Embryonic development anomaly: causes, symptoms, and treatment

This abnormality generally develops before the 9th week of pregnancy, when the embryo is still forming. Any disruption during this period can lead to early pregnancy termination.

Symptoms of embryonic development anomaly

Its symptoms are non-specific. Often, women notice a sudden decrease or disappearance of the early signs of pregnancy, such as nausea, vomiting, and increased salivation.

Additional symptoms depend on the duration of non-progressing pregnancy within the uterine cavity. If the gestational sac remains empty for 3 to 4 weeks, weakness, dizziness, and a mild fever may occur. After 2 to 6 weeks of missed periods, lower abdominal pain and dark red bleeding can happen.

A gynecological examination may reveal a decrease in uterine size. In the presence of alarming symptoms or anomalies during pregnancy follow-up, an emergency ultrasound is recommended to assess the condition of the gestational sac, the embryo, and the extra-embryonic structures.

The causes

The causes are multiple and can be classified as follows:

• Genetic: chromosomal abnormalities in gametes or the embryo.
• Infectious: inflammation of the uterus (e.g., chronic endometritis).
• Endocrine: thyroid dysfunction, progesterone deficiency.
• Immunological: antiphospholipid syndrome, genetic incompatibility between partners at the HLA level.
• Anatomical: uterine malformations, tumors.

The most common causes are genetic abnormalities occurring before fertilization (gametopathies) or after (blastopathies).

Factors favoring genetic anomalies:

• Vitamin and trace element deficiencies
• Viral infections
• Poor habits of both parents
• Mother's age (over 35 years)
• Environmental factors
• Chronic diseases
• Underweight in women

The diagnosis

The reference standard for diagnosis is transvaginal ultrasound.

Types of embryonic development anomaly based on ultrasound data:

• Type 1: 5 to 7 weeks, gestational sac diameter of 20 to 25 mm, no embryo but visualization of the chorion. During follow-up ultrasound, no growth of the gestational sac is observed.
• Type 2: 10 to 11 weeks, absence of embryo and chorion. The egg's contours are irregular, and the structure is heterogeneous. Diameter: 45 to 55 mm.

The diagnosis is confirmed by a color Doppler showing the absence of blood flow inside the egg.

Additional tests for high-risk patients:

• Measurement of hormone levels (including hCG)
• Pregnancy markers (PAMG-1, placental lactogen)
• Immunological diagnosis
• Caryotype analysis of the parents

Histological analysis of the sampled tissue helps identify the genetic or infectious causes of the pathology.

The treatment

Once the diagnosis is confirmed, evacuation of the uterine cavity content is necessary.

The medicinal method involves two steps:

1. Taking medications that destroy the connection between the fertilized egg and the endometrium.
2. After 24 hours, stimulating uterine contractions to expel the contents. The process may be accompanied by heavy bleeding, and the gestational sac may then resemble a whitish clot.

A follow-up ultrasound is performed two weeks later to confirm complete evacuation. An earlier exam may give falsely positive results due to the presence of clots.

Surgical treatment—vacuum aspiration—is preferred in cases where rapid resolution is needed. The extracted tissue is sent for histological examination to determine the causes and prevent recurrences.

During IVF

Embryonic development anomalies can occur both during natural conception and after in vitro fertilization (IVF). In the case of IVF, this condition may be caused by anomalies at the stage of fertilization or embryo culture, as well as by sperm or egg abnormalities.

After a IVF with donor eggs, these anomalies are more often related to issues not involving the egg itself, as donors undergo strict medical screening. The main causes are immunological anomalies, chronic uterine inflammations (endometritis), and poor sperm quality.

In programs IVF with Double Donation (donor egg and sperm), the risk of chromosomal abnormalities is minimal, which is why embryonic development anomalies may indicate poor endometrial receptivity or implantation window disorders. In such cases, a thorough examination of the endometrium (biopsy, immunohistochemistry, PCR, receptor protein expression) is necessary.

A comprehensive diagnosis and correction of concomitant factors are key to future IVF success.

Scientific data and statistics

According to WHO, up to 20% of clinically recognized pregnancies end in miscarriage during the first trimester. Embryonic development anomalies account for about 50% of these cases. The main cause is a chromosomal abnormality, most commonly trisomy 16.

The modern BoBs BACk-on-Beads™ method allows for accurate detection of chromosomal abnormalities. It is based on the use of artificial bacterial chromosomes (BAC) incorporated into microbeads and analyzed at the DNA level.