What is the sequence of artery embolization in a postpartum hemorrhage (PPH) patient with no known medical history?

Arterial Embolization Sequence in Postpartum Hemorrhage

In postpartum hemorrhage requiring arterial embolization, bilateral uterine arteries should be embolized first as the primary target vessels, with internal iliac artery embolization reserved for cases where uterine artery embolization fails or when bleeding originates from non-uterine pelvic sources. 1, 2

Primary Target: Bilateral Uterine Arteries

The uterine arteries are the first-line target for embolization in PPH, as they are the most common source of hemorrhage regardless of etiology (atony, placental abnormalities, or trauma). 2

• Bilateral uterine artery embolization achieves hemostasis in 90.5% of cases clinically and 99.3% technically, making it highly effective as initial intervention 2
• The uterine arteries are engorged and tortuous in virtually all PPH cases, making them readily identifiable on angiography 1
• Success rates reach 95.7% when performed in hemodynamically stable patients 3

Embolization Technique and Agents

Use gelatin sponge particles (500-1000 μm diameter) as the primary embolic agent, followed by gelatin sponge pieces for proximal occlusion. 1, 2

• The coaxial catheter technique allows selective catheterization of uterine arteries for precise particle delivery 1
• Medium-sized polyvinyl alcohol particles (250-355 μm) can be used initially via coaxial catheter, followed by gelatin sponge pieces via 4F Cobra catheter for more proximal occlusion 1
• Microcoil embolization should be added only when active contrast extravasation is visible on angiography, as it provides more permanent occlusion 1

Secondary Target: Internal Iliac Arteries

Internal iliac artery embolization is the second-line approach when uterine artery embolization is insufficient or technically not feasible. 2

• This broader approach is indicated when bleeding originates from branches other than the uterine arteries (vaginal, pudendal, or vesical arteries) 2
• Internal iliac artery embolization has lower specificity but can control hemorrhage from multiple pelvic sources simultaneously 2

Critical Timing Considerations

Embolization must follow adequate resuscitation from vascular collapse—attempting embolization in a severely vasoconstricted patient leads to technical failure. 4

• Two documented failures of uterine artery embolization occurred specifically due to severe vasoconstriction from inadequate resuscitation 4
• The patient must be hemodynamically stable enough to tolerate the procedure time (typically 30-60 minutes) 3, 5
• CTA should be performed after failed empiric embolization to identify the bleeding source, as it detects active extravasation in 41-74% of cases with 97% accuracy 6

Special Circumstances Requiring Modified Approach

For placenta accreta cases, embolization is significantly more effective when combined with placement of multiple compression sutures in the placental bed before embolization. 4

• All eight patients with placenta accreta in one series were successfully treated with this combined approach 4
• For placental polyps, embolization combined with uterine packing improves success rates 4

Common Pitfalls to Avoid

• Do not proceed with embolization in severely vasoconstricted patients—this represents inadequate resuscitation and leads to technical failure 4
• Do not perform empiric bilateral embolization without angiographic confirmation of the bleeding source when CTA has already identified a specific arterial source 6
• Avoid using only permanent embolic agents (coils, glue) initially, as temporary agents (gelatin sponge) allow for vessel recanalization and preserve fertility 1, 2

Complications and Outcomes

The most common complication is postembolization syndrome (transient fever, pain, nausea), which is self-limited. 6, 2

• Serious complications including lumbosacral plexopathy can occur but are rare (documented in 1 of 23 cases in one series) 4
• Up to 12% of patients develop uterine synechiae after embolization, but this risk is lower than with uterine compression sutures or curettage 6
• Subsequent pregnancy rate is 76% with no increase in miscarriage or growth restriction, though there is a 20% risk of recurrent PPH and elevated risk of invasive placental disorders 6
• Menstrual function returns in 95.2% of women with regular cycles 3, 2