Enhanced Myometrial Vascularity (EMV): The Most Misunderstood Doppler Finding After Pregnancy Loss
Enhanced Myometrial Vascularity (EMV) is one of the most striking and often misunderstood sonographic findings encountered after miscarriage, medical termination, or delivery. For years, many clinicians labelled it as uterine arteriovenous malformation (AVM) — a diagnosis that carries heavy implications and often leads to unnecessary interventions such as uterine artery embolization.
A recent expert review by Dewilde et al. (2023) clarifies the confusion and emphasizes that EMV is not an AVM — and recognizing this distinction is crucial for safe, evidence-based management.
What Exactly Is EMV?
EMV refers to dilated, tortuous, high-velocity, low-resistance myometrial vessels seen on Doppler imaging beneath retained pregnancy tissue.
It is a physiological, temporary, pregnancy-related vascular change, not a congenital malformation.
It arises because the placental bed vessels remain open and high-flow as long as any trophoblastic tissue persists.
Once the retained tissue is removed or expelled, the vessels collapse and EMV disappears — sometimes within minutes.
Why EMV Is NOT a Uterine AVM
The term AVM has been misused for years. But physiologically, the two are entirely different:
Uterine AVM
Congenital or post-traumatic.
Persistent abnormal artery-to-vein shunts.
Does not regress spontaneously.
Often requires selective embolization.
EMV
Always related to recent intrauterine pregnancy.
Caused by residual trophoblast keeping placental bed vessels patent.
Reverses completely once the tissue is removed or passes.
Rarely requires embolization.
Confusing EMV for an AVM can lead to overtreatment, unnecessary embolization, and fertility-compromising complications.
Why Does EMV Occur? (The Physiology Made Simple)
During pregnancy:
Spiral and radial arteries dilate massively to deliver ~700 mL/min blood to the placenta.
After delivery, myometrial contractions clamp these vessels shut.
But when pregnancy tissue persists:
These vessels remain open.
High-velocity flow persists beneath the retained tissue.
Doppler shows a striking low-resistance, high-flow pattern.
This is normal placental physiology persisting longer than it should — not pathology.
How EMV Looks on Ultrasound
On grayscale:
Anechoic, serpiginous, tubular myometrial spaces.
Located beneath or adjacent to retained products of conception (RPOC).
On Doppler:
Very high peak systolic velocities (PSV).
Low-resistance flow.
Turbulent, chaotic color patterns.
Importantly, the presence of high PSV does not correlate with bleeding risk.
Thus, PSV must not be used to decide management.
Clinical Scenarios Where EMV Appears
After early miscarriage
After medical termination of pregnancy
Postpartum when RPOC persists
After incomplete evacuation
It is not seen in unrelated uterine conditions unless there is a traumatic arteriovenous shunt (e.g., after surgery), which has a different appearance and mechanism.
Managing EMV Safely: A Practical Guide
1. No heavy or persistent bleeding → Expectant management
Most cases resolve naturally.
Once tissue passes, EMV disappears rapidly.
2. Persistent light bleeding or fertility concerns → Hysteroscopic management
Operative hysteroscopy with cold loop resection or morcellation.
Ultrasound mapping is essential for precise removal.
3. Heavy or acute bleeding → Emergency steps
Bladder emptying
Uterine massage
Tranexamic acid
Uterotonics
Ultrasound-guided suction or forceps removal
4. If bleeding still persists → Intrauterine balloon tamponade
5. Life-threatening bleeding unresponsive to all above → Consider embolization
Rarely needed in EMV.
Reserved for true emergencies to avoid hysterectomy.
Key Takeaways for Clinicians
EMV is common (1.5–6.3%) after miscarriage or delivery.
It is a normal physiological response to retained pregnancy tissue.
Not an AVM. Do not label EMV as AVM.
A high PSV does not predict bleeding.
Management is primarily expectant, with targeted removal only when indicated.
Embolization is almost never necessary unless bleeding is life-threatening.
Recognizing EMV prevents misdiagnosis, avoids unnecessary radiation/embolization, and preserves fertility.
Conclusion
Enhanced myometrial vascularity is a benign, self-resolving vascular phenomenon driven by retained pregnancy tissue. Understanding its physiology, imaging characteristics, and appropriate management can completely transform patient outcomes — reducing unnecessary interventions and offering reassurance in what is often an emotionally difficult period for patients.
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