In vitro fertilization (IVF) is a medical treatment that combines an egg and sperm outside the body before transferring the resulting embryo into the uterus. This process helps overcome various fertility challenges by ensuring fertilization and implantation. A blighted ovum, also known as an anembryonic gestation, is a specific type of early pregnancy loss. The fertilized egg successfully implants and forms the gestational sac, but the embryo fails to develop or stops growing very early. The surrounding tissues continue to secrete pregnancy hormones, often leading to a positive pregnancy test and early symptoms, even though the embryo is non-viable.
Blighted Ovum and IVF: The Clinical Reality
The immediate answer to whether a blighted ovum can happen after an IVF embryo transfer is yes. IVF successfully bypasses issues related to fertilization and transport, ensuring implantation in the uterine lining. However, the procedure does not guarantee the embryo is genetically perfect or that its development will proceed normally. The body’s biological mechanisms for recognizing and halting the growth of a non-viable pregnancy remain active, regardless of how conception was achieved.
A blighted ovum is a recognized form of early pregnancy loss within assisted reproductive technology (ART) cycles. This outcome is challenging for patients who have invested significant time and resources into the transfer. The risk is not eliminated even when high-graded embryos or those that have undergone preimplantation genetic testing are used, because the condition is primarily rooted in the embryo’s internal programming.
Underlying Causes of Anembryonic Gestation After Embryo Transfer
The primary reason an anembryonic gestation develops is due to severe chromosomal abnormalities, or aneuploidy, within the embryo. These genetic errors usually occur randomly during the formation of the egg or sperm, or during the first cell divisions after fertilization. Although the embryo may look morphologically perfect in the lab, a genetic flaw prevents the formation of the fetal pole following implantation. The pregnancy tissue that forms the sac and the beginnings of the placenta, called the trophoblast, can continue growing and producing hormones for a time.
Even when embryos are screened using Preimplantation Genetic Testing for Aneuploidy (PGT-A), a blighted ovum remains possible. PGT-A checks for the correct number of chromosomes by analyzing only a small sample of cells from the outer layer of the blastocyst, and it is not 100% comprehensive. Developmental issues can also arise after the embryo has been transferred to the uterus. Errors in early cell division (mitosis) that occur post-transfer can lead to developmental arrest, resulting in an empty sac. Other less common causes include problems related to egg or sperm quality that only manifest after implantation, or rare epigenetic errors.
Detection and Diagnostic Process
The detection of a blighted ovum in an IVF pregnancy often involves intense monitoring, beginning with serial measurements of the human chorionic gonadotropin (hCG) hormone. Initially, hCG levels rise because the trophoblast tissue is growing, leading to a positive pregnancy test and early symptoms. However, the rise in hCG may eventually plateau or slow down compared to a typically developing pregnancy.
The definitive diagnosis is made through a transvaginal ultrasound, which provides clear images of the uterus and gestational sac. A blighted ovum is suspected when the ultrasound shows a gestational sac of a specific size without a visible yolk sac or fetal pole. Current diagnostic criteria often look for a mean sac diameter (MSD) of 25 millimeters or more without a visible embryo.
If dating is uncertain or the sac size is borderline, the doctor will schedule a follow-up ultrasound seven to fourteen days later to confirm the diagnosis. This follow-up ensures that an extremely early viable pregnancy is not mistakenly diagnosed. The confirmed absence of an embryo when one would be expected based on the sac size confirms the blighted ovum.
Management and Implications for Future IVF Cycles
Once an anembryonic gestation is diagnosed, patients have several clinical management options:
- Expectant management involves waiting for the body to naturally recognize the non-viable pregnancy and miscarry.
- Medical management utilizes medication, such as misoprostol, to induce uterine contractions and facilitate the miscarriage process.
- Surgical management, typically dilation and curettage (D&C), involves the surgical removal of the pregnancy tissue from the uterus.
The choice of management is a personal one, made in consultation with the fertility team. Experiencing a blighted ovum does not typically reduce the chance of a successful pregnancy in future IVF cycles. A single occurrence is usually considered a random genetic event that does not indicate a persistent fertility problem. For future transfers, couples may discuss PGT-A to screen embryos for chromosomal abnormalities, although this does not eliminate all risk. The focus remains on transferring a genetically healthy embryo, and most individuals who experience this outcome eventually have successful pregnancies with subsequent transfers. Emotional support and counseling are often recommended to help process the grief associated with this early loss.