Definition of Early Pregnancy Loss
Early pregnancy loss (EPL) is defined as the loss of an intrauterine pregnancy within the first trimester, specifically prior to 20 completed weeks of gestational age. 1, 2, 3, 4
Standardized Terminology
The term "early pregnancy loss" has replaced older terminology such as "pregnancy failure" and is now the preferred nomenclature endorsed by obstetric and gynecologic professional societies. 1 The terms miscarriage and spontaneous abortion are considered synonymous with EPL, though miscarriage is preferred by patients in surveys and should be explicitly stated as equivalent to spontaneous abortion in clinical documentation for patient clarity. 1
Clinical Categories of Early Pregnancy Loss
EPL encompasses five distinct clinical scenarios based on ultrasound findings: 1
1. Concerning for EPL (Uncertain Prognosis)
This category indicates findings suggesting the pregnancy may not progress, including: 1
- Embryonic crown-rump length (CRL) <7 mm with no cardiac activity
- Mean sac diameter (MSD) 16-24 mm with no embryo
- Absence of embryo with cardiac activity 7-13 days following visualization of gestational sac with no yolk sac
- Absence of embryo ≥6 weeks after last menstrual period
2. Diagnostic of EPL (Definite Non-Progression)
This category confirms the pregnancy will definitively not progress, with criteria including: 1
- CRL ≥7 mm with no cardiac activity (termed embryonic demise)
- MSD ≥25 mm with no embryo (termed anembryonic pregnancy)
- Absence of embryo with cardiac activity ≥14 days after visualization of gestational sac with no yolk sac
- When gestational age ≥11 weeks 0 days, the term fetal demise is used instead of embryonic demise
3. EPL in Progress
The gestational sac is located in the cavity of the lower uterine segment or endocervical canal and is actively being expelled. 1 If cardiac activity is present in this location, consider cervical or cesarean scar ectopic pregnancy instead.
4. Incomplete EPL
Presence of intracavitary tissue (typically with internal vascularity) or persistent gestational sac following EPL. 1 Alternative terminology includes retained or residual products of conception (RPOC), with "residual" preferred as tissue may spontaneously expel.
5. Completed EPL
No persistent gestational sac or intracavitary tissue following EPL. 1
Broader Context: Recurrent Pregnancy Loss
Recurrent pregnancy loss is specifically defined as the failure of two or more clinically recognized pregnancies before 20-24 weeks of gestation and includes both embryonic and fetal losses. 5 This affects approximately 2.5% of women trying to conceive. 5
Key Distinctions
EPL is distinct from: 1
- Ectopic pregnancy: A pregnancy outside the uterine cavity (including cervical and cesarean scar locations), diagnosed by ultrasound, surgical visualization, or histopathology
- Stillbirth: Death of a fetus after 20 completed weeks of gestational age
- Termination of pregnancy: Intentional loss through medical, surgical, or unspecified intervention
Terms to Avoid
The following outdated or potentially distressing terms should not be used: 1
- "Blighted ovum"
- "Pregnancy failure"
- "Suspicious for pregnancy failure"
- "Nonviable pregnancy"
- "IUP of uncertain viability" (replace with "IUP of uncertain prognosis")