Fetal surgery is a highly specialized medical procedure performed on a developing fetus while it is still inside the mother’s uterus, or in utero. This intervention is reserved for severe congenital conditions that pose a significant threat to the fetus’s survival or long-term health if left untreated until after birth. The primary goal is to correct or mitigate a structural abnormality before it causes irreversible damage to the developing organs and nervous system. Fetal surgery requires complex collaboration between maternal-fetal medicine specialists, pediatric surgeons, and a multidisciplinary team to offer a better prognosis than postnatal treatment alone.
Rationale for Early Fetal Intervention
The primary reason to intervene before birth is that certain congenital anomalies cause progressive, time-sensitive damage within the uterine environment. Delaying treatment means accepting a worsening condition for the fetus. The intervention aims for a curative or preventative approach by repairing the defect during rapid fetal development. This window of opportunity is typically between 16 and 26 weeks of gestation, though it varies by condition. Early surgical repair can prevent secondary injuries, such as the exposure of the spinal cord to amniotic fluid in spina bifida, allowing the fetus to mature until delivery.
Specific Conditions Treated In Utero
Fetal surgery is indicated for conditions where the uterine environment actively contributes to the damage.
Myelomeningocele (MMC)
This is the most severe form of Spina Bifida. Prenatal repair of this open neural tube defect reduces the need for a shunt to treat hydrocephalus and improves motor function outcomes.
Congenital Diaphragmatic Hernia (CDH)
Abdominal organs protrude into the chest cavity through an opening in the diaphragm, preventing proper lung development (pulmonary hypoplasia). Fetal intervention, such as temporary tracheal occlusion, promotes lung growth before delivery.
Twin-to-Twin Transfusion Syndrome (TTTS)
This complication occurs in identical twin pregnancies when blood is unevenly shared through placental vascular connections, leading to severe complications for both twins. Laser ablation seals these connecting blood vessels, restoring circulatory balance.
Sacrococcygeal Teratoma (SCT)
These tumors can shunt a large volume of blood away from the fetus, potentially causing high-output cardiac failure. Reducing the tumor’s blood supply or removing it in utero relieves the strain on the fetal heart.
Techniques and Methods of Fetal Surgery
The methods used in fetal surgery range from minimally invasive procedures to extensive open operations, depending on the condition.
Fetoscopic Surgery
This minimally invasive approach is preferred because it causes less trauma to the mother and the uterus. It involves small incisions through which a fetoscope (a camera tube) and specialized instruments are passed. Fetoscopic surgery is used for procedures like laser ablation for TTTS or placing shunts for urinary tract obstruction. This method results in easier maternal recovery and a lower risk of preterm labor compared to open surgery.
Open Fetal Surgery
For complex structural repairs, Open Fetal Surgery is required, which is the most invasive method. The mother is placed under general anesthesia, and an incision is made in her abdomen to access the uterus. The surgeon makes a large incision in the uterine wall, partially exposing the fetus to perform the repair, such as closing the defect in Myelomeningocele. After the repair is complete, the uterus and the maternal abdomen are carefully closed.
Post-Operative Care and Outcomes
Following fetal surgery, both the mother and the fetus require intensive, specialized post-operative care. The mother is closely monitored for complications, particularly premature labor or rupture of the membranes. Medications, often including tocolytics to relax the uterus, are administered to prolong the pregnancy. The mother typically requires a hospital stay followed by restricted activity to manage the healing uterine incision.
Ongoing fetal monitoring, including frequent ultrasounds, assesses the success of the repair and the fetus’s well-being until delivery. Delivery planning is significantly affected by the surgery type. Mothers who undergo open fetal surgery will require a C-section for all current and future pregnancies to prevent the risk of uterine rupture through the surgical scar. While outcomes vary widely, prenatal repair for conditions like Spina Bifida significantly improves neurological function and reduces the severity of associated disabilities compared to repair after birth.