UWise - Objectives 20-24 Flashcards
List 2 clues of twin gestations.
- Elevated AFP (roughly double that of singleton pregnancies)
- Fundal height exceeding gestational age in weeks
List 7 causes of elevated maternal serum AFP.
- Neural tube defects
- Multiple gestation
- Fetal abdominal wall defects
- Fetal death
- Pilonidal cysts
- Cystic hygroma
- Sacrococcygeal teratoma
List 4 U/S markers suggestive of dizygotic (non-identical) twins.
- Dividing membrane thickness >2 mm
- Twin peak (lambda) sign
- Different fetal genders
- 2 sparate placentas (anterior and posterior)
Discuss the difference between di/di, di/mono, and mono/mono placentation.
Diamniotic dichorionic placentation occurs with division prior to the morula state (within 3 days post-fertilization). Diamniotic monochorionic placentation occurs with division between days 4 and 8 post-fertilization.
Monoamniotic monochorionic placentation occurs with division between days 8 and 12 post-fertilization.
What happens with division of the zyogte at or after day 13?
Conjoined twins
Discuss the risks related to twin gestations with ARTs.
- Twin infant death is 5x higher than that of singletons.
- Risk for development of cerebral palsy in twin infants is 5-6xx higher than that of singletons
- Twins had a higher incidence of IUGR than singletons.
- 58% of twins delivery prematurely; 12% deliver very prematurely
The incidence of ___ anomalies is increased in twins, particularly monozygotic twins, compared to singletons. Note that the majority of twin pairs in which an anomaly is present will be discordant for this anomaly.
Congenital anomalies
True or false - twin gestations tend to deliver later than singleton gestations.
False - twin gestations tend to deliver earlier than singleton gestations with the average length of twin gestation being 35-37 weeks.
True or false - twins typically weigh less than singletons of the same gestational age.
True - but their weights usually remain within the normal range
True or false - prematurity is a major cause of morbidity and mortality among twin gestations.
True
What is one intervention that may help reduce the risk of having preterm and low-birth weight babies in a multiple gestation?
Adequate weight gain in the first 20-24 weeks of pregnancy.
What is twin-twin transfusion syndrome and in what type of twins is it most common?
The result of an intrauterine blood transfusion from one twin to the other; monochorionic, diamniotic twins
How do the twins present in twin-twin transfusion syndrome?
Donor twin: smaller and anemic
Recipient twin: larger and plethoric
List 2 clues to the presence of twin-twin transfusion syndrome.
- Large weight discordance (not necessary for diagnosis)
2. Polyhydramnios around the larger recipient twin and oligohydramnios are the smaller donor twin.
What is superfecundation?
Fertilization of two different ova at two separate acts of intercourse in the same cycle
___ increases the risk of morbidity and mortality and increases with higher orders of multiple gestations.
Preterm delivery (50+% of twins, 90+% of triplet, almost all quadruplet)
What are the associated risks of premature birth?
- Respiratory distress syndrome
- Intracranial hemorrhage
- Cerebral palsy
- Blindness
- Low birth weight
The optimal mode of delivery for twins in which the first twin is in the breech presentation is by ___.
Cesarean delivery (ECV in twins is contraindicated for the presenting twin)
In pregnancies with size greater than dates and an elevated maternal serum AFP, what is the next best step in management?
U/S
Conjoined twins can be diagnosed using standard U/S as early as when?
The end of the first trimester
What are thoracopagus twins?
Conjoined twins joined face to face at the chest
What is the most common abnormal karyotype encountered in spontaneous abortions, accounting for ~40-50% of cases?
Autosomal trisomy
Triploidy - 15%, Tetraploidy - 5%, Monosomy X - 15-25%
What is the most common chromosomal aneuploidy noted in spontaneous abortions?
Trisomy 16
The risk of developing microcephaly and severe intellectual disability is greatest between ___ weeks gestation.
8-15
The Committee on Biological Effects reported that no risk of intellectual disability has been documented with doses even exceeding 50 rad at less than ___ weeks and or greater than ___ weeks gestation.
8; 25
___ is the most common inherited thrombophilic disorder, affecting ~5% of Caucasian women in the United States.
5
What happens in FVL mutation?
Point mutation alters factor V, making it resistant to inactivation by protein C, leading to a thrombophilic effect
The FVL mutation is associated with obstetric complications, including what 4 things?
Stillbirth, preeclampsia, placental abruption, and IUGR
How might a fetus with Trisomy 18 be detected?
Likely to have congenital anomalies on prenatal U/S
More than ___% of cases of Trisomy 21 and 18 may be detected with the ___ screen.
90; quad
A congenital parvovirus infection associated with fetal demise would likely cause ___ in the fetus, which would be identified on U/S.
Hydrops
Uncontrolled ___ during ___ is associated with a high rate of birth defects.
Diabetes; organogenesis
What are the most common sites affected by uncontrolled diabetes during organogenesis?
The spine and the heart (although all birth defects are increased)
What happens when fetuses in utero are exposed to high levels of glucose transplacentally?
Increased growth and polyuria leading to an increase in the amniotic fluid volume
While some viral infections are also associated with placentomegaly and polyhydramnios, the fetus will have ___ growth depending on the timing of the infection.
Normal or decreased
Severe HTN and active anti-phopspholipid antibody syndrome are often associated with ___ and ___.
Oligohydramnios; IUGR
The risk of ___ is increased if hypothyroidism goes untreated.
Miscarriage
The most likely cause of painless cervical dilation that leads to pelvic pressure, bulging membranes, and fetal loss is ___.
Cervical incompetence or insufficiency (look for a history of cone biopsy)
True or false - although uncontrolled diabetes can lead to fetal malformations and early miscarriage, it is not typically a cause of fetal loss in the second trimester.
True
What risks are associated with advanced maternal age?
Stillbirth, preeclampsia, gestational diabetes, IUGR