GAIA Level 1 First Trimester Spontaneous Abortion

**Semantic type:** Classification

**Definition:** GAIA Level 1 First Trimester Spontaneous Abortion is defined by two criteria: first, at least one of the following three requirements must be met: a) Crown-rump length greater than or equal to 7 mm and no visible heartbeat on transvaginal ultrasound; OR b) Crown-rump length greater than or equal to 15 mm and no visible heartbeat on abdominal ultrasound; OR c) Ultrasound examination demonstrating mean gestational sac diameter greater than or equal to 25 mm and no visible embryo or yolk sac; second, at least one of the following three requirements must be met: a) A second transvaginal ultrasound performed greater than or equal to 7 days later (or 14 days later if transabdominal) confirming the diagnosis of a non-viable pregnancy; OR b) The absence of an embryo with heartbeat 2 weeks or more after a transabdominal scan that initially showed a gestational sac without a yolk sac; OR c) The absence of an embryo with a heartbeat 11 days or more after a transvaginal scan that initially showed a gestational sac with a yolk sac. Alternatively, GAIA Level 1 First Trimester Spontaneous Abortion can be defined by the following two criteria: first, the gestational age is within the pre-defined range for the selected abortion definition as assessed by maternal and/or fetal parameters ( Level 1-2) (using the Brighton Preterm Birth Gestational Age algorithm); second, at least one of the following four requirements must be met: a) Positive urine or blood pregnancy test that becomes negative after 7 days; OR b) Products of conception found on histopathological evaluation of pregnancy tissue; OR c) Ultrasound examination demonstrating an empty uterine cavity in a woman who had clear evidence of intrauterine pregnancy on previous ultrasound examination; OR d) Vaginal bleeding, external cervical os open or closed, with visible expulsion of pregnancy tissues/products of conception.

**Synonyms:** - Global Alignment of Immunization safety Assessment in pregnancy Level 1 First Trimester Spontaneous Abortion - Level 1 First Trimester Spontaneous Abortion