The use of arterial embolization for obstetric haemorrhage was first reported in the 1970s. Following on from this, the use of Interventional Radiology (IR) in treating elective and emergency obstetric cases has increased. Most IRs would expect to be able to carry out embolization in cases of acute haemorrhage for these patients in the same way as they would for any other case of emergency haemorrhage. Similarly, the use of IR in elective cases mirrors the practise in other areas of prophylactic or adjunctive embolization. A growing area has been the use of prophylactic occlusion balloons in the management of patients with abnormally adherent placenta.
What do the guidelines say about indications?
The most comprehensive IR guidelines were produced by CIRSE in 2020 and is the Standards of Practice document for gynaecological and obstetric haemorrhage, covering the use of IR for elective and emergency procedures. The indications for IR are wide ranging and include emergency use of embolization in post-surgical bleeding and post-partum haemorrhage (PPH), elective use of prophylactic occlusion balloons for abnormal placentation, embolization in tumours either primarily or as an adjunct to surgery, and embolization for arterio-venous fistulae and malformations. Whilst there are no absolute contraindications, patients who are allergic to contrast, have renal impairment or anatomical variations that make embolization difficult or impossible, are all relative contraindications.
A key element: good knowledge of anatomical variants
To perform these procedures well, it is important to have a good understanding of the anatomy of the arteries of the pelvis, and possible anatomical variants. Embolization would ideally be carried out in an IR suite or a hybrid theatre, however there are occasions when an interventional radiologist may be compelled to carry out an embolization in an obstetric theatre using a portable image intensifier. When the imaging is suboptimal, it is even more important to be vigilant against the possibility of non-target embolization. Bleeding from a focal point may be a result of supply from non-uterine arteries and it is important to be aware of this and to look for alternative blood supply as failing to do so could result in incomplete embolization. In an elective situation or one in which the patient is stable, CT imaging can be useful for outlining the anatomy, identifying extra uterine sources of bleeding and any focal bleeding points.
What materials to choose and when to use them
Non-permanent material is generally utilised for post-partum haemorrhage in the form of absorbable gelatin sponge. This allows later recanalization of the artery when it has healed. However, when embolization is carried out for a focal bleeding point such as a pseudoaneurysm or for malignant disease, permanent embolic agents are utilised. The choice of these will depend on the operator’s expertise and local availability.
In emergency situations the patient is not stable enough to wait for a CT angiogram and should proceed directly to catheter angiography. In PPH, a focal bleeding point or pseudoaneurysm is uncommon. Dilated pelvic arteries and increased vascularity is usually seen due to the postpartum uterus and appearances are very different from what is seen on an angiogram for elective uterine artery embolization. If focal bleeding is identified, targeted, selective embolization can be carried out. If it is not, non-targeted, bilateral uterine artery embolization is performed. 5- 10% of patients can rebleed after embolization for PPH and repeat embolization can be carried out. If the uterine arteries are still patent these should be re-embolized. Collateral supply and extra uterine arterial supply should also be sought and embolized if identified.
The success rates for embolization in PPH range from 79 to 100%. Factors associated with failure include the presence of accessory arterial blood supply, previous surgical ligation or dilatation and curettage, unilateral embolization, and abnormal placentation.
Potential complications include non-target embolization resulting in limb and buttock claudication, necrosis of various structures supplied by the iliac arteries such as bladder, buttock, bowel and vagina and ovarian necrosis. The risks can be minimized by optimizing imaging, avoiding the use of very small particles and an awareness of cross uterine and collateral blood supply.
IR continues to be underutilised
Despite the high success rates, minimally invasive nature, and effectiveness of embolization in treating post-partum haemorrhage, IR remains underutilised in the management of these patients. The use of IR should be considered after conservative measures to control haemorrhage fail and before surgery is contemplated. In addition, the use of IR should be considered early in the patient’s management. The recent 2022 FIGO (The International Federation of Gynecology and Obstetrics) guidelines state that embolization is ‘cited as a conservative management strategy’ before going on to imply that it is only available in highly specialised units. It is important that the use of IR in haemorrhage control is recognised as a core skill in interventional radiology and becomes available to more women.