Abnormals Flashcards
What’s the incidence of aneuploidy in stillbirths
4%
+13, +18, +21
What’s the incidence of aneuploidy in livebirths
0.3%
+13, +21, +18, XXX, XXY, XYY
What’s the incidence of aneuploidy in spontaneous abortions
35%
XO, +16, +21, +22
What’s Polyhydromnios a symptom of
Maternal diabetes.
Impeded fetal swallowing.
Neural tubes defects. Severe abns of CNS. BWS.
Detailed ultra sound required
What’s oligohydromnios a symptom of
Premature membrane rupture.
Urinary tract abns. Renal agenesis (lack of fetal urine).
Cause deformities of the foetus: amniotic bands, IUGR, pulmonary hypoplasia.
Why carry out an AF/CVS
Manages remaining weeks of pregnancy.
Determine outcome of pregnancy.
Plan for problems that might occur as a neonate.
Decide whether to continue with pregnancy.
Diagnose conditions that could affect future pregnancies.
What’s the maternal age risk figure for T21 for a 30yr old
1/890
What’s the maternal age risk figure for T21 for a 35yr old
1/355
What’s the maternal age risk figure for T21 for a 37yr old
1/220
What’s the maternal age risk figure for T21 for a 40yr old
1/90
What chromosomal abnormalities of seen in 1st trimester spontaneous pregnancy losses
50%: Trisomies (3rd are trisomy 16).
25%: 45,X.
18%: triploid.
Tetraploid are seen
10%: mosaic
What chromosomal abnormalities of seen in 2nd trimester spontaneous pregnancy losses
40% Trisomies (majority T13 (13%), T18 (23%), T21 (63%))
20% 45,X.
10% triploid.
What chromosomal abnormalities of seen in 3rd trimester spontaneous pregnancy losses
Over 50% : Trisomies (50%: T18. Only 13 (17%),18, 21(32%) seen).
Less than 5%: 45,X.
15% other sex chromosome abnormalities.
20% structural abnormalities.
15%: mosaic.
What chromosomal abnormalities of seen in livebirths
1/3: other sex chromosome abnormal.
1/3: structural.
1/3: trisomy (80-90%: T21)
What percentage of T16 conceptuses are lost
100% lethal
What percentage of T21 conceptuses are lost
80%
What percentage of T13, 18 conceptuses are lost
90%
What percentage of Triploid and tetraploid conceptuses are lost
Almost 100%
What percentage of 45,X conceptuses are lost
95-99%
What percentage of Unbalanced structural conceptuses are lost
Up to 95%: depends on imbalance
What’s the pregnancy loss rate with a normal karyotype
8%
What’s the loss rate of a 1st trimester pregnancy and what percentage of the losses are chromosomally abnormal
20% loss
50% abn
What’s the loss rate of a 2nd trimester pregnancy and what percentage of the losses are chromosomally abnormal
2-5% loss
20% abn
What’s the loss rate of a 3rd trimester pregnancy and what percentage of the losses are chromosomally abnormal
Less than 1% loss
5% abn