Prenatal Flashcards
Tracheoesophageal Fistula
- the most common anomaly of the lower respiratory tract
- 1 in 3000-4500 live births
- predominantly affects males
- polyhydramnios commonly seen in pregnancy
VACTERL assocication
Vertebral anomalies Anal atresia Cardiac defects TEF Renal anomalies Limb defects
Congenital Diaphragmatic Hernia
- 1 in 2000-5000 births
- 80% left sided
- 60-70% survival
- abdominal contents can herniate causing pulmonary hypoplasia and hypertension
When do the intestines return to the abdomen in fetal development?
during the 10th week of development
Omphalocele
- 1 in 5000 herniation of intestines
- failure of intestines to return to the abdominal cavity
- associated with increased risk for chromosome abnormalities and imprinting defects (BWS)
Gastroschisis
- 1 in 10,000 births
- more common in males and on right side of umbilicus
- generally isolated
- due to incomplete closure of the lateral folds during the 4th week of gestation
Pyloric stenosis
- narrowing of the segment between the stomach and duodenum
- causes projectile vomiting
- 1 in 150 males, 1 in 750 females
- RR is higher if the index case is a female
Duodenal atresia
- causes polyhydramnios and “double bubble” sign on US
- 20-30% of affected infants have T21
Renal agenesis
- unilateral more commonly (frequently L kidney), M>F
- bilateral: 1 in 3,000-10,000
- causes Potter sequence when bilteral
Potter sequence
- Anuria
- Oligohydramnios
- Hypoplastic lungs
- Characteristic facies
- Renal failure
hypospadius
- 3-5 in 1000
- rate has doubled; due to rise of environmental estrogens (?)
limb defects
- 1 in 10,000 live births
- often associated with other birth defects
- 4-5wks of development is the most sensitive time
- Meromelia: partial absence of limb
- Amelia: complete absence of limb
- Phocomelia: absent long bones, rudimentary hands and feet attached to the trunk
- Micromelia: all segments are present but abnormally short
Polydactyly
- extra digits
- often a dominant trait in families
Syndactyly
- fusion of fingers/toes
- failure of mesenchyme to break down
Ectrodactyly
- “lobster claw” deformity
Club foot
- 1 in 1000
- M>F
- Can be unilateral or bilateral
Arthrogryposis
- stiff joints and abnormal muscle development
- decreased fetal movement
Klippel-Feil syndrome
- short neck, low hairline, restricted neck movement
- reduced number of cervical vertebral bodies (normal is 7)
- can be n
Amniocentesis
- after 15 weeks GA
- allows for cytogenetic analyss, molecular genetic analysis (if the specific mutation is known), and biochemical analysis
- Indicated for ONTD or AWD: increased AFAFP and presence of AChE
- test for CMV, toxoplasmosis, etc.
- results: rapid FISH in 24-48 hours, AFAFP in 2-3 days, full karyotype in 10-14 days
Chorionic villus sampling
- performed between ~10-13 weeks
- transcervical (better for posterior placenta, higher chance of MCC) or transbdominal (better for anterior placentas)
- cannot test for ONTDs
- slightly higher risk than amnio
- results: rapid FISH in 24-48 hours, full karyotype in 10-14 days
- slightly less accurate than amnio due to chance for mosicism and MCC
Mosaicism in CVS
- occurs ~1% of the time
- 90% of the time it represents confined placental mosaicism
- 10% = fetal mosaicism
Percutaneous Umbilical Blood Sampling (PUBS)
- generally used after 18 weeks
- best site of collection is at the placental cord insertion
- indications: fetal infection, fetal anemia, thrombocytopenia, hemophilia, immune hydrops
- higher risk of miscarriage than CVS and amnio
1st trimester screening
- US for NT measurement
- Serum analytes: Beta HCG and PAPP-A
- Accuracy for T21: 85%
Low PAPP-A in FTS
- considered <5th %ile
- spontaneous fetal loss
- low birth weight
- preeclampsia, gestational hypertension
- preterm birth
- stillbirth, preterm premature rupture of membranes, placental abruption
Quad Screen
- evaluares risk of trisomies, NTDs and placental abnormalities
- analytes: AFP, hCG, uE3, and Inhibin A
Crown-rump length
Used for pregnancy dating in 1st trimester US
2nd trimester US dating markers
- femur length
- biparietal diameter
- abdominal circumference
- cerebellum
Indications for growth ultrasounds
- risk of stillbirth/poor fetal growth: HTN, renal disease, obesity, hx poor fetal growth, small for dates, abnormal serum screening
- suspected large baby: diabetes, larger for dates
Miscarriage
- loss <20 weeks GA
- 1 in 6 clinical pregnancies end in miscarriage
- 1 in 4 chemical pregnancies end in miscarriage
Causes of miscarriage
- ~50% chromosomal abnormalities: 30% trisomy (T16 most common in SABS), 20% monosomy X, 15% tirploidy
- Single gene disorders: alpha thal, myotonic dystrophy, X-linked dominant
- 5-15% immunologic factors: antiphospholopid syndrome
- 15-60% endocrine abnormalities: PCOS, progesterone deficiency, thyroid abnormalities, diabetes
- thrombophilias: Factor V leiden & Prothrombin
- 10-15% anatomical abnormalities (i.e. spetate uterus, bicornate uterus)
- environmental: chemicals, lifestyle, infections
Recurrent pregnancy loss
definition: > 2 or 3 miscarriages, cause not determined for >50% of couples, up to 75% of couple with RPL will have a successful next pregnancy
evaluations:
- parental karyotypes
- karyotype on POC when possible
- immunological work-up: antiphospholipid syndrome
- endocrine abnormalities: PCOS, progesterone deficiency, thyroid function, diabetes
- thrombophilia work-up: Factor V and prothrombin
- screening for uterine abnromalities
hemoglobin A1C
levels of HbA1C tells how well glucose has been regulated during critical period in pregnancy
IUFD/Stillbirth
- defined as >20 weeks GA in MA
- 86% occur pre-labor, 14% during L&D
- Cause determined in 50% of cases
- 6.5/1000 pregnancies in the US
