Two cases of acardius acephalus twins

An acadius is a monster that sometimes develops in single-ovum twin pregnancies as the results of inequalities in the communicating placental circulation. One twin is well developed and normal, whereas the other is imperfectly formed, with either a rudimentary-hemiacardius or an absent heart-holoacardius. The most common variety of the holoacardiac monster is the acephalus, or headless fetus. Authors report a case of acardius acephalus twins associated with hydramnios in a 28 years old, para 1-0-0-1, diagnosed amorphous twins with serial sonograms, terminate in the 23th week pregnancy and the other in 1-25 years old,para 0-0-0-0, diagnosed twins with FDIU in sonogram. We present these two cases with brief review of literatures.