What is the best approach to manage a female patient with new onset abnormal uterine bleeding?

Management of First-Time Abnormal Uterine Bleeding

For a woman presenting with new-onset abnormal uterine bleeding, begin with pregnancy testing in all reproductive-age women, assess hemodynamic stability, and proceed directly to combined transabdominal and transvaginal ultrasound with Doppler as the first-line imaging study. 1

Immediate Assessment

Hemodynamic Evaluation

• Urgent evaluation is required if bleeding saturates a large pad or tampon hourly for at least 4 hours, indicating potential hemodynamic instability 1
• Perform abdominal examination to assess for hemodynamic compromise and palpate for enlarged uterus or masses 1

Essential Initial Testing

• Pregnancy test (β-hCG) is mandatory in all reproductive-age women before proceeding with further workup 1, 2
• Obtain thyroid-stimulating hormone and prolactin levels as part of the diagnostic evaluation 1
• Complete blood count with platelets to assess for anemia and coagulopathy 2

First-Line Imaging Strategy

Ultrasound Protocol

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 3, 1

The rationale for this combined approach:

• Transabdominal ultrasound provides anatomic overview and is essential when the uterus is significantly enlarged, as the limited field of view of transvaginal ultrasound cannot capture all portions 3
• Transvaginal ultrasound offers superior spatial and contrast resolution for detailed pelvic assessment 3
• Doppler imaging is a standard component that helps identify vessels within endometrial polyps or cancer, with visualization of a vascular pedicle having 62-98% specificity for detecting endometrial polyps 3

When to Advance Imaging

• Saline infusion sonohysterography has 96-100% sensitivity and 94-100% negative predictive value for uterine and endometrial pathology, and should be considered when initial ultrasound shows thickened endometrium or focal abnormalities 1
• MRI pelvis should be reserved for when ultrasound incompletely visualizes the uterus or findings are indeterminate, with sensitivity up to 79% and specificity up to 89% for endometrial cancer 1

Physical Examination Components

• Speculum examination to visualize cervix and vagina, excluding cervical or vaginal sources of bleeding 1
• Bimanual examination to assess uterine size, contour, mobility, and adnexal masses 1

Risk Stratification for Endometrial Cancer

Consider the following high-risk features that necessitate more aggressive evaluation:

• Postmenopausal status 1
• Obesity, diabetes, hypertension 1
• Unopposed estrogen exposure or tamoxifen use 1
• Lynch syndrome or family history of endometrial cancer 1

Endometrial Thickness Thresholds

• In postmenopausal women, endometrial thickness less than 4 mm has nearly 100% negative predictive value for cancer 1
• Endometrial thickness ≥4 mm in postmenopausal women requires referral to gynecology 2

Classification Framework

Use the PALM-COEIN system to categorize the bleeding cause 1, 2:

Structural causes (PALM):

• Polyp 1
• Adenomyosis 1
• Leiomyoma (fibroids) 1
• Malignancy and hyperplasia 1

Non-structural causes (COEIN):

• Coagulopathy 1
• Ovulatory dysfunction 1
• Endometrial 1
• Iatrogenic (including anticoagulation—70% of women on anticoagulation experience heavy menstrual bleeding) 1
• Not yet classified 1

Mandatory Gynecology Referral Criteria

Refer immediately to gynecology if:

• Endometrial sampling shows hyperplasia or malignancy 1
• Postmenopausal bleeding with endometrial thickness ≥4 mm 2
• Failed medical management 1

Critical Pitfalls to Avoid

• Do not rely on endometrial biopsy alone to rule out focal lesions, as it has variable sensitivity; saline infusion sonohysterography is superior for assessing intracavitary pathology 2
• In patients with cardiovascular disease or on anticoagulation, avoid NSAIDs and tranexamic acid due to MI and thrombosis risk 1, 2
• For patients on antiplatelet therapy, reassess the indication and consider discontinuation before initiating treatment 1
• Sonohysterography cannot distinguish between benign endometrial pathology and endometrial cancer with high certainty; endometrial sampling or hysteroscopy is required for suspected pathology 3