Last year, 3 patients experienced unsuccessful removal of the drain after surgery. These patients all received orthopedic surgeries, includes femoral intramedullary nailing fixation, pedicle screw fixation for the second lumbar vertebra, and open reduction and internal fixation for distal femoral fractures. The silicone drains were placed at the time of the procedure without the drain being secured with a fascial closure. Attempts were made to remove it on the second or third postoperative day, which was met with great resistance. Considering that the drains were likely to be sewn by mistake, no more attempts were made. Finally, we decided to remove the drains by open the incisions limitedly under anesthesia.
The first patient was transferred to the operating room. Because of the long incision, it was difficult to choose where to reopen the incision. When the anesthesiologist was preparing for ultrasound-assisted nerve block anesthesia, we discussed trying to locate the sutured site of the drain by ultrasound. Finally, we used ultrasound to clearly identify the route of the drain. By slowly pulled and relaxed the drain several times, the sliding sign can be detected by the ultrasound, which indicates the point where the drain was sutured. Finally, the suture was loosened through a small incision, and the drain was completely removed. The second and third patients were not transferred to the operating room, the sutured drains were removed successfully through small incisions positioned by ultrasound. To better characterize the image of the drain under ultrasound and the imaging features of the sliding sign, we demonstrated the process of removing drain based on the pork model.
Pork models were used because they are simple and cost-effective models and have similar anatomic structures and echogenicities as human tissue. A boneless pork phantom (28 × 8 × 6 cm) was used. We simulated the operation at room temperature (23 °C). The drain (XY-16Fr), which was produced by the Chinese company XIANGYUE, was inserted into the phantom, and the segment approximately 3 cm from the proximal end was sutured. Then, the incision was closed (Fig. 1). The tube could not be removed after repeated traction. An ultrasound machine (Mindray, M9) equipped with a high-resolution 7–10 MHz linear array transducer was used. First, the drain was scanned transversely to identify the cross-section, and then the skin was marked to determine the length and path of the drain. Afterwards, the longitudinal view of the drain, the front and rear wall, and the side hole of the drain were detected (Fig. 2). At this time, the drain was slowly pulled and relaxed repeatedly from the distal end, and it was observed that the drain was sliding in the soft tissue, that is, creating a sliding sign. After the transducer was slowly moved to the proximal end, the segment where the sliding sign disappeared was identified (vanishing point) (Fig. 3). This area is where the drain was being tethered. A video of this process from the ultrasound display is provided in the supplementary files (File 1 and File 2). The tube segment located by ultrasound was consistent with the sutured site (Fig. 4). With the use of ultrasound, a targeted incision was made, and the tethered drain was removed quickly without unnecessary exposure.