Stage 1 Twin-twin Transfusion Syndrome Trial Compares Treatment Options

Results are being analyzed for an international research study comparing conservative management and selective laser photocoagulation (SLPC) surgery in stage 1 twin-twin transfusion syndrome (TTTS). SLPC is performed before birth to stop the uneven blood flow between the two fetuses.


TTTS affects 10 percent to 15 percent of monochorionic twin pregnancies (shared placenta). This condition results from an imbalance in the direction of blood flow within the shared placenta, resulting in one twin receiving too much blood volume and the other twin not receiving enough. Without intervention, TTTS results in the death of one or both fetuses in 80 percent to 100 percent of cases.

Over the last several decades, great progress has been made in the ability to treat TTTS. While the overall benefit of fetoscopic laser surgery as a first-line treatment has been established for patients with more severe stages of the condition, patients with stage 1 TTTS, the least severe stage, have traditionally been followed by close observation. This “conservative management” has never been formally compared to first-line fetoscopic laser surgery in patients with stage 1 TTTS.

Study objective

The objective of this research study is to compare both strategies for patients with stage 1 TTTS to determine an evidence-based standard of care. The study is now closed and results are being analyzed.

Study details

Study participants were assigned to one of two groups:

  1. The conservative management group was followed on a weekly basis as long as mother and babies remained stable and until an adequate gestational age was reached to allow delivery. If the condition of the mother or twins worsened, the appropriate intervention was performed. 
  2. The immediate laser group was treated with SLPC within 72 hours following assignment.

Contact us

To refer a patient or discuss a case, call us at 1-800-IN UTERO (800-468-8376).

Additional study details and criteria can be found on

Next Steps
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