Pre-procedure diagnostic imaging
Prior to embolization, it is necessary to confirm the diagnosis, rule out other pathologies, and assess the location of fibroid nodules (fibroids).
- Ultrasound (US): An accessible yet subjective method that is highly operator-dependent and provides poor visualization of the blood supply to the nodules.
- MRI (MRI): The undisputed method of choice. Performed strictly with contrast enhancement. The primary goal is to detect non-enhancing fibroids (non-enhancing fibroids), as UAE is inappropriate for them.
No imaging modality can reliably detect an incidental leiomyosarcoma with no evidence of spread beyond the uterus. If the patient has concomitant adenomyosis (adenomyosis), this is not a contraindication, although the clinical effect of UAE may be less pronounced than in isolated fibroids.
Procedural technique
The patient is hospitalized on the day of surgery and is required to stay overnight for management of post-embolization pain syndrome. The analgesia protocol requires the administration of opioids and antiemetics.
Main steps:
- Access: Most commonly achieved via the right common femoral artery (common femoral artery).
- Catheterization: A cobra-shaped catheter (4–5F) is used. It is advanced through the aortic bifurcation into the contralateral anterior division of the internal iliac artery. For selective cannulation of the uterine artery, a coaxial catheter is used, which ensures free blood flow and reduces the risk of spasm.
- Embolic agent administration: Non-spherical polyvinyl alcohol (PVA) with a particle size of 300–700 µm is used. Administration continues until complete stasis is achieved (complete stasis).
- Completion: After embolizing one side, the catheter is withdrawn, and a similar procedure is performed on the ipsilateral uterine artery.
Safety and comparison with surgery
The main advantage of embolization over surgical treatment is a faster patient recovery. However, the method is not without complications:
- Mild: Post-embolization syndrome (pain, fever), vaginal discharge.
- Severe (rare): Fibroid expulsion (fibroid expulsion), severe infection, premature ovarian insufficiency.
An important disadvantage of UAE is that a significant number of women (20–30%) require repeat intervention due to symptom recurrence. Furthermore, surgery is more effective for certain types of fibroids (e.g., hysteroscopic resection of pedunculated submucosal nodules).
UAE in postpartum hemorrhage (PPH)
Severe bleeding complicates approximately 10% of live births. Embolization is never used as first-line therapy in PPH. It is a method reserved for cases where uterotonics, intrauterine balloons, and compression sutures are ineffective.
Specifics of embolization in obstetrics:
- Access must always be bilateral due to the robust collateral blood supply in the pelvis.
- The target vessel is embolized with a gelatin sponge (Gelfoam).
- Pre-procedural CT angiography is rarely performed because the fact of hemorrhage is obvious.
- If no clear source is visible on the angiogram (which is often the case with uterine atony), "empirical embolization" is performed.
Failures are rare, but possible in severe placental anomalies. In such cases, hysterectomy may be required.
Placental anomalies
A formidable cause of obstetric hemorrhage is a defect of the decidua basalis, causing chorionic villi to invade the myometrium. There are three degrees:
- Placenta accreta — 84% of cases. Invasion into the myometrium.
- Placenta increta — 13%. Invasion reaching the serosa.
- Placenta percreta — 3%. Penetration beyond the uterus (e.g., into the urinary bladder).
The risk of such anomalies increases dramatically when a uterine scar and placenta previa are combined. The ideal strategy is prenatal detection (MRI/US) to plan delivery in an interventional suite equipped with a cell saver (cell salvage).
Briefly: answers to topical questions
What are the absolute and relative contraindications to uterine artery embolization?
The sources do not classify contraindications into absolute and relative, but they do indicate conditions under which the procedure is not performed.
- Non-enhancing fibroids (non-enhancing fibroids) — unsuitable for the procedure.
- Doubt regarding the diagnosis of fibroids (fibroids) — make embolization inappropriate.
Adenomyosis (adenomyosis) is not a contraindication to the intervention, although clinical outcomes are less pronounced than with isolated fibroids.
Class and exam questions
Is adenomyosis a contraindication to UAE?
No, it is not. However, symptoms may be identical to fibroids, and the clinical outcomes of the intervention in adenomyosis are typically less pronounced.
Can treatment of postpartum hemorrhage begin with embolization?
No, this is a "last resort" method. The algorithm begins with the administration of uterotonics, application of an intrauterine balloon, and placement of compression sutures.
Why is an MRI mandatory before UAE rather than just an ultrasound?
Contrast-enhanced MRI is the only reliable way to detect non-enhancing fibroid nodules, as embolization is ineffective for them.
What else to study on this topic
- Specifics of UAE in women desiring to preserve fertility (FEMME trial)
- Analgesia protocols and management of post-embolization syndrome
- Types of embolic agents and their differences (PVA, Gelfoam)
- Interventional rescue techniques in placenta percreta
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