The present invention provides surgical apparatus for liposuction in which microwave energy is delivered from a probe into a treatment region to perform a fat liquefying function or a haemostasis function. The apparatus is arranged such that an output microwave field automatically adopts a configuration suitable for the fat liquefying function or haemostasis function depending on the type of tissue encountered by the probe in the treatment region. In particular, by suitable selection of the frequency of the microwave energy, the difference in skin depth of the microwave energy in fat and blood may enable the microwave field to automatically switch its configuration between one suitable for fat liquefying and one suitable for haemostasis without any change required to the amount of microwave power or the energy profile delivered to the probe.
