Abnormal Fetal Dev, Ectopic Preg, Screening for genetic dz Flashcards
Causes of sporadic and recurrent pregnancy loss
- Sporadic: most are chromosomal abnormalities; most common of which is aneuploidy; 1st most common aneuploidy is Tri16, 2nd is Tri21
- Recurrent:
• insufficient cervix: loss in 2nd trimester
• uterine anomalies: ex: T-shaped uterus
• antibody syndromes: like antiphospholipid Ab syndrome
• parent is a carrier of a balanced translocation
Presentation of pregnancy loss
- bleeding and cramping (25% of women experience bleeding in 1st trimester, but with cramping = worrisome)
- TAUS can detect gestational sac when hCG is 2000, TVUS can detect when hCG is 1000
- progesterone
Types of congenital anomalies
- chromosomal anomalies - assoc. with maternal age
- single gene defects/mutations - i.e., SCD, or CF
- structural anomalies - usually sporadic or due to teratogen, polygenic/multifactorial
* All women should have US at 18-20wks, some anomalies may be detectable by then
Anencephaly
failure of the rostral end of the neural tube to close, resulting in absence of a major portion of the brain, skull, and scalp
Cystic nuchal translucency
- an enlarged nuchal space on US which may be related to a cystic hygroma (lymph accumulation in neck region due to obstruction) or mesenchymal edema
- associated with aneuploidy, as well as with cardiac and neural tube defects
Ventriculomegaly
- results from hydrocephalus
- will see on US
- head circumference may not be enlarged, but there will be marked enlargement of the ventricle(s)
Gastroschisis
- ventral wall hernia where the guts are outside the abdomen, no enclosed in peritoneum like an omcephelocele
- this can be seen on US at 20 weeks
How many cases of twins are... present at the start of pregnancy? monozygotic? dizygotic? liveborn?
at start of pregnancy: 1/30
monozygotic (identical): 1/3 dizygotic (fraternal): 2/3
liveborn: 1/76
Risk factors for dizygotic and monozygotic twins
- Dizygotic: black, maternal family hx, young maternal age
- Monozygotic twinning: sporadic/random, only RF is IVF (because they use it as a technique to inc. embryos)
Chorionicity and Amnionicity
Chorionicity: refers to placental development; can be seen on US
- monochorionic: one placenta, two babies
- dichorionic: two placentas, two babies
Amnionicity: refers to amniotic sac
- monoamniotic: one amniotic sac
- diamniotic: two amniotic sacs
*These can be in any combination except dichorionic/monoamniotic
Complications with twins
- prematurity: avg delivery age is 36wks
- maternal DM, maternal hemorrhage
- twin-twin transfusion: in monochorionic/diamniotic twins one dies as the fluid is shunted to the other; only happens in monozygotic twins
Malpresentation
- when the baby’s head isn’t first down the birth canal, happens in 5% of cases
- requires c-section
- could be arm, foot, face, cord (cord prolapse), breech (butt), or placenta previa instead of vertex
Growth disturbances: small for gestational age
- Intrauterine growth restriction can be dx’d with serial US
- if symmetric, usually from chromosomal abnormality
- if asymmetric (that means that the head is growing normally but not the rest), often due to placental insufficiency (doesn’t deliver adequate Oxygen/nutrients), such as when the mother smokes
Growth disturbances: large for gestational age
- maternal DM can cause macrosomic babies as Glu crosses placenta; at risk for shoulder dystocia (birth injury)
- Beckwith-Wiedemann syndrome = syndrome characterized by macrosomia, macroglossia, midline abdominal wall defects, ear creases/ear pits, neonatal hypoglycemia
- Can determine estimated weight and develop birth plan (CD vs. vaginal)
What is the most common cause of maternal death in the first trimester?
Ectopic pregnancy
Risk factors for ectopic pregnancy
- History of chlamydia or gonorrhea
- Pelvic inflammatory disease
- Tubal ligation
- Previous ectopic pregnancy
- Pregnancy achieved through IVF
- Endometriosis
- Previous tubal re-anastomisis
* These basically inc. risk by causing scarring which deters the embryo from traveling down fallopian tube to implant intruterinely
Ectopic pregnancy presentation
- usually around 7-8wks
- present with irregular bleeding and pain
- preg test is positive but US shows empty uterus
- at this point, ddx includes ectopic pregnancy, early IUP, spontaneous abortion/complete abortion
Ectopic pregnancy treatment
- if the pt is unstable - identify blood in abdomen, tachycardia, hypotension, anemia –> type and cross, take to OR for emergent laparotomy
- if the pt is stable - counsel about signs of rupture, check quant hCG (should double q48hr) and progesterone (
Medical management of ectopic pregnancy
- if mass is MTX
- FU hCG levels to determine effectiveness
What is the recurrence risk of ectopic pregnancy?
7%
Heterotopic pregnancy
- 1 IUP and 1 ectopic pregnancy
- 1/1000 chance when naturally occurring, chance is higher with IVF
How can you screen for fetal genetic diseases?
- Investigate risk factors:
- patient’s reproductive history: previously affected offspring (1-2%), stillbirths, SABs, infertility/assisted reproductive technology (ART), teratogenic exposure, pedigree
- maternal (>35yo) and paternal age
- family history - AD/AR disorders, XLDs, MR; ethnic risks - Then can do screening/testing:
- maternal serum screening for cell free fetal DNA (cffDNA)
- US findings
- amniocentesis - ≥14wk, >99.5% detection rate
- chorionic villus sampling - testing placental tissue for chromosomal abnormalities, around 10-12wks (preferred if done before 15wk), can be done transcervical or transabdominal
What fetal defect is associated with an increased maternal serum AFP?
neural tube defects
What fetal defect is associated with an increased/decreased hCG?
hCG is high in T21; low in T18
What first trimester screen indicates aneuploidy?
- hCG high in T21, low in T18
- pregnancy associated plasma protein A high in aneuploidy
- cystic nuchal translucency on US
- algorithm taking into account the above plus age has an 82% detection rate
Current practice and progression of tests to screen for chromosomal abnormalities
- maternal serum screen, including cffDNA (reliably detected after 10wk)
- US
- invasive testing (CVS, amniocentesis)
These tests will analyze the fetal DNA and return a risk of chromosomal abnormalities
