TTTS survival rate after laser surgery

Of those 145 pregnancies diagnosed with Twin to Twin Transfusion Syndrome, there were 34 cases of single fetal demise after laser therapy – this means that one twin died in 24.1 percent of the cases treated at the centre. Out of the 34 babies, 26 donors and 8 recipients died. This means that out of the 145 pregnancies, the donor baby died in 18.4 percent of cases. The recipient baby died in 5.7 percent of cases.

60 percent of losses happen within a week

Earlier studies have shown that the death of one baby after laser surgery for TTTS occurs in 20 to 25 percent of pregnancies. 60 percent of those losses occur within a week after laser surgery. At the centre in Japan 73,5 percent of losses happend within 14 days after laser therapy. 26.5 percent occurred later than 14 days after laser therapy.

Receiving treatment for severe, progressive TTTS is crucial. TTTS is associated with near to 100 percent mortality if left untreated. Read our TTTS and TAPS survivor stories.

Dr. Ruben Quintero describes in his research how he noticed an apparent sequence of events in progressive TTTS. He grades the severity of TTTS by the characteristics of amniotic fluid volume, bladder filling and multiple features of cardiovascular function, in five stages.

Be aware though that one of the weaknesses of the staging system is that it creates the impression that the natural history of TTTS follows an orderly progression over time. According to the National Organization for Rare Disorders in the U.S., clinical experience has shown that this is not the case. Progression of the disease processes are highly variable.

The 5 TTTS stages

Stage 1: There’s an imbalance of amniotic fluid.* A small amount is found around the donor twin – there’s a maximum vertical pocket of less than 2 cm. A large amount is found around the recipient twin. The maximum vertical pocket is greater than 8 cm. There’s sometimes a size discordance observed. However, most cases of TTTS do not have this sign. Size discordance is not considered to be strongly associated with TTTS. The bladder in the donor twin is still visible. When a Doppler ultrasound is conducted, the findings are not critically abnormal. A Doppler ultrasound is a noninvasive test that can be used to estimate blood flow through blood vessels in the placenta and umbilical cords.

* Low amniotic fluid is termed oligohydramnios, while a high level of amniotic fluid is called polyhydramnios. Please note that both these conditions must be present for the diagnosis of TTTS. 

Stage 2: In addition to the findings in stage 1, the bladder of the donor twin is no longer visible.

Stage 3: A Doppler ultrasound shows that there’s abnormal blood flow through blood vessels in the placenta and the umbilical cords of the babies.

Stage 4: In addition to all of the above findings, the recipient twin is swelling and appears to be experiencing heart failure.

Stage 5: In addition to all of the above findings, one (or both) of the twins has died. It can happen to either twin.

TTTS can occur at different stages. How the disease is treated depends on what stage it has progressed to when it’s discovered. For Stage 1 cases, observation may be all that’s necessary. For Stage 2 or higher cases, fetal laser surgery may be the best option. Read more about the different possibilities of treatment.

The surgeons use a fetoscope – a long tube – with a camera at the end of it. They insert the fetoscope and a laser device into the uterus. The surgeons look for the vessels that are providing the blood flow between the two babies and blazer those vessels, so blood flow can no longer happen between them. This should enable the babies to each have their own blood supply.

Look at this video from the Fetal Care Center in the U.S showing how TTTS laser surgery is done. Many doctors believe that this type of TTTS surgery will lead to the best outcome in severe TTTS cases. Research backs this up, showing that TTTS surgery by laser is associated with a 75-80 percent survival rate of at least one twin.

Some babies develop Twin Anemia Polycythemia Sequence (TAPS) after having had laser surgery for TTTS. Studies show that the post-laser form of TAPS might affect up to 16 percent of TTTS cases. Occurrence of TAPS after laser treatment is often due to very small residual anastomoses –  and is often regarded as a treatment failure.

Interview with chief physician Karin Sundberg

Karin Sundberg specializes in Obstetrics and Gynecology. She is employed at Rigshospitalet, Denmark’s largest hospital. It’s the only hospital in Denmark that treats TTTS and she is overall responsible.

How do you detect TTTS?

“The women, who are referred to us, have all been diagnosed with TTTS. Any well trained sonographer can spot TTTS during an ultrasound. Midwives can also help in order to ensure that women pregnant with twins are sent to a specialized doctor in time. If a woman’s uterus grows too fast due to an overload of amniotic fluid in the recipient twin, her stomach will usually hurt or feel very uncomfortable. It’s important not to write that off as common pregnancy discomforts. We often experience that a mother feels instantly physically relieved after we’ve done an amnioreduction,” says Karin Sundberg.

How do you classify at what stage the disease has progressed to?

“To a great extent we use Dr. Ruben Quinteros staging system. The staging system isn’t perfect, but it’s the best we’ve got. We also look at the length of the cervix. If the TTTS is at stage 1 we’re presented with a dilemma. The babies who stay at stage 1 survive, but half of the cases progress to a higher stage, where intervention is crucial. Intervention, however, has it’s own risks. Together with the parents we discuss whether we perform laser surgery or we do amnioreduction instead. Amnioreduction is not a treatment for TTTS, but helps prevent the spontaneous breaking of water and premature labor from the enlarged uterus. The cases we treat at our hospital have typically progressed to TTTS stage 2 and 3,” says Karin Sundberg.

How do you treat stage 2 and 3 TTTS?

“About half of our patients get laser surgery and half choose selective termination of one baby. This is often the case if we can determine that one of the children is brain damaged, has a neural tube defect, other malformations or a large size discrepancy. In Denmark there’s generally a very liberal attitude towards abortion and that also influences the risks a family are willing to take during a pregnancy,” says Karin Sundberg.

Are all TTTS cases eligible for laser surgery?

“No, not all severe TTTS cases can be successfully treated with laser surgery. The outcome is usually better if TTTS is detected early in a pregnancy. After 25-26 weeks we usually don’t perform laser surgery and more often have to rely on amnioreduction or premature delivery. We do experience cases, where laser surgery is a last option and where the outlook even after surgery isn’t great. This is for instance cases involving triplets or if the placenta is filled with liquid. There can also be an accumulation of blood in the uterus. Most often we perform laser surgery, even if the odds aren’t great, because if we don’t, the children die or are born extremely preterm,” says Karin Sundberg.

If you have experience or knowledge about TTTS surgery and would like to share, please feel free to leave a comment below this article or e-mail us at kate@about-twins.com