Lithopedion

A lithopedion (also spelled lithopaedion or lithopædion; from Ancient Greek: λίθος "stone" and Ancient Greek: παιδίον "small child, infant"), or stone baby, is a rare phenomenon which occurs most commonly when a fetus dies during an abdominal pregnancy,^[1] is too large to be reabsorbed by the body, and calcifies on the outside as part of a foreign body reaction, shielding the mother's body from the dead tissue of the fetus and preventing infection.

Lithopedia may occur from 14 weeks gestation to full term. It is not unusual for a stone baby to remain undiagnosed for decades and to be found well after natural menopause; diagnosis often happens when the patient is examined for other conditions that require being subjected to an X-ray study. A review of 128 cases by T.S.P. Tien found that the mean age of women with lithopedia was 55 years at the time of diagnosis, with the oldest being 100 years old. The lithopedion was carried for an average of 22 years, and in several cases, the women became pregnant a second time and gave birth to children without incident. Nine of the reviewed cases had carried lithopedia for over 50 years before diagnosis.^[2]

According to one report, there are only 300 known cases of lithopedia^[3] recorded over 400 years of medical literature. While the chance of abdominal pregnancy is one in 11,000 pregnancies, only between 1.5 and 1.8 percent of these abdominal pregnancies may develop into lithopedia.^[4]