What are the most appropriate initial investigations for a patient with abnormal uterine bleeding?

Initial Investigations for Abnormal Uterine Bleeding

For patients with abnormal uterine bleeding, combined transabdominal and transvaginal ultrasound of the pelvis with Doppler is the most appropriate initial imaging study. 1

Primary Imaging Approach

• Combined ultrasound approach: Transvaginal ultrasound (TVUS) combined with transabdominal ultrasound and Doppler imaging provides the most comprehensive initial evaluation 1
• Transvaginal ultrasound advantages: Superior visualization of the endometrium and myometrium, allowing detection of structural causes such as polyps, fibroids, adenomyosis, and endometrial hyperplasia 1, 2
• Doppler assessment: Essential for evaluating vascularity patterns, which can help differentiate between various pathologies and identify vascular lesions 1

Laboratory Investigations

• Complete blood count: To assess for anemia and determine its severity 3, 4
• Coagulation studies: To rule out bleeding disorders, particularly von Willebrand disease which is present in approximately 1% of the population 5, 3
• Thyroid function tests: To exclude thyroid dysfunction as a cause of abnormal bleeding 3, 4
• Pregnancy test: To rule out pregnancy-related bleeding 1
• Quantitative hCG: Particularly important if gestational trophoblastic disease is suspected 1

Follow-up Imaging When Initial Ultrasound is Inconclusive

If the initial ultrasound is inconclusive or the uterus is incompletely visualized:

• Sonohysterography: When an endometrial polyp is suspected on the original ultrasound 1
• MRI of the pelvis without and with contrast: When the uterus is incompletely visualized due to factors such as patient body habitus, uterine position, or presence of leiomyomas or adenomyosis 1
  • MRI provides excellent tissue contrast resolution and multiplanar capability
  • Diffusion-weighted imaging should be included to improve sensitivity and specificity for uterine pathology 1

Special Considerations

• 3D ultrasound: May be considered for spatial assessment and treatment planning of leiomyomas and other uterine pathologies 1
• CT imaging: Generally not recommended as an initial investigation for abnormal uterine bleeding due to radiation exposure and limited soft tissue contrast compared to ultrasound and MRI 1
• Endometrial sampling: Should be considered if the endometrium cannot be adequately visualized by ultrasound, particularly in patients with risk factors for endometrial cancer 1, 3

Common Pitfalls to Avoid

• Inadequate bladder filling: Can limit visualization during transabdominal ultrasound; proper patient preparation is essential 1
• Overlooking the cervix: Complete evaluation should include visualization from external to internal os 1
• Missing vascular lesions: Failure to use color Doppler can lead to missed diagnoses of vascular abnormalities 1
• Incomplete evaluation: In persistent abnormal bleeding despite normal initial imaging, additional studies should be performed rather than assuming a non-structural cause 1

By following this systematic approach to imaging and laboratory investigations, clinicians can effectively diagnose the underlying causes of abnormal uterine bleeding and develop appropriate management plans to improve patient outcomes.