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ARDMS Obstetrics
What is the first trimester risk sonographic examination also called? - The nuchal translucency examination What does the nuchal translucency examination measure? -
- Measurement of the nuchal translucency
- CRL (Crown-Rump Length)
- Visualization of the fetal nasal bone What does the standard obstetric sonography examination evaluate? -
- Gestational age by fetal biometry
- Fetal number
- Placental position
- Cardiac activity
- AFI (Amniotic Fluid Index)
- Fetal anatomic survey Define gravidity - The number of pregnancies Define parity - A numeric system that describes all possible pregnancies What are the numbers representing in the parity numeric system? -
- Full term pregnancies
- Premature births and stillborns
- Miscarriages or termination
- Living children What is the standard way to date a pregnancy? - LMP (Last Menstrual Period) Pregnancy is divided into how many trimesters? - 3 How long is the first trimester? - From beginning of the pregnancy to 13 weeks and 6 days. How long is the second trimester? - From 14 weeks to 26 weeks and 6 days. How long is the third trimester? - Begins at 27 weeks gestation until term. What is Nagele's rule? - EDD (Estimated Due Date) = 3 months from LMP + 7 days
What fetal biometry is used in the estimate in fetal weight? - AC (Abdominal Circumference) What is conceptual age also known as? - Embryonic age What is conceptual age? - With conception as the first day of pregnancy What is gestational age? - Considers the first day of the last menstrual period as the beginning of gestation What is gestational age also known as? - Menstrual age What is the conceptus called during the implantation process? - A zygote What is the zygote called from the implantation to 10 weeks? - An embryo What is the embryo called after the 10 weeks? - A fetus What is the cell division process of a zygote? - 1.Rapid cellular division forms the 16-cell morula 2.Further division brings the morula to the blastocyst stage 3.The blastocyst contains trophoblastic calls. 4.The trophoblastic cells begin to secrete hCG True or False hCG levels plateau and decline while normal gestation continues. - True Increased hCG levels can be used s a screening marker for Down syndrome during the first and second trimester. What does the anechoic center is the first trimester represent? - Chorionic cavity What does the echogenic rim surrounding the chorionic cavity represent in the first trimester ultrasound? - Desidual reaction What is the first structure seen in the intragestational sac? - The secondary yolk sac
What appears in the 5th week of gestation? - Yolk sac What is seen in the 5.5-6 weeks of gestation? - Fetal heartbeat What is two structures are seen sonographically in the 7.5 weeks of gestation? - -Spine -Lower limbs When are the upper limbs seen sonographically? - 8 weeks When are the the body movements and midline falx seen? - 9 weeks What is seen sonographically in the 9.5 week of gestation? - -Midgut herniation -Choroid plexus -Hindbrain What forms the fourth ventricle and part of the aqueduct of Sylvius? - The enclosing of the rhomboid fossa by the medulla, medullar oblongata, and the cerebellum. What is the first organ to function within the embryo? - The fetal heart What parameters for a first trimester sonographic gestational dating may be used? -
- CRL (Crown-Rump Length)
- MSD (Gestational sac size) How should a sonographer measure the MSD? - The sonographer should only measure the gestational sac fluid space not the echogenic decidua. How to calculate the MSD - Length (mm) + Width (mm) / 3 = MSD How to calculate the menstrual age - MSD (mm) + 30 = Menstrual age (days) Menstrual age (days) / 7 = Menstrual age (weeks) What is the marker for the beginning of CRL measurements? -
The embryonic heart motion The CRL is considered accurate until what week? - 12th week Why is the CRL not considered accurate after 12 weeks? - Because at this time the fetus begins to "curl" into the fetal position, making the measurement of length more difficult. What measurements are used after 13 weeks (second trimester) for pregnancy dating? -
- BPD (Biparietal Diameter)
- FL (Femur Length) What combined test is the standard for first trimester risk assessment? -
- Maternal age
- The nuchal translucency measurement
- Biochemistry analyses for hCG and PAPP-A What is the small pocket of fluid along the back of the fetus? - Nuchal translucency What sonographic appearance is associated with trisomy 21 in the first trimester? - Absence of the fetal nasal bone True or False A multiple gestation pregnancy is a high risk pregnancy - True Twin gestations have a seven to ten times greater mortality rate then singletons. *This risk increases when the twins are monozygotic and share membrane components How would a dichorionic and diamniotic twin appear sonographically? - Appear as two separate gestational sacs with individual trophoblastic tissue. *Which allows the appearance of thick dividing membrane. How would a monochorionic and monoamniotic twin appear sonographically? - Appear as one gestational sac containing: -One yolk sac -One amniotic membrane -Two embryos within a single amniotic cavity What may an early sign of twin-to-twin transfusion? - Differences in the NT measurements Define threatened abortion - Pregnancies of fewer than 20 weeks with a: -Heartbeat
A large empty gestational sac that does not demonstrate a yolk sac, an amnion, or an embryo. Define gestational trophoblastic disease - A proliferative disease of the trophoblast that occurs after an abnormal conception. What are the three types of the benign form of gestational trophoblastic disease, called hydatiform? - -Partial -Complete -Coexistent What is the more malignant form called in gestational trophoblastic disease? - Invasive mole OR choriocarcinoma What is the clinical hallmark for gestational trophoblastic disease? - -Vaginal bleeding -Serum levels of beta-hCG are dramatically elevated In which hydatiform mole will the serum alpha-fetoprotein levels be notably low? - Complete hydatiform mole How does a partial hydatiform mole commonly occur? - When a normal egg is fertilized by two sperm. *Fetal parts mat develop concurrently with abnormal trophoblastic disease. How does a complete hydatiform mole commonly occur? - When an egg is without a nucleus is fertilized by one normal sperm. *Trophoblastic tissue proliferates, but no fetal parts ever develop. What is the sonographic hallmark of a hydatiform mole? - "Snowstorm" appearance What is the sonographic appearance of molar pregnancy? - -Moderately echogenic soft tissue filling the uterine cavity that is filled with small cystic spaces representing chorionic villi. *May not be apparent initially, but will present with advancing time. -May reveal an enlarged uterus larger than dates and filled with heterogenous patter (Cluster of grapes) -Bilateral adnexal fullness that may represent ovarian enlargement of THECA LUTEIN CYST What is the primary treatment of a molar pregnancy? - Uterine curettage followed by serial serum hCG levels Describe the sonographic appearance of partial mole? -
-Placenta is grossly enlarged and engorged in cystic spaces *Which represent the hydraulic villi. What cyst is commonly reported with molar pregnancies? - Theca lutein cyst *Will be demonstrated as enlarged ovaries with multiple cystic areas throughout What are the terms used for the malignant forms of trophoblastic disease? - -Invasive mole -Choriocarcinoma When does an invasive mole occur? - When the hydraulic villi of a partial or complete hydatiform mole invade the myometrium and may further the uterine wall. If the invasive mole is persistent postoperatively what is it referred to as? - Persistent trophoblastic disease What are the clinical symptoms of a molar pregnancy? - -Vaginal bleeding -Dyspnea -Abdominal pain Choriocarcinoma is a fast growing tumor and commonly metastasizes to the ______, _____, and _____ - -Lungs -Liver -Brain Variations in embryonic cardiac rate during the first trimester range between - beats per minute -
Cardiac rates less than 90 within the first trimester is considered _____. -
- To have a poor prognosis Where does the embryonic disk lie? - Between the amnion and the yolk sac Define an ectopic pregnancy - A pregnancy located outside of the central/fundal of the uterus. What are the classical clinical findings associated with an ectopic pregnancy? - -Vaginal bleeding -Empty uterus
Describe the sonographic hallmark of acrania? - "Mickey Mouse" head Define anencephaly - Congenital absence of the brain and cranial vault With the cerebral hemispheres missing or reduced to small masses Define cephalocele - A midline cranial defect in which there is a herniation of the brain and meninges Define ventriculomegaly - Dilation of the ventricular system WITHOUT enlargement of the cranium What is the sonographic hallmark of ventriculomegaly - The choroid plexus is shown to be "dangling" within the dilated lateral ventricle Define holoprosencephaly - The failure of the prosencephalon differentiating into cerebral hemispheres and lateral ventricles between the 4th-8th gestational weeks. What are the different types of holoprosencephaly? - -Alobar -Semilobar -Lobar Which of the three types of holoprosencephaly is the most severe? - Alobar What does lobar holoprosencephaly consist of? - -Single ventricle -Small cerebrum -Fused thalami -Agenesis of the corpus callosum and falx cerebri What is the normal fetal brain appearance before 9 weeks? - Appears to have a single ventricle until the falx cerebri develops. *After 9 weeks. Define Dandy-Walker malformation - Results from cystic dilation of the fourth ventricle. With: -Dysgenesis or complete agenesis of the cerebellar vermis -Frequent hydrocephaly When does Dandy-Walker malformation occur? -
6th-7th week Describe Dandy-Walker malformation sonographically - -Large posterior fossa cyst continuos with the 4th ventricle -Absent cerebellum -Dilated third and lateral ventricles. Describe spina bifida - Results from the neural tube failing to close after 6 weeks. Describe spina bifida sonographically - -Spinal irregularities within the posterior contour of the fetal spine. -Extrusion of a mass from the vertebral column. -Lemon sign (scalloping of the frontal bones) -Banana sign (curved appearance of the cerebellum) When will the cranial signs of spina bifida be more appreciated? - 12 weeks Describe the normal bowel herniation sonographically - Will appear as an echogenic mass at the BASE of the umbilical cord between 8-12 weeks Any gut herniation larger than ___ should be considered suspicious and should be followed for resolution after __ weeks and __ days. -
- 6mm
- 11 weeks
- 5 days What anterior wall defect is commonly on the RIGHT of the umbilical cord? - Gastrochesis What anterior wall defect is commonly at the BASE of the umbilical cord? - Omphalocele When does the fetal bladder become sonographically apparent? - 10 - 12 weeks Describe obstructed uropathy sonographically - A very large urinary bladder that may be large enough to extend out of the pelvis and into the fetal abdomen and even protrude outside the body (bladder exstrophy) What is the most commonly seen abnormality seen within the 1st trimester? - Cystic hygroma Cystic hygromas seen early in life have a high association with chromosomal abnormalities. The most common abnormalities are trisomies __, __, __. -
How can a sonographer tell the difference between a uterine contraction and a fibroid? - Observe the focal lesion over time (typically 20-30 minutes), the contraction should disappear whereas a fibroid will persist. Describe a yolk sac sonographically - A small, spherical structure with an anechoic center within the gestational sac. What should a normal yolk sac measure? - 6mm What is the most accurate sonographic measurement during the first trimester? - CRL (Crown Rump Length) Why is the CRL no longer considered accurate after the 12th week of gestation? - Because of the flexion and extension of the active fetus. What is the first and most widely accepted means of measuring the fetal head and estimating fetal age? - BPD (Biparietal Diameter) What level should the BPD be measured at? - At the level of the thalamus and the cave septum pellucidum How should the calipers be placed to measure the BPD? - Outer edge to inner edge (Leading edge) What is another valuable measurement of the fetal head to asses gestational age? - Head circumference What is the cephalic index formula? - BPD/OFDx -Biparietal diameter -Occipitofrontal diameter What is the normal cephalic index? - 75% to 85% Define Brachycephaly - When the head is elongated in the tv plane (BPD) and shortened in the anteroposterior diameter (OFD). If the CI is greater than 85%, what does that suggest? - Brachycephaly Define Dolichocephaly -
The head is shortened in the tv plane (BPD) and elongated in the anteroposterior diameter (OFD). If the CI is less than 75%, what does that suggest? - Dolichocephaly What measurement is more useful as a growth parameter than predicting gestational age? - Abdominal circumference (AC) What level should the abdominal circumference be measured? - In the tv plane at the level of the umbilical vein as it joins the left portal vein within the liver How should an abdominal circumference be measured? - The calipers should be placed along the external perimeter of the fetal abdomen to include subcutaneous soft tissue Which measurement is about as accurate as BPD in determining gestational age? - Femur Length (FL) What parameter can be used when the fetal head cannot be measured? - FL What is considered preterm? - The fetus is born before 38 weeks What is considered term? - The fetus born between 38 and 42 weeks What is considered postterm? - The fetus being born after 42 weeks ________ is best described as a decreased rate of fetal growth. - Intrauterine Growth Restriction (IUGR) What is the difference between SGA (Small for Gestational Age) and IUGR? - SGA describes the fetus with a weight below the 10th percentile without a cause while IUGR is SGA as a RESULT of pathologic processes. What are the two basic clarifications of IUGR? - -Symmetric -Asymmetric Which IUGR is usually the result of a first trimester insult? - Symmetric IUGR
What does severe preeclampsia usually indicate? - -The patient should be delivered immediately What exists if a pregnant woman vomits so much that she develops dehydration and electrolyte imbalance? - Hyperemesis gravidarum What are the 5 signs of fetal death? - -Absent heartbeat -Absent fetal movement -Spalding sign (Overlapping skull bones) -Exaggerated curvature of the spine -Gas in the fetal abdomen What are the two types of twin pregnancies? - -Dizygotic -Monozygotic Dizygotic is also called _____ twins. - Fraternal Monozygotic is also called _____ twins. - Identical Describe a dizygotic twin - Arises from two SEPARATELY fertilized ova and each ovum implants its own: -Placenta -Chorion sac -Amnion sac Describe a monozygotic twin - Arises from a SINGLE fertilized egg resulting in two genetically identical fetuses If the division of monozygotic twins occurs early (0-4 days) post conception there will be _____ and _____. - 2 Amnions (Diamniotic) 2 Chorions (Dichorionic) If the division of monozygotic occurs 4-8 days there will be _____ and _____. - 1 Amnion (Monoamniotic) 2 Chorions (Dichorionic) If the division of monozygotic twins occurs after 8 days there will be _____ and _____. - 1 Amnion (Monoamniotic) 1 Chorion (Monochorionic)
If the division of monozygotic twins occurs after 13 days the division may be incomplete and _____ may result. - Conjoined twins Conjoined twins may be joined at a variety of sites. Name at least 2 different sites. -
- Head
- Thorax
- Abdomen
- Pelvis Which type of monozygotic pregnancy is associated with umbilical cord entanglement, which cuts off the blood supply to the fetuses? - Monoamniotic sac What is the difference between twin-to-twin transfusion syndrome and fetus papyraceous? - Twin-to-twin is the phenomenon where one twin vanishes and the other continues to grow while the fetus papyraceous is when the fetus is too large for reabsorption the fetus is flattened. Name the three genetic testing done to diagnose congenital anomalies -
- Chorionic villus sampling
- Amniocentesis
- Cordocentesis
- Quadruple screen What is a chorionic villus sampling? - It is an ultrasound guided biopsy of the placenta. What are the advantages to CVS (Chorionic villus sampling)? -
- Performed early in the pregnancy (10-14 weeks)
- Results are available within one week; Earlier results allow more options for the parents What is an amniocentesis? - Is a test offered to expectant parents who are at risk for a chromosomal abnormality. In where amniotic fluid is taken from the uterus to be tested for chromosomal abnormalities. When is an amniocentesis performed? - 15 -20 weeks of gestation What is the optimal collection site for an amniocentesis? - Away from the fetus, umbilical cord, placenta, and near the midline to avoid maternal uterine vessels What is a cordocentesis? - A method in which fetal blood is obtained through a needle aspiration of the umbilical cord.
-Cerebellar hyperplasia -Clubbed foot What is Patau's syndrome also known as? - Trisomy 13 What are the common sonographic appearances of trisomy 13? Name at least 3 - -Holoprosencephaly -Heart defects -Cleft lip and palate -Omphalocele -Renal abnl -Meningomyelocele -Micrognathia -Clubbed foot The prognosis of _____ is extremely poor, with 80% of infants dying within the first month. - Trisomy 13 What is triploidy the result of? - An ova fertilized by two sperm What are the common sonographic appearances of triploidy? Name at least 3 - -Hydatiform placental degeneration -Heart defects -Renal abnl -Omphalocele -Cranial defects (Holoprosencephaly, Dandy-Walker Malformation, agenesis of the corpus callosum) -Facial defects (Hypertelorism, cleft lip and palate, and micrognathia) What is a major role of the placenta? - To permit the exchange of oxygenated blood with deoxygenated fetal blood. What are the two components of the placenta? -
- The maternal portion
- The fetal portion What is the maternal portion of the placenta also known as? - Deciduas basalis What is the fetal portion of the placenta also known as? - Chorion frondosum What is the deciduas basalis of the placenta formed by? - The endometrial surface
_____ blood passes through the umbilical vein into the fetal abdomen. - Oxygenated Where is the attachment of the umbilical cord normally placed? - Usually near the center of the placenta What is a battledore placenta? - When the umbilical cord inserts itself at the margin of the placenta, within 10mm from the edge. What velamentous placenta? - An umbilical cord that inserts itself on the membranes What is vasa previa? - What the umbilical cord is positioned across the internal os _____ occurs when the placenta implants itself within the lower uterine segment. - Placenta previa The umbilical cord is surrounded by a mucoid connective tissue called _____. - Wharton's Jelly The normal umbilical cord has one large _____ and 2 smaller _____. - -Vein -Arteries What are Braxton-Hicks contractions? - focal myometrial contractions that may mimic a fibroid. For the sonographer to visualize the internal os of the cervix, a (Sagittal or Transverse) image of the lower uterine segment and cervix should be obtained. - Sagittal When there are additional placental lobes joined to the main placenta by blood vessels _____ should be considered. - Succenturiate lobe What is succenturiate lobe also known as? - Accessory lobe What is placental migration? - The concept that the placenta changes its position within the uterine cavity. A placenta previa should not be diagnosed before __ weeks' gestation. - 20
