It is defined as asymmetry of the enlarged uterus, palpable during pelvic examination, after the first few weeks of pregnancy.
It is attributed to lateral implantation of the embryo, which can enlarge one uterine horn before the other.
[1][2] It has also been described as focal softening of the uterus, contrasted to the firmness of the area where the placenta is implanted.
[3] It is named after obstetrician Ludwig Piskaçek, who described it in Vienna in 1899, though it had already been noted by Robert Latou Dickinson of New York in 1892.
A similar physical sign had been described by Carl von Fernwald Braun.