Retroperitoneal haematoma is a relatively rare pathological condition and most cases are related with ruptured aortic or iliac aneurysm, or lumbar trauma. Patients may present with back or lower abdominal pain, hypotension, haemodynamic instability and decreased haemoglobin levels (Chan et al., 2008). Urgent CT with i.v. is mandatory in order to assess haematoma localization and extent, and also to identify active bleeding and possible underlying causes. In patients with hemodynamic instability or confirmed active bleeding urgent angiography is indicated with intention to embolize. The endovascular embolization can be performed with multiple embolic agents including coils, particles, liquid agents as N-butyl cyanoacrylate glue, Onyx, absorbable gelatin sponge and others. There is no consensus on which embolic agent to use, so the decision must be based on the differential characteristics of each case and the operator’s experience with each agent. Onyx, despite its use is technically demanding, was the chosen option for the case previously presented above because it is effective regardless any underlying coagulopathy, and its differential characteristics (permanent embolic agent, no need of free flow to embolize, minimal risk of reflux, no risk of microcatheter entrapment) were considered advantageous in embolizing the vascular network responsible for the bleeding. There is wide evidence in the literature that Onyx is safe and effective in the treatment of retroperitoneal haemorrhage (Mahdjoub et al., 2020; Kolber et al., 2015), and the final result was excellent, achieving a complete embolization as detailed in the case presentation. The major complication rate as Kolber et al. (Kolber et al., 2015) point out in a systematic review article is under 5%.
The association of FMD with a retroperitoneal haematoma is very infrequent, although it has been previously described in the literature. In most cases it is related to the presence of a mass, or a vascular rupture from an aneurysm or a dissection (Phillips & Lepor, 2006; Shimada et al., 2009). However none of these conditions was identified in our case. The authors think that the bleeding was probably the product of the rupture of the collateral network as a consequence of a hypertensive crisis. The development of collaterals in the context of FMD is not common, but its presence in the context of FMD has been previously described (Sekar & Shankar, 2013).
Once the embolization was performed and the bleeding was controlled, the operator focused on the detailed study of FMD vascular lesions and its need for urgent treatment. It was decided to perform urgent angioplasty of the left renal artery given its intense degree of stenosis, considering performing the treatment of the right one in a second stage.
FMD comprises a group of pathological conditions of unknown aetiology, that cause stenosis of non-atheromatous origin in arteries of medium or small calibre (Doody et al., 2009; Brinza & Gornik, 2016). Due to the fact that it is an infrequent pathology, the majority of the scientific evidence is derived from descriptive articles and systematic reviews. The association of fibrous proliferation foci and segments with collagen loss causes the typical occurrence in string of beads, alternating segmental stenosis (fibrotic foci) with pseudodilatations (collagen loss). It generally affects Caucasian women aged 15–50 years. The main target are renal and extracranial carotid arteries, though it has been described in multiple arterial locations (Brinza & Gornik, 2016). Symptoms are variable based on the location and severity of the involvement. The most common are hypertension, headache and pulsatile tinnitus and cervical pain or dizziness. Other symptoms can also occur, such as stroke, renal fossa pain, myocardial infarction (Doody et al., 2009; Brinza & Gornik, 2016), and even retroperitoneal haematoma (Phillips & Lepor, 2006; Shimada et al., 2009).
In most cases non-invasive imaging studies (Angio-CT, Angio-MRI and Doppler) are enough to make the diagnosis. Arteriography is reserved for cases in which there are diagnostic doubts or for endovascular treatment (Gottsäter & Lindblad, 2014).
There is no established treatment regimen for FMD since the treatment is usually individualised (Doody et al., 2009; Brinza & Gornik, 2016). Background treatment with platelet aggregation inhibitors or ACEIs is frequent (Brinza & Gornik, 2016). Considering endovascular treatment renal angioplasty (RA) has become the treatment of choice. RA can be performed not only for the main renal artery but also when branch arteries are affected (Gottsäter & Lindblad, 2014). Balloon-catheter size is recommended to be 10–20% greater than the expected artery diameter but sometimes it can be difficult to estimate due to extensive disease, in those cases it is best to underestimate balloon size and redilate with a larger balloon if needed (Meuse et al., 2010). Technical success rates are around 100% (Mousa & Gill, 2013) and patency rates following RA have been reported from 80 to 90% over 10 years (Meuse et al., 2010), however they may vary depending on the type of FMD affectation, reporting worse patency rates in multifocal FMD compared to unifocal FMD (Gottsäter & Lindblad, 2014). Major complications after RA have been reported below 10% (Barrier et al., 2010). Cutting-balloon angioplasty is usually reserved to treat lesions resistant to conventional angioplasty. Typically cutting-balloons are undersized to the target artery diameter by 1 mm to decrease the risk of vessel rupture, which is a well known complication. Stents and stent-grafts are reserved almost exclusively for treating angioplasty complications such as a dissection or vessel rupture (Meuse et al., 2010). Other techniques like renal artery denervation therapy or drug coated-balloon angioplasty has been recently described obtaining good outcomes (Mousa & Gill, 2013; Kelle et al., 2013; Morosetti et al., 2018) however more studies are needed before generalizing these new therapy options in the context of FMD. Surgical therapy is currently reserved for patients with patients with severe complications that cannot be handle with endovascular techniques (Gottsäter & Lindblad, 2014). Finally, recommendations such as quitting smoking, keeping an adequate weight, avoiding extreme exercise or contact sports, are also very common and highly important.