Symptoms of Anembryonic Pregnancy (Blighted Ovum)
A blighted ovum (now termed "anembryonic pregnancy") most commonly presents with irregular vaginal bleeding and a positive pregnancy test, though many patients may be completely asymptomatic until routine ultrasound examination reveals the diagnosis. 1
Clinical Presentation
The clinical symptoms of anembryonic pregnancy are indistinguishable from other forms of early pregnancy loss and include:
Primary Symptoms
- Vaginal bleeding - irregular pattern, ranging from light spotting to heavier flow
- Positive pregnancy test - due to continued hCG production from trophoblastic tissue
- Absence of typical pregnancy symptoms - or resolution of early pregnancy symptoms (breast tenderness, nausea) that were previously present
Less Common Presentations
- Asymptomatic discovery - many anembryonic pregnancies are detected incidentally during routine first-trimester ultrasound when the patient has no symptoms
- Lower abdominal cramping or pain - particularly if the pregnancy is beginning to miscarry 2
- Pelvic discomfort
Important Clinical Context
The diagnosis of anembryonic pregnancy is made by ultrasound criteria, not by symptoms alone. 1, 3, 1 Specifically, the diagnosis requires:
- A gestational sac measuring ≥25 mm mean sac diameter (MSD) without an embryo on transvaginal ultrasound, OR
- Absence of an embryo with cardiac activity ≥14 days after an initial scan showing a gestational sac without a yolk sac, OR
- Absence of an embryo with cardiac activity ≥11 days after an initial scan showing a gestational sac with yolk sac but no embryo 1
Critical Pitfall to Avoid
Do not diagnose anembryonic pregnancy based on a single early ultrasound showing an "empty" gestational sac. 2, 4 A gestational sac without visible embryonic structures may simply represent a very early viable pregnancy. Serial ultrasound examinations with appropriate time intervals are essential to avoid misdiagnosis and inappropriate intervention in a potentially viable pregnancy 1, 4.
Terminology Update
The term "blighted ovum" is now considered obsolete and should be avoided 1, 3, 1. The preferred modern terminology is:
- "Anembryonic pregnancy" - for the specific diagnosis
- "Diagnostic of early pregnancy loss (EPL)" - for the general category 1, 3, 1
This terminology change reflects a more respectful, patient-centered approach to communication about pregnancy loss.