Duplex ultrasound allows accurate preoperative flap planning through mapping of perforator location and anatomy. In the hand and upper extremity, where thickness of the subcutaneous fat is less compared with other areas of the body, color Doppler ultrasound is particularly sensitive for analyzing the location and characteristics of perforators. Here, we will first review evidence on use of ultrasound in flap planning and also discuss case examples that show the use of ultrasound for accurate perforator mapping to facilitate rapid flap harvest. In addition, experience with the thin and superthin profunda artery perforator (PAP) flap in extremity reconstruction will be discussed. With its concealed donor site on the medial thigh and bulk, the PAP has become popular for reconstruction in the breast, head, and neck. The thickness of the subfascial PAP flap is decreased through elevation on the thin or superthin plane, making it more suitable for extremity reconstruction. The thin and superthin PAP flap has multiple favorable characteristics, making it suitable for extremity reconstruction, and it has become the workhorse skin flap in our institution. Conventional low-frequency CDU together with CTA can be used effectively to map the dominant perforator preoperatively, allowing accurate flap design and rapid flap harvest.