DMS 220- Unit 3

Chorionic villus sampling (CVS)

US directed bx if the placenta

• Chromosomal abnormalities may be detected due to fetal origin

• Performed 10-14 weeks gest

• Results within 1 week

Embroscopy

Direct viewing of the embryo via transcervical endoscope

• 1st trimester

• Detects fetal anomalies

Amniocentesis indications

• Polyhydramnios

• Rh isoimmunization

• Fetal lung maturity

• Risk of chromosomal defect

• AMA

• Abnormal AFP

• Congenital anomaly

Weeks

Amniocentesis results can take 1 to 3 ______ to get a result, some may opt for testing that takes less time

FISH (flourecence in-situ hybridization)

This test detects a less broad amount of abnormalities than an amnio

• Detects Trisomy 21, 18, 13 & Turners

• Results in 24 hrs

Cordocentesis

Another method to analyze chromosomes

• Blood obtained by needle aspiration of umbilical cord

• Karyotype results in 2-3 days

Normal Karyotype

• 46 chromosomes (23 pairs)

• 23rd pair is the sex chromosome (an X/Y combination)

Aneuploidy

Term for abnormal chromosomes

• Presence of one or more extra

• Abscence of one or more

Quad screen

• MSAFP

• BHCG

• Estriol (UE3)

• Addition of Inhibin-A

Trisomy 21 Quad Screen Values

• High HCG and Inhibin A

• Low AFP and Estriol

Trisomy 18 Quad Screen Values

• Low HCG, AFP, Estriol, and Inhibin A

High

Open neural tube defects will have a _____ AFP due to exposure to amniotic fluid

Hypoploidy

Term for less than 46 chromosomes

• Turner’s syndrome

Hyperploidy

Term for more than 46 chromosomes

• Trisomy 21, 18, & 13

Estriol (UE3)

This is estrogen produced by the fetus and placenta

Inhibin-A

This protein is produced by the placenta and ovaries

MSAFP

This is produced by the fetal liver and the yolk sac

bHCG

This is produced by the trophoblastic tissue of the placenta

Exposure

Omphalocele, spina bifida, gastroscesis, and anencephaly all have a high level of AFP due to __________ to amniotic fluid in these processes

AFP testing routes

• Cordocentesis- FSAFP

• Amniocentesis- AFAFP

• Maternal blood- MSAFP

PAPP-A

Test done in the 1st trimester to detect fetal anomalies, derived from trophoblastic tissue that is then diffused into maternal circulation

• Increases throughout pregnancy

• Decreased in pregnancy with chromosomal abnormalities

Trisomy 21 Markers (Down Syndrome)

• CHD (endocardial cushion defect)

• Increased nuchal fold

• Sandal gap toe

• Simian crease/clinodactyl of 5th finger

• Macroglossia

• Brachycephaly

• Flattened nasal fold

• Duodenal atresia- “double bubble” sign

• Omphalocele

• Ventriculomegaly

Mental retardation is always present, severity varies

Trisomy 18 Markers (Edward’s Syndrome)

• Club or rocker bottom feet

• Choroid plexus cyst

• Agenesis corpus callosum

• Cerebellar hypoplasia

• Poluhydramnios

• Clenched hands

• 2 vessel cord

• Cleft lip

• Micrognathia

Trisomy 13 Markers (Patau syndrome)

• MOST severe anomaly, least common

• Lethal condition

• CNS/congenital heart defects

• Holoprosencephaly resulting in mid facial anomalies and brain malformation

• Proboscis and eyes extremely close together

• Echogenic chordae tendinae

• Rocker bottom/club feet

• Polydactyly

• 2-vessel cord

Turners Syndrome

Abscence of X or Y chromosomes

• Cystic hygroma is most common finding (grave if large)

• AO coarctation, VSD, tetrology of fallot

• Lymphedema and hydrops

• Small stature, short femur

• Sexual infantilism

• Renal anomalies

Dandy Walker Syndrome

Congenital brain malformation is how the brain forms

• Cerebellum and spaces around it

• Hydrocephalus and slow motor development

• Large head

Triploidy

Term of complete extra set of chromosomes, 69 pairs total Results from an ova fertilized by 2 sperm

• Most will abort in 1st trimester

• Hydatiform placenta

• Meningomyelocele

• Single umbilical artery

• Syndactyly- webbing

• Cranial defects

• Facial anomalies

• Heart and renal defects

Failure

Pericardial effusion is a good indication of heart __________

Diaphragmatic hernia

When there is a perforation in the diaphragm and the stomach is seen on the same plane as the heart in TRV in the fetus

Autosomal dominant

Single defective gene inherited from one parent who is affected

• 50% chance child will be affected

Autosomal recessive

Pair of defective genes inherited from each parent

• 25% chance child will be affected

X-linked disorder

Genes inherited by boys from their mothers

• Affected males do not pass this on to their sons

• ALL their daughters will be carriers

Chorionic plate

Layer of the placenta closest to the fetus

Intervillous space

Layer of the placenta where nutrient exchange occurs

Basal plate

Layer of placenta that is against the uterus, decidual basalis

Chorionic villus

The functional unit of the placenta

Cotylendons

These are composed of main stem villi and their branches, thin layer of the decidua basalis

• Cobblestone appearance

Functions of the placenta

• Respiration

• Nutrition

• Excretion

• Protection

• Storage

• Secretes hormones

Vein

Oxygenated blood comes to fetus through the umbilical ______.

Arteries

Deoxygenated blood leaves fetus through umbilical _______ returning to placenta

Intermingling

There is no gross __________ of fetal and maternal blood

Battledore placenta or marginal insertion

Cord that attaches closely to the margin or edge of the placenta

• < 2cm away from the edge

Velamentous insertion

Cord inserts into the fetal membranes, makes the cord fragile

• Lack of whartons jelly

• Can hemorrhage

Vasa previa

Diagnosis of when the umbilical cord crosses the internal cervical os

• Caused from velamentous placenta or succenturiate lobe

Placenta previa

Diagnosis of placenta close to internal cervical os or completely covering it

• Within 2 cm of the internal os or covering it

Migrate

A low lying placenta may _______ away from the cervix as the uterus grows with pregnancy. If the edge of the placenta covers interal os more than 15 mm, it will probably not resolve.

Thick placenta

Placenta measuring AP > 4cm

• May indicate a TORCH infection, diabetes, hydrops, or congenital anomalies

Thick placenta

Placenta measuring AP > 4cm

• May indicate a TORCH infection, diabetes, hydrops, or congenital anomalies

Anywhere

Placenta can be located __________ on the uterus

Succenturiate placenta

Additional lobe(s) joined to the main placenta by blood vessels

• AKA accessory placenta

Grade 0-3

Placenta grading range

Grade 3 Placenta

Placenta grade that is most heterogenous

• Calcium deposits in placental septae

• Acoustic shadowing

• Echo spared area

• Indentations/irregular borders

High resistance

Spectral doppler artery in the 1st tri demonstrates _____ ____________

Low resistance

Spectral doppler artery in the 2nd tri demonstrates _____ ____________

Eval of the placenta

• 15-20 cm in diameter

• Approx 600 g (1.5 lb)

• < 4cm thick

• Ensure intactness

• Eval cord length

Short umbilical cord

Cord that measures < 30 cm

• At risk for tearing of cord and cord abruption

Neck

Long umbilical cords are at risk for wrapping around the fetus’ _____.

Placentomegaly

Enlarged placenta

• Weighing over 600g or 1.5 lb

• Thickened on US > 4cm

• Caused by maternal diabetes, maternal anemia, thalassemia, hydrops, fetomaternal hemorrhage, chronic intrauterine infections, and fetal malformations

3 cm

The cervix should measure approximately ______, should have no fluid within and appear as a “T” shaped at internal os

“U” shape

Bulging of membranes through the external os of the cervix appears as a ____ ________

Measuring an incompetent cervix

• Cervical length

• Funnel length

• Funnel width

Placental accreta

Chorionic villi of placenta attaches to the myometrium without muscular invasion

• Villi anchor to myometrium rather than Decidua

• Increased risk with previa and previous c/s scar

Placenta Increta

Placental invasion deep into the myometrium

Placental percreta

Placental penetration of chorionic villi through the uterus

• May extend into urinary bladder

• Most dangerous, high mortality rate

• End up with hysterectomy after delivery of baby

Sonographic appearance of placental invasion

• Observe retroplacental space or zone (btwn placenta and uterus)

• Define vessels that may extend into the wall