How is Trisomy 13 Diagnosed?

Due to the fact that Trisomy 13 has a distinctive set of physical characteristics, a doctor may be able make a diagnoses simply by performing a physical examination. The risk of Trisomy 13 does not increase as a result of a tubal reversal, but the risk does increase with age. To either rule out or verify this disorder, a small blood test can be performed. This blood test, a chromosomal analysis, allows doctors to ultimately verify the existence of an extra #13 chromosome.

Babies with Trisomy 13 generally have low birth weights and look premature even when they are at full-term. Babies with Trisomy 13 often have a small head with an inclined, or prone, forehead. This abnormality is due to structural malformations in the scull and in the brain. In babies with this particular genetic disorder, these characteristics can be identified after birth. Genetic disorders are not increased by a tubal reversal surgery.

Holoprosencephaly (a disorder that causes the front of the brain to be divided improperly) is also common in babies with Trisomy 13. Holoprosencephaly leads to structural problems in the growth of the baby’s face. These babies tend to have close-set eyes, cleft lips, and cleft palates. Their nostrils are not fully grown and their ears are low-set with abnormal shapes. In many cases, skin problems such as cutis aplasia (a scalp abnormality that looks like ulcers on the scalp), birthmarks (purplish-red in color), or hemangiomas (abnormal blood vessels) are also present.

Other major problems for Trisomy 13 babies include:

• Extra fingers and toes (polydactyly)
• Heart defects
• Kidney problems
• Abdominal wall disorders (omphalocele or gastroschisis)
• Malformations of the uterus

Diagnosis before birth

Any chromosomal abnormality, such as Trisomy 13, can be diagnosed before birth. The cells from the amniotic fluid or from the placenta can show defects. A fetal ultrasound (performed during a pregnancy) is not always 100 percent accurate, but can predict whether or not the fetus is at risk. To confirm the physical findings, a blood test can be taken and chromosomes can be analyzed to determine the presence of an extra #13 chromosome. As most tubal ligation reversal patients are older, and maternal age is a predictor for Trisomy 13, many tubal reversal patients will opt for definitive diagnosis prior to birth.

Correlation between Trisomy 13 and tubal ligation reversal

As a woman’s age increases, her chances of having a baby with a chromosomal abnormality also increases. Most women who desire a tubal reversal are older than the average woman trying to get pregnant. In general, the woman who opts for tubal reversal has previously had at least a couple of children before she decided to have her tubal ligation performed. Since these women are older, they are at increased risk for chromosomal abnormalities due to their age, and not due to the actual tubal reversal surgery. A tubal ligation reversal has no affect whatsoever on the risk of a Trisomy 13 or any other chromosomal abnormality.

Trisomy 13, also known as Patau’s syndrome, and Trisomy 18, also known as Edwards’ syndrome, are conditions where the presence of chromosomal abnormalities generally result in severe mental retardation and physical disfigurement.  Children born with either condition usually

die within the first year of life.  Parents of these children often

undergo a tubal ligation surgery for fear that their next child would be

affected with the same disorder.

Some of these parents, after much consideration and consultation with

experts, recognize that this condition may not occur in future

pregnancies.  A tubal reversal is an option that will help these couples

bear children again.  Woman who are interested in a tubal reversal should be very aware of all the possible problems which may arise, especially if they are over the age of 40 . Although a tubal reversal may be the best option, these women should also explore other alternatives such as adoption. While the main concern will be the related risk of a trisomy 13 or trisomy 18, the fact is that the risk is the same for patients who undergo a tubal reversal as for those in the general population.

What is the possibility that parents with a child with trisomy 13 or trisomy 18 will have another baby with the same problem?

There is very little possibility that the parents of a child with trisomy 13 or trisomy 18 will have another baby with the same problem.  The likelihood of this occurrence is only 1% or less, as the majority of these cases are not inherited.  Trisomy 13 and trisomy 18 mostly occur secondary to random events occurring during sperm and egg cell formation.  The risk is different, however, in cases of translocation and mosaic trisomies of chromosomes 13 and 18. The chromosomal abnormalities present in these conditions have varied genetic implantation risks.

The risk of having children affected with these conditions is higher among mothers of advanced age. The average age of a mother who has a baby with trisomy 13 is 32 years old. For trisomy 18 the average age is 31.  The risk increases with each added year.

The physician will perform a karyotype to analyze the chromosomes of an infant suspected of having trisomy 13 or 18. A Karyotype is performed by extracting blood fromthe newborn.  Results give significant information to parents about their risk in future pregnancies.  The physician may also refer parents for genetic testing to determine if the condition was a translocation or a mosaic type. This determination will help predict the risk of recurrence in future pregnancies.

Is there a therapy which can cure or prevent trisomy 13 or trisomy 18?

Gene therapy has done immensely well over the past few decades in many fields, but there are still no specific therapies available to avert the

erratic chromosomal events that cause trisomy 13 or trisomy 18.

If I have a child with trisomy 13 or 18, will IVF be a better choice for me than a Tubal Reversal?

The major advantage of IVF over Tubal Reversal is the ability for Pre-implantation Genetic Determination. With IVF, the embyo can be Karyotyped prior to implantation to ensure that the child will not have trisomy 13 or 18. A patient who has a Tubal Reversal will not have this same luxury as the embryo produced from a Tubal Reversal pregnancy will not be selected out for either of these abnormalities.