“Litho-“, the Greek prefix meaning stone, and “-pedion”, the Greek suffix meaning “child,” creates a literal translation of lithopedion as “stone child” (The American Illustrated Medical Dictionary). Lithopedion is the condition where a dead fetus becomes mummified and calcified as a result of an ectopic pregnancy. During this form of pregnancy, a fertilized egg is implanted outside of the uterus and therefore develops within the abdominal cavity (Hacker, Gambone, and Hobel 2010). In developed countries, ectopic pregnancies are usually discovered long before the process of lithopedion formation occurs; therefore, the condition of lithopedion is quite rare.
After fertilization the egg becomes a blastocyst. The outer cell layer of the blastocyst is called the trophoblast, the portion that attaches to a vascular organ. The blood supply to the fetus eventually becomes inadequate and the fetus dies. At this stage lithopedion formation begins – the dead fetus will mummify, shrink, and calcify (Padubidri, 2005). There are three forms of Lithopedion,each depending on the process of calcification: (1) lithocelyphos, (2) lithocelphopedion, and (3) lithopedion. Lithocelyphos is when the fetus is mummified and the extra-embryonic membranes are calcified. Lithocelphopedion is when the fetus is attached to certain points of the extra-embryonic membranes and these points are subject to calcify, while everything else is mummified. Lithopedion, in the narrower sense, is when the extra-embryonic membranes rupture releasing the fetus into the abdominal cavity where it is calcified by lime salts (Ziegler, 1895).