App note from ON Semiconductor on eFuse current measurement. Link here (PDF)
This application note describes the load current measurement solution for the eFuses which do not provide load current monitoring feature. Since almost all of the eFuses provide adjustable current limit functionality by utilizing an external current limiting resistor between “ILIM” and “SRC” pins, it is possible to connect a current sense amplifier across that resistor and measure the voltage drop across it which would be proportional to the load current. This method mainly requires a current sense amplifier and allows user to measure the system load current without introducing any additional resistance in series with the load path.