Multiple Pregnancy: Selective Reduction and Microwave Ablation

Key Takeaways

• Selective reduction is a procedure used to reduce the number of fetuses in a multiple pregnancy.
• It may be considered when continuing the pregnancy as it is would put the fetuses or pregnant person at serious risk.
• In pregnancies where twins share a placenta, microwave ablation is used as the method for selective reduction.
• In pregnancies where fetuses have separate placentas, medication may be used to stop the heartbeat of one fetus.
• Microwave ablation is a minimally invasive procedure that does not require major surgery.
• UChicago Medicine is one of a few centers in Illinois that offers advanced fetal care for complex multiple pregnancies.

Specialized Care for Complex Twin and Multiple Pregnancies

Complications in a twin or multiple pregnancy can be overwhelming and may require highly specialized care.

Selective reduction and microwave ablation may be considered in situations where one fetus has a condition that places the other fetus or the pregnancy at risk.

At the University of Chicago Medicine's Fetal and Neonatal Care Center, our team evaluates complex twin and multiple pregnancies and helps families understand all available options. We provide care with clear communication, time for questions, and support throughout the process.

If you've been diagnosed with a complication involving twins, triplets or higher-order multiples, early evaluation is important. The sooner our specialists can assess your pregnancy, the more treatment options may be available.

Schedule an appointment online or call us at 1-844-UCFETAL (1-844-823-3825).

What Is Selective Reduction?

Selective reduction is a procedure used to reduce the number of fetuses in a multiple pregnancy. It may be recommended when continuing the pregnancy with the current number of fetuses would create serious health risks.

This may be considered when:

• One fetus has a severe medical condition or birth defect
• One twin’s condition is affecting the health of the other twin in a shared placenta pregnancy
• A higher-order multiple pregnancy (triplets, quadruplets, or more) carries significant health risks

The exact approach used for selective reduction depends on the type of pregnancy:

• In pregnancies where twins share a placenta, microwave ablation is used as the treatment method.
• In pregnancies where each fetus has a separate placenta, a different technique may be used.

Your care team will explain which option is appropriate for your situation.

We understand this is a difficult decision. Our team will explain every option clearly and support you throughout the process without pressure or rush.

What Is Microwave Ablation?

Microwave ablation is a minimally invasive procedure used a part of selective reduction in certain twin pregnancies.

Minimally invasive means the procedure does not require major surgery. Instead, a thin needle is placed through the skin and guided using ultrasound imaging.

This method is used in monochorionic (shared placenta) twin pregnancies where selective reduction is needed. It works by stopping blood flow to the affected fetus in a controlled and precise way to protect the healthy twin.

Compared to older techniques, microwave ablation is very precise. It targets a small area, which helps protect surrounding tissue.

What Conditions Can Selective Reduction and Microwave Ablation Treat?

These procedures may be recommended when a complication in one baby threatens the health of the other baby or the pregnancy as a whole.

Twin-to-Twin Transfusion Syndrome (TTTS): TTTS occurs when twins who share a placenta develop an uneven blood flow between them. One twin receives too much blood while the other receives too lite, which can become dangerous for both babies.

Twin Reversed Arterial Perfusion (TRAP) Sequence: TRAP sequence is a rare condition in which one twin does not develop a functioning heart and relies on the health twin's circulation. This places extra strain on the healthy twin's heart.

Twin Anemia-Polycythemia Sequence (TAPS): TAPS is a blood disorder that can occur in twins who share a placenta. One twin develops too few red blood cells, while the other develops too many.

Selective Fetal Growth Restriction: This condition occurs when one twin is significantly smaller than the other because it is not growing as expected.

Discordant Fetal Anomaly: A discordant fetal anomaly means one twin has a serious birth defect or medical condition while the other does not. In some cases, the affected twin's condition may place the healthy twin or the pregnancy at risk.

Higher-Order Multiple Pregnancies: Pregnancies involving triplets, quadruplets or more carry a higher risk of complications for both the babies and the parent. In some situations, selective reduction may be recommended to improve the chances of a healthier pregnancy and delivery.

What to Expect Before, During and After the Procedure

Before the Procedure

Before any procedure, your care team will complete a detailed evaluation. This includes ultrasound imaging and consultations with fetal medicine specialists.

Your care team may include:

• Maternal-fetal medicine specialists (high-risk pregnancy doctors)
• Fetal therapy experts (doctors who specialize in treating babies before birth)
• Neonatologists (newborn intensive care doctors)
• A genetic counselor, if needed
• A dedicated fetal and neonatal care coordinator who serves as your liaison to the whole team

We will explain your diagnosis, review your options and help you make an informed decision about your care.

During the Procedure

The procedure is performed in a hospital setting using ultrasound guidance.

You will receive local anesthesia and medication to help keep you comfortable. A thin needle is used to deliver treatment with real-time imaging.

After the Procedure

After the procedure, your care team will monitor you and your pregnancy closely. Follow-up care may include:

• Regular ultrasound visits
• Monitoring for signs of preterm labor
• Ongoing pregnancy management and delivery planning

Our team stays involved and available for the rest of your pregnancy.

Risks and Outcomes

Like any medical procedure, selective reduction and microwave ablation carry potential risks, including:

• Preterm labor (labor starting too early)
• Infection
• Pregnancy loss
• Complications affecting the remaining fetus

Your care team will review your individual risk factors and answer any questions in detail.

For many families, treatment can improve the chance of a healthier outcome for the remaining fetus and pregnancy.

Why Choose UChicago Medicine

UChicago Medicine is one of the few centers in Illinois offering advanced fetal therapies for complex multiple pregnancies.

At UChicago Medicine, one of Illinois’ most advanced newborn intensive care units — the NICU — is just steps from where you will deliver. If your baby needs specialized care the moment they are born, they will receive it right away, with no transfers, no delays and no separation from your care team.

We care for patients referred from across the region and provide coordinated, expert-led care for high-risk pregnancies.

Our goal is to help you understand your options clearly and support you through every step of your care journey.