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DMS333_CA5
Trisomies, multiple gestation review
Question | Answer |
---|---|
What is the test called that can help determine chromosomal abnormalities for at risk expectant patients and most commonly evaluates for numeric abnormalities of chromosomes 21, 13, 18, X, and Y. The results are available within 24 hours. | FISH, also known as, Fluorescence in situ hybridization |
What is the risk of having a fetus with down syndrome? | One in 365 women who is 35 years of age, whereas the risk for a woman who is 21 years of age is only about one and 2000. |
What is the earliest an amniocentesis may be done? | As early as 12 weeks gestation. |
T or F: Ultrasound is an extremely valuable tool in the assessment of multiple gestation pregnancies. | True |
What are monozygotic twins? | Identical twins that arise from a single fertilized egg, which divides, resulting in two genetically identical fetuses. |
What are dizygotic twins? | Dizygotic twins are fraternal twins that arise from two separately fertilized ova. |
T or F: All dizygotic pregnancies are dichorionic/diamnionic. | True |
T or F: In diamnionic pregnancies two layers of amnion and two layers of chorion separate the fetuses. | False. In dichorionic pregnancies, whether monozygotic or dizygotic, two layers of amnion and two layers of chorion separate the fetuses |
Are the majority of multiple gestation pregnancies dichorionic or monochorionic? | The majority (75% ") are monochorionic (one placenta). |
If the division of the fertilized egg occurs after 13 days what may happen? | The division may be incomplete and conjoined twins may result. |
Are monozygotic twins or dizygotic twins at more of a high-risk situation and increased incidence of fetal anomalies? | Monozygotic twins because the circulations of the monozygotic twins communicate through a single placenta, they are at increased risk for a syndrome known as twin-to- twin transfusion. |
What percentage of pregnancies begin with twins and end with a singleton? | One study showed that 70% of pregnancies begin with twins and end with the Singleton. |
What is Poly- oli sequence also known as? | Stuck twin syndrome. This is characterized by a diamnionic pregnancy with polyhydramnios in one sack and severe oligohydramnios into smaller twin in the other side. |
True or false, there are several abnormalities that are specific to just multiple gestation pregnancies. | True |
What is twin-to-twin transfusion syndrome? | TTS exists when their is an arteriovenous shunt within the placenta. The arterial blood of one twin is pumped into the venous system of the other twin. As a result, the donor twin becomes anemic and growth restricted. |
What is Acardiac anomaly? | A cardiac anomaly is a rare anomaly, occurring in monochorionic twins, in which one twin develops without a heart and often without the upper half of the body. |
What are the five types of conjoined twins? | 1) Thoracopagus (joined at the thorax) 2) omphalopagus (joined at the anterior wall) 3) craniopagus ( joined at the cranium) 4) pyopagus (joined at the ischial region) 5) ischiopagus (attached at the buttocks) |
When scanning a multiple gestation pregnancy, in addition to the anatomy what else should the ultrasound report include? ( 5 things) | 1) Number of sacs 2) Number and location of placentas 3) Gender of the fetuses 4) Biometric data 5) Presence of anomalies |
What type of trisomy has these common sonographic features? Nuchal thickness, heart defects, duodenal atresia, shortened femur, mild pyelectasis, mild ventriculomegaly, and echogenic bowel. | Trisomy 21 |
What type of trisomy has these common sonographic features? Heart defects, Choroid plexus cyst, clenched hands, micrognathia, talipes, renal anomalies, cleft lip and palate, omphaloce, CDH, cerebellar hypoplasia. | Trisomy 18 |
What are some common sonographic features of trisomy 13? | Holoprosencephaly, heart defects, cleft lip and palate, omphalocele, polydactyly, talipes, echogenic chordae tendineae, renal anomalies, meningomyelocele, and micrognathia. |