Poorly defined mass in the posterior uterine body causing obstruction to the endometrial cavity and resultant haematometra. There is a generalized increase in vascularity to the uterus (arrows). Note the 3 layers in the blood: dependent red cells (containing metHb as low T2 signal), serum as supernatant (high T2 signal), and an intervening thin grey layer (i.e. the buffy coat of platelets).