Pregnancy Flashcards

Question

Crown rump length vs. fetal heart rate . . . at what length with no hear beat is a pregnancy 100% non-viable?

Answer 1

7mm. If the fetus has no heart beat at \>/=7mm, then fetus is not viable.

Answer 2

* Between 5 and 6 weeks gestation, gestational age is determined based on three typical appearances of the early pregnancy. * gestational sac only (with or without double sac sign): 5.0 weeks. * gestational sac with a yolk sac, but without an embryo: 5.5 weeks. * gestational sac with an embryo \<3 mm and heartbeat: 6 weeks. * For embryos \>3 mm in length, the crown-rump length is used to assign gestational age using established reference tables. The CRL can estimate gestational age up to 12 weeks. After 12 weeks, dating is estimated using multiple fetal measurements.

Answer 3

* An especially dangerous location for an ectopic pregnancy is the interstitial portion of the fallopian tube. * An interstitial ectopic carries an especially high risk of catastrophic hemorrhage due to its propensity for delayed rupture and proximity to the ovarian vessels. * Ultrasound of an interstitial ectopic shows absent myometrium along the lateral edge. The interstitial **line-sign** represents a thin, echogenic line extending from the endometrial canal to the center of the interstitial ectopic mass. This echogenic line is thought to represent the nondistended, empty endometrial canal.

Answer 4

The trunk should fill up entire amniotic sac + smaller pockets are communicating.

Answer 5

* A heterotopic pregnancy is a **simultaneous IUP and ectopic pregnancy**. * Patients undergoing assistive reproductive techniques are at increased risk for heterotopic pregnancy. Prior to the popularity of these fertilization procedures, heterotopic pregnancies were extremely rare. * Given the increased prevalence of assistive reproductive techniques, however, the adnexa must be carefully evaluated even in the presence of an IUP.

Answer 6

* The classic clinical presentation of ectopic pregnancy is a positive pregnancy test, vaginal bleeding, pelvic pain, and tender adnexal mass. This presentation is seen in less than 50% of patients. * Any woman with a newly positive pregnancy test and either pain or bleeding is classified as a rule-out ectopic or clinically suspected ectopic patient and has about a 15% chance of having an ectopic pregnancy before any imaging is performed. * A rule-out ectopic patient may have an intrauterine pregnancy (IUP), ectopic pregnancy, or spontaneous abortion. The IUP may be normal, abnormal, or too early to detect.

Answer 7

* In the absence of an IUP, an adnexal mass has a 92% positive predictive value of being an ectopic. * In the absence of an IUP, an adnexal ring has a 95% positive predictive value of being an ectopic. * An extrauterine embryo (with or without heartbeat) or mass with yolk sac has a 100% predictive value of being an ectopic. * The nonspecific ring of fire sign describes increased peripheral color doppler flow surrounding an adnexal mass. This sign is rarely helpful as it can be seen in both ectopic pregnancy and corpus luteum. * In a rule-out ectopic patient, an ovarian mass is overwhelmingly more likely to be a corpus luteum than an ectopic pregnancy unless a definite embryo or yolk sac is identified. In contrast, an extra-ovarian mass would be concerning for ectopic. In ambiguous cases, it may be helpful to gently apply pressure with the ultrasound probe and watch for movement of the mass with respect to the ovary to identify if a mass is ovarian or adnexal in origin.

Answer 8

* Gestational trophoblastic disease, also called hydatidiform molar pregnancy (or molar pregnancy for short), is an invasive neoplastic overgrowth of the trophoblast into the myometrium or beyond. The trophoblast normally develops into the placenta. * The classic clinical presentation of molar pregnancy is **hyperemesis, markedly elevated hCG, and an enlarged uterus.** The patient may also present with painless vaginal bleeding. * On ultrasound, molar disease causes **uterine enlargement with a classic heterogeneous and multicystic snowstorm appearance**. visualization of fetal parts suggests a partial mole. * Treatment of a molar pregnancy is **endometrial suction curettage and close follow-up of serum hCG levels**.

Answer 9

* Complete hydatidiform mole does not contain any fetal parts. It is caused by loss of the egg’s DNA prior to fertilization by the sperm and has a diploid karyotype of 46,XX (most commonly) or 46,XY. Pathoma MNEMONIC: "Completely the dad's fault and the one that has risk of progressive to metastatic chorioCA * A complete mole may progress to **metastatic choriocarcinoma**. * Molar pregnancy is associated with **theca lutein cysts, which arise in response to elevated** **hCG****.**

Answer 10

* Chorioadenoma destruens is a complete mole that invades the myometrium.

Answer 11

* Partial hydatidiform mole is associated with some fetal development. It is usually caused by two sperm fertilizing the same egg and has a triploid karyotype of 69,XXX, 69,XXY, or 69,XYY. * Partial mole is less likely to progress to choriocarcinoma.

Answer 12

* Retained products of conception are placental or fetal tissues that remain the uterus after delivery, miscarriage, or termination. * Untreated RPOC can lead to continued **maternal bleeding and endometritis.** * The sonographic findings of an endometrial blood clot and RPoC overlap and it is often not possible to differentiate between these two entities. An endometrial mass, with or without Doppler flow, in the appropriate clinical context has only about a 50% positive predictive value. The presence of Doppler flow is not diagnostic of RPOC, as endometrial color doppler flow can be detected in the presence or absence of RPOC. * Color Doppler flow is seen more commonly with RPOC, however. * A normal-appearing uterus, with an endometrial thickness of less than 10 mm, is highly unlikely to contain RPoC.

Answer 13

* The zygosity (number of fertilized eggs) cannot always be determined by ultrasound. * Monozygotic twins can have any placentation type, depending on when the developing zygote splits. dizygotic twins, however, are always diamniotic/dichorionic, and only dizygotic twins can be different sexes. * Monozygotic (“identical”) twins arise from a single egg fertilized with a single sperm. * Dizygotic (“fraternal”) twins arise from two individually fertilized eggs. * Dizygotic twins are always dichorionic/diamniotic.

Answer 14

* onozygotic twins are the result of splittng of the blastocyst or embryo, formed by fertilization of a single egg by a single sperm. Although “identical” monozygotic twins are always the same sex, they may not be identical phenotypically due to local differences in the uterine and placental environment. * 33% split early (0-4 days), before the formation of either the placenta or amnion, leading to dichorionic-diamniotic twins. * 66% split intermediate (4-8 days), after formation of the placenta but before the amnion has developed, leading to monochorionic-diamniotic twins. * 1% split late (\>8 days), after formation of the chorion and amnion, leading to monochorionic-monoamniotic twins. * Very late splitting may result in conjoined twins, which are always monochorionic/monoamniotic.

Answer 15

* Di/di twins each have a separate placenta and amniotic sac. * On ultrasound, two placentas can usually be separately identified. * The **inter-twin membrane will be relatively thick** as there are two layers of chorion and two layers of amnion separating each twin. * In the second and third trimesters, the thickness of the inter-twin membrane is less reliable to determine chorionicity because the membrane becomes thinner as gestation progresses. * The **twin peak sign (also called lambda sign)** represents a triangle-shaped placental infolding at the interface of the placenta and the thick inter-twin membrane that is seen in di/di twins. The twin peak sign is most useful when it is difficult to distinguish two placentas. * If the twins are different sexes, they must be dizygotic twins, which are always di/di.

Answer 16

* Mono/di twins share a placenta, but have separate amniotic sacs. * The shared placenta is usually apparent on ultrasound. * The **inter-twin membrane is thin**, as it is composed of only two layers of amnion.

Answer 17

* ono/mono twins share both a placenta and a single amniotic sac. * mono/mono twins have a shared placenta with no intervening membrane between the twins. Intertwined cords are diagnostic of mono/mono placentation when seen. * Isolated lack of visualization of an inter-twin membrane is not sufficient to diagnose mono/mono twins. If no inter-twin membrane (or intertwining cord) is seen, then the amnionicity cannot be determined. Because mono/mono twins are so rare, it is more common to have mono/di twins with non-visualization of the inter-twin membrane.

Answer 18

* Conjoined twins are caused by late (\>13 days) incomplete division of the embryo.

Answer 19

* Twin-twin transfusion syndrome (TTTS) is a complication of monochorionic twins (either mono- or di-amniotic) caused by disproportionate blood flow between the fetuses. * The donor twin transfers excess blood flow to the recipient twin. The donor twin is small and has oligohydramnios. The recipient twin is larger and has polyhydramnios. * There are three criteria to diagnose TTTS by ultrasound: * **Disproportionate fetal sizes, with at least 25% discrepancy.** * **Disproportionate amniotic fluid, with the small twin having oligohydramnios and the large twin having polyhydramnios.** * **Single shared** **placenta** **(monochorionic).** * There is a spectrum of severities of TTTS. In the earliest stages, the donor twin’s bladder is still visible and the direction of umbilical artery doppler flow is normal. Later stages are marked by fetal hydrops or death.

Answer 20

* Treatment options of TTTS include laser ablation of placental arteriovenous fistulas, therapeutic amniocentesis from the recipient (large, poly) twin, or selective coagulation of the umbilical cord of the less viable twin.

Answer 21

* A stuck twin describes severe oligohydramnios in the donor (small) twin. A stuck twin has so little amniotic fluid that the amnion is wrapped around the twin like shrink wrap.

Answer 22

* Acardiac twinning, also called twin reversed arterial perfusion (TRAP) sequence, is a severe variant of twin-twin perfusion syndrome. Similar to TTTS, acardiac twinning is a complication of monochorionic twins (either mono- or di-amniotic). * In acardiac twins, the donor fetus supplies circulation to itself and an acardiac twin, enabled by placental fistulous connections. The acardiac twin has rudimentary or no development of structures above the thorax. * Doppler of the umbilical arteries and vein shows reversed flow in the acardiac twin. * Normally, the umbilical arteries carry deoxygenated blood out of the fetus, pumped by the fetal heart. In the acardiac twin, the umbilical arteries carry nutrient-depleted, poorly oxygenated blood into the fetus, pumped by the donor twin’s heart. doppler of the acardiac twin’s umbilical arteries show an arterial waveform going into the fetus. * Normally, the umbilical vein carries oxygenated blood into the fetus, from the placenta. In the acardiac twin, the umbilical vein carries deoxygenated blood out of the fetus. doppler of the acardiac twin’s umbilical vein shows a venous waveform going out of the fetus. * Treatment is the coagulation of the acardiac twin’s umbilical cord.

Answer 23

* When one monochorionic twin dies in utero, the surviving twin is at risk for twin embolization syndrome, which can cause CNS, gastrointestinal, or renal infarcts. * In general, the prognosis for a surviving monochorionic twin is very poor when one twin dies in utero. In contrast, the prognosis is generally good for a surviving dichorionic twin when one twin dies in utero.

Answer 24

* The crown-rump length (CRL) is used to assign gestational age from 6-12 weeks. measuring the CRL is straightforward in the first trimester as the fetus cannot flex or extend the neck.

Answer 25

* By 8 weeks, the forebrain (prosencephalon) can be distinguished from the hindbrain (rhombencephalon). Both prosencephalon and rhombencephalon are hypoechoic, although the rhombencephalon is much more prominent. Absence of these structures may be the earliest finding of anencephaly.

Answer 26

* The midgut normally herniates through the ventral abdominal wall in the first trimester. during this herniation, the midgut rotates 270 degrees around the axis of the superior mesenteric artery. * Physiologic midgut herniation is usually complete by 12-13 weeks. Therefore, a pathologic ventral wall defect, such as omphalocele or gastroschisis, is generally not diagnosed before 13 weeks. * It is common to see some fullness at the base of the umbilical cord before 13 weeks, which usually represents physiologic midgut herniation. If the fullness is especially prominent then it may be prudent to bring the patient back for a follow-up at 13 weeks to evaluate for a true ventral wall defect.

Answer 27

* Increased thickness of the nuchal translucency is associated with increased risk of down syndrome and other chromosomal abnormalities. With a fixed false-positive rate of 5%, nuchal translucency alone can detect approximately two-thirds of cases of trisomy 21. * The nuchal lucency must be measured properly to obtain an accurate value.d * At 11 weeks, the upper limit of normal is 2.2 mm. * At 14 weeks (CRL 79 mm), the upper limit of normal is 2.8 mm. * Nuchal translucency is combined with maternal serum testing to calculate an overall risk of trisomy 21.

Answer 28

* A thickened nuchal fold is the most sensitive and specific ultrasound finding to suggest down syndrome. * Compared to nuchal lucency, measurement of nuchal fold is performed later in pregnancy. In contrast to the nuchal lucency, the nuchal fold is measured in the axial plane at the level of the posterior fossa. * The nuchal fold is only measured from 16-20 weeks. * 5 mm is normal. * 5-5.9 mm is borderline. * 6 mm is a major marker for trisomy 21. * A very thick nuchal fold may represent a cystic hygroma, which is associated with Turner syndrome (45,X).

Answer 29

* Shortening of the cervix is a risk factor for pre-term delivery. **A cervical length \<3 cm is abnormal**. The presence of cervical funneling (change in shape) is an ancillary finding. * The mnemonic *trust your vaginal ultrasound* can be used to remember the sequence of cervical funneling. A T -shaped cervix is normal. As funneling progresses, the cervix resembles Y, V, and U shapes. * Prior to viability (24 weeks), treatment is cervical cerclage. After 24 weeks, treatment tends to be conservative (bedrest) due to concern for membrane rupture with any procedure.

Answer 30

* The normal umbilical cord has **two umbilical arteries and a single umbilical vein**. * A single umbilical artery is associated with fetal anomalies (most commonly cardiovascular) in up to 50% of fetuses. * There is an increased incidence of a single umbilical artery in **trisomies 13 and 18.**

Answer 31

* Placental thickness is not routinely measured, but in fetal hydrops the placenta may become thickened. * In polyhydramnios, the placenta usually becomes stretched and thinned. In the presence of polyhydramnios, if the placenta looks normal in thickness, or especially if the placenta looks thickened, concern should be raised for fetal hydrops.

Answer 32

* Vasa previa is the traversing of fetal placental vessels across the internal cervical os, which can be caused by velamentous insertion or a placental succenturiate lobe. * **Velamentous insertion** is the insertion of the umbilical cord outside the margin of the placenta. * A **succenturiate lobe** is an island of placental tissue separate from the main placenta, connected to the main placenta by blood vessels.

Answer 33

* Placental abruption is premature separation of the placenta from its uterine attachment. * There is an increased incidence of abruption in maternal hypertension, drug abuse, trauma, or rapid decompression of a distended uterus (e.g., from a large-volume amniocentesis). * A subchorionic hematoma is a variant seen early in pregnancy, where a hypoechoic crescent is present around the gestational sac. * Placental abruption can have variable ultrasound findings and may even appear normal. Because a normal ultrasound is seen in 20% of cases of abruption, a negative ultrasound cannot exclude abruption. Typically, ultrasound of abruption shows a placental hematoma, which can be subchorionic (most commonly), retroplacental, or pre-placental. On clinical exam, blood may be present in the vaginal canal.

Answer 34

* Placenta accreta is a spectrum of abnormally tenacious or deep attachment of the placenta into the myometrium, carrying a risk of hemorrhage at the time of placental separation. * Accreta is thought to be caused by scarring (which may be secondary to prior C-section, D&C, endometritis, or adenomyosis) and resultant endometrial deficiency. It is especially important to **consider** **accreta** **if an anterior placenta is present with a history of prior C-section.** Placenta previa also increases the risk of accreta. * In placenta Accreta, the placenta Attaches deeply into the myometrium but does not invade. * Ultrasound shows thinning or absence of the normal hypoechoic subplacental zone. * In placenta **i**ncreta, the placenta **i**nvades into the myometrium. * In placenta **P**ercreta, placenta Penetrates through the myometrium and into or through the serosa.

Answer 35

* Ultrasound findings of accreta include l**oss of the normal retroplacental clear space, abnormalities at the bladder/placental interface, and prominent vascular lacunar spaces**. The presence of a **moth-eaten placenta with vascular lacunar spaces near the bladder is highly specific for** **accreta**.

Answer 36

* Hydrops is a fluid-overload state characterized by at least two of the following: * Ascites, pleural or pericardial effusion, skin thickening, polyhydramnios, and placental enlargement. * Hydrops may be classified as immune or non-immune. Prognosis is variable but tends to be poor for non-immune hydrops.

Answer 37

* Identify chambers (find spine -\> descending aorta -\> that's next to left atrium) * Evaluate size of chambers / heart (chamber diameters should be equal [r. atrium can be larger], black blood should go down to apex of left ventricle, and heart (transverse cardiac diameter) should be around 1/3 of transverse thoracic diameter) * Look for a mediastinal shift (mentally draw a line from spine to anterior midline [only the right atrium is predominantly on the right hemithorax) * Check for heart axis (draw a line through interventricular septum and the angle made between this line and the line from spine to anterior midline should be ~ 45 degrees). * Check situs (apex and stomach on the same side)

Answer 38

It should cause oligo but it actually causes polyhydramnios!

Answer 39

* Abnormalities that interfere with swallowing and absorption * CNS anomalies * GI tract obstruction * Neuromuscular disorders * Conditions associated with increased perfusion * Twin-Twin Transfusion syndrome * Macrosomia (most common fetal cause of polyhydramnios) * large teratomas * Rh Isoimmunization * Maternal Diabetes * Idiopathic

Answer 40

* Twin Genders: any * Chorionicity/Amionicity: DC/DA * Zygosity: either

Answer 41

* Chorionicity/Amionicity: DC (fused)/DA * Zygosity: DZ

Answer 42

* Twin Genders: any * Chorionicity/Amionicity: DC/DA * Zygosity: either (because DC/MA does not exist! and you're just not seeing the membrane)

Answer 43

* Chorionicity/Amionicity: * DC (fused)/DA **(****thick "double-peak" membrane sign)** * or * MC/DA **(thin membrane)** * Zygosity: DZ or MZ (ie either as above) Beware! The membrane may get thinner in late pregnancy!

Answer 44

* Immune-mediated hydrops is fetal hemolytic anemia caused by prior maternal exposure to fetal antigens, by far most commonly the Rh antigen. * Prognosis is good if treated with intrauterine or peripartum fetal blood transfusions.

Answer 45

* Non-immune hydrops can be due to a diverse array of causes, most of which lead to a common pathway of extracellular fluid overload. Prognosis of non-immune hydrops tends to be poor, as the primary cause is often not effectively treatable. * Etiologies include * **Primary cardiac abnormalities**, including structural abnormalities and arrhythmias. * **Extra-cardiac** **shunt**, including vein of Galen malformation, hepatic hemangioendothelioma, and twin-twin transfusion syndrome, all of which may lead to high-output cardiac failure. * **Infectious**, especially parvovirus B19 and TORCH infections. * Decreased oncotic pressure, due to hepatitis and fetal nephrotic syndrome. * Increased capillary permeability, which can be due to anoxic injury. * Venous obstruction, seen in Turner (45,XO) syndrome.

Answer 46

* When seen with other abnormalities, ascites is one of the criteria for the diagnosis of hydrops. * Isolated fetal ascites may be due to urinary obstruction and resultant calyceal or bladder rupture or meconium peritonitis. * Fetal pleural effusion is a criterion for the diagnosis of hydrops. * When seen in isolation fetal pleural effusion is most commonly caused by congenital chylothorax. Fetal * Chylothorax is thought to be due to thoracic duct or lymphatic malformation. At birth the pleural fluid is simple, but after the baby begins to drink milk it becomes chylous. * Fetal pleural effusions can also be seen in Turner or down syndromes.

Answer 47

* Oligohydramnios is too little amniotic fluid. * Oligohydramnios may lead to Potter sequence, which describes the typical malformations induced by confinement from oligohydramnios including facial dysmorphism, pulmonary hypoplasia, club feet, and musculoskeletal contractures. * Most commonly, oligohydramnios is associated with intrauterine growth restriction (IUGR) without a fetal structural anomaly. * Although malformations are relatively uncommon, the genitourinary system must be carefully evaluated in the setting of oligohydramnios. * Several genitourinary anomalies may lead to oligohydramnios, including: * Renal agenesis - fatal if bilateral. * Congenital bladder outlet obstruction, including posterior urethral valves. * Bilateral ureteropelvic junction obstructions. * Renal dysplasias, including ARPKD.

Answer 48

* Polyhydramnios is too much amniotic fluid. * Greater than half of cases of polyhydramnios are idiopathic, with a normal fetus. The remainder may be associated with chromosomal abnormalities, diabetes, or structural defects (primarily of the gastrointestinal tract), including: * Primary upper gI obstruction or atresia, such as laryngeal, esophageal or duodenal atresia. * Secondary obstruction, due to diaphragmatic hernia, gastroschisis, or omphalocele. * Severe CNS anomalies (which often cause disorders in swallowing). * Monochorionic twin syndromes, such as twin-twin transfusion syndrome. * Placental abnormalities, such as chorioangioma. **Chorioangioma** is a benign placental hemangioma that may cause polyhydramnios when highly vascular.

Answer 49

* Throughout gestation, the lateral ventricles should each measure less than 10 mm when measured at the atrium. The atrium is the confluence of the lateral ventricle, temporal horn, and occipital horn. The normal choroid plexus has a rounded border in this location. * Ventriculomegaly is \>10mm; Mild ventriculomegaly: **10**-12 mm; moderate: 12-15 mm; marked: \>15 mm * Normally, the choroid plexus fills the lateral ventricle. The **dangling choroid sign** represents the dependent drooping of choroid plexus seen in ventriculomegaly. * ventriculomegaly may be present even in a ventricle measuring \<10 mm if there is \>3 mm of fluid between the medial margin of the ventricle and the choroid. * Ventriculomegaly is a sign that something else is wrong, with a diverse array of etiologies: * Primary CNS structural (aqueductal stenosis, Dandy-Walker, Chiari II, holoprosencephaly, agenesis of the corpus callosum). * Genetic (trisomies 13 and 18). * Destructive (due to infection, hemorrhage, or infarct). * Idiopathic.

Answer 50

* Anencephaly is a lethal anomaly with complete lack of development of fetal cerebral cortex and calvarium above the orbits. * AFP is elevated in anencephaly, as there is direct exposure of neural tissue to the amniotic fluid. * Anencephaly may cause polyhydramnios due to impairment in swallowing. * Angiomatous stroma is residual neural-type tissue that may be tethered above the head and may be confused with an encephalocele. * The differential of anencephaly is amniotic band syndrome, which is almost always asymmetric.

Answer 51

* A cephalocele is a midline neural tube defect characterized by protrusion of intracranial structures outside of the calvarium. The occipital skull is the most common location. * A meningocele contains only meninges. An encephalocele also contains neural tissue. * In addition to cephalocele, the primary differential consideration of a mass posterior to the occipital skull is a cystic hygroma, which is a congenital lymphatic malformation and the most common fetal neck mass.

Answer 52

* Dandy-Walker is a diverse spectrum of diseases characterized by **hypogenesis of the cerebellar vermis and resultant fourth ventricular dilation.** * Dandy-Walker is associated with agenesis of the corpus callosum. MNEMONIC: Dandy-Walker? Think of Johny Walker whiskey, which is a fluid, just like whats in the posterior fossa!

Answer 53

* Chiari II is the combination of a small posterior fossa and a neural tube defect. **By far the most common associated neural tube defect is a lumbar myelomeningocele**. A myelomeningocele contains both neural elements and meninges. * The **banana sign** describes the characteristic flattened cerebellar hemispheres in the small posterior fossa. The banana sign is very specific for Chiari II. In fact, if the banana sign is seen, then a myelomeningocele is presumed to be present even if not identified on ultrasound. * The **lemon sign** describes flattening of the frontal bones, causing the calvarium to have the morphology of a lemon when seen axially. Unlike the banana sign, the lemon sign is not specific for Chiari II.

Answer 54

* Holoprosencephaly is failure of midline cleavage of the primitive prosencephalon in early embryologic development. The most severe form, alobar holoprosencephaly, leads to fused thalami and a single monoventricle that may communicate with a large dorsal cyst. Brain tissue surrounds the monoventricle, forming a characteristic **boomerang shape**. * Holoprosencephaly is associated with trisomy 13, facial hypoplasias, and midline facial anomalies including clefts.

Answer 55

* Hydranencephaly is complete cortical destruction due to infarct or infection. The brain parenchyma is obliterated and replaced by fluid. * The most common cause of hydranencephaly is in utero complete occlusion of the MCA. * In contrast to severe hydrocephalus, a cortical mantle is absent in hydranencephaly. * In contrast to holoprosencephaly, a falx is typically visualized in hydranencephaly.

Answer 56

* Cysts within the choroid plexus are common (seen in 1-5% of fetal surveys). The vast majority of choroid plexus cysts are present in normal fetuses and resolve on follow-up scans. However, up to 50% of trisomy 18 fetuses will have choroid plexus cysts. * Choroid plexus cysts can be considered an incidental finding in the absence of any other sonographic abnormality and with a normal maternal serum screen. * A potential mimicker of a choroid plexus cyst is the spongy choroid, which describes a heterogeneous echogenic choroid that is a normal variant. * Also, a scary pitfall is subependymal hemorrhage! (ie from minifellow) A more chronic SEH looks cystic! Use anatomy to differentiate this (ie the choroid plexus is not in the frontal horns it's in the atrium).

Answer 57

* Vein of Galen malformation is **dilation of the vein of Galen (in the pineal region) caused by an arteriovenous fistula.** * Vein of Galen aneurysm is a shunt lesion that may cause **high-output cardiac failure, leading to hydrops.**

Answer 58

* Congenital diaphragmatic hernia (CDH) is herniation of abdominal organs (most commonly bowel) into the thorax through a diaphragmatic defect. CDH is the most common fetal intrathoracic mass lesion. * Most cases are isolated anomalies; however, a prominent minority of fetuses have other anomalies, most commonly congenital heart disease. * By far, the most common location for CDH is the left posterior thorax, called a Bochdalek hernia (mnemonic: “back to the left”). A Bochdalek hernia may displace the heart. * When a CDH occurs on the right it is called a Morgagni hernia. The diaphragmatic defect of a Morgagni hernia tends to be anterior, with the liver the most commonly herniated organ. * The two classic fetal ultrasound findings of CDH are a cystic intra-thoracic mass representing the stomach and/or bowel, and absence of the stomach bubble below the diaphragm. * Complications of CHD include pulmonary hypoplasia on the affected side, bowel obstruction with resultant polyhydramnios, and obstruction of venous return due to IVC compression, which may lead to ascites.

Answer 59

* Congenital pulmonary airway malformation (CPAM) is a hamartomatous proliferation of small airways that communicates with the bronchial tree. Blood supply is from the pulmonary circulation. CPAM was previously called congenital cystic adenomatoid malformation. * CPAM can be classified into three types based on the size of cysts (Type I - large cysts; Type II - small cysts; Type III - tiny cysts too small to see on ultrasound). Today this classification is not used much because prognosis is dependent on the size of the entire lesion rather than the size of the individual cysts. * CPAM is not associated with other anomalies (unlike CDH). * CPAM may appear to spontaneously regress on ultrasound but will remain apparent on CT or mR.

Answer 60

* Sequestration is aberrant lung tissue with a **systemic blood supply**, usually from the aorta. The most characteristic location of sequestration is the left lower lobe. * The classic ultrasound appearance of sequestration is an echogenic mass at the left lung base. The sequestration may occasionally be subdiaphragmatic and simulate an adrenal mass. * Systemic blood supply should be confirmed with color Doppler. In the absence of the doppler findings, sequestration may be difficult to differentiate from CPAM. In contrast to the findings of CPAM, cysts are less common, there is less mass effect, and location is almost always in the lower lobes. * Bronchogenic, gastrointestinal duplication, and neurenteric cysts almost always appear as solitary, simple cysts on ultrasound.

Answer 61

* Pulmonary hypoplasia is inadequate lung development. Hypoplasia can be due to a thoracic mass lesion (such as CDH), oligohydramnios, or a skeletal dysplasia affecting the ribs. * It is important to evaluate the size of the fetal thorax in relation to the abdomen on coronal images. A small, bell-shaped fetal thorax suggests pulmonary hypoplasia.

Answer 62

* Atresia of the upper airway, otherwise known as congenital high airway obstruction syndrome (CHAOS), is lethal and may cause **bilateral enlarged echogenic lungs.**

Answer 63

* Esophageal atresia is a blind-ending esophagus, due to an **incomplete division of the foregut in early embryologic development.** * Esophageal atresia is usually associated with a **tracheoesophageal fistula. VACTRL** too! * The classic ultrasound findings of esophageal atresia are **polyhydramnios and an absent stomach bubble**.

Answer 64

* Duodenal atresia causes duodenal obstruction from **lack of recanalization** of the duodenal lumen. duodenal atresia is the most common cause of fetal duodenal obstruction. * Approximately one-third of babies with DA will have **down syndrome**. If a double bubble sign is seen, a careful screen for additional findings of down syndrome should be performed (e.g., thorough heart exam, nuchal fold if 16-20 weeks, etc.). * The classic appearance of DA is the **double bubble sign**, representing a dilated stomach and dilated proximal duodenum. The differential diagnosis of the **double bubble sign includes duodenal web, stenosis,** **and** **annular pancreas.**

Answer 65

* Structural causes of distal bowel obstruction include jejunal atresia, ileal atresia, andanorectal malformation. * Anorectal malformation is commonly associated with additional abnormalities, including the VACTERL association (vertebral, anorectal, cardiac, tracheoesophageal, renal, and limb anomalies).

Answer 66

* Functional bowel obstruction may be due to **Hirschsprung disease or meconium ileus**. * Hirschsprung disease results in a functional obstruction due to absent distal enteric ganglion cells. * Meconium ileus causes obstruction from impaction of meconium in the ileum. Nearly all infants with meconium ileus have cystic fibrosis; however, meconium ileus is rarely identified before the 3rd trimester.

Answer 67

* **Meconium ileus** is bowel obstruction caused by impacted meconium in a fetus with cystic fibrosis. * **Meconium peritonitis** is peritoneal inflammation secondary to in utero bowel perforation and resultant spillage of meconium into the peritoneal cavity. This leads to peritoneal adhesions and, ultimately, dystrophic calcifications. * **Meconium pseudocyst** is a cystic abdominal structure, often with peripheral calcification, representing a walled-off bowel perforation. It is a sequela of meconium peritonitis.

Answer 68

* Hyperechoic or echogenic bowel is a nonspecific finding that is associated with **down syndrome**. other causes of hyperechoic small bowel include **TORCH infection, cystic fibrosis, and swallowing of intra-amniotic blood**. It may also be associated with **intrauterine growth restriction**. * If the bowel is only mildly echogenic (less echogenic than bone) and no mass effect is present, this appearance may represent a normal variant.

Answer 69

* An omphalocele is a midline anterior abdominal wall defect with resultant herniation of intra-abdominal contents covered by a peritoneal membrane. Omphalocele is the most common anterior abdominal wall defect. * The key to differentiate omphalocele from gastroschisis is the **position of the umbilical cord insertion**. In omphalocele, the umbilical cord inserts centrally at the base of the herniated sac. * When small, omphaloceles often contain just bowel. Larger omphaloceles may also contain liver and carry a worse prognosis. * omphalocele is associated with other anomalies in 50-75% of cases, including **cardiac anomalies, trisomies, and Beckwith-Wiedemann syndrome** (a congenital overgrowth syndrome characterized by omphalocele, macroglossia, hemihypertrophy, and visceromegaly).

Answer 70

* Gastroschisis is a paraumbilical (usually right-sided) anterior abdominal wall defect, through which bowel herniates without a peritoneal covering. Gastroschisis is the second most common abdominal wall defect. * Unlike omphalocele, gastroschisis is usually seen as an isolated anomaly. * Gastroschisis is seen more commonly in very young (teenage) mothers. * Prognosis is similar to a simple omphalocele (with no other associated abnormalities).

Answer 71

* Pentalogy of Cantrell is a rare disorder consisting of ectopia cordis (extra-thoracic heart), omphalocele, diaphragmatic defect, pericardial defect, and disruption of the sternum.

Answer 72

* Fetal hydronephrosis (obstructive uropathy). * Cystic renal disease. * Bilateral renal agenesi * Bilateral multicystic dysplastic kidneys * Bilateral renal agenesis * ARPKD

Answer 73

* 1mm / week of gestation * For instance, a 20-week fetus should have kidneys approximately 2 cm in length.

Answer 74

* A ureterocele is dilation of the intramural portion of the ureter which balloons out into the bladder and causes a functional obstruction at the ureterovesicular junction. Ureterocele is also associated with ectopic insertion of the upper pole moiety of a duplicated system.

Answer 75

* Distal ureteral obstruction from ectopic insertion of the ureter into the bladder is often associated with the upper pole moiety of a duplicated collecting system. The most common ectopic insertion of an upper pole moiety is **inferior and medial to the normally inserting lower pole ureter**.

Answer 76

* Posterior urethral valve is **congenital obstruction of the posterior urethra due to a membranous flap in the proximal urethra**. * Ultrasound shows severe dilation of the posterior urethra resulting in the **keyhole sign**. The bladder is typically enlarged and thickened. **Hydroureteronephrosis and oligohydramnios are usually present.**

Answer 77

* ARPKD is a congenital disorder of diffuse collecting tubule dilation, leading to innumerable tiny renal cysts that are too small to be resolved by sonography. * Ultrasound findings include **very large and echogenic kidneys and severe oligohydramnios**, caused by markedly reduced renal function. * Prognosis is poor. ARPKD is associated with **hepatic fibrosis** if the baby survives infancy. MNEMONIC: "cysts in kidney, cysts in liver (leading to congenital hepatic fibrosis and protal htn, cystic dilation in brain (aneursym), butt (diverticuli) and the heart (MVP)!

Answer 78

* Multicystic dysplastic kidney (MCDK) is thought to be the end result of fetal obstructive uropathy. * If MCDK is unilateral and there are no associated abnormalities, the prognosis is excellent. MCDK may be fatal if bilateral, however. * MCDK may affect only the upper pole of an obstructed duplicated system. * On imaging, multiple noncommunicating cysts are interspersed with dysplastic renal parenchyma. In contrast to hydronephrosis, the cysts of MCDK do not connect to the collecting system. * The natural history of MCDK is gradual involution.

Answer 79

* Osteogenesis imperfecta (OI) is a spectrum of congenital bone anomalies characterized by multiple fractures due to **abnormal type I collagen**. There are several types, with type 2 being lethal. Type 2 can be diagnosed in the second trimester, but types 1, 3, and 4 are not typically diagnosed until the third trimester * OI causes severe shortening of the long bones (\>3 SD below the mean). The long bones and ribs appear “wrinkled” due to multiple fractures. The thorax is usually small due to broken and structurally soft ribs. * Unlike thanatophoric dysplasia, bony mineralization is decreased. Decreased calvarial mineralization causes the entire brain (including the nearfield) to be visualized well.

Answer 80

* Thanatophoric dysplasia is a lethal skeletal dysplasia with characteristic **telephone receiver femurs, severe limb shortening and bowing, and rib shortening.** * **Platyspondyly** is characteristic, which is flattening of the ossified portions of the vertebral bodies. * The classic ***cloverleaf skull*** is caused by protrusion of the frontal and temporal lobes. * Bony mineralization is **normal** (unlike osteogenesis imperfecta)

Answer 81

* Sacrococcygeal teratoma is a germ cell tumor of the sacrum. It often presents prenatally as a mixed solid and cystic complex mass. * Sacrococcygeal teratoma may be associated with high output cardiac failure. * The other primary differential consideration for a distal fetal spinal mass is a myelomeningocele, which is associated with spine abnormalities and a dorsal skin defect.

Answer 82

* The germinal matrix is the site of neuronal precursor cells located in the caudothalamic groove. * Grade I: Hemorrhage confined to the germinal matrix. * Grade II: Hemorrhage extends into the ventricles without ventriculomegaly. * Grade III: Hemorrhage extends into the ventricles with ventriculomegaly. * Grade IV: Hemorrhage extends out of the ventricles into the parenchyma.

Answer 83

* Holoprosencephaly and midline facial anomalies. * Encephalocele. * Congenital heart disease. * Omphalocele. * Horseshoe kidney. * Polycystic kidneys. * Polydactyly.

Answer 84

* Strawberry sign: Inward bowing of the frontal bones creates a strawberry shape to the calvarium, with the tip of the strawberry projected anteriorly. * Choroid plexus cysts. * Facial cleft. * Micrognathia. * Cardiac anomalies. * Omphalocele. * Congenital diaphragmatic hernia. * Horseshoe kidney. * Hydronephrosis. * Clenched hand that never opens, with overlapping fingers. * Rocker bottom feet.

Answer 85

* Increase in nuchal fold (\>6mm) measured between weeks 15 and 21, is the single most sensitive and specific ultrasound finding for trisomy 21. * In contrast, nuchal translucency is measured earlier in the pregnancy (11–14) weeks, and is less specific for trisomy 21 * Absent ossification of nasal bone. * Cystic hygroma (although more common in Turner syndrome). * Congenital heart disease: VSD and endocardial cushion defect in particular. * Echogenic bowel. * Duodenal atresia. * Echogenic intracardiac focus. * Shortened femur and humerus. * Hypoplasia of the middle phalanx of the little finger. * Sandal gap toes.

Answer 86

* Beckwith-Wiedemann syndrome (BWS) is a syndrome of overgrowth that carries an increased risk of childhood cancers. BWS is mostly sporadic, but 10-15% of cases follow an autosomal dominant inheritance. * BWS increases the risk of developing **Wilms tumor** (the most common tumor in BWS), **hepatoblastoma**, and other childhood tumors. The standard of care is screening with abdominal ultrasound every 3 months until age 8. * **Hemihypertroph****y**,**organomegaly**. * **macroglossia**. * **Omphalocele**. * **Perinatal hypoglycemia.**

Answer 87

* Meckel-Gruber is an autosomal recessive multi-organ syndrome. * Encephalocele. * Renal dysplasia causing multiple tiny renal cysts, which appear as echogenic kidneys, analogous to ARPKP * Polydactyly.