Overview of Obstetric Imaging and The First Trimester

Presented By:Dr. Bharat Jain

VMKVMC

Introduction

Use of ultrasound Scans in pregnancy introduced in late 1950s

Provision of good information about the foetus and its environment

Determining early intervention or conservative management

Safe, non-invasive, accurate and cost effective investigation in foetus

Important role in care of pregnant woman

Indication for first-trimester ultrasound

To confirm the presence of an intrauterine pregnancy. To evaluate a suspected ectopic pregnancy. To define the cause of vaginal bleeding. To evaluate pelvic pain. To estimate gestational (menstrual) age. To diagnose or evaluate multiple gestations. To confirm cardiac activity.

As an adjunct to chorionic villus sampling, embryo transfer, and localization, and removal of an intrauterine device.

To assess for certain fetal anomalies, such as anencephaly, in high-risk patients.

To evaluate maternal pelvic masses or uterine abnormalities. To measure nuchal translucency when part of a screening

program for fetal aneuploidy. To evaluate a suspected hydatidiform mole.

Estimation of gestational (menstrual) age Evaluation of fetal growth Vaginal bleeding Abdominal or pelvic pain Cervical insufficiency Determination of fetal presentation Suspected multiple gestation Adjunct to amniocentesis or other procedure Significant discrepancy between uterine size and clinical dates Pelvic mass Suspected hydatidiform mole Adjunct to cervical cerclage placement Suspected ectopic pregnancy Suspected fetal death Suspected uterine abnormality

Indications for second and third trimester ultrasound

Evaluation of fetal well-being Suspected amniotic fluid abnormalities Suspected placental abruption Adjunct to external cephalic version Premature rupture of membranes and/or premature labor Abnormal biochemical markers Follow-up evaluation of a fetal anomaly Follow-up evaluation of placental location for suspected placenta previa History of previous congenital anomaly Evaluation of fetal condition in late registrants for prenatal care To assess for findings that may increase the risk for aneuploidy screening for fetal anomalies

GUIDELINES FORFIRST-TRIMESTER ULTRASOUND

Gestational sac Location of pregnancy: intrauterine vs extrauterine Gestational age (as appropriate) Mean sac diameter Embryonic pole length Crown-rump length Yolk sac or embryo/fetus Cardiac activity on M-mode ultrasound Fetal number (amnionicity/chorionicity) Maternal anatomy: uterus and adnexa

Normal first-trimester ultrasound images: pregnancy location and adnexa. A, Transabdominal sagittal sonogram shows an intrauterine gestational sac. B, Transverse image to the left of uterus shows normal appearance for the ovary(arrow). C, Transvaginal color Doppler image shows normal hypervascular rim around corpus luteum.

A B

C

Normal first-trimester ultrasound images: mean sac diameter. Transvaginal sagittal image shows sagittal measurement of sac diameter (calipers). Measurements in three orthogonal planes are averaged to calculate the mean sac diameter. Note yolk sac within the gestational sac.

First-trimester ultrasound images: embryo and fetus. A, Normal embryo at 6.5 weeks’ gestation. Noteembryonic pole (calipers) adjacent to yolk sac. B, Normal embryo at 8 weeks’ gestation. Note embryo (calipers) and adjacent yolk sac(arrow). C, M-mode ultrasound from same embryo as in B. Note normal heart rate of 160 beats/min. D, Normal embryo at 9 weeks’gestational age. Note embryo within amnion (arrow) and umbilical cord (arrowhead). E, Just lateral to image in D, note yolk sac (arrow-head) is located outside the amnion (arrow). F, Sagittal ultrasound at 10.5 weeks’ gestation. G, Sagittal ultrasound at 11.5 weeks’ gestation.H, Coronal view of face at 13 weeks’ gestation. I, Sagittal ultrasound of nuchal translucency (calipers) at 13 weeks’ gestation.

A B C

D E F

G H I

Multiple gestations. Be sure to examine the entire gestational sac to identify multiple gestations. A, Transabdominal image of diamniotic dichorionic twins. Note the thick, dividing membrane. B, Transvaginal image of diamniotic monochorionic twins at 8 weeks’ gestational age (calipers denote crown rump length) with two thin membranes (arrows, amnion) still close to embryonic poles.

Anencephaly. A, Sagittal ultrasound at 10 weeks’ gestation. B, Sagittal ultrasound in a different fetus at 12 weeks’ gestation. Note the orbits (arrow) with absent ossified cranium above this level with angiomatous stroma.

A

B

B

A B

Omphalocele at 11 weeks’ gestational age. Sagittal view of fetus (calipers) shows a large, abdominal wall defect (arrow).

GENERAL SURVEY Cardiac activity: document with M-mode Presentation: cephalic, breech, transverse, variable Fetal number: for multiples, amnionicity/

chorionicity, concordance with size, amniotic fluid Maternal anatomy: uterus, adnexa, and cervix Gestational age and fetal weight assessment

Biparietal diameter Head circumference Abdominal circumference Femur length Amniotic fluid Estimate as normal If abnormal, qualify if high or low Placenta: position

GUIDELINES FOR SECOND-AND THIRD-TRIMESTER ULTRASOUND

FETAL ANATOMIC SURVEYFETAL ANATOMIC SURVEYHead, Face, and NeckHead, Face, and Neck Cerebellum Choroid plexus Cisterna magna Lateral cerebral ventricles Midline falx Cavum septi pellucidi Upper lipChestChest Four-chamber view Outflow tracts “if technically feasible”Abdomen Stomach (presence, size, and situs) Kidneys, bladder Umbilical cord insertion site into fetal abdomen Umbilical cord vessel number

Spine Cervical, thoracic, lumbar, and sacralExtremities Legs and arms: presence or absenceGender (Sex) Medically indicated in low-risk pregnancies only for evaluation of multiple gestations

Overview of uterus, cervix, and fetal position. A, Sagittal sonogram of uterus shows a normal-appearing cervix (C) and an anterior placenta (P), with the placental tip far away from the internal cervical os; B, bladder. B, Transverse sonogram of posterior placenta (P). C, Transabdominal image of normal-appearing cervix (arrow on internal os). Note bladder (B) and fetal head (H). With the head as the presenting part, the fetus is in cephalic position. D, Transvaginal sonogram of normal-appearing cervix (calipers).

A B

C D

Determination of situs. A, Scan plane, and B, transverse scan diagram. With fetus in cephalic position and spine on the maternal right side, the left-sided stomach is “up” on the side closest to the transducer. C, Scan plane, and D, with the fetus in breech position and spine on the maternal right side, the left-sided stomach is “down” on the side farthest away from the transducer.

ADDITIONAL VIEWS FOR TARGETEDFETAL SONOGRAMS

Corpus callosum Cerebellar vermis Outflow tracts Orbits Extremities, including hands and feet Profile/chin Nuchal fold (at appropriate gestational age) Individual long-bone measurements Hands and feet

Second-trimester biometry. A, Biparietal diameter. Note the level of this ultrasound image at the thalamus and third ventricle. The calipers are placed from the outer skull in the near field to the inner skull in the far field. B, Head circumference. Note how circumference is measured around the outside of the skull. Arrow depicts cavum of the septum pellucidum. C, Abdominal circumference. Note the curve of the portal vein and stomach on this transverse image, with circumference drawn around the outside of the skin. D, Femur length. Note that the “upside” femur should be measured, with the shaft of the bone as near to perpendicular to the scan plane as possible, excluding the distal femoral epiphysis.

A B

C D

Routine sonographic views of fetal head. In addition to the biparietal diameter and head circumference, required views of the head include images of the cerebral ventricles, cerebellum, cavum of the septum pellucidum, and midline falx. Additional views that can be obtained are angled views to demonstrate both sides of the choroid plexus, and views through the anterior fontanelle or midline sutures to demonstrate the corpus callosum. A, Axial image shows cerebral ventricles filled with choroid plexus. B, Angled axial view shows both ventricles with choroid plexus. C, Axial image shows cerebellum (arrow) and cavum of the septum pellucidum (arrowhead). D, Transvaginal sagittal view of the corpus callosum (arrows).

A B

C D

Views of fetal face. Required view of the face is of the nose and lips. Additional views include orbits and profile. A, Coronal view of nose and lips. B, Coronal view of orbits. C, Sagittal view of facial profile. D, 3-D image of fetal face.

A B

C D

Views of fetal heart and outflow tracts. Required views include demonstration of normal situs, with heart and stomach on left side, four-chamber view of the heart, documentation of normal heart rate, and outflow tracts “if possible”. A, Axial image shows normal four-chamber view of fetal heart. Note the normal axis of the heart, at about 60 degrees from midline. B, M-mode ultrasound. Note normal heart rate (146 beats/min). C, Angled view shows left ventricular outflow tract (arrow) with heart and stomach(s) on the same side of the fetus. D and E, Right ventricular outflow tract in oblique axial (D) and oblique sagittal (E) views with ductus arteriosus (arrow) extending posteriorly to aorta.

A B

C D

E

Views of fetal abdomen and pelvis. Note normal stomach documented on abdominal circumference. Other required views are cord insertion, kidneys, and bladder. Additional views document the diaphragm and fetal gender. A, Cord insertion site in the anterior abdominal wall. B and C, Transverse views of kidneys at 18 and 28 weeks’ gestation. A small amount of central renal pelvic dilation (2 mm in this fetus) is a normal finding. D, Transverse image of bladder. Note umbilical arteries on either side of bladder. E, Sagittal view shows liver, diaphragm (arrow), and lungs. Note how the liver is of lower echogenicity than the lungs. F, Male genitalia. G, Female genitalia.

A B C

D E F

G

Views of fetal spine. Note transverse image of thoracic spine on four-chamber view and transverse image of lumbar spine between the kidneys . A, Transverse image of cervical spine. B, Transverse view of lumbosacral spine. Note how the posterior elements point towards each other and the skin covers the distal spine. C, Oblique sagittal image of cervical and thoracic spine. D, Oblique sagittal view of entire spine. E, Sagittal view focused on the distal spine. Note how the spinal canal narrows and has a gentle upturn distally.

A B

D

E

C

View of fetal extremities. Required views include documentation of all four extremities. Additional views include measurements of all the long bones and demonstration of the fingers and toes. A and B, Lower extremities. C, D, and E, Upper extremities. F, Hand. Note four fingers with thumb partially out of the field of view. G, Foot. H, 3-D view of upper extremity.

A B C

D E F

G H

Views of umbilical cord. Required views include cord insertion site into the anterior abdominal wall (see Fig. A) and documentation of number of vessels in the umbilical cord. Additional views include cord insertion site into the placenta and Doppler examination of the cord. A, Transverse image of three-vessel umbilical cord. Note two arteries (arrows) that are smaller than the single vein (arrowhead). B, Color Doppler longitudinal image of three-vessel cord. C, Cord insertion site (arrow) into the placenta. D, Spectral Doppler image documents normal umbilical arterial systolic/diastolic ratio in third-trimester fetus.

A B

CD

BENEFITS OF ROUTINE SECOND- TRIMESTER ULTRASOUND SCREENING

More accurate gestational age Detection of major malformations before birth Earlier detection of multiple pregnancy Fewer low-birth-weight singleton births Lower incidence of induction for postterm pregnancy• Early detection of placenta previa• Reassurance of a normal pregnancy Identification of twin / multiple pregnancies Fetal malformation: Diagnostic accuracy 3D&4D ultrasound

MRI in Pregnancy When additional information regarding fetal anatomy

or pathology is needed, fast MRI increasingly being used.

There is no biological risk from MRI MRI provides excellent soft tissue contrast, multiple

planes for reconstruction and large field of view.

Normal fetal MRI: representative T2-weighted images. A, Sagittal view of fetal head with fetal body in coronal plane. B, Sagittal view of fetal head. Note normal appearance of corpus callosum and soft palate, with fluid outlining the soft palate above the tongue. C, Coronal view of the brain, chest, and abdomen. Note normal appearance to the lungs, diaphragm, stomach, and kidneys. D, Axial view of brain with normal-appearing lateral ventricles. E, Oblique axial view of brain shows normal cerebellar hemispheres and vermis. F, Axial view at level of globes. Note the dark lens in each globe. G, Axial view at level of palate. Note that majority of the alveolar tooth-bearing ridge is well depicted. H, Axial view at level of stomach and gallbladder. Note spinal cord outlined by fluid in thecal sac. I, Axial view at level of bladder.

A B C

D E F

G H I

GOALS OF FIRST TRIMESTER SONOGRAPHY

Visualization and localization of the gestational sac Early identification of embryonic demise and other forms

nonviable gestation In multifetal pregnancies, number of embroyos and the

chorionicity-amnionicity First trimester focuss on nuchal translucncy screening

combined with maternal age and maternal serum to determine risk of chromozomal abnormalities

Schematic drawing of interrelationships among the hypothalamus, pituitary gland, ovaries, and endometrial lining. FSH, Follicle-stimulating hormone; LH, luteinizing hormone. (From Moore KL, Persaud TVN, editors. The developing human: clinically oriented embryology. 6th ed. Philadelphia, 1998, Saunders.)

Maternal physiology and Embryology

Diagram of ovarian cycle, fertilization, and human development to the blastocyst stage.(From Moore KL, Persaud TVN, editors. The developing human: clinically oriented embryology. 6th ed. Philadelphia, 1998, Saunders.)

Implantation of the blastocyst into endometrium. Entire conceptus is approximately 0.1 mm at this stage. A, Partially implanted blastocyst at approximately 22 days. B, Almost completely implanted blastocyst at about 23 days.

Formation of secondary yolk sac. A, Approximately 26 days: formation of cavities within extraembryonicmesoderm. These cavities will enlarge to form extraembryonic coelom. B, About 27 days, and C, 28 days: formation of secondary yolksac with extrusion of primary yolk sac. Extraembryonic coelom will become chorionic cavity.

Gestational Sac First reliable evidence of an IUP is visualsation of the

gestational sac within the thicken decidua (Yeh et al.) Gestational sac should be eccentrically located within the

endometrium and should abut the endometrial-canal Demonstrate an early IUP as a small intra decidual sac

between 4.5 and 5 weeks gestational age using TVS The threshold level identifies the ealiest one can expect

to see a sac (4 weeks, 3 days), and the discriminatory level identifies when one should always see the sac (5 weeks, 2 days)

Double decidual sign is based on visualisation of the gestational sac as an ecogenic ring formed by the decidua capsularis and chorion, forming 2 ecogenic rings

Intradecidual sac sign. A, Sagittal scan at 4 weeks, 4 days shows implantation site as a 2-mm focal thickeningof posterior endometrium (arrow). The chorionic fluid in the sac is just barely visible. The mass slightly displaces the endometrial stripe and has a slightly echogenic rim. B, Color Doppler image shows prominent terminal portion of a spiral artery (arrow) extending up to the sac.

A B

Intradecidual sac sign. A, Transabdominal scan at 32 days. The small sac is not visualized in this scan. B and C,Transvaginal scans the same day showing the echogenic ring of the sac (black arrow) implanted just below the endometrial interface ( arrowhead). D, Color Doppler flow of a feeding spiral artery adjacent to the sac with low-velocity flow of 10 cm/sec.

A B

DC

Double-decidual sign.Diagram of anatomic basis showing three layers of decidua and endometrial cavity.

Decidual layers. Sagittal transvaginal sonogram at 7 weeks shows the gestational sac (arrowhead) and the maternal decidua (arrow) as separate echogenic bands.

Subchorionic hemorrhage. A, Transab-dominal scan at 10 weeks. The sac and embryo are seen as well as a fluid collection (arrow) behind the chorion, a subchorionic hemorrhage. (arrow) B, Transvaginal sagittal and 3-D scans show the fluid collections (arrows); e, embryo; c, chorion.

A

B

Echogenicity of fluids. Transvaginalsonogram of a 12-week sac with the echo-free amniotic fluid (AC),mildly echogenic chorionic fluid (CC), and more echogenic bloodin the subchorionic space (SCH).

AC

CC

SCH

It is the first structure to be seen normally within the gestational sac

It os often seen when MSD is 10-15 mm and always be visualised by an MSD of 20 mm

In TVS, it can be visualised by an MSD of 8 mm Double decidual sign is not 100% specific for presence of

an IUP, yolk sac within the early gestational sac is diagnostic of IUP

Yolk sac has a role in transfer of nutrients to the developing embryo

Angiogenesis occurs in the wall of the yolk sac in the 5th week

YOLK SAC

Vascular network in the wall of yolk sac joins the fetal circulation via the paired vitelline arteriesand veins through a stalk called vitelline duct

Dorsal part of the yolk sac is incoporated into the embryo as a primitive gut

The yolk sac remains connected to the mid gut by the vitelline duct

No. of yolk sacs present can be helpful in determing amnionicity

In a monochorionic monoamniotic twin gestation, there will be two embryos, one chorionic sac, one amniotic sac, and one yolk sac

Early sac and embryo. A, Transverse transvaginal sonogram of the anteverted uterus (UT) demonstrates a smallgestational sac at 4 weeks, 3 days. B, Sonogram at 5 weeks, 6 days shows an enlarging gestational sac with the appearance of a 2-mm yolk sac (arrow). C, Magnified view of the sac reveals a 2.5-mm embryo (calipers); CRL, crown-rump length. D, M-mode ultrasound shows cardiac motion at a fetal heart rate (FHR) of 107 beats/min (arrow).

A B

C D

Normal yolk sac. A, Nine weeks. B, Eight weeks.

Normal embryo at 8 weeks. Transvaginal sonogram shows vitelline duct (arrow), yolk sac (ys), and embryo (e).

Vitelline duct. Three-dimensional (3-D) ultrasound image of an embryo at 8 weeks with the vitelline duct (VD) connecting to the yolk sac (YS). There is also a subchorionic hemorrhage.

A B

e

ys

Six-week monochorionic diamniotic (MCDA) twins. Two separate yolk sacs are seen within a singlegestational sac at 6 weeks on 2-D (A) and 3-D (B) images.

A B

Normal yolk sac and vitelline duct. Transvaginal scans of 9-week pregnancy focusing on the yolk sac (A)and flow within the vitelline duct (B and C).

A B

C

Monochorionic and diamnioticTwins with one intrauterine embryonic death and one alive. Transvaginal sonogram at 10 weeks. On the left the arrow is pointing to one of two adjacent sacs, one is the amnion and the other the yolk sac. To the right is a single yolk sac (calipers) with the live embryo not in the scan plane. Both embryos went on to abort.

Embryo and Amnion Double-bleb sign as the earliest demonstration of the

amnion The two blebs represents the amnion and yolk sac and

can be identified as early as five and half weeks when the crown rump length is 2mm

Amniotic fluid is initially colorless, kidneys begin to function at about 11 weeks, it becomes pale yellow.

Fluid accumulates at about 5 ml per day at 12 weeks, amniotic cavity expands to fill the chorionic cavity completely by 14-16 weeks

Amnion as a separate membrane or sac within the chorionic cavity before 14-16 weeks

Normal 9-week embryo/amnion.Normal separation of amnion (arrow) and chorionic sacs at 9weeks. Transvaginal sonography shows the embryo (calipers) and the amnion (AM).

AM

Embryonic Cardiac activity In normal pregnancies, the embryo can be identified in

gestational sac as small as 10 mm and should be identified when MSD is 16-18 mm

The tubular heart begins to beat at 36-37 days of gestational age

Absent cardiac activity may be normal in embryos of less than 4-5 mm CRL

General cardiac activity can be visualised in normal embryos of greater than 5 mm CRL

Normal embryonic cardiac activity is greater than 100 beats per minute

Normal 6-week embryo. A, Image shows 6-week embryo (calipers) adjacent to the yolk sac. B, M-mode ultra-sound shows a heart rate of 141 beats/min.

Umbilical cord and Cord cyst The umbilical cord is formed at the end of the 6th week

(CRL=4 mm) as the amnion expands and envolpes the connecting stalk, yolk stalk and allantois.

Cord contains two umbilical arteries, a single umbilical vein, allantois, yolk stalk all of which are imbedded in Wharton's jelly.

Cysts are usually seen in the 8th week and disapperaed by the 12th week.

Cyst are singular , closer to the fetus with the mean size of 5.2 mm.

Cysts may originate from remnants of the allantois or yolk stalk.

A B

C

Umbilical cord cyst. A, Live embryo at 9 weeks’ menstrual age with a cyst on the cord (arrow) close to the embryonic end. On subsequent examination (not shown) the cyst was no longer seen. B, Color Doppler image of the cord and cyst with flow in the vessels of the cord and no flow in the cyst. C, Another example of a 9 week cord cyst (arrow) in the midportion of the cord, with good visualization of the whole cord, embryo, and yolk sac.

Estimation of Gestational Age Gestational Sac = 5 weeks Gestational Sac+ yolk sac = 5.5 weeks Gestational Sac + yolk sac +Embryo = 6 weeks CRL>5 mm - fetal cardiac activity present Measure CRL when embryo >7 mm End of the first trimester measurement of BPD becomes

more accurate than the CRL

Early Pregnancy Failure

MSD of equal to or greater than 25 mm without an embryo

Crown-Rump length of equal to or greater than 7 mm without cardiac activity

Absence of embryo with heartbeat at 2 or more weeks after an ultrasound that showed a gestational sac without a yolk sac

Absence of embryo with heartbeat at 11 days or more after an ultrasound that showed a gestational sac without a yolk sac

Early pregnancy failure with large, empty sac. A, Transvaginal coronal, and B, transvaginal sagittal,images of an empty gestational sac. Mean sac diameter (calipers) is 18 mm. No yolk sac is identified.

A B

Early pregnancy failure with irregular sac. A, Transvaginal sagittal and transverse views of an irregular empty gestational sac in a 40-year-old woman with spotting at 11 weeks. Mean sac diameter (calipers) is 25 mm. No yolk sac or embryo is present, the sac is irregular, and the trophoblast is thin. B, Power Doppler ultrasound with a small area of vascularity at the implantation site (arrow).

A B

Aborting sac. A 23-year-old pregnant woman at 8 weeks’ gestation presented with cramps and spotting. A, Transvaginal sagittal scan shows a gestational sac in the lower uterine segment extending into the cervix. B, Sagittal scan of the sac within the upper cervix. Note the small yolk sac and the adjacent small embryo. No cardiac activity was detected.

A

B

Aborted gestation at 7 weeks, 3 days. A recently aborted but intact sac about 2.8 cm in diameter with an embryo. The sac was scanned in a water bath so that the frondlike chorionic villi can be seen around the sac floating freely. A and B, Embryo with 12-mm crown-rump length is attached to the wall by a short umbilical cord. No yolk sac was seen; it likely regressed. C, 3-D view. D, Sac is floating in a water bath so that the white chorionic villi are seen extending outward. The villi only cover a portion of the sac. The villi normally degenerate over the area of the sac not at the implantation site. E, Magnified view of the villi, and F, a vessel within the sac (arrow).

A B

C D

E F

Collapsed amnion. Transvaginal powerDoppler ultrasound scan of a gestational sac in a 39-year-old woman who presented with spotting at 9 1 2 weeks. The embryo is small with a crown-rump length (calipers) of 7 mm, consistent with 7 weeks. No cardiac activity is seen. The amniotic membrane (arrow) is collapsed adjacent to the embryo.

Sonographic Predictors of Abnormal Outcome

Embryonic Bradycardia Mean sac Diameter and Crown-Rump length Yolk sac size and shape Low human Chorionic Gonadotropin Subchorionic Hemorrhage

Amniotic sac abnormalities

Fetal bradycardia. A small embryo in a 10-week gestation with a heart rate of 69 beats/min. This embryo died, and the pregnancy aborted within 1 week. The embryo is seen within a round amniotic sac on the left and lies beside a large yolk sac on the right.

Twins: one normal, one with small sac. A, Transverse transvaginal scan at 8 weeks shows two sacs (A, B), with the left larger than the right sac. B, At 9 weeks the normal-sized embryo on the maternal right is of appropriate size, 19.9 mm (calipers), with a normal-sized gestational sac. The other twin did not grow normally.

Small gestational sac and embryo.Sagittal transvaginal scan of a 21-year-old woman at 9 weeks’ gestational age with spotting. There is a small gestational sac that is no larger than the embryo (arrow). The crown-rump length and mean sac diameter are about equal. No heartbeat was seen.

Large yolk sac. Transvaginal scan at 9 weeks shows gestational sac with a small embryo with bradycardia (not shown) and a large yolk sac (calipers) with mean internal diameter of 5.9 mm. On follow-up examination 7 days later (not shown), no cardiac activity was identified, indicating embryonic demise and the yolk sac had become smaller and more echogenic

Intrauterine embryonic death with yolk sac calcification. A, Transvaginal color Doppler ultrasound scan of a pregnancy at 6 1 2 weeks’ menstrual age (CRL, 6.5 mm) shows an embryo with no cardiac activity (no color), and a normal appearing yolk sac (arrow). B, Repeat scan 5 days later shows no change in the size of the embryo (calipers) and a dense yolk sac (arrow) with faint distal shadowing. C, In a different pregnancy, transvaginal sagittal scan shows calcified yolk sac (ys). No cardiac activity was identified in embryo with crown-rump length of 18 mm. a, Amnion; e, embryo.

AB

C

YS e

a

Echogenic material within yolk sac. A, Single live embryo at 7 weeks’ gestational age with echogenic material within the yolk sac (ys) next to a live embryo. B, One week later the yolk sac looks normal, and the pregnancy continued uneventfully.

A

B

Moderate subchorionic bleed. Sagittal transvaginal scan of an 8-week gestation with no spotting. The moderate subchorionic bleed (*) is seen adjacent to the gestational sac. The live embryo was not in the field of view. The bleed resolved and pregnancy continued uneventfully

*

Small subchorionic bleed. A, Sagittal transvaginal scan of a 10-week gestation with a small subchorionic hemorrhage (*) elevating the posterior placental edge in the lower uterine segment. B, Transverse scan of the small bleed. C, Sagittal transvaginal color Doppler ultrasound showing no flow in the subchorionic bleed.

A B

C

*

*

*

Retained Products of Conception

It can have spectrum of sonographic appearances like empty uterus to a large echogenic mass of tissue filling the endometrial canal.

Presence of focal increased vascularity is of great importance in distinguishing between blood clots and RPOC.

There can be a single vessel or a large group of vessels, either superficially in the myometrium or extending deep within it.

Beacuse of the high flow , can raise concern about performing D&C.

Retained products of conception. A, Sagittal transvaginal scan of a 22-year-old woman who presented 5 weeks after a suction dilation and curettage (D&C) therapeutic abortion with vaginal bleeding. The endometrial canal is distended with a 1.8 × 2.5–cm echogenic mass (arrows). B, Color Doppler ultrasound shows an area of marked increase in vascularity at the base of the mass at its attachment to the myometrium. C, Sagittal transvaginal scan of a 28-year-old woman who had suction D&C for a therapeutic abortion 6 weeks previously with vaginal bleeding. The myometrium in the body anteriorly was heterogeneous with increased echogenicity. D, Color spectral Doppler ultrasound shows increased vascularity with velocities of 1.3 m/sec.

A B

DC

Ectopic Pregnancy It is the implemetation of the GS anywhere outside the

endometrial cavity. A pseudosac is an intra utrine fluid collection surrounded

by a single decidual layer as opposed to the two concentric rings of the doule decidual sign.

Live embryo in the ednexa is specific for the diagnosis of ectopic pregnancy.

Tubal ring sign (the second most common sonographic finding), which is the presence of a hyperchoic ring around the gestational sac.

Ectopic pregnancy most commonly occurs in the ampullary or isthmic portions of the fallopian tube.

About 26% of ectopic pregnancy have normal pelvic sonograms on TVS ultrasound.

Ruptured ectopic pregnancy with hemoperitoneum. A 35-year-old woman presented at 6 weeks’ gestation with right lower quadrant pain. A, Sagittal transvaginal scan shows echogenic material within the endometrial cavity but no gestational sac. Blood clot is (*) seen around the uterus. B, Coronal transvaginal scan of the uterus (U) and a complex right adnexal mass with a sac at its posterior aspect (arrow). C, Coronal color Doppler sonogram with no vascularity seen. D, Sagittal scan of the left upper abdomen showing free fluid (*).

A B

C D

*

*

Pseudogestational sac. A, Coronal transvaginal scan of a 33-year-old woman (G2P1) at 8 weeks with pelvic pain. There is a rounded intrauterine sac filled with low-level echoes. No yolk sac or embryo is seen. There is a single echogenic ring around the fluid (arrow). This is a fluid-filled endometrial canal, a decidual cast, or pseudogestational sac. B, Sagittal transvaginal scan shows a large pseudogestational sac with echogenic debris. Note the acute angle at the lower end, uncommon in a gestational sac.

Live ectopic pregnancy. A 33-year-old woman presented with left lower quadrant pain at 9 weeks’ gestation. A, Coronal transvaginal scan shows the empty endometrial cavity on the right and a gestational sac and embryo on the left. B, M-mode image demonstrates a live embryo with cardiac activity at a rate of 173 beats/min. C, The embryonic crown-rump length is 19 mm. D, In a different patient, coronal transvaginal scan of the right ovary with a corpus luteum cyst (c) and a gestational sac with a single live embryo immediately adjacent (arrow).

A B

C D c

RO

Isthmic ectopic pregnancy. A 35-year-old woman (G3P1A1) presented with no pain but was at risk for an ectopic pregnancy. A, Coronal transvaginal scan shows an empty uterus and a tubal ring (arrow) immediately adjacent to the uterus. B, Magnified view of the ring shows a gestational sac with a yolk sac, confirming an ectopic pregnancy. C, Color flow Doppler ultrasound shows increased vascularity around the sac with high-velocity flow. D, At laparoscopy, ectopic site can be seen bulging the isthmic portion of the tube (arrow). It was successfully removed by salpingostomy.

A

C

B

D

Ectopic pregnancy seen as echogenic mass. A 33-year-old woman presented at 7 weeks’ gestation with right lower quadrant pain. A, Transvaginal scan shows an empty uterus. B, Free fluid (ff ) in the cul-de-sac. C, In right adnexa there was a 1.4 × 1.6–cm echogenic mass (arrow) adjacent to a normal ovary (ro). The mass was focally tender to palpation with the vaginal probe. D, Power Doppler ultrasound shows minimal internal vascularity.

A

C D

B FF

ro

Ectopic pregnancy seen as mixed- echogenicity mass. A 30-year-old woman presented withleft lower quadrant pain at 7 weeks’ gestation and β-hCG of 500 mIU/mL and falling over a 3-day period. A, In the left adnexa, medial to the left ovary, there was a 2-cm mass (arrow) with mixed echogenicity, and B, only minimal peripheral vascularity. A left ectopic pregnancy was confirmed and based on a falling β-hCG was treated expectantly and resolved without complication.

A

B

Interstitial ectopic pregnancy. An 18-year-old woman presented with mild pelvic discomfort with a bulging left cornua. A, Sagittal transvaginal sac just to the left of midline. The empty endometrial canal is seen in the body of the uterus with the thin echogenic “interstitial line” (arrow) leading to the interstitial ectopic pregnancy. B, Postoperative specimen of the wedge resection and removal of the left cornua. C, Coronal transvaginal scan of the expanded left cornua with a thin myometrial mantle (white arrow), the gestational sac, and the small embryo (black arrow). D, Bisected specimen shows the sac and the white embryo (arrow) that corresponds to the sonogram in C.

A

C

B

D

Cesarean scar implantation. A 33-year- old woman presented at 10 weeks’ gestation. A, Transabdominal scan shows a sac (arrow) in the lower uterine segment. B, Transvaginal scan shows a sac in the lower segment with an embryo. C, Magnified view with color Doppler ultrasound shows flow in a beating heart and peritrophoblastic flow anteriorly. Notice how close the echogenic trophoblast is to the anterior serosal surface of the uterus and to the bladder wall.

A B

C

Heterotopic pregnancy. A 30-year-old woman presented at 6 weeks with pelvic pain and a positive pregnancy test. A, Sagittal scan shows a retroverted uterus with a normally positioned 6-week gestational sac with yolk sac. B, In the left adnexa, adjacent to the left ovary (LO), there is a tubal ring (arrow) that proved to be an ectopic sac at laparoscopy.

A B

Ectopic pregnancy with hematoma after methotrexate injection. A, Transvaginal coronal scan through the uterine fundus shows an early isthmic ectopic pregnancy in the right adnexa. B, Three days after intramuscular methotrexate, the patient returned with increasing pelvic pain. Transverse scan of the fundus and right adnexa now shows an echogenic mass (arrowheads) surrounding the irregular gestational sac (arrow). C, Sagittal power Doppler ultrasound through the uterus shows vascularity in the myo- metrium but not in the hematoma superior to it (short arrows).

A B

C

Evaluation of the Embryo

Normal Embryologic Development Mimicking Pathology

* Intracranial Cystic Structures in First Trimester

* Physiologic Anterior Abdominal wall Herniation

Normal appearing abnormal Embryos* Anencephaly

* Renalagenesis

* Discrepancy between dates and embryo size

Normal embryonic intracranial anatomy. A and B, Sagittal, and coronal images of 9-week embryo (CRL, 19 mm) clearly show the cystic rhombencephalon.

A B

Normal lateral ventricles. Transverse scan of a 13-week fetus with choroid plexus filling most of the lateral ventricles.

Physiologic midgut herniation. A, Ten-week embryo has the typical echogenic bowel herniated into the baseof the umbilical cord (arrow). B, 3-D view of an 11-week embryo also shows midgut herniation (arrow).

A

B

Anencephaly. Coronal scan of anencephalic fetus at 11 weeks’ gestational age shows a large, irregular cranial end inferiorly with no visible echogenic calvarium.

FIRST TRIMESTER MASSES

Ovarian Masses* Most common mass seen in first trimester of pregnancy

is the corpus luteum cyst.

* Other cystic masses may present in the first trimester of pregnancy because of displacement by the enlarge uterus.

* Torsion, Rupture and Dystocia have all been described as complication of ovarian cystic masses.

* Dermoid cysts may ne present the characeristic appearance of a cystic mass with focal calcification and fluid- fluid level.

Hemorrhagic corpus luteum cyst (arrow) at 6 weeks. A, The filamentous bands within the cyst are consistent with hemorrhage. There is also a paraovarian cyst (p), which is echolucent. B, Hemorrhaging corpus luteum with a small amount of adjacent free fluid. C, The vascularity is a typical ring of fire with flow in the wall around the cyst. D, Pathologic specimen of an ovary with a corpus luteum cyst (arrow).

A B

CD

Mucinous cystadenoma of low malignant potential. A, Sagittal scan with the bladder anterior and the cystic mass posterior compressing the lower segment of the gravid uterus. B, Transvaginal scan shows low-level echoes within the mass and some debris at the lower end. C, Color Doppler ultrasound shows no flow in the debris. D, The fluid was aspirated before delivery and was old blood. The mass recurred and was removed at cesarean delivery.

A B

C D

Uterine Masses* Uterine fibroids are a common palvic mass often

identified during pregnancy and often associated with localised pain and tenderness.

* Fibroids may distort the uterine contour whereas focal myometrial contractions usually buldge into the amniotic cavity.

* Fibroids are associated with almost twice the spontaneous loss rate in early singleton pregnancies with documentated cardiac activity.

CONCLUSION

First trimester sonography plays an important role in establishing the location of a pregnancy and determining if the pregnancy is potentially viable.

Knowledge of the landmarks with respect to the appearance of the gestational sac , yolk sac and embryo are important in the appropriate triage of patients.

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