Are you sure you know what you are talking about?

First, never heard "heart tumor";
Second, never heard prenatal baby has "tumor" (or never heard it is diagnosed");
Third, even the baby has tumor, it is not likely that the mother will "腹痛难忍".

Besides, as it is "可能", suggest your friend seeking 2nd, 3rd... opinions. There was a post about misdiagnose a 30wk prenatal baby several days ago in this forum.