Interventional radiologist's tactics in Cesarean section
Complex interventions carrying a risk of massive blood loss, such as a Cesarean section with planned hysterectomy, require a multidisciplinary approach and the patient's informed consent (her opinion regarding uterine preservation is of critical importance). A basic prerequisite is ensuring bilateral access via the common femoral arteries (a. femoralis communis).
Two main operational strategies for the specialist are distinguished:
- Expectant management: After introducing the sheaths and establishing access, the physician simply monitors the situation. If obstetricians successfully manage the bleeding using traditional surgical methods, the endovascular stage is omitted.
- Proactive management: Guide wires are advanced in advance before making the incision on the uterus or placenta. When necessary, occlusion balloons are inflated in the common iliac (a. iliaca communis), internal iliac (a. iliaca interna), or directly in the uterine arteries (a. uterina). This preemptively reduces blood flow to the pelvic organs at the most critical moment of the surgery.
Features of balloon occlusion and hidden risks
A key technical aspect of the procedure is the mathematically precise sizing of the intravascular balloon. It is extremely crucial to remember fetal safety: if catheterization of the uterine arteries is performed prior to delivery, extreme caution is required. These vessels are highly sensitive, and their reflex spasm can provoke acute anoxia in the fetus.
The uterus has a rich collateral network and is capable of receiving additional (parasitic) blood supply from branches of the femoral artery. For this reason, the preferred tactic is the placement of balloons in the common iliac arteries—this blocks the majority of extrauterine blood inflow. As a last resort (a desperate lifesaving maneuver), an aortic occlusion balloon may be used. If bleeding is stopped after balloon deflation—and the obstetrician has reliably sutured the source—subsequent embolization is usually not required.
Indications and embolization technique
If bleeding resumes rapidly after balloon deflation, immediate embolization is indicated. The procedure must be as selective (targeted) as possible to minimize the ischemic zone. Gelfoam sponge serves as the standard material, although technically almost all types of microparticles can be used.
Interestingly, if a multidisciplinary team decides to leave the placenta accreta in situ (without removal), uterine artery embolization can stimulate subsequent safe involution of the placental tissue. The main technical difficulty is working in the obstetric operating room: the abundance of personnel and the use of a mobile C-arm (providing suboptimal imaging) complicate the task. Whenever possible, it is recommended to transport the patient to a specialized angiographic suite.
According to statistics, the cumulative success rate of embolization reaches 91%. As second-line therapy, embolization shows an 86% efficacy rate, outperforming compression sutures (75%) and pelvic vessel ligation (36%).
Impact of placentation anomalies and ectopic pregnancy
The efficacy of endovascular hemostasis directly depends on the nature of the obstetric pathology. Invasive placenta is the main predictor of embolization failure. There are three degrees of invasion: adherence to the myometrium (accreta), invasion into it (increta), and complete penetration through the uterine wall (percreta). The deeper the invasion, the more aggressively the blood supply from extrauterine arteries forms, which are very difficult to completely occlude. To prevent massive blood loss in such diagnoses, preemptive balloon occlusion of both uterine arteries is considered the standard.
Cervical ectopic pregnancy requires special attention. Although it is rare (about 0.15%), the risk of profuse bleeding is colossal. Embolization is used here both to stop ongoing bleeding and prophylactically—before curettage. However, the recurrence rate of hemorrhage is high (about 25%), which may ultimately require radical surgery.
Pelvic congestion syndrome (PCS)
In addition to emergency life-threatening situations, interventional radiologists treat chronic pelvic pain associated with dilation and reflux in the pelvic veins (although a direct causal link has not been fully proven). Predisposing factors include multiple pregnancies, venous valve incompetence, the influence of estrogens, and anatomical compressions (e.g., compression of the left ovarian vein by the superior mesenteric artery).
Patients with this syndrome often undergo a long diagnostic journey, including diagnostic laparoscopy (cysts are found in half of them). The gold standard for instrumental diagnostics remains traditional ovarian venography, performed with the head of the table elevated. This helps avoid vein collapse, which is typical for ultrasound and MRI in the supine position. The diagnosis is confirmed if the ovarian vein is dilated > 5 mm, retrograde blood flow is present, tortuous collaterals exist, and contrast clearance from the small pelvis is delayed.
Complications of endovascular procedures
Despite high safety in experienced hands, interventions carry risks, most commonly related to the arterial access site. Major complications include:
- Ischemic lesions of the lower extremities and gluteal region.
- Tissue necrosis of the uterus, cervix, vagina, small intestine, and urinary bladder wall.
- Neurological damage (ischemia and involvement of the femoral or sciatic nerves).
Briefly: answers to topical questions
Which parietal and visceral branches does the internal iliac artery give off?
The internal iliac artery (a. iliaca interna) divides into two main branches, although the exact list of vessels originating from them is not specified in the materials. The following branching information is available:
- Anterior branch — supplies blood to the internal pelvic organs (visceral).
- Posterior branch — supplies blood to the surrounding musculature (parietal).
In the context of endovascular hemostasis, uterine arteries (a. uterina), which participate in supplying blood to the uterus, are also mentioned.
What are the absolute and relative contraindications to uterine artery embolization?
The sources do not classify contraindications into absolute and relative; the final decision is made by the attending physician. However, the following limitations are highlighted where embolization is not performed or not recommended:
- Non-enhancing fibroids (non-enhancing fibroids) — formations that do not accumulate contrast on MRI are not suitable for the intervention.
- Placental invasion — routine use of the method is not recommended, as it does not reduce blood loss volume or hysterectomy rates, and carries a risk of uterine necrosis.
What types of embolic agents (microparticles), besides Gelfoam hemostatic sponge, are used for selective embolization?
Besides the Gelfoam sponge, polyvinyl alcohol and several other occlusive materials are used for selective embolization. Interventional radiology utilizes:
- Polyvinyl alcohol (polyvinyl alcohol) — microparticles used to reduce tumor vascularity.
- Coils and microcoils (coils / microcoils) — devices whose action is similar to surgical vessel ligation.
- Liquid embolic agents (liquid embolic agents) — sclerosants (absolute alcohol, sodium tetradecyl sulfate), adhesive glue compositions (Histoacryl glue, n-butyl-2-cyanoacrylate), and non-adhesive preparations (Onyx).
Class and exam questions
In which case is embolization still required after balloon inflation?
Embolization is indicated if bleeding resumes during control balloon deflation. The procedure must be as targeted as possible using Gelfoam particles.
Why does placenta accreta reduce the chances of successful embolization?
When the placenta accreta invades the myometrium, an extremely aggressive and chaotic blood supply develops. The process actively involves not only the uterine arteries, but also extrauterine arteries, which are technically difficult to completely isolate.
Why is venography preferred over MRI for pelvic congestion syndrome?
During an MRI or ultrasound, the patient lies supine, which can cause dilated veins to temporarily collapse. Venography is performed with the head of the table elevated, allowing for an objective assessment of reflux and true vessel diameter.
What else to study on this topic
- Clinical examples of extravasation from muscular branches of the rectus abdominis muscle (after Cesarean section)
- Technique of aortic balloon occlusion in obstetrics
- Comparison of the efficacy of embolization, compression sutures, and recombinant factor VII
- Endovascular control in post-abortion hemorrhage
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