Fetoscopic Laser Ablation

In pregnancies where identical twins share a single placenta, they also share 'plumbing.' Naturally occurring connections between their blood vessels (anastomoses) are usually balanced. However, in TTTS, these connections become one-way. This creates a 'donor' twin who gives away too much blood and a 'recipient' twin who receives too much.

Fetoscopic laser ablation is the only way to fix this mechanical plumbing error. Using a thin telescope (fetoscope), we enter the amniotic sac and visualize the surface of the shared placenta. We then identify every single connecting vessel and use laser energy to seal them. This effectively 'divides' the shared placenta into two separate, independent territories. In our Unit, we utilize the Solomon Technique, which involves drawing a laser line across the entire placental equator to ensure no hidden connections are missed, significantly improving long-term outcomes and preventing recurrence.

This procedure is not a 'choice' but a medical necessity for pregnancies where the biological balance of twin development has failed. It is primarily indicated for:

• TTTS (Stage II, III, or IV): When there is a visible fluid imbalance (too much in one, too little in the other) or abnormal blood flow detected via Doppler.
• TAPS (Twin Anemia Polycythemia Sequence): A slower, more subtle transfusion where one twin becomes severely anemic while the other becomes 'thick-blooded' (polycythemic).
• Twin Reversed Arterial Perfusion (TRAP): Where an acardiac twin's blood supply is provided by a pumping twin.

The procedure is most successful when performed between 16 and 26 weeks of pregnancy, before the physiological stress on the babies' hearts becomes irreversible.

The path to laser surgery requires extreme diagnostic precision. Before we even enter the operating room, our subspecialists perform a comprehensive 'placental mapping' session:

1. Staging Review: We use Quintero Staging to determine the severity. This involves measuring the 'Deepest Vertical Pocket' (DVP) of fluid and verifying the visibility of the donor twin's bladder.
2. Hemodynamic Doppler Survey: We measure blood flow in the umbilical arteries, the ductus venosus, and the middle cerebral arteries of both babies to assess cardiac stress.
3. Cervical Integrity: We measure the mother's cervix to assess the risk of premature labor and to plan the surgical entry point.

This data allows us to transition from 'suspected TTTS' to a definitive surgical plan in a matter of hours.

At the MFM Unit, laser ablation is performed in a world-class fetal therapy suite. The process is designed for safety and minimal disruption:

• Precision Entry: The mother is typically given local anesthesia with light sedation. A 3mm fetoscope is inserted through the abdomen into the amniotic sac of the recipient twin.
• Direct Visualization: We view the placenta 'live' on a high-definition monitor, identifying the distinct vascular network of each twin.
• The Laser Barrier: Using the Solomon method, we do not just 'spot weld' individual vessels; we create a continuous laser line (a new equator) across the entire placenta.
• Fluid Volume Restoration: We finish by performing an 'amnioreduction,' removing the excess fluid from the recipient twin to reduce pressure on the uterus and the risk of early water breaking.

Post-surgical care is just as critical; mothers remain for 24-hour observation with continuous monitoring of the fetal heartbeats to ensure a smooth transition to the 'new' placental environment.

The survival of twins with severe TTTS has been revolutionized by laser ablation. Without surgery, the loss rate for both twins is nearly 90%.

• Survival Statistics: At the MFM Unit, our approach yields survival rates of over 90% for at least one twin, and approximately 70-80% for both twins.
• Cardiac Recovery: One of the most remarkable outcomes is the potential for the recipient twin's heart to recover significantly once the blood pressure overload is disconnected.
• Long-Term Outlook: Over 90% of surviving twins lead healthy, normal lives with no neurological or developmental deficits. By curative intervention at 20 weeks, we allow these babies to be born at or near term, avoiding the complications of extreme prematurity.

TTTS is an obstetric emergency that waits for no one. It can progress from a mild fluid difference to a life-threatening state in as little as 48 to 72 hours.

If you have been told that your 'twins are at different fluid levels' or if you notice a sudden, dramatic increase in the size of your abdomen (polyhydramnios), you must seek an immediate subspecialty review. Our lead consultant, Dr. Werner Diehl, is one of the most experienced laser surgeons in the world, having pioneered these techniques in some of the most prestigious centers in Europe. We provide the rapid-access assessment required to ensure that you are treated in the critical window for success.