- endochondral ossification begins at 10 weeks LMP - mandible and maxilla (8-10 wks LMP)
-all long bones ossified by end of 1st Trimester
- fetal spine 18wks LMP
-4 SD GA for skeletal dysplasias (-2SD for chromosomal anomalies)
T or F: Dysplasias that manifest later with less severity will have better prognosis?
True
what to assess when considering skeletal anomaly?
patterns of shortening of long bones
shape/contour/density of bone
spine (ossification) - Radiograph
thoracic circumference/shape
hands/feet
calvarium and facial features
skin folds
amniotic fluid
What are the three Common Lethal Dysplasias?
Thanatophoric Dysplasia
Achondrogenesis
Osteogenesis Imperfecta II
What are the three Rare Lethal Dysplasias?
Congenital Hypophosphatasia
Camptomelic dysplasia
Homozygous Achondroplasia
Dysplasias are considered lethal when?
severe micromelia (all shortened) >4SD
decrease thoracic circumference <5th %
pulmonary hypoplasia
long bone fractures
K
leeblattchadel
severe micromelia (rhizomelia) macrocrania with frontal bossing narrow, bell shaped chest thickened redundant skin folds bowed limbs ("telephone appearance) Platyspondyly (flattened vertebral bodies) Kleeblattschadel (Cloverleaf skull)
Thanatophoric Dysplasia (common lethal)
**most common lethal skeletal dysplasia
AD mutation
severe micromelia macrocrania and frontal bossing narrow chest thick redundant skin folds bowing limbs (fractures may be present) decreased mineralization (vertebral bodies, ischium, public bones) polyhydramnios severe hydrops
Achondrogenesis(common lethal)
**2nd most common dysplasia
AR mutation
Type I (20% most severe) abnormal cranial and spinal ossification
Type II (80%) abnormal vertebral body but normal cranium
defective collagen "brittle bones"
Type I, III, IV Type II (lethal) severe micromelia, with multiple fractures "accordian bones",decreased mineralization,platyspodyly
Osteogenesis Imperfecta (common lethal)
AD or AR
profound hypomineralization (skull may look like acrania)
severe micromelia
bowed, thin long bones/absent (+/-) fractures shortened ribs, small circumference
Congenital Hypophosphatasia(rare lethal)
AR mutation
bent limbs (no fractures)
narrow thorax
severe clubbed foot
absent/hypoplastic fibulae
Camptomelic Dysplasia(rare lethal)
"bent bone"
rhizomelia
narrow thorax brachydactyly large cranium
narrow spine
Homozygous Achondroplasia (rare lethal)
One parent must be affected but usually both carry gene
Non-lethal Skeletal dysplasias
Heterozygous Achondroplasia
Asphyxiating Thoracic Dysplasia
Diastrophic Dysplasia
normal lifespan and normal intelligence late onset rhizomelia (27 wks) macrocrania and frontal bossing
brachydactyly
normal thoracic circumference
Heterozygous Achondroplasia
**most common form of non lethal dysplasias
--> absent or short radius
Radial Ray Abnormalities
1) Holt-Oram Syndrome (skeletal/cardiac anolamies)
2) Thrombocytopenia-absent radius syndrome (blood disorer with RR)
3) Roberts-Phocomelia (pseudothalidomide syndrome)
4) VACTERL sequence
are associated with what focal limb anomaly?
Radial Ray Abnormalities
--> medial deviation and inversion of sole of the foot
males>females due to: chromosomal, NTD, skeletal dysplasias, decreased fluid
Talipes Equinovarus "Clubfoot"
--> absent arch due to large calaneus
associated with T18
Rockerbottom Foot
--> presence of extra digits (+/- bone)
associated with T13
Polydactly
--> three digits
Oligodactyly
--> fusion of digits (webbed)
Syndactyly
--> marked shortening of hand digits with trident (pitchfork) configuration
associated with homozygous achondroplasia
Brachydactyly
--> permanent incurvature of digits (may seen clenched fists with overlapping fingers)
bilateral or unilateral
associated with T18
Clinodactyly
--> abducted thumb
associated with diastrophic dwarfism
Hitchhiker's Thumb
--> from RR, or absent ulnar
isolated Karyotype abnormality
Talipomanus "Clubhand"
--> amnionic bands extend from chorionic surface to fetal tissue resulting in organ dissruption, amputations, clefting, or constriction rings
**occurs from 1st trimester rupture of amnion
Amniotic Band Syndrome (ABS)
--> believed to result form early amnion rupture, vascular disruption or error in development resulting in lethal complex malformaitons
- short cord/abdomen attached to placenta
- evisceration of organs (omphalocele/open abdominal defect)
- limb and spine defects (scoliosis, etc)
Limb-Body Wall Complex (LBWC) or Body Stalk Anomaly
embryology of this begings at 5 wks LMP and is complete by 10 wks LMP?
Embryology of the face and neck
5 main processes of the face and next migrate and fuse together?
1) 1 Nasal Frontal Process
2) 2 Maxillary Prominences
3) 2 Mandibular Prominences
NasalFrontal Process starts superior; move inferior (form mid forehead, nose, central upper lip, central maxilla, anterior palate)
Nose start above orbits; move medially and inferiorly
Eyes move medially
Ears start below mandible; move laterally and superiorly
Facial anomalies occur in ? births? Polyhydramnious occurs with what % of those facial anomalies
?% of the time other nonfacial anomalies occur due to chromosomal abnormalities
1/600
60%
50%
List the drugs that can affect the development of the face
alcohol
codeine
valium
anti-epileptic drugs
Axial view through face (orbits and cranium are in view) assesses what?
binocular distance
orbital size
presence of hard palate
Tangential coronal view of nose lip assesses?
cleft lip
presence of 2 nostrils
Profile view assess?
**limited by: oligohydramnious and obesity
prominence of chin and forehead
protruding tongue
flattened nose
nasal bone
What is the orbital "Rule of Thumb"?
orbits should be separated by about the distance of an orbital globe (eye)
"Eyeballing It"
* Outer orbital distance can be used to date pregnancy (if no BPD)
--> congenital absence/sever hypoplasia of the eye
Anophthalmia
associated with T13
--> small eyes (interocular measurement)
Micropthalmia
associated with T13
--> wide spread eyes
- Commonly due to mass blocking anterior migration (ex. encephalocele)
- also due to craniosynostoses
Hypertelorism
--> closely spaced eyes
Hypotelorism
associated with T13
--> fusion of eyes into one; typically with supraorbital proboscis
Cyclopia
associated with T13
twoclosely spaced, but separate eyes, with supraorbital proboscis
Ethmocephaly
--> two closely spaced, but separate eyes, with centrally placed nose having one blind ended nostril
Cebocephaly
--> tuft of tissue (usually above eyes; absence of abnormal nose)
Proboscis
--> cleft in middle of nose (nasal and maxillary fail to fuse)
** also have cleft lip
Median cleft face
occurs with 40% of T18 and 60% of T13
isolated cleft palate is likely associated with other anomalies
Cleft palate is associated with polyhydramnios and small stomach
Cleft lip and palate (5 Types)
--> abnormally large protruding tongue beyond lips
associated with T21 and Beckwith-Wiedemeann Syndrome
Macroglossia
-macroglossia
-macrosomia (large baby)
-omphalocele
-renal hyperplasia/dysplasia (increased risk for Wilm's tumor or hepatoblastoma)
Beckwith-Wiedemann Syndrome
--> receding chin
Micrognathia
--> protruding forehead ( + hydrocephaly or skeletal dysplasia)
Frontal Bossing
If ? are placed low or small, can be associated with Trisomies
Ears
Fetal thyroid begins function at ? weeks?
12wks
hyperthyroidism or hypothyroidism will cause thyroid to enlarge in fetus true or false?
True
can be caused by Maternal Graves disease
may see neck mass/hyperextended neck on u/s
**due to Thyroid Dysfunction see IUGR, oligohydramnios, and tachycardia
--> bilateral right sidedness
associated with AVSD
no spleen 2 RA 2 RT lings midline liver bilateral SVC
Asplenia "Right isomerism"
AKA: Ivenmark's syndrome
T or F: heart defects with polysplenia are much worse?
False: they are worse with asplenia
commonly associated defects with cardiosplenic syndromes?
TGA
Pulmonary stenosis/atresia
common atrium
total anomalous pulmonary venous return with asplenia (2 RA)
complete heart block
clues to diagnose Cardiosplenic Syndromes in fetus? difficult to diagnose
Interruption of IVC
Large azygous vein
abnormal liver, stomach or heart position
Multiple gestation accounts for ? % of natural pregnancies?
1%
--> fertilization of two separate ova 70% of all natural twins
1/80 births hereditary (maternal side) own genetic mix separate or fused placentas ()
Dizygotic Twins "fraternal"
Frequency of Dizygotic Twins depend on?
Maternal age/parity
hereditary
Racial Background (nigerian, african american)
Pharmaceutical Agents (clomide and pergonal)
--> single fertilized ovum replicates 30% of all natural twims
1/250 births
random occurance genetically the same
Monozygotic Twins "identical"
What is the most important predictor of pregnancy outcome in twins?
Chorionicity
best determined between 10-14 weeks
Lambda (or peak) = dicorionic (fused)
T sign = monochorionic/DA
if 2 placentas implant close together they may fuse
some placenta may grow up between membranes
this is known as?
Twin Peak Sign/ Lambda Sign
when division of ova occurs after implantation
one placenta and membrane creates what?
T sign
Types of Monozygotic Twinning
Dichorionic-Diamniotic
Monochorionic-Diamniotic
Monochorionic-Monoamniotic
Conjoined
-occurs with all dizygotic twins
-may occur with monozygotic twins (18-30%) -Morula splits before implant (2 days post fertilization)
--implants separately (2 chorion+2amnion=4 layer membrane) -2 placentas (may be fused )
(may be ant/post placenta)
(fused=lambda sign)
Dichorionic-Diamniotic
-occurs only with monozygotic twins (70%)
- division occurs at blastocyst stage (4-8 post fertilization)
- 1 chorion; 2 amions (2 layer membrane)
- 1 placenta (T sign)
Monochorionic- Diamniotic
- occurs only with monozygotic twins (4%)
- division occurs at embryonic disc stage after amnionc sac hs formed (8-12 days post fertilization)
- no membrane
- 1 placenta *increased risk of mortality
Monochorionic - Monoamniotic
Which Twinning variation is impossible?
Dichorionic-Monoamniotic
--> incomplete divion at embryonic disc stage
occurs on day 13
no membranes
Conjoined Twins
Indications for Multiple Gestation scan?
strong family hx
LGA
increased maternal hCG
two or more heartbeats heard
Multiple Gestation Protocol
1. identify number of fetuses
2. position of fetuses
3. label Twin A/Twin B and side
4. presence of membrane, placenta(s), twin peak sign
5. treat each fetus as singleton
6. show similar fetal parts in same image
7. r/o polyhydramnios (5-10%)
8. r/o fetal demise "papyraceous"
- MC/MA twins
- Thoracopagus (chest) and Omphalopagus (abdomen) are most common join sites
- "Diprosopus" localized anatomic duplication of anatomy (nose, face, head)
- 70% are female
- 1/3 are stillborn; 1/3 die day 1
Conjoined Twins
- lack of separating membranes
- more than three vessel cord
- complex fetal anomalies
--> Twin reversed arterial profusion (A-A or V-V shunts in placenta)
--> acardiac twin possesses no heart or very abn heart and completely profused by donor twin & only develops legs and trunk
--> donor twin has high risk of developing hydrops due to high output cardiac failure Monochorionic Twins only
--> parasitic twin within abdomen of its sibling (looks like teratoma)
Fetus in Fetu
--> fertilization of two separate ova
Superfetation
Complications with Twins
twin to twin transfusion Syndrome (TTTS)
twin embolization syndrome
premature delivery
congenital anomalies
cord accidents
Other abnormal Twinning variations
Hydatidiform mole with normal twin
heterotopic pregnancies
fetus in fetu
superfetation
--> arteriocenous fistulas in the placenta (A-A or V-V or A-V) blood is not divided equally
**A-V is the worst (difference in pressure gradient)
--> anemic donor (small, hypotensive, oligohydramnios) "Stuck Twin"
--> fluid overload recipient (large, edematous, hypertensive, polyhydramnios) Monochorionic Twins only
Twin to Twin Transfusion Syndrome
- >20% discrepancy in size
- disparity in amniotic fluid
- single placenta
- thin or no membrane
- hydrops of 1 twin
--> donor twin may have little or no fluid aroud it (the amniotic membrane holds baby tightly to uterine wall)
Stuck Twin
--> occurs in dichorionic twins due to placental insufficiency
--> occurs in monochorionic twins due to TTTS
demise of twin in monochorionic twins may result in renal, hepatic, and cerebral damage in surviving twin (clots pass causing infarct)
demise of twin in di-di results in papyraceous fetus (resorbed twin)
Twin Embolization Syndrome
- ventriculomegaly
- porencephalic cysts
- cerebral atrophy
- mocrocephaly
uterus unable to accommofate two fetuses
Premature Delivery
genetic and developmental anomalies are more commin in monozygotic twins
Congenital Anomalies
tangled, prolapsed or wrap around neck and strangled cord
--> abnormal accumuation of serous fliud in at least 2 body cavities or tissues
Hydrops
*common; but each etiology is rarebased in Immune or non-immune etiologies
terminal stage for many conditions (signifies fetal decompensation - 24-48hrs demise)
Son Pres of Hydrops
Ascites
Pleural effusion
Pericardial effusion
Subcutaneous Edema
Placental Edema
A or V doppler abnormalities
low BPP scores
--> fluid collecting in fetal abdomen (seen in pelvis first)
can track down to scrotal sac causing hydrocele
Ascites (w Hydrops)
Pseudoascites - <2cm hypo ring
DDx: baby's fat layer under skin
--> fluid in pleural space around lungs (>pleural effusion > pressure on mediastinum causing upper body edema, polyhydramnios, pulm hypo)
Pleural Effusion
--> fluid in sac surrounding heart (causes pressures on heart and great vessles)
Pericardial Effusions
--> general, local or limited to upper/lower body depending on etiology
(generally first seen at fetal scalp adn face, then abd and limbs)
Subcutaneous Edema (Hydrops)
"Anacarca" --> general edema
--> ground glass appearance >4cm placenta; late sign of hydrops
Placenta Edema
If hydrops is of fetal etiology (whole thickened placenta)
IF hydrops is due to placental vascular malformation (partial hydropic placenta)
with Immune Hydrops: Ascites>edema>pleural/pericardial effusions
with Thoracic abn (chylothorax/heart defects) pleural/pericardial first
Patterns Of Hydrops
--> occurs when Rhesus sensitized mother has antibodies to fetal RBC Hemolysis occurs when maternal immunoglobin antibodies cross placenta and attack antigen positive fetal RBC
Immune Hydrops
"alloimmune Hydrops"
"erythroblastosis fetalis"
85% of pop are Rh+ (have Rhesus factor)
80% of IH is due to anti D antibodies
Rhesus Factor - red cell protein
Attach on fetal RBC in IH causes?
anemia
hepatosplenomegaly
Erythroblastosis fetalis (outpouring of immature RBC which can not carry oxygen)>>causes: tissue hypoxia, hydrops, cardiac failure, demise)
Assessment of Immune Hydrops
assess maternal antibody titers
sonographic assessment for signs of hydrops
MCA doppler (increase in velocities due to decreased viscosity of blood)
Optical Density Determination (ODD)- amnio to assess bilirubin in AF
Treatment for Immune Hydrops
Fetal Blood Sampling/Transfusion (PUBS)
with transfusion:
--- 70-85% hydropic fetuses survive
--- 85-90% nonhydropic fetuses survive
commonly seen in 1st/2nd trim spontaneous abortions
etiology varies geographically
Non-Immune Hydrops
--> blood disorder not compatible with life (if both parents pass gene, fetus has profound anemia>death)
Homozygous Thalassaemia
--> only one parent passes gene then fetus has relatively mild red cell anomalies