Obstetrics Flashcards
What are the functions of the placenta?
respiration, nutrition, storage, excretion, immunity, hormone production
Maternal circulation from aorta.
ovarian artery, arcuate, radial, spiral
How early can the placenta be seen?
8 weeks
Grade 0 placenta
no visible calcifications, smooth chorionic plate
Grade 1 placenta
Scattered tiny calcifications, subtle indentations
Grade 2 placenta
Larger basal echogenicities, larger indentations of chorionic plate
3 part of the early umbilical cord
Allantois, body stalk, vitelline duct
What does the allantois become?
develops into the bladder and will leave a remnant called the urachus.
Carries oxygenated blood from placenta to fetus.
Umbilical vein
Carries deoxygenated blood from the fetus to the placenta.
Umbilical artery
Where does gas exchange occur?
Placenta
Umbilical vein shunt to IVC
Ductus venosus
RA shunt to LA
Foramen ovale
PA shunt to AO
Ductus arteriosus
What does diastolic flow represent in a doppler of the umbilical artery?
Vascular resistance in placenta
When are the fetal kidneys functioning and produce the majority of fluid?
14 weeks
When does the fusion of the amniotic and chorionic membranes occur?
End of 16th week
What type of solids can be found within amniotic fluid (other than water)?
vernix, fetal cells, proteins, urea
Role of amniotic fluid
nutrition, free fetal movement, growth of GI tract, lung growth, protection, maintains fetal body temperature, bacteriostatic for potential infections
Define oligohydramnios.
< 2cm x 1 cm pocket or < 5 cm AFI
Define polyhydramnios.
> 8 cm x 1 cm pocket or > 25 cm AFI
Define placenta previa.
Placenta implanted in lower segment of uterus
Symptoms of placenta previa
Painless vaginal bleeding
Risk factors for placenta previa.
Previous c-sections, maternal age, multiparas, smoking, twins, infertility treatments
Define low lying placenta.
1-19 mm from internal os
Define complete previa.
Placental edge overlaps internal os by 1 mm or more
Define marginal previa.
Placental edge exactly reaches internal os by 0 mm
What is Braxton Hicks?
Uterine contractions
Abnormal adherence of the placenta to the uterus with subsequent failure to separate after delivery.
Placenta accreta
Define placenta accreta.
Implantation directly onto myometrium rather than decidua basalis
Define placenta increta.
Implantation directly into myometrium.
Define placenta percreta.
Placental growth extending through the myometrium or through the uterine serosa.
Define placental abuption.
Defective maternal vessels rupture and cause separation of the placenta - leads to bleeding and decidual hematoma.
Risk factors for placental abruption.
Maternal chronic HTN, smoking, cocaine, preeclampsia, PROM, trauma
Risk factors of Succenturiate & Bilobed placentas.
Vasa previa, retained placenta, velementous or marginal CI
Vessels presenting in front of fetus.
Vasa previa
Elevated placental edge.
Circumvellate
Flat margin placental edge.
Circummarginate
Marginal CI
Umbilical cord inserts < 2 cm from the placental edge
Velamentous CI
Umbilical cord inserts into membranes instead of directly into the placenta - lack of Wharton’s jelly surrounding the vessels
Most common benign and vascular tumor found in placenta
Chorioangioma
Solid highly vascular mass within or projecting from placenta
Chorioangioma
Scar tissue within the uterus
Uterine synechia(e)
Scar tissue within the uterus
Uterine synechia(e)
What are the differentials for bleeding after 20 weeks gestation?
Placenta previa, placental abruption, vasa previa, gestational trophoblastic disease (GTD)
3 Fetal head views?
Ventricular, Thalamic, Cerebellar
What is seen in the Ventricular view of fetal head?
falx, lateral ventricles (anterior, posterior), atrium (< 10mm), choroid plexus, calvarium (bone)
What is seen in the Thalamic view of the fetal head?
falx, thalami, 3rd ventricle, CSP, calvarium
What is seen in the Cerebellar view of the fetal head?
Cerebellum, nuchal fold (< 6 mm), cisterna magna (< 10 mm), vermis, falx, calvarium, CSP, thalamus
How is NF measured?
Outside of bone to outside of skin
Normal axis of fetal heart
45 degrees from midline and levocardia
Which heart view rules out 96% of abnormalities?
4CH view
Echogenicity of fetal lungs
Hyperechoic
When is the GB visualized?
After 20 weeks
When should the stomach always be visualized by?
14 weeks
When should the kidneys be visualized?
14-16 weeks
Echogenicity of kidneys
Hyperechoic then isoechoic
Normal amount of fluid in renal pelvis?
< 5 mm
What part of femur is measured?
Diaphysis
What is Frank Breech?
Babys hip joints are fixed and knee joints are extended
What is a Complete Breech?
Babys hip and knee joints are fixed
What is included in Biometry?
BPD, HC, FL, HL, AC=EFW (estimated fetal weight)
What is the most accurate predictor of GA?
Head Circumference
Normal CI range? Brachycephaly? Doliocephaly?
Normal 70-85%
Brachy > 85%
Dolio < 70%
What is SGA? LGA?
SGA is < 10%ile
LGA is > 90%ile
SGA - types?
- small but healthy
- small because of chromosomal or environmental etiology
- high risk for poor perinatal outcome including death and may have IUGR
Criteria for IUGR?
Fetal weight falls below 10%tile, a drop of more than 2 quartiles (50%)
Asymmetrical IUGR causes?
Maternal: HTN, smoking, medications, chronic disease, infection
Environmental: abruption, placenta previa, twin to twin transfusion (TTTS)
3T signs of IUGR?
Delayed/absent growth with serial scans, abnormal umbilical artery dopplers, oligohydramnios, grade 3 placenta, low BPP score
Causes of fetal death?
Asphyxia, maternal complications, congenital/chromosomal abnormalities, infection, unknown
Causes of fetal hypoxia?
uteroplacental insufficiency, reduced O2 in blood due to low hemoglobin, reduced blood flow to fetal tissues (ischemia)
What does UA circulation indicate?
Status of placental circulation
PI equation
PI=S-D/M
What should PI be around?
1
Does MCA have low or high resistance?
High
Does UA have low or high resistance?
Low
What is the Ductus Venosus?
Connection between IVC and umbilical vein
Normally biphasic and antegrade
BPP scoring guide?
Breathing, movement, tone, SDP/AFI, UA Dopplers scored over 30 min window
*Score below 6: increased risk of asphyxia, low cord pH, cerebral palsy, still birth
What is a Non-Stress Test?
2+ heart accelerations above 15 bpm or more lasting 15 secs over 20 min period, done twice
Acute Hypoxia indicator? Chronic?
Acute: BPP & NST
Chronic: amniotic fluid
What does the Prosencephalon become?
Telencephalon, Diencephalon
Forebrain
What does the Mesencephalon?
Mesencephalon
Midbrain
What does the Rhombencephalon become?
Metencephalon, Myelencephalon
Hindbrain
Foramen of Munro
Connection between paired lateral ventricles and 3rd ventricle of brain
Foramen of Magendie
Links 4th ventricle to CM (spinal cord)
Foramen of Luschka
Links between 4th ventricle and subarachnoid space (paired)
Role of Choroid Plexus
Produce CSF
Corpus Callosum
Myelinated nerve fibres that connect brain hemispheres
Enlarged ventricles with increased intracranial pressure
Hydrocephalus
-may lead to irreversible damage
Most common cranial abnormality
Ventriculomegaly
-when atria are > 10 mm
Which chromosomal abnormality is Ventriculomegaly a soft marker for?
Trisomy 21
Which lab is increased with NTD?
AFP
Absent calvarium/skull
Acrania/Exencephaly
Absent brain and skull. “Frog-like” eyes. Polyhydramnios.
Anencephaly
Anencephaly + extending to spine
Craniorachischisis
Herniation of meninges and brain through bony skull defect. Solid extra-cranial mass.
Encephalocele
Herniation of meninges/CSF through bony skull defect. Most are occipital. Extra-cranial cystic mass protruding from skull. Microcephaly and increased incidence of ventriculomegaly.
Cranial meningocele
Extreme flexion of head, open spinal defect, occiput defect. Lethal. “Star Gazing”
Iniencephaly
Abnormal cleavage of prosencephalon leads to failure of brain to divide into halves. Associated w/ Trisomy 13 (most common) and Trisomy 18. Facial abnormalities.
Holoprosencephaly
- Lobar
- Semi-lobar
- Alobar (monoventricle)
Absent corpus callosum (ACC) and CSP
Alobar and Semi Lobar Holoprosencephaly
Arrested development or hypoplasia of cerebellar vermis - obstruction of Foramen Magendie and Luschka
Dandy Walker
Cystic dilatation of 4th ventricle, absent vermis, ventriculomegaly, displacement of cerebellar hemispheres due to fluid
Dandy Walker
Amniotic fluid and bile
Meconium
Esophagus doesn’t connect to stomach. Transesophageal fistula seen in 90%. Polyhydramnios seen.
Esophageal Atresia
VACTERL?
V-vertebral A-anorectal atresia C-cardiac TE-esophageal atresia R-renal L-limb
Esophageal atresia is associated with which aneuploidy?
T18 (most common), T21
Duodenal Atresia is associated with…
Down syndrome, cardiac anomalies, all of VACTERL
U/S: Double bubble (dilated duodenum & stomach), polyhydramnios
Echogenic bowel is assoc. w/ which aneuploidy?
T21
Causes of large bowel obstuction?
Imperforate anus, anal atresia, Hirschsprung’s disease
Anorectal atresia is assoc. w/…
Caudal regression, VACTERL
Hirschsprung’s disease…?
Congenital mega colon - no control of peristalsis
Hydrops
large amounts of fluid builds up in baby
Focal dilatation of umbilical vein
Umbilical vein varix
Failure of abdominal wall to close, protrusion of intestines. Assoc. w/ ascites, polyhydramnios, IUGR. Increased AFP. NOT assoc. w/ chromosomal anomalies.
Gastroschisis
Midline defect - mass at base of umbilical cord containing organs. Umbilical vessels seen entering mass. Usually assoc. w/ chromosomal anomalies.
Omphalocele
Limb body wall complex
Severe form of amniotic band syndrome - lethal! short cord and exposed organs seen
Most severe anorectal malformation that can develop hydrocolops - in females only!
Persistent cloaca
When can kidneys be reliably seen?
12 weeks
Findings of bilateral renal agenesis.
Potter facies - limb deformities, pulomonary hypoplasia, low set ears, oligohydramnios
How to get LVOT from 4CH view?
Angle superiorly
How to get RVOT from 4CH view?
Angle more superiorly than LVOT and rotate transducer to demonstrate RV and PA
3VV?
PA, ascending AO, SVC
Bulbis cordis becomes?
Outflow tracts
Truncus arteriosis becomes?
Great vessels (PA and AO)
Sinus Venosus becomes?
Atrium, SA node, oblique vein, coronary sinus, IVC, SVC
Ostinum Secundum aka…
Foramen Ovale
Septum primum…
Divides atrium into left and right
Most common congenital heart defect
VSD - most commonly perimembranous
VSD is assoc. w/?
T21, T18, T13
Most common cardiac anomaly in fetus w/ down syndrome..
ASD - absent septum secundum
AVCD aka atrioventricular canal defect…
Septum primum ASD + VSD + common AV valve
Look at 4CH view
Assoc. w/ T21
Tetralogy of Fallot…
Large VSD, AO override, PA stenosis
Look at LVOT view
Ebstein anomaly is assoc. w/…
ASD, TOF, coarctation of aorta, transposition (common), mat use of lithium
Truncus arteriosus…
Single great artery - common trunk w/ a large VSD
Transposition of great arteries (TGA)….
VA discordance - RV connects to AO, LV connects to PA
Vessels will be parallel, hard to line up for 3VV
Most common cardiac tumor…
Rhabdomyosarcoma - round, hyperechoic masses assoc. w/ Tuberous Sclerosis
Causes of pulomnary hypoplasia…
oligohydramnios, no thoracic space, skeletal/neural malformations, chromosomal syndromes
U/S: Bell-shaped chest/abdomen
CPAM…
congenital pulmonary malformation
What is CPAM?
Multiple cystic masses of segmental lung tissue. May lead to hydrops - pressure on heart. 3 types: 1. Macrocystic (2-10 cm) 2. Macrocystic (0.5-2 cm) 3. Microcystic (< 0.5 cm)
Pulmonary sequestration…
congenital anomaly, non-functioning portion of lung tissue - most commonly extralobar and on left side
Most common diaphragmatic hernia…
Foramen of Bockdalek - left posterior lateral defect involving stomach & bowel
Right anterior medial diaphragmatic hernia…
Foramen of Morgagni - usually bowel & liver involved
Most common non-lethal skeletal dysplasia. Short long bones.
Achondroplasia
“trident” hand, macrocranium
Most common lethal skeletal dysplasia.
Thanatophoric dysplasia - severe micromelia, cloverleaf skull aka Kleeblattschadel, bell-shaped abdomen, polyhydramnios, head anomalies
Achrondrogenesis
- micromelia
- hypomineralization
- macrocranium
Osteogenesis Imperfecta
Inherited collagen disease - extremely fragile bones
Diastrophic dysplasia
club foot, hitchhiker thumb, cleft palate/micrognathia, micromelia
Rocker bottom feet assoc. w/…
T18 and T13
Soft markers for T21
NF, echogenic bowel, ventriculomegaly, echogenic intracardiac focus, short long bones, absent/hypo NB
Soft marker for T18
Choroid plexus cyst, enlarged CM
Increased hCG levels in 2T are a soft marker for…
T21
T18 Findings…(Edward’s Syndrome)
Strawberry shaped head, CP cysts, ACC, dandy walker, micrognathia, hypotelorism, clenched hand, crytorchidism, VSD, coarct. ao, diaphragmatic hernia, omphalocele, rocker bottom feet, polyhydramnios
T21 Findings…
Brachycephaly, ventriculomegaly, flattened face, duodenal atresia, echogenic bowel, hydronephrosis, NF thick, AVSD, VSD, TOF, echogenic focus, short limbs, absent/hypo NB, clinodactyly
Findings with T13…(Patau Sydrome)
holoprosencephaly, facial abnormalities (cleft lip, etc.), ventriculomegaly, ACC, NF thick, NTD, cardiac and renal anomalies, echogenic bowel, omphalocele, polydactyly, 1 UA, microcephaly
Triploidy Findings….
Meningomyelocele, cystic hygroma, omphalocele, NF thick, club foot, holoprosencephaly, ACC, dandy walker, etc.
Turner syndrome Findings…
always female, short stature, streak gonads, 45X, lethal, cystic hygroma, ascites, pleural effusion, horseshoe kidney, etc.
Fluid-filled sac-like structure that protrudes from back of head or neck
Cystic hygroma
Distinct feature of Apert Syndrome
Frontal bossing, beaked nose
Undescended testes
Crytorchidism
Fetal parts entrapped in fibrous septa
Amniotic band syndrome
Herniated viscera within a complex membrane
Limb-body-wall complex
Fetal Alcohol Syndrome Findings…
microcephaly, micrognathia, cleft lip and palate, depressed nasal bridge, low forehead, malformed ears, small eyes, ASD, VSD, IUGR
Risk factors for a multi pregnancy…
ART (assisted reproductive technology), maternal age, race, genetics, environment
Unprotected fetal umbilical cord vessels run across internal os
Vasa Previa
Maternal complications of twins…
morbidity, mortality, PROM, preeclampsia, HTN, placenta previa, post partum hemorrhage, anemia, pyelonephritis
Type of twins - zygote divides at day 3…
DC/DA
Type of twins - zygote divides at day 4-7….
MC/DA
Type of twins - zygote divides at day 8-13…
MC/MA
Type of twins - zygote divides at day 13+ …
Conjoined
of gestational sacs
chorionicity
of yolk sacs
amnionicity
“T-sign” thin membrane (< 2mm)
MC/DA
Fused lambda/chorionic peak sign (> 2mm)
DC/DA
Twin A is labelled…
Closest to internal os
What is considered discordant growth in twins?
discrepancy of 20% based on EFW
“vanishing twin”
demise of co-twin
Highest mortality of all twins…
MonoAmniotic
Embedding of fetus due to vitelline duct anastomosis
Fetus in fetu or heterotopic parasitic twin
Arterial-arterial anastomoses across fetuses
TRAP aka twin reversed arterial perfusion (acardiac twinning)
What happens in TRAP syndrome?
Deoxygenated blood flows from donor twin to acardiac twin (no head or heart).
Pump twin has risk of CHF. Treated with laser ablation.
TTTS?
Twin to twin transfusion - imbalance of twin placental vessels. Donor (oly) and Recipient (poly). MC/DA and same gender. Major imbalance of amniotic fluid and weight discordance.
Genetic screening method where had previously abnormal triple screen and hx of spontaneous abortions or fetal anomalies. 2-4 weeks for results. Performed between 15-20 weeks gestation.
Amniocentesis
AFP and fetal risk of isoimmunization (bili levels) analysis and detection of NTDs method..
Amniocentesis
Byproduct of RBC breakdown in Rh sensitization?
Bilirubin
Fetal distress is evaluated by?
Meconium
What is Chorionic Villus Sampling?
High risk 1T procedure where trophoblastic tissue is sampled. Results within 3-10 days.
What is PUBS?
Percutaneous umbilical blood sampling. Performed 17 weeks to term. Sedative is used. Used to evaluate and treat fetal conditions.
Erythroblastosis Fetalis
Destruction of fetal RBCs by maternal IgG antibodies which results in fetal anemia. MCA needs to be doppler.
