Fig. 4

Pre- and postoperative sagittal pelvic imaging using CT (a–d, f) or MRI (e), showing the recurrent and persisting abscess (*) despite omentoplasty (OP) and drainage procedures, and subsequent postoperative result after distal sacrectomy with gluteal V–Y fasciocutaneous advancement flap (GF) in the first (a, b), second (c, d), and third patient (e, f). Some residual fluid below the flap was observed in the first patient (b), which was successfully drained