Background <p>Percutaneous sacroiliac screw fixation is an effective option for unstable pelvic ring fractures. It is minimally invasive, causes little soft tissue damage, and reduces complication risk. Nevertheless, complications such as screw loosening or nerve root damage are reported. Although vascular injuries are also described, detailed management strategies are rarely found in the literature.</p> Case presentation <p>A 58-year-old white German female suffered polytrauma, including a type c posterior pelvic ring fracture, after a fall from great height. The fracture was treated with screw osteosynthesis of the anterior and posterior ring. After transfer to our hospital for further treatment, X-ray and CT revealed sacroiliac screw malposition with suspected external iliac vein injury. During an interdisciplinary procedure involving angiology and trauma surgery, the screw was removed, and subsequent bleeding from the injured vein was controlled by coiling before a new sacroiliac screw was inserted. The subsequent hospital stay remained complication free.</p> Conclusions <p>Sacroiliac screw osteosynthesis is a safe and established procedure for unstable pelvic ring injuries. However, due to complex anatomy such as sacral dysmorphia and difficult fracture patterns, complications including nerve or vascular injury may occur. Preventing these requires careful preoperative planning to identify a suitable corridor. While 2D-fluoroscopy is well established intraoperatively, 3D-navigation further reduces malposition risk in challenging anatomy. In cases of screw malposition, exact analysis and interdisciplinary consultation are essential to determine the safest and most effective treatment and to successfully manage complications.</p> Key clinical message <p>The incorrect positioning of a sacroiliac screw can lead to serious complications. Exact analysis and the full spectrum of complication management is necessary for successful treatment of misplaced screws in pelvic surgery.</p>