Transvaginal Ultrasound for Post-Miscarriage Bleeding
Order a transvaginal ultrasound (TVUS) to evaluate for retained products of conception (RPOC), which is the most common cause of persistent bleeding after miscarriage. 1, 2
Primary Imaging Recommendation
Transvaginal ultrasound is the first-line and most appropriate imaging modality for evaluating persistent vaginal bleeding after miscarriage, as it provides superior resolution for detecting RPOC and other intrauterine pathology compared to transabdominal approaches. 1, 3
A combined transabdominal and transvaginal approach is typically used, with the transabdominal view providing anatomic overview and the transvaginal approach offering greater contrast and spatial resolution. 1
Key Ultrasound Findings to Assess
The presence of hyperechoic material within the endometrial cavity is the most specific finding for RPOC, with 78% sensitivity, 100% specificity, and 100% positive predictive value. 2
Endometrial thickness >8 mm is a nonspecific finding that can overlap with normal postpartum appearance, but when combined with hyperechoic material or vaginal bleeding, increases diagnostic accuracy. 1, 2
The combination of hyperechoic material and/or vaginal bleeding has 98% sensitivity and 95% negative predictive value for RPOC—meaning if both are absent, RPOC is extremely unlikely. 2
Additional Diagnostic Considerations
Doppler ultrasound should be included to assess for vascular abnormalities, though high peak systolic velocities have considerable overlap and limited predictive value for intervention. 1
Evaluate for complications including endometritis (thick heterogeneous endometrium with fluid/air), hematoma, or abscess formation. 1
If the initial ultrasound is inconclusive and bleeding persists, sonohysterography (saline infusion sonography) can be considered as it has 75% accuracy for detecting intrauterine abnormalities compared to hysteroscopy. 1
Critical Clinical Pitfalls
Do not rely on endometrial thickness alone—a thickened endometrium without hyperechoic material is nonspecific and can represent normal postpartum changes rather than RPOC. 1, 2
Ultrasound showing an "empty uterus" does not definitively confirm complete miscarriage without serial beta-hCG confirmation, as 6% of such cases may represent ectopic pregnancy. 4
After clinical assessment suggesting complete miscarriage, 45% of women will still have retained tissue on ultrasound, emphasizing the importance of imaging rather than clinical assessment alone. 4
When to Consider Advanced Imaging
If TVUS is technically inadequate or the uterus is incompletely visualized, MRI pelvis without and with contrast is the next appropriate study. 1
MRI is not first-line but may be useful if there is concern for gestational trophoblastic disease (GTD), which appears as an echogenic mass with possible myometrial invasion and elevated beta-hCG. 1