PRISMA guidelines (13) were followed and a literature search was performed using MEDLINE, EMBASE, SCOPUS, Web of Science. Articles either published or e-published on angioembolization for BRI between January 2008 and September 2020 were searched. The Mesh terms used for search were: “renal” (“kidney”); “trauma” (“injury”); “embolization”; “angiography”; (“Renal Angio Embolization” or “RAE”). An additional manual search of EMBASE as well as bibliographies of each included study was done to identify studies not covered by the initial search.
The results of the literature search were screened preliminarily by one reviewer (GR), then a secondary screening was performed by two other reviewers (GL, AS). The full texts and references of potentially appropriate literature were searched for further screening as recommended in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.
Retrospective studies evaluating adult patients who underwent RAE were included and the following data were required: 1) basic demographics of patients, medical history; 2) indications for RAE; 3) RAE techniques and/or embolic materials used; and, 4) the number of either severe life-threatening complications or complications which eventually needed further re-intervention or surgical management of the same kidney.
The exclusion criteria were as follows: 1) reviews or editor letters and single case report; 2) non-English language publications; 3) studies only involving open injury, penetrating trauma, paediatric patients or iatrogenic injury; and, 4) studies with insufficient or unconfirmed information.
Data including the first author, publication year, number of patients, age, gender, indications and materials for embolization were extracted from the selected papers. The outcomes, number of successfully treated patients, severe and life-threatening complications (i.e., re-bleeding, re-do RAE procedures, and contrast medium-induced renal failure) and the need for further surgical treatment were included. A meta-analytic approach was not possible due to the heterogeneity of the data and the lack of prospective studies.
Final study selection
Using these search criteria, an initial selection of 302 articles was considered. After title screening, we excluded case series, review articles and narrowed these downs to 81 studies. After a comprehensive review process of all retrieved titles and abstracts, 30 studies were preliminarily identified for full text evaluation. Of the 30 selected, 13 studies had been finally reviewed (Figure 1). A further sub-analysis of high-grade trauma cases was performed.
Indications for RAE: The indications were available in all studies. According to the American Association for the Surgery of Trauma (AAST) renal injury scale, the most common indication is blunt kidney trauma (II to IV grade) in hemodynamically stable patients. These patients usually present gross haematuria as the primary symptom of the renal injury. In the event that haematuria becomes persistent the patient could benefit from RAE (14) (15) (16).
CT criteria, such as perirenal hematoma rim distance (PRD), discontinuity of Gerota’s fascia, or intravascular contrast extravasation (ICE) are used to select patients for RAE (12) (17) (18). Failure of conservative management due to unresponsive to fluid resuscitation hypotension represent further indication. Non operative management was described in hemodynamically unstable patients with grade V renal injuries, both at the parenchymal and renovascular level (19) (6). It should be noted that those patients had no evidence of other intra-abdominal injuries requiring surgical exploration. All patients underwent RAE within 24 - 48 hours in urgency or emergency settings. Angioembolization of renal artery pseudoaneurysm and/or arteriovenous fistulas were not included in the selected studies.
Pre-procedure diagnostic work-up: Computed tomography scan and angiography are considered complementary to define the precise site of bleeding and the actual possibility to perform angioembolization. All patients were primarily screened with a CT scan to identify the bleeding site.
Technique of RAE
Route: Most RAE procedures were performed through femoral approach, using 4 - 6 F sized arterial sheaths (20). Radial or brachial approach was rare but necessary in case of iliac artery occlusion or unusual anatomic conditions (21).
Selective catheterization: Selective embolization was performed on angiographic findings, after comparing the CT and the arteriogram findings. Comparison between CT and arteriogram allows the choice between super selective embolization or embolization of the proximal branches of the renal artery (19) (17).
Embolizing agents: Usually selection depends on preference of the interventional radiologists. Numerous general indications among different embolizing agents have been described (22); indeed, both temporary and permanent agents were used in the selected studies. The most used materials were micro coils and overall success rate was between 90% and 100%, regardless of the material choice. (Table 2).
Technical success - The complete resolution of active extravasation was obtained between 90% and 100% of the cases. To achieve technical success, 4 patients required a more proximal vessel embolization to stop the angiographic extravasation (12) (14).