrial sampling
• Endometrial biopsy shows hyperplasia or malignancy
• Saline infusion sonohysterography identifies intracavitary masses requiring surgical management

Hysteroscopy allows direct visualization of the endometrial cavity and endocervix, helping diagnose focal lesions possibly missed by endometrial sampling 2.

Common Pitfalls to Avoid

• Do not skip pregnancy testing – even in perimenopausal women, pregnancy must be excluded 1
• Do not rely on transabdominal ultrasound alone in non-virgins – transvaginal approach provides superior endometrial assessment 2
• Do not perform routine endometrial biopsy in all perimenopausal women – target those with risk factors for endometrial cancer or failed medical management 1
• Do not miss cervical or vaginal sources – always perform speculum examination before attributing bleeding to uterine causes 1, 3

Referral Criteria

Refer to gynecology when 1:

• Endometrial sampling shows hyperplasia or malignancy
• Failed medical management
• Endometrial thickness ≥4 mm with persistent bleeding
• Intracavitary masses identified on imaging requiring surgical intervention