Early Pregnancy Loss (Spontaneous Abortion)

Excerpt

The terminology used to describe the loss of an intrauterine pregnancy before fetal viability (ie, a fetus likely to survive outside of the uterus) is inconsistent in the literature and has varied over time. Traditionally, spontaneous abortion referred to a natural pregnancy loss before 20 weeks of gestation; however, more recently, the medical literature has been transitioning away from the phrase. Patients prefer the term miscarriage, presumably to avoid the stigma associated with induced abortion. The reVITALize gynecology definitions from the American College of Obstetricians and Gynecologists (ACOG), which are also endorsed by the American Academy of Nurse-Midwives, the American Academy of Family Physicians, and numerous other American professional organizations, now recommend the terms miscarriage or intrauterine pregnancy loss. Both terms are synonymous and are defined as the loss of a documented nonviable (ie, a pregnancy not expected to develop normally) intrauterine pregnancy.

Some organizations use the cut-off of <10 weeks of gestation to define an early miscarriage. The ACOG and the European Society of Human Reproduction and Embryology (ESHRE) use a similar term—early pregnancy loss. ACOG defines it as "an empty gestational sac or a gestational sac containing an embryo or fetus without fetal heart activity within the first 12 6/7 weeks of gestation," while the ESHRE considers an early loss as occurring before 10 weeks of gestation. Although there is no consensus among societies concerning the correct terminology, early pregnancy loss will be used here, defined in concordance with ACOG as a nonviable intrauterine pregnancy ≤12 6/7 weeks of gestation.

Classification

Early pregnancy loss is a process and may be diagnosed at multiple stages.

1. Biochemical pregnancy loss: A diagnosis entirely based on decreasing human chorionic gonadotropin levels without a pregnancy ever visualized on ultrasound. Generally, miscarriage occurs before 6 weeks of gestation in pregnancies achieved with the assistance of reproductive technology.

2. Asymptomatic pregnancy loss (ie, missed abortion): The missed death of the embryo or fetus without symptoms or expulsion of the products of conception (POC).

3. Threatened pregnancy loss: Symptoms (eg, bleeding and cramping) of an impending early pregnancy loss; however, the cervical os remains closed, and the embryo or fetus still appears viable on ultrasound.

4. Inevitable pregnancy loss: Similar to a threatened pregnancy loss, symptoms (eg, bleeding and cramping) are present; however, the cervical os is open. This term, in particular, is falling out of favor, as it can be clinically challenging to identify inevitable abortions with certainty.

5. Incomplete pregnancy loss: POC that remains within the uterus and the open cervical os after the diagnosis of an early pregnancy loss.

6. Complete pregnancy loss: The passage of all POC.

7. Recurrent pregnancy loss: The consecutive loss of multiple pregnancies. The American Society for Reproductive Medicine defines recurrent as ≥2 pregnancy losses; other organizations define it as ≥3 consecutive losses.

8. Septic miscarriage: An early pregnancy loss complicated by an intrauterine infection, which is rare. Alternatively, septic abortion has traditionally been used to mean any pregnancy loss, spontaneous or induced, complicated by infection. Septic abortions occur most often in the setting of nonsterile abortion procedures.