Vanishing twin syndrome occurs in multifetal pregnancies when one fetus stops developing and is reabsorbed by the mother’s body or the surviving twin. This is a relatively common occurrence, especially in early pregnancy.
What Vanishing Twin Syndrome Is
This condition is often discovered incidentally during an early ultrasound. Initially, two gestational sacs or fetal heartbeats are observed, but a subsequent ultrasound reveals only one. Before the widespread use of early ultrasound, many instances of vanishing twin syndrome likely went unnoticed, as the loss occurred without significant symptoms.
The primary reason for a twin to vanish is often chromosomal abnormalities within that specific embryo. Other contributing factors can include advanced maternal age, assisted reproductive technologies like in vitro fertilization (IVF), and placental issues. This natural biological event is generally not preventable and is estimated to occur in 10% to 40% of multiple pregnancies.
Bleeding Characteristics and Duration
Bleeding is a common symptom of vanishing twin syndrome. Its characteristics vary significantly. Some individuals experience only light spotting or a brownish discharge, while others might have heavier bleeding resembling a menstrual period. The discharge color can range from light pink to dark brown, indicating older blood.
The duration of bleeding is also highly individual. It can last for a few days or continue intermittently for up to a couple of weeks. Bleeding occurs as the body reabsorbs tissue from the non-viable twin. If the vanishing occurs very early in pregnancy, the body might reabsorb the tissue with minimal or no noticeable bleeding.
Signs Requiring Medical Attention
While some bleeding is normal with vanishing twin syndrome, certain signs require immediate medical evaluation. Contact a healthcare provider if you experience heavy, bright red bleeding exceeding a typical menstrual period or pass large clots.
Report severe abdominal pain or cramping, especially if it intensifies or is persistent. Fever, chills, or a foul-smelling vaginal discharge could suggest an infection or other complication, necessitating prompt medical care. These symptoms, while potentially related to the reabsorption process, could also signal a different underlying issue that requires diagnosis and treatment.
Effects on the Surviving Twin
In most instances, especially when the loss occurs during the first trimester, vanishing twin syndrome does not negatively affect the surviving twin’s development or health. The surviving baby typically grows normally, and the pregnancy proceeds without significant complications directly linked to the vanished twin.
However, if the loss occurs later in pregnancy, such as during the second or third trimester, there can be minor complications for the surviving twin. These include a slightly increased risk of intrauterine growth restriction, preterm labor, or lower birth weight. While a potential link to conditions like cerebral palsy has been explored, especially with a shared placenta, this risk is generally low. Healthcare providers will closely monitor the surviving twin in such cases.