A blighted ovum, also known as an anembryonic pregnancy, occurs when a fertilized egg implants and a gestational (embryonic) sac forms and grows, but the embryo fails to develop.
- Blighted ovum is the single leading cause of miscarriage
- Miscarriage (loss of a pregnancy before 20 weeks of gestation or ejection/removal of embryo/fetus ≤ 500 g)
Etiology
Early pregnancy loss (EPL) risk factors:
Etiological factors for anembryonic pregnancies are generally understood and studied in the broader context of early pregnancy loss (EPL) which includes both embryonic and anembryonic pregnancies
- Morphological abnormalities of embryo that prevents implantation or prevents long term survival of the embryo after implantation
- Chromosomal abnormalities: Autosomal trisomy, polyploidy, sex chromosomal polysomy, and monosomy X
- Obesity and advanced maternal age
- Reproductive tract infections
- Uterine malformation: Didelphic, bicornuate, and septate uteri
- Immunologic disorders: NK cell dysfunction, autoantibodies, hereditary, and acquired thrombophilia
- Hormonal factors (low progesterone) and endocrinological disorders (thyroid autoimmunity and thyroid dysfunction)
- Polycystic ovarian syndrome (PCOS)
- Alcohol consumption
Presentation
Signs and symptoms can potentially mirror those of an ectopic pregnancy. Anembryonic pregnancy is often incidentally noted on an initial first-trimester pregnancy sonogram.
Early pregnancy loss (EPL):
Early pregnancy loss in the setting of an anembryonic pregnancy can be clinically silent.
- Abdominal cramping
- Vaginal bleeding
Diagnosis
Pregnancy test (done via urine/serum hCG levels) is usually positive.
Ultrasound exam (transabdominal or transvaginal):
- CLASSICAL finding: Absence of fetal pole in a gestational sac of diameter 20mm
Management
Expectant management: “Watchful waiting” approach:
Patient closely followed without intervention for spontaneous and complete passage of tissue
- Repeat sonograms and trending hCG levels to confirm complete passage of tissue
Medical management:
- Vaginal misoprostol (prostaglandin analog)
Surgical management:
Employed in patients with hemodynamic instability
- Uterine aspiration/evacuation with a manual vacuum