-4 SD GA for skeletal dysplasias (-2SD for chromosomal anomalies)
T or F: Dysplasias that manifest later with less severity will have better prognosis?
what to assess when considering skeletal anomaly?
patterns of shortening of long bones
shape/contour/density of bone
spine (ossification) - Radiograph
calvarium and facial features
What are the three Common Lethal Dysplasias?
Osteogenesis Imperfecta II
What are the three Rare Lethal Dysplasias?
Dysplasias are considered lethal when?
severe micromelia (all shortened) >4SD
decrease thoracic circumference <5th %
long bone fractures
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
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
**2nd most common dysplasia
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)
bowed, thin long bones/absent (+/-) fractures shortened ribs, small circumference
Congenital Hypophosphatasia(rare lethal)
bent limbs (no fractures)
severe clubbed foot
Camptomelic Dysplasia(rare lethal)
narrow thorax brachydactyly large cranium
Homozygous Achondroplasia (rare lethal)
One parent must be affected but usually both carry gene
Non-lethal Skeletal dysplasias
Asphyxiating Thoracic Dysplasia
normal lifespan and normal intelligence late onset rhizomelia (27 wks) macrocrania and frontal bossing
normal thoracic circumference
**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
--> presence of extra digits (+/- bone)
associated with T13
--> three digits
--> fusion of digits (webbed)
--> marked shortening of hand digits with trident (pitchfork) configuration
associated with homozygous achondroplasia
--> permanent incurvature of digits (may seen clenched fists with overlapping fingers)
bilateral or unilateral
associated with T18
--> abducted thumb
associated with diastrophic dwarfism
--> from RR, or absent ulnar
isolated Karyotype abnormality
--> 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)
--> 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?
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?
--> 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?
Racial Background (nigerian, african american)
Pharmaceutical Agents (clomide and pergonal)
--> single fertilized ovum replicates 30% of all natural twims
random occurance genetically the same
Monozygotic Twins "identical"
What is the most important predictor of pregnancy outcome in twins?
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?
Types of Monozygotic Twinning
-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)
-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)
- 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?
--> incomplete divion at embryonic disc stage
occurs on day 13
Indications for Multiple Gestation scan?
strong family hx
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
- 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
Complications with Twins
twin to twin transfusion Syndrome (TTTS)
twin embolization syndrome
Other abnormal Twinning variations
Hydatidiform mole with normal twin
fetus in fetu
--> 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)
--> 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
- porencephalic cysts
- cerebral atrophy
uterus unable to accommofate two fetuses
genetic and developmental anomalies are more commin in monozygotic twins
tangled, prolapsed or wrap around neck and strangled cord