Health Scan: When a twin fetus ‘disappears’

Now new research compares 278 pregnancies in which one fetus disappeared with 252,000 children born in normal single and 1,800 twin pregnancies.

By JUDY SIEGEL-ITZKOVICH
A doctor stands with stethoscope in this undated handout photo. (photo credit: REUTERS)
A doctor stands with stethoscope in this undated handout photo.
(photo credit: REUTERS)
Vanishing twin syndrome, first recognized in 1945, occurs when one of a set of twins or multiple fetuses disappears in the uterus during pregnancy.
In this miscarriage, fetal tissue is absorbed by the other fetus(es).
Until the use of ultrasound, it could be diagnosed only after the remaining baby was born by examining the placenta, but today, the presence of a vanishing twin can be discovered even during the first trimester. The cause of the miscarriage is often unknown, but it may be abnormal chromosomes in one fetus, while the surviving one is normal.
Now new research at Soroka University Medical center and Ben-Gurion University that was published in the journal Fertility and Sterility has compared 278 pregnancies in which one fetus disappeared with 252,000 children born in normal single and 1,800 twin pregnancies.
The team, headed by Soroka deputy director-general and gynecologist Prof. Eyal Sheiner, found that the rate of pregnancy complications including gestational diabetes, intrauterine growth delay and low birth-weight was higher among survivors of the syndrome compared to healthy twins, and was lowest among individual pregnancies.
The results remained significant even when controlling confounders such as maternal age and fertility treatments.
“The significance of disappearing- twin pregnancies has caused disagreement among doctors for many years, so our results surprised the team. It is known that pregnancies with twins have a higher risk of health problems due to the tendency to deliver before reaching full term,” he said. “Here we examined the outcomes of pregnancies when a twin disappears versus two control groups, and we thought more complications would occur when twins were born than in those with a twin survivor. In fact, the main complications including preterm delivery was actually a group of twins disappearing.
There is no doubt that we have to wait for more studies on a large scale that would include mothers delivering at a number of medical centers to know what advice to give to women with pregnancies involving a disappearing twin.”
KNOWING IN ADVANCE If patients are briefed in advance about a medical procedure they have to undergo for the first time – from having a tooth pulled to giving birth – is much less scary if it’s explained to you in advance, and all the more so for children. Dr. Ayana Friedman, a physician and artist, understood this enough to write a charming children’s book in Hebrew called Hahlama Mehira! (Get Well Soon!).
Published by Ofir Bikurim (www.
ofir.org.il), the 22-page, hard-cover and nicely illustrated volume is presented in rhymes.
A girl named Elisheva falls on pavement while playing at camp and injures her leg. She is rushed to a nearby children’s hospital and is overwhelmed by white-coated doctors and nurses rushing about. After being examined, it is decided she will be sent to an inpatient ward for a day or two. She cries, because she didn’t have her teddy bear with her.
But the nurses, Margalit and Mahmoud, ae very kind, as is department head Dr. Havakuk, who is pudgy with red suspenders holding up his pants. At the teaching hospital, medical students follow the doctor around to lern how to listen to the lungs and make sad children laugh.
Elisheva learns about real illnesses among other children, such as juvenile diabetes and celiac, and what they have to do to live with them.
A medical clown amuses her so that when her mother comes to take her home, Elisheva suggests she go home for another night, while she stays in the ward.
Thus there is a happy ending, without fear – even though in today’s health system, conditions don’t often seem so rosy.
CLOSER TO CHANGE OF BLOOD TYPES Scientists have for years been trying to solve the problem of what do when a patient needs a blood transfusion but a pint of their blood type is unavailable. They haven’t been able to find an affordable potential solution – until now.
University of British Columbia chemists and scientists in the Center for Blood Research have created an enzyme that could potentially solve this problem. The enzyme works by snipping off the sugars (antigens) found in Type A and Type B blood, making it more like Type O. Type O blood is known as the universal donor and can be given to patients with all blood types.
“We produced a mutant enzyme that is very efficient at cutting off the sugars in A and B blood and is much more proficient at removing the subtypes of the A-antigen that the parent enzyme struggles with, said Dr. David Kwan, the lead author of the study.
To create this high-powered enzyme, researchers used a new technology called “directed evolution” that involves inserting mutations into the gene that codes for the enzyme and choosing mutants that are more effective at cutting the antigens. In just five generations, the enzyme became 170 times more effective.
With this enzyme, the university were able to remove the wide majority of the antigens in Type A and B blood. But before it can be used in clinical settings, the enzyme used would need to remove all of the antigens. The immune system is highly sensitive to blood groups, and even small amounts of residual antigens could trigger an immune response.
“The concept is not new but until now we needed so much of the enzyme to make it work that it was impractical,” the researchers said, adding that they believe they can now take their