Uterine Artery Embolization - IR procedure

Overview

Interventional radiology plays an increasingly central role in gynaecological and obstetric management. Procedures span diagnostic imaging studies evaluating tubal patency and uterine morphology through to therapeutic vascular interventions for fibroids, adenomyosis, and haemorrhage. This note covers diagnostic procedures (hysterosalpingography, amniocentesis, chorionic villus sampling, saline infusion sonography) and therapeutic procedures (fallopian tube recanalisation, lipiodol flush, uterine artery embolisation, percutaneous drainage catheter placement).

Diagnostic Procedures

Hysterosalpingogram (HSG)

Indications

• Investigation of female infertility, primary and secondary
• Evaluation of tubal patency (proximal and distal)
• Assessment of uterine cavity morphology (congenital anomalies, polyps, fibroids, synechiae)
• Postoperative evaluation after tubal surgery or sterilisation reversal

Contraindications

• Active pelvic infection / pelvic inflammatory disease
• Confirmed or suspected pregnancy
• Allergy to iodinated contrast (relative, use CO₂ or pre-medicate)
• Active uterine bleeding (relative, obscures anatomy)

Timing: Optimally performed in the first 10 days of the menstrual cycle (follicular phase), avoiding active menstruation, reduces risk of retrograde seeding of endometrial tissue and maximises tubal visualisation.

Technique and Reporting

• Water-soluble iodinated contrast injected via a balloon catheter seated at the cervical os under fluoroscopic guidance.
• Normal: smooth triangular uterine cavity, bilateral contrast opacification of fallopian tubes to fimbriated ends, free peritoneal spill.
• Pathological: filling defects in the cavity (fibroids, polyps, synechiae), cornual occlusion (proximal obstruction), hydrosalpinx (distal dilatation without spill), peritubal adhesions (puddling without free spill).

Complications

• Pain / uterine cramping (common, transient)
• Vasovagal reaction
• Contrast reaction
• Pelvic infection / salpingitis (reduce with pre-procedural infection screening and prophylactic antibiotics)
• Haemorrhage (uncommon)
• Radiation exposure (minimise dose in reproductive-age women)

Limitations

• Transient tubal spasm can simulate true proximal occlusion, key pitfall; repeat injection or antispasmodic (e.g. glucagon) may clarify.
• Does not evaluate ovarian morphology or myometrial pathology.
• Does not provide tissue diagnosis for filling defects.

Amniocentesis

Indications

Timing: Diagnostic amniocentesis is performed between 15 and 18 weeks gestation. Procedures before 15 weeks carry higher complication rates.

Technique

• Real-time continuous ultrasound guidance is mandatory.
• 20-22 gauge needle advanced into the amniotic cavity under sterile technique, avoiding the fetus, placenta, umbilical cord, uterine vessels, and fibroids.
• In twin pregnancies: 2-5 mL of indigo carmine dye injected into the first sac; colourless fluid on second needle pass confirms entry into the second sac.

Advantages Over CVS

Complications

• Fetal loss: procedure-related risk ~0.5-1%
• Amniotic fluid leak
• Chorioamnionitis
• Needle injury to fetus
• Premature labour

Chorionic Villus Sampling (CVS)

CVS involves aspiration of cells from the chorion frondosum for genetic analysis (karyotype, DNA analysis, biochemical assay). Its principal advantage is that results are available more than two weeks earlier than amniocentesis.

Timing: 9-11 weeks gestation. Before 9 weeks carries significantly elevated risk of limb reduction defects.

Approaches

Note: Transabdominal CVS in the 2nd and 3rd trimester is equivalent to a placental biopsy and enables rapid karyotyping.

Chromosome Analysis Methods

Errors (~2%)

• Confined placental mosaicism: cytotrophoblast cell line carries abnormal karyotype while fetal cell line is normal.
• Maternal contamination: maternal decidual cells may overgrow mesenchymal core cells.

Complications

• Spontaneous abortion (~1%)
• Amniotic sac perforation
• Infection
• Limb reduction defects (teratogenesis, greatest risk before 9 weeks)

Saline Infusion Sonography (SIS) / Sonohysterography

Indications

• Evaluation of uterine cavity abnormalities detected on transvaginal ultrasound (polyps, submucosal fibroids, synechiae)
• Assessment of fallopian tube patency (when microbubble solution used)
• Abnormal uterine bleeding evaluation

Technique

• A 5F balloon catheter is introduced through the cervix and sterile saline (or microbubble contrast solution) is instilled under real-time transvaginal ultrasound visualisation.

Contraindications and Complications

• Contraindications are similar to HSG: active pelvic infection and pregnancy.
• Complications: pain, vasovagal response, rare pelvic infection.

Advantages Over HSG

• No ionising radiation.
• Can be performed at the same appointment as the routine gynaecological ultrasound.
• Better characterisation of endometrial lining and intracavitary lesions.
• Real-time visualisation of fluid dynamics.

Limitations

• Does not provide detailed evaluation of the full course of the fallopian tube.
• Operator dependent.
• Inferior to MRI for ovarian anatomy and myometrial disease assessment.

Therapeutic Procedures

Fallopian Tube Recanalisation (FTR)

Indications

• Proximal fallopian tube occlusion (cornual occlusion) confirmed on HSG, with patent distal tube.
• Preferred over IVF in women with isolated proximal occlusion.

Contraindications

• Active pelvic infection.
• Distal tubal disease (hydrosalpinx, extensive peritubal adhesions).
• Suspected endosalpingeal disease (e.g. tuberculosis).

Procedure Principles

• Follows diagnostic HSG confirming cornual occlusion.
• Small coaxial catheters and hydrophilic guidewires are used to cannulate each fallopian tube at the cornual ostium.
• The wire is advanced to and across the obstruction; patency is confirmed by free contrast spill.

Results

• Pregnancy rates of approximately 60% have been reported following the procedure.
• Post-procedure HSG documents restored tubal patency and bilateral peritoneal spill.
• Recurrence of occlusion is possible; the tube can be recanalised more than once.

Complications

• Tubal perforation (most common, usually minor, self-limiting)
• Pelvic infection
• Ectopic pregnancy (due to underlying tubal damage)

Lipiodol Flush for Subfertility

Indications

• Subfertility (unexplained or with mild tubal disease).
• Proposed mechanism: the oil-based contrast medium (Lipiodol) flushes intraluminal debris and may exert immunomodulatory or endometrial effects that improve implantation rates.

Contraindications

• Active pelvic infection
• Pregnancy
• Hypersensitivity to iodinated contrast

Reporting

• Successful uterine cavity and tubal opacification is documented.
• Free peritoneal spill of Lipiodol is the desired endpoint.
• Residual Lipiodol may be visible on subsequent abdominal plain films or CT for months to years, expected finding; must not be misinterpreted as pathology.

Limitations

• Evidence regarding efficacy is evolving; magnitude of benefit and optimal patient selection remain subjects of ongoing research.
• Not suitable for patients with distal tubal obstruction or significant tubal disease.

Uterine Artery Embolisation (UAE) for Fibroids and Adenomyosis

Indications

UAE has been in use for PPH since the 1970s, and was introduced for fibroid management in the United States in 1997.

Contraindications

CO₂ angiography should be considered when contrast allergy or renal failure cannot be optimally managed with pre-medication. Coagulopathy (low platelet count, elevated INR) should be corrected prior to the procedure. The first 10 days after menstruation is the optimal procedural window. Any adnexal infection must be treated before UAE. If imaging raises suspicion of malignancy, tissue sampling must exclude this before proceeding.

Fibroid Location Considerations

• All locations (submucosal, intramural, subserosal) are eligible; however:
• Large fibroids tend to have less shrinkage and less symptom improvement.
• Intracavitary fibroids have higher rates of post-embolisation expulsion.
• Pedunculated subserosal fibroids: relative contraindication in some series due to risk of detachment; other series show no additional complications.

Pre-procedure Assessment

• MRI pelvis is the investigation of choice: maps fibroid number, location, size, and signal characteristics; identifies adenomyosis; excludes malignancy; assesses for hypertrophic ovarian artery supply.
• Suspicious lesions must undergo tissue sampling to exclude sarcoma before UAE.

Angiographic Technique

• Arterial access: right common femoral artery (preferred) or radial artery.
• A Roberts uterine catheter (5F) or cobra-shaped catheter is used to select the bilateral uterine arteries.
• DSA in the 30-degree contralateral oblique position identifies the uterine artery origin from the anterior division of the internal iliac artery. If the uterine artery arises from a trifurcation, the ipsilateral anterior oblique projection is used.
• The catheter is advanced to the transverse segment of the uterine artery, distal to any cervicovaginal branches. A coaxial microcatheter is used in cases of spasm or tortuosity.
• Pre-embolisation flush abdominal aortography at the renal artery level is performed only when hypertrophic ovarian arteries are suspected on pre-procedural imaging or when uterine arteries do not appear hypertrophied relative to fibroid burden.
• Prophylactic antibiotics (typically a broad-spectrum cephalosporin, single dose) and pre-procedural IV analgesia / NSAIDs are administered. A hypogastric nerve block (0.25% bupivacaine, caudal to aortic bifurcation) may be used to manage peri-procedural pain.
• Embolic agents: non-spherical PVA particles, spherical PVA, or trisacryl gelatin microspheres (e.g. Embosphere). Particle size typically $300\text{-}700\ \mu\text{m}$; when using gelatin microspheres, the recommended starting size is $500\text{-}700\ \mu\text{m}$.
• Embolisation endpoint: devascularisation of fibroid branch arteries with maintained slow antegrade flow in the main uterine artery trunk; complete stasis in the uterine artery is also accepted. Proximal coil embolisation of the main uterine artery trunks is not recommended, allows collateral reconstitution via distal filling and leads to clinical failure.
• Bilateral embolisation is performed; unilateral embolisation is performed only when catheterisation of the contralateral side fails.

PPH-Specific Considerations

• UAE is never first-line but should not be a last resort; units should have an agreed algorithm.
• Standard approach includes uterotonics and removal of retained placental components, followed by intrauterine balloon tamponade if required, before proceeding to embolisation.
• Patients with placenta praevia or placenta accreta spectrum should be considered for prophylactic insertion of internal iliac balloon catheters pre-operatively.

Post-procedure Imaging, MRI Findings

• Successful fibroid devascularisation: loss of fibroid enhancement on T1 post-contrast sequences.
• Fibroid and uterine volume reduction: typically assessed at 3-6 months.
• Adenomyosis response: reduction in junctional zone thickening and uterine volume on T2-weighted sequences.

Complications

Reporting Structure for UAE

1. Pre-procedure fibroid burden: number, size, location, MRI signal characteristics.
2. Angiographic findings: uterine artery anatomy, fibroid vascular supply, presence of ovarian artery contribution.
3. Embolisation: laterality, embolic agent used, particle size, final angiographic endpoint achieved.
4. Post-procedure: clinical symptom assessment at follow-up; MRI volume changes at 3-6 months.

Image-Guided Percutaneous Drainage Catheter Placement

Indications

• Accessible fluid collection (abscess, haematoma, lymphocele, seroma, ovarian cyst) in a patient not requiring immediate surgery.
• Diagnostic aspiration for microbiological or cytological analysis.
• Symptomatic relief.
• Temporising bridge to definitive surgery.
• Note: infected collections accumulate antibiotics to a limited extent, precluding effective antibiotic-only treatment unless the collection is very small (1-3 cm).

Imaging Guidance

• Ultrasound: preferred for superficial and gynaecological collections (ovarian, pelvic); real-time needle guidance; no radiation. ~97% of intra-abdominal abscesses are now drained percutaneously.
• CT: preferred for deep pelvic collections, complex multilocular abscesses, or where bowel interposition must be avoided.
• Fluoroscopy: useful for catheter exchanges and check sinograms.

Contraindications

• No safe access window (interposed bowel, major vessels)
• Uncorrectable coagulopathy
• Uncooperative patient
• Infected tumour (relative, catheters often cannot be removed; requires MDT discussion and informed patient consent before insertion)

Approach Options for Pelvic Collections

Catheter Management and Reporting

• Catheter position confirmed with small-volume contrast injection (sinogram) to confirm intracavitary placement.
• Daily output monitored; catheter removed when output <10 mL/24 hours and clinical resolution confirmed.
• An established fibrous tract forms at approximately 2-4 weeks; catheters dislodged before this require prompt reinsertion (long-term catheters can generally be rescued within 24 hours of dislodgement).
• Follow-up imaging (ultrasound or CT) confirms collection resolution.
• Fistula development (biliary, urinary, bowel, pancreatic) often results in long-term catheter dependence; diversion of upstream fluid by surgical or endoscopic means should be considered.

Complications

Differential Diagnosis and Reporting Considerations

Key Pitfalls and Errors

1. HSG or SIS in active pelvic infection, risk of ascending infection, salpingitis, and sepsis.
2. Cornual spasm mistaken for true proximal tubal occlusion on HSG, unnecessary IVF referral when FTR may succeed.
3. Lipiodol residue on follow-up CT, can mimic peritoneal calcification; must be contextualised with clinical history.
4. Pedunculated subserosal fibroids, embolisation may lead to detachment and free intraperitoneal fibroid; identify and counsel patient pre-procedure.
5. Unrecognised ovarian artery supply to fibroids, failure to perform aortography when indicated leads to UAE clinical failure.
6. UAE in unsuspected uterine sarcoma, always exclude malignancy with MRI before UAE; atypical MRI signal (T2 heterogeneity, haemorrhage, rapid growth) should prompt biopsy.
7. CVS before 9 weeks, significantly elevated risk of limb reduction defects.
8. Drainage of infected tumour, catheters often cannot be removed; MDT discussion and patient counselling mandatory before insertion.
9. Amniocentesis in twins, failure to confirm second sac entry by indigo carmine dye risks sampling the same sac twice.
10. Proximal coil embolisation in UAE, leads to collateral reconstitution via distal filling and clinical failure; distal particulate embolisation is the correct technique.
11. UAE as first-line treatment for infertility due to fibroids, not recommended; may be used only in poor surgical candidates with comorbidities.
12. Performing UAE without excluding pelvic infection, adnexal infection must be treated before the procedure; proceeding risks pyometrium and sepsis.

Sources

• ACR Appropriateness Criteria (American College of Radiology)
• NICE guidance (National Institute for Health and Care Excellence, UK)