It is known that the vascular perforators upon which the medial sural artery perforator (MSAP) flap is based are subject to considerable variation. This study seeks to evaluate the use of colour flow Doppler (CFD) as an imaging technique to establish the presence of suitable vessels, the discriminatory findings from that imaging, the rate of flap abandonment and flap complications.

All patients undergoing MSAP in our institution since 2015 had a pre-operative CFD using a standardised technique. A prior group of 22 patients not having CFD acted as a control group. Data were  collected prospectively.

Fourteen patients had CFD. In one patient, no suitable vessels were found. In 13 patients, vessels of suitable size and position were identified, which then correlated precisely with operative findings. Three had suitable vessels in one leg only. No flaps in the CFD group were abandoned. One flap in the CFD group was partially lost. One flap in the prior control group was abandoned.

CFD provided reliable discriminatory information to decide on flap suitability/which leg and correlated precisely with operative findings, with no flap abandonment. Flap survival rate was very high.