How Surgeons Repair Birth Defects Inside the Womb

Before a baby is born, its organs, bones, and nervous system are still developing, making the fetal period one of the most critical stages of human development. When a birth defect is detected during pregnancy, parents are often told to wait until after delivery for treatment. In many cases, delaying treatment can allow progressive and irreversible damage to occur. Fetal surgery is a specialised field designed to treat defects that worsen during pregnancy or threaten a baby’s life. Through a combination of precision imaging and minimally invasive techniques, surgeons can now correct life-threatening conditions before birth, giving babies a higher chance at survival and long-term health.

The process starts with high-resolution imaging—usually advanced ultrasounds and fetal MRI scans—to precisely map the defect and guide surgical planning. This helps doctors determine whether the benefits of fetal surgery outweigh the risks of premature labor, infection, or maternal complications.

Open fetal surgery involves an abdominal incision similar to a C-section. The uterus is partially opened just enough to access the fetus. The fetus is carefully positioned and often anesthetised as well as the surgeons perform the repair. One of the most widely known examples of this approach is the prenatal repair of spina bifida, a spinal cord defect that exposes nerves to amniotic fluid that damages them over time. Surgeons would close the exposed spinal cord and return the fetus to the uterus, where the pregnancy is then continued under close monitoring.

Fetoscopic surgery is less invasive and uses a small instrument called a fetoscope, which has a camera and tiny surgical tools. It is inserted into the uterus through one or more small incisions, allowing surgeons to operate on the fetus under ultrasound guidance without removing the fetus from the womb. The procedure often involves a single incision for the fetoscope and others for instruments, which allows for a less traumatic approach than open surgery. In conditions such as Twin-to-Twin Transfusion Syndrome (TTTS), surgeons use laser therapy to seal off abnormal blood vessel connections between twins sharing a placenta, significantly improving survival rates for both babies.

Needle-guided treatments are the least invasive and are used when a defect can be corrected by draining fluid or placing a shunt (a tube-like device that diverts blood and other bodily fluids to another part of the body). For example, in cases of lower urinary tract obstruction, a small tube can be inserted to relieve pressure and allow normal kidney and lung development.

Some birth defects cause damage that intensifies as the fetus grows. Spina bifida leads to progressive nerve injury; congenital diaphragmatic hernia can severely limit lung development; TTTS can cause heart failure in both twins. Intervening early allows surgeons to stop the damage before it becomes permanent.

Research shows that prenatal repair of spina bifida leads to significantly improved motor function and reduced need for lifelong shunting compared with postnatal repair. TTTS survival rates have increased dramatically due to fetoscopic laser therapy, transforming outcomes that were once uniformly fatal. These successes demonstrate how fetal surgery can prevent disability rather than simply treat it after birth.

Despite its benefits, fetal surgery remains a high-risk intervention. Maternal risks include premature labor, uterine scarring, and infection. The fetus also faces risks such as preterm birth or the possibility that the surgery will not resolve the condition. Because of these risks, fetal surgery is only offered in specialised centres with experienced multidisciplinary teams.

by Shanisse Tan at Incisionary

APA References

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