Is Blighted Ovum Counted in Recurrent Pregnancy Loss Workup?
Yes, blighted ovum (now termed anembryonic pregnancy) is counted when calculating recurrent pregnancy losses for workup purposes, as it represents a confirmed early pregnancy loss that meets diagnostic criteria for failed pregnancy. 1
Modern Terminology and Classification
The term "blighted ovum" is now obsolete and should be replaced with "anembryonic pregnancy" or "early pregnancy loss (EPL) - diagnostic of" according to current radiological and obstetric guidelines. 1, 2 This terminology change reflects a more precise understanding of the condition while maintaining clinical utility for classification purposes.
An anembryonic pregnancy is specifically defined as:
- A gestational sac measuring ≥25 mm without an embryo, OR
- Absence of an embryo on serial examinations obtained at appropriate discriminatory time intervals 1
Inclusion in Recurrent Pregnancy Loss Definition
All types of confirmed early pregnancy losses, including anembryonic pregnancies, are counted toward the diagnosis of recurrent pregnancy loss (RPL). 3, 4 The current definition of RPL is two or more consecutive pregnancy losses before 20-24 weeks of gestation, which explicitly includes both embryonic and fetal losses. 5, 6
The key requirement is that the pregnancy must be clinically recognized (confirmed by ultrasound or hCG) to be counted. 5 An anembryonic pregnancy meets this criterion because:
- It demonstrates an intrauterine gestational sac on ultrasound 1
- It represents a confirmed conception that failed to develop properly 7
- It requires the same diagnostic workup as other forms of early pregnancy loss 3, 4
When to Initiate RPL Workup
Begin comprehensive evaluation after two or more pregnancy losses, including anembryonic pregnancies. 8, 9 While some older definitions required three losses, current practice recognizes that two losses warrant investigation, particularly given:
- The psychological burden on couples 5
- The potential for treatable underlying causes 8, 10
- The improved prognosis with early intervention 3
Clinical Implications
The inclusion of anembryonic pregnancies in RPL counts is clinically important because:
Genetic factors: Some patients with recurrent anembryonic pregnancies (particularly recurrent complete hydatidiform moles) may have mutations in NLRP7 and KHDC3L genes, representing a specific autosomal recessive condition (familial recurrent hydatidiform mole). 7, 3, 4 These patients require genetic counseling and may benefit from ovum donation rather than conventional IVF. 7
Chromosomal abnormalities: Anembryonic pregnancies frequently result from chromosomal errors (50-60% of early losses), the same underlying mechanism as other forms of early pregnancy loss. 2, 5
Anatomical and endocrine factors: Uterine cavity abnormalities, endocrine dysfunction, and other treatable causes can manifest as anembryonic pregnancies. 4, 10
Common Pitfall to Avoid
Do not exclude anembryonic pregnancies from your loss count when determining whether to pursue RPL workup. This outdated practice may delay diagnosis of treatable conditions and prolong the couple's distress. 6, 5 All confirmed intrauterine pregnancy losses, regardless of whether an embryo was visualized, should be included in the total count for RPL evaluation. 1, 3