Obstetrics (#3)

- 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

indications for skeletal dysplasias (4)

errors of Morphogenesis (etiologies)

Patterns of shortening?

Abnormal femur length is defined as?

T or F: Dysplasias that manifest later with less severity will have better prognosis?
True False

what to assess when considering skeletal anomaly?

What are the three Common Lethal Dysplasias?

What are the three Rare Lethal Dysplasias?

Dysplasias are considered lethal when?

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)

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

defective collagen "brittle bones"
Type I, III, IV
Type II (lethal) severe micromelia, with multiple fractures "accordian bones", decreased mineralization, platyspodyly

profound hypomineralization (skull may look like acrania)
severe micromelia
bowed, thin long bones/absent (+/-) fractures
shortened ribs, small circumference

bent limbs (no fractures)
narrow thorax
severe clubbed foot
absent/hypoplastic fibulae

rhizomelia
narrow thorax
brachydactyly
large cranium
narrow spine

Non-lethal Skeletal dysplasias

normal lifespan and normal intelligence
late onset rhizomelia (27 wks)
macrocrania and frontal bossing
brachydactyly
normal thoracic circumference

--> absent or short radius

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?

--> medial deviation and inversion of sole of the foot

males>females
due to: chromosomal, NTD, skeletal dysplasias, decreased fluid

--> 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

--> 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)

embryology of this begings at 5 wks LMP and is complete by 10 wks LMP?

5 main processes of the face and next migrate and fuse together?

Nasal Frontal Process starts superior; move inferior (form mid forehead, nose, central upper lip, central maxilla, anterior palate)

Maxillary Prominences move medially (form lateral upper lip, maxilla, hard palate)

Mandibular Prominences move medially (form mandible)

Migration of nose, eyes, and ears?

Facial anomalies occur in ? births?
Polyhydramnious occurs with what % of those facial anomalies
?% of the time other nonfacial anomalies occur due to chromosomal abnormalities

List the drugs that can affect the development of the face

Axial view through face (orbits and cranium are in view) assesses what?

Tangential coronal view of nose lip assesses?

Profile view assess?
**limited by: oligohydramnious and obesity

What is the orbital "Rule of Thumb"?

--> congenital absence/sever hypoplasia of the eye

--> small eyes (interocular measurement)

--> wide spread eyes

- Commonly due to mass blocking anterior migration (ex. encephalocele)
- also due to craniosynostoses

--> closely spaced eyes

--> fusion of eyes into one; typically with supraorbital proboscis

two closely spaced, but separate eyes, with supraorbital proboscis

--> two closely spaced, but separate eyes, with centrally placed nose having one blind ended nostril

--> tuft of tissue (usually above eyes; absence of abnormal nose)

--> cleft in middle of nose (nasal and maxillary fail to fuse)
** also have cleft lip

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

--> abnormally large protruding tongue beyond lips

associated with T21 and Beckwith-Wiedemeann Syndrome

-macroglossia
-macrosomia (large baby)
-omphalocele
-renal hyperplasia/dysplasia (increased risk for Wilm's tumor or hepatoblastoma)

--> receding chin

--> protruding forehead ( + hydrocephaly or skeletal dysplasia)

If ? are placed low or small, can be associated with Trisomies

Fetal thyroid begins function at ? weeks?

hyperthyroidism or hypothyroidism will cause thyroid to enlarge in fetus true or false?
True False

--> cord looped 2+ times around the neck

--> septated nuchal fluid (multiocular lymphatic fluid limed by endothelium lymphatic endothelium

^{thought to arise from failure of lymphatic system to develop a communication to venous system in neck}

associations of Cystic Hygromas

DDx of Cystic Hygromas *seen as early as 10wks

11-14 wks
< 3mm thick normal
associated with trisomies if thickened

--> thickening due to subcutaneous edema
16-20 wks
<6mm normal
associated with Down's

--> solid mass composed of ectoderm, mesoderm, endoderm (may see hyperextension of neck)

may cause polyhydramious, or dystocia

-begins to develop at 5wks
- paired heart tubes form and fuse to single heart by 10 wks

Describe fetal circulation?

clinical indications for Fetal Echo?

u/s findings Associated with Heart Defects?

Fetal Echo Routine

4ch view r/o ? cardiac defects
outflows r/o ? cardiac defects

120-160 normal
<110 bpm (bradycardia) heart blocks
>200bpm (tachy) decreased SV (treated with Digoxin)

--> partial or complete absense of IAS (3rd most common cardiac anomaly)

SAX best views
**Foramen of Ovale should be no larger than the aortic root

--> Complete or partial absense of IVS ( most common cardiac anomaly)

SUBC & SAX best views
** may close on own

--> occurs when endocardial cushions fail to fuse resulting in one common valve  with 5 leaflets

_{*heart begins as one common ventricle/atrium that communicate through AV valve}

50% of fetuses with AVSD have?

--> inferior displacement of tricuspid valve
associated with hydrops, pulmonary stenosis, lithium injestion (bipolar meds)

--> secondary to pulmonary atresia with no VSD

--> due to increased flow into/out of the left ventricle

associated with coarction of aorta

--> occurs from muscle hypertrophy; replaced by collagen and elastic tissue causing decreased CO and CHF

associated with hypoplastic LT heart

VSD
Overriding aorta
RVH (postnatally)
Pulmonary stenosis

--> single large vessel arising from base of heart (supplies CA, Pulmonary and systemic)

VSD
Large overriding ao
pulmonary artery origin off aorta

--> aorta and pulmonary arteries arise from RV

VSD
Maternal DM and alcohol abuse

closed circut (80%)
RA to RV
Great vessels are parallel
seen in SAX
may have VSD

RV to LA
normal pulmonary to systemic circulation
parallel great vessels
may be asymptomatic throughout life

--> narrowing of aortic lumen (@ ductus arteriosus, arch, after aortic branches)

prominent RV
Small Lv
narrowed portion of Aortic Arch
associated with AVSD and VSD (dm)

Rhabdomyoma (cardiac hamartoma) most common

solid echogenic tumors (usually of the IVS)
*may obstruct outflows

--> damage to heart muscle (viral, bacterial, metabolic, maternal DM)

--> heart outside thoracic cavity

associated with Pentalogy of Cantrell

--> PM calcification (usually LV)

associated with T21

Isomerism
Situs Ambiguous
Heterotaxia

--> bilateral left sidedness

multiple spleens
2LA
2 LT lungs
midline liver
IVC intrahepatic interruption (to azygous vein>SVC)
Dextro or mesocardia

--> bilateral right sidedness
associated with AVSD

no spleen
2 RA
2 RT lings
midline liver
bilateral SVC

T or F: heart defects with polysplenia are much worse?
True False

commonly associated defects with cardiosplenic syndromes?

clues to diagnose Cardiosplenic Syndromes in fetus?
_{difficult to diagnose}

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 ()

Frequency of Dizygotic Twins depend on?

--> single fertilized ovum replicates
30% of all natural twims
1/250 births
random occurance
genetically the same

What is the most important predictor of pregnancy outcome in twins?

if 2 placentas implant close together they may fuse

some placenta may grow up between membranes

this is known as?

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 )

-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

Which Twinning variation is impossible?

--> incomplete divion at embryonic disc stage
occurs on day 13
no membranes

Indications for Multiple Gestation scan?

Multiple Gestation Protocol

- 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

--> 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)

--> fertilization of two separate ova

Complications with Twins

Other abnormal Twinning variations

--> 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

--> donor twin may have little or no fluid aroud it (the amniotic membrane holds baby tightly to uterine wall)

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)

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

Functionc of Amniotic Fluid

Amniotic Fluid Production

- 1cm pocket required for fetal breathing
- max level reached at 22 weeks
- begins to deminish at 34 weeks

Estimating Amniotic Fluid Volume

>8cm pocket
>25cm AFI
"fetus floating"

may cause maternal abdominal pain, SOB, PROM, preterm delivery

Tx: Amniocentisis/drugs to reduce fluid
(PROM, preterm delivery, infecton, premature closure of ductus arteriosus are complicaitons)

Causes of Polyhydramnios

Causes of Oligohyramnios

<5cm AFI
<2x2 cm pocket
limb anomalies (clubfoot)
pulmonary hypoplasia
restricted growth

--> abnormal accumuation of serous fliud in at least 2 body cavities or tissues

Son Pres of Hydrops

--> fluid collecting in fetal abdomen (seen in pelvis first)
can track down to scrotal sac causing hydrocele

--> fluid in pleural space around lungs
(>pleural effusion > pressure on mediastinum causing upper body edema, polyhydramnios, pulm hypo)

--> fluid in sac surrounding heart (causes pressures on heart and great vessles)

--> general, local or limited to upper/lower body depending on etiology
(generally first seen at fetal scalp adn face, then abd and limbs)

--> ground glass appearance >4cm placenta; late sign of hydrops

with Immune Hydrops: Ascites>edema>pleural/pericardial effusions

with Thoracic abn (chylothorax/heart defects) pleural/pericardial first

--> occurs when Rhesus sensitized mother has antibodies to fetal RBC
Hemolysis occurs when maternal immunoglobin antibodies cross placenta and attack antigen positive fetal RBC

85% of pop are Rh+ (have Rhesus factor)
80% of IH is due to anti D antibodies

Attach on fetal RBC in IH causes?

Assessment of Immune Hydrops

Treatment for Immune Hydrops

commonly seen in 1st/2nd trim spontaneous abortions
etiology varies geographically

--> blood disorder not compatible with life (if both parents pass gene, fetus has profound anemia>death)

--> only one parent passes gene then fetus has relatively mild red cell anomalies

Maternal CAuses of NOn-Immune Hydrops

Placental causes for Non-Immune Hydrops

Fetal causes for Non-Immune Hydrops

Investigation of NIH

U/S assessment of NIH

Therapy for NIH
*depends on etiology

(Therapy for TTTS and NIH