Internal pudendal perforator artery flap harvesting without pre-operative imaging: Reliability and approach

Since its initial description in 1996 by Yii and Niranjan, the internal pudendal perforator flap (also known as the Singapore flap, the gluteal fold flap, and the lotus petal flap) has become a workhorse in perineal soft tissue reconstruction. In 2001, Hashimoto described the presence of three to five perforators in the perineal anogenital triangle. The ischial tuberosity has thus become a useful anatomic landmark for the safe boundary of medial dissection during flap elevation, in order to avoid damaging the perforator vessels. The objective of the present study was to evaluate the perforators’ positions within the anogenital triangle by using color Doppler ultrasound. In a study of 15 subjects in the lithotomy position, we identified a total of 24 perforator vessels with a diameter greater than 5 mm. We noted the vessels’ positions using orthonormal measurements, according to the distance from the midline and the distance on a straight line between the two ischial tuberosities (i.e. consistent bony anatomic landmarks that are independent of the patient's height and body mass index). The mean distance between the ischial tuberosity and the internal pudendal perforator was 27.3 mm. Based on our present results, we consider that routine ultrasound identification and dissection of the perforators is not always required before pudendal flap harvesting. This decreases the operating time and simplifies the flap harvesting procedure.