In brief — the direct answer
Selected complications of a shared-placenta twin pregnancy may lead to discussion of an intervention that stops circulation to one twin. Connected vessels can place the other twin at risk when one becomes severely ill or dies. The decision depends on the diagnosis, gestation and family preferences and requires non-directive counselling about monitoring, intervention, pregnancy loss and neurological uncertainty.
What is Selective Reduction (Monochorionic)?
Because of the shared blood supply, we cannot simply use medication. Instead, we must use techniques that physically block the blood flow in the target twin's umbilical cord:
- Bipolar Cord Coagulation (BCC): Using a specialized 3mm forceps, we use electrical energy to 'pinch' and seal the umbilical cord.
- Radiofrequency Ablation (RFA): Using a fine needle to cauterize the cord base (often used for earlier gestations or specific twin positions).
- Laser Cord Coagulation: Using high-powered laser light to seal the vessels.
Who is at risk?
This procedure is indicated when one twin in a shared placenta pregnancy has:
- A Severe Structural Anomaly: Such as anencephaly or a major heart defect that cannot be treated.
- Stage III sFGR: Where the small twin's blood flow is so unpredictable that it poses a 30-40% risk of sudden stroke or death for the healthy twin.
- Severe TTTS: In specific cases where laser ablation of individual vessels is not possible.
How we diagnose it
The evaluation is technically rigorous:
- Doppler Mapping: Identifying the 'point of no return' in the umbilical cord where the closure must occur.
- Brain Assessment: Using specialized ultrasound to confirm the healthy twin has not yet been affected by their sibling's condition.
- Counseling: Providing families with a dedicated multidisciplinary team to discuss the medical necessity of protecting the healthy twin's survival and brain function.
What does management involve?
The procedure is done in our fetal surgery suite:
- Precision Entry: Under ultrasound guidance, the chosen instrument (BCC forceps or RFA needle) is guided into the uterus.
- The Seal: The umbilical cord of the affected twin is grasped or ablated until all blood flow has permanently stopped.
- Confirmation: We verify that the healthy twin's heart remains strong and their blood pressure is stable throughout the procedure.
- Recovery: A 24-hour hospital stay for observation is typical to monitor for any signs of premature labor.
What are the outcomes?
The potential benefit and risk depend on the diagnosis, gestation, technique and condition of the other twin. A procedure does not guarantee survival or freedom from neurological injury. Discuss the possibilities of losing one or both twins, membrane rupture, prematurity and further intervention, together with the alternatives. Published results from selected series must not be presented as this unit’s audited outcomes. Ongoing ultrasound and appropriate postnatal follow-up remain important.
When to see a subspecialist
Complications in monochorionic twins can escalate suddenly. If you are told that 'one twin is not growing' or 'one twin has a major defect,' you must see a fetal therapy expert immediately.
Our team, led by Dr. Werner Diehl and Dr. Ali Al-Ibrahim, performs these highly specialized surgeries regularly. We understand the technical 'shared destiny' of monochorionic twins and provide the expert intervention needed to safeguard the health of your healthy baby.