OB 1 Flashcards
What is the formula for MSD?
L+W+H / 3
MSD of what measurement with absent fetal pole indicates pregnancy failure (missed miscarriage) seen via EV?
> 25mm
When the MSD measures what via EV, should a YS be visible?
8mm
On TA, at what measurement of MSD should we see a yolk sac?
20mm
On TA, at what measurement MSD should a fetal pole be visible?
> or =25mm
What is a normal yolk sac measurement?
<6mm
What is the minimum number of weeks where we can accurately date a pregnancy?
7W 0D
What landmarks should be seen within the BPD and HC measurement?
CSP
IHF
Thalamus
What landmarks should be seen when assessing cerebellum?
CSP
Falx
Cerebellar hemispheres
What is the ideal measurement plane for an accurate CRL?
Sagittal
How many mm should a CRL be to establish dates?
10mm
What is known as the stretching of ligaments and shifting of bones to accommodate the enlarging uterus during pregnancy?
Ligamentous laxity
What is the most serious cause of pelvic pain in the pregnant patient ?
Ectopic
A threatened miscarriage is vaginal bleeding prior to how many weeks?
A) <20
B) <15
C) <12
D) <10
<20
What percent of pregnancies result in spontaneous abortion before 20 weeks?
10-20%
Wha is a blighted ovum?
Gestational sac with no contents
A demise is an embryo of how many mm without cardiac activity?
5mm
A crescent-shaped sonolucent fluid collection between the gestational sac and the uterine wall is evidence of a?
SCH
Genetic testing can tell you the chance of your baby having what 3 abnormalities?
1) trisomy 21
2) trisomy 18
3) ONTD
When can an NT test be done?
Between 11 W 0 D and 13 W 6 D
What percentage of pregnancy losses are due to genetic abnormalities?
50-70%
Implantation occurs how many days after ovulation?
6 days
What decidua becomes the maternal portion of the placenta?
Basalis
What structure becomes the embryonic placenta?
Chorion Frondosum
What is the first structure seen sonographically within the gestational sac?
SECONDARY yolk sac
Which embryonic structure migrates from the yolk sac to the gonadal ridges during 6th week of development?
Allantois - blood vessels of the allantois become umbilical arteries
What is responsible for forming the primary yolk sac?
A) Cytotrophoblast
B) Epiblast
C) Synciotrophoblast
D) Hypoblast
Hypoblast
What is responsible for forming the amnion?
A) Cytotrophoblast
B) Epiblast
C) Synciotrophoblast
D) Hypoblast
Epiblast
What brain structure can be seen at 7 weeks?
Rhombencephalon
HcG is produced by what structure?
A) Cytotrophoblast
B) Epiblast
C) Synciotrophoblast
D) Hypoblast
C
How many days after conception does the heart beat?
23 days / 5 weeks
When can the ventricles in the brain be seen?
8-9 weeks
When can the CP be seen?
9-19 weeks
When do limb buds form and embryonic gut herniates into umbilical cord?
8 weeks
When should the umbilical herniation measure?
<7mm
At how many weeks does the gut recede back into the abdomen?
12 weeks
What are the 3 layers of the blastocyst?
Trophoblast - outer layer that forms the maternal placenta
Blastocele - fluid filled cavity
Embryoblast -froms embryo
What are the ball of cells called once egg is fertilized and travels down fallopian tubes?
Morula
How many standard deviations below the mean for GA is suspicious of IUGR?
2
A uterus LARGE for GA may be due to what? (4)
1)Fibroids
2) Incorrect dates
3) Multiple gestations
4) Molar pregnancy
Anembryonic pregnancy is also known as what?
Blighted ovum
What kind of abortion is known as “anembryonic pregnancy or embryo demise that has not yet been expelled from the uterus”?
Missed abortion
What kind of abortion is known as “placental or fetal tissue has been expelled but some products of conception remain in the uterus”?
Incomplete abortion
What are the SF of RPOC?
1) thickened endometrium
2) vascularity within endo
3) hyperechoic tissue in uterus
What kind of abortion is known as “profuse bleeding and the cervical os has begun to dilate”?
Impending/inevitable abortion
What kind of abortion is known as an “empty low-lying GS with an open cervix”?
Impending abortion
Gestational trophoblastic disease is also known as what?
Molar pregnancies
What is the difference between a complete and partial hydatidiform molar pregnancy?
Complete: the egg has 0 chromosomes, but one sperm donates 23 chromosomes - will NOT see fetal tissue
Partial: A normal egg is fertilized by sperm that duplicates itself, resulting in 69 chromosomes - May see an embryo and placenta with be thick and hydropic
What percentage of patients with complete molar pregnancies develop bilateral, enlarged ovaries with multiple theca lutein cysts, a result of hyperstimulation from the elevated hCG?
46%
Do partial or complete molar pregnancies have a higher incidence of developing a choriocarcinoma?
Complete
What abnormality may be described as “cystic to solid areas of necrosis, coagulated blood, or tumor tissue invading and extending as a mass outside the uterine wall with metastatic lesions located in the liver?
Choriocarcinoma due to a molar pregnancy
What abnormality occurs when the neural tube fails to close at the base of the skull?
Anencephaly
What abnormality causes a developing baby’s brain to not properly separate into the right and left hemispheres?
Holoprosencephaly
What abnormality is describes as a cystic dilation of the fourth ventricle that fills the posterior fossa and extends into the cisterna magna AND hypoplasia or complete agenesis of the cerebellar vermis?
Dandy-walker
What abnormality occurs when the superior neural tube does not close completely?
Encephalocele
What abnormality occurs when the abdominal wall does not develop and thus the peritoneal cavity is open to the extraembryonic coelom and the fetus is attached to the placenta?
Body stalk anomaly
What abnormality is known as malformation of the lymphatic system, which is also called nuchal edema or increased NT?
Cystic hygroma - associated with turners syndrome AKA monosomy X
Megacystitis is the enlargement of the bladder measuring what?
LBD > or = to 7mm
What is the difference between a true umbilical cyst and pseudocyst?
True - from fluid of the embryo and usually resolves
Pseudo - fluid from inside the umbilical cord and is associated with genetic abnormalities
What is the most common defect of the hand and foot?
Polydactyly
At 6 weeks GA, what HR is bradycardia and tachy?
Brady - <90 bpm
Tachy - >155 bpm
What does PUBS stand for and what is it also known as?
Percutaneous Umbilical Blood Sampling AKA cordocentesis
What are the two most common clinical techniques for obtaining living fetal cells?
Amniocentesis and Chorionic villus sampling (CVS)
When is an appropriate GA range to perform amniocentesis?
14-20 weeks
Indications for amniocentesis?
-AMA
-Patient anxiety
-Increased or decreased levels of MSAFP
-Lung maturity assessment
-Isoimmunization status
-Previous pregnancy of known abnormalities
When would we use CVS vs. amnio?
- Earlier results than amnio - 24-48 hours vs 7-10 days
- Can be performed earlier - b/w 9-12 weeks after LMP
What is a normal cut off for NT assessment?
< or equal to 2.9mm
What is the gestational period to perform an NT test?
11W 0 D to 13 W 6 D
What CRL must a fetus be to perform an NT test?
45-84mm
What kind of tissue is sampled in CVS?
Trophoblastic tissue
Ectopic pregnancies account for what percent of all pregnancies?
2%
What is the classic triad for ectopic pregnancies?
Bleeding, pain, palpable adnexal mass
Where do ectopic pregnancies most often occur?
Fallopian tubes (95%) - most commonly in ampullary portion (70%)
What is the rarest ectopic?
C-section scar
What is a heterotopic pregnancy?
One normal IUP and one ectopic - the IUP survives in 66% of all heterotopics
Absence of an IUP with BhCG above what level should prompt careful evaluation for ectopic pregnancy?
1500-2500 mIU/mL
What SF is the most obvious indicator of an ectopic?
Free fluid
What are the three treatments for ectopics?
1) Expectant management - when there is no GS and BhCG levels decline
2) Medical treatment - those whos BhCG <5000 and hemodynamically stable
3) Surgical treatment - for those hemodynamically UNSTABLE
What drug is used for medical treatment for an ectopic?
Methotrexate
How many week is pregnancy vs how many weeks INCLUDING LMP
38 weeks pregnant
40 weeks includes LMP
Fertilization occurs in the ampullary portion of the fallopian tube how many hours after ovulation?
24-36
Implantation occurs how many days after conception?
6 days
What vessels are formed by the blood vessels of the allantois?
Umbilical arteries
The yolk sac cells contribute to the development of what fetal systems? (3)
Respiratory
Digestive
Urogenital
By the end of the 5th week/beginning of sixth, the embryo can be detected endovaginally at how man mm in length?
2-4 mm
The intra-decidual sign can be seen how early via ultrasound?
3W 4D
The yolk sac can be seen by EV at how many weeks and transabdominally at how many weeks?
EV - 5 wks
TA - 6-7 wks
What fetal head structure appears as a diamond shaped sonolucent structure posteriorly at 7 wks?
Rhombencephalon
What is the average HR of a fetus at 5 wks GA?
110
What hormone do we detect in pregnancy?
A) Alpha - HCG
B) Beta - HCG
Beta
What kind of ectopic pregnancy has a 2.5-5x greater probability of hemorrhage?
A) Cornual
B) Interstitial
C) Intramural
D) Ampullary
Interstitial because it’s close to uterine arteries
Abdominal Pregnancies have been reported in what structures?
- Uterine surface
- Spleen
- Liver
- Diaphragm
- Bowel
- Omentum
- Broad Ligament
- Large Vessels
- Cul- de-sacs
How do you differentiate between a pseudosac and true GS?
True GS - vascular and has double decidual sac sign
Pseudo - Avascular and only single sac sign
DZ twins make up 70% of twins and are influenced by what factors?
- AMA
- Genetic
- Environmental
- ART
Dizygotic twins will always have two?
A) Chorions
B) Amnions
C) Placentas
Placentas - the number of chorions = the number of placentas
2 placentas =2 chorions = DC/DA
What sign represents a Di/Di pregnancy?
Lamda/twin peak sign
What sign represents a Mono/di pregnancy?
T-sign
Number of YS will be the same number as?
A) GS
B) Amnions
C) Placentas
D) Chorions
Amnions
At how many weeks is amnionicity and chorionicity determined?
11-14 weeks
What is TRAP sequence?
Twin Reversed Arterial Perfusion AKA Acardiac twinning
One twin = pump twin
Other twin = acardiac twin
Arterial-to-arterial and venous-to-venous anastomoses occur on the surface of the shared placenta
What are some SF in TRAP sequence?
- Polyhydramnios
- Acardiac twin only has lower extremities and pelvis
- Retrograde UA flow into acardiac twin
- CHF in normal twin due to increased load
What is TTTS?
Twin to Twin transfusion syndrome
Donor twin - returning blood from donor twin gets shunted directly to recipient. Donor twin becomes smaller with Oligo
Recipient - gets larger with Poly
What abnormality causes the appearance of a “stuck twin” ?
TTTS
What type of twins have the highest risk of cord entanglement, TTTS, premature birth & congenital
abnormalities?
A) DC/DA
B) MC/DA
C) MC/MA
MC/MA
The majority of multiple gestations are due to what?
ART
What percentage of twins will have a vanishing twin in the first trimester?
20%
What abnormality in known as fetal loss occurring in the second or third trimester or within a MZ twin gestation and appears ‘paper like’ ?
Fetus Papyraceus
What type of pregnancy occurs with TRAP sequence? What type of pregnancy occurs with TTTS?
TRAP - MC/MA
TTTS - MC/DA - usually presents in 2nd trimester
What is the normal measurement of a yolk sac?
2-6mm
In early pregnancy, size of gestational sac should increase by how many mm per day?
A) 1mm
B) 2mm
C) 3mm
D) 4mm
A
Nuchal translucency should not exceed what measurement?
A) 2.0mm
B) 2.5mm
C) 3.0mm
D) 3.5mm
2.5mm
What is the most dangerous type of ectopic pregnancy?
A) Ampullary
B) Interstitial
C) Ovarian
D) Fimbrial
Interstitial as it’s such close proximity to uterine artery
What is seen with a “double bleb” sign?
A) Amnion and chorion
B) Amnion and YS
C) Chorion and YS
D) Two gestational sacs
Amnion and YS
When does normal embryonic gut herniation occur?
A) 5 wks
B) 6 wks
C) 7 wks
D) 8 wks
D - 8 wks
What linear structure can be seen connecting the embryo and YS?
A) Amniotic band
B) Chorionic villi
C) Umbilical cord
D) Vitelline duct
D
Prior to the 2nd trimester, what abnormality can pregnancy induced hypertension be a cause of?
Molar pregnancy
In what portion of the fallopian tube does fertilization occur?
Ampullary - 24 to 36 hours after ovulation
A MSD of 2-3mm correlates to what GA?
A) 4 weeks
B) 5 weeks
C) 6 weeks
D) 7 weeks
B
MSD grows by how much per week?
A) 0.5mm
B) 1mm
C) 1.5mm
D) 2mm
1mm/week
How much do embryos grow per day?
A) 0.5-1mm
B) 1-1.5mm
C) 1-2mm
D) 2-3mm
1-2 mm/day
