docSonography of the 1st Trimester Pregnancy
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Sonography of the 1st Trimester Pregnancy
Sonography of the 1st Trimester Pregnancy Oksana H. Baltarowich, M.D. Department of Radiology, Thomas Jefferson University Philadelphia, Pennsylvania Objectives • Describe the sonographic signs of normal first trimester pregnancy • Describe the definite sonographic signs of early pregnancy failure • Discuss suggestive signs of early pregnancy failure SONOGRAPHIC DETECTION Implantation Earliest US detection 3.0 wks 4.5 wks 1st TRIMESTER SONOGRAPHY FIRST STEP • Establish that the gestational sac is in the uterus • Check cervix and lower uterine segment –shape –continuity with uterine walls EARLY PREGNANCY SONOGRAPHIC VISUALIZATION Gestational sac Yolk sac Embryo Heart beat NORMAL GESTATIONAL SAC • • • • • Chorionic and amniotic cavity Round /oval, smooth Hyperechoic rim > 2 mm Position: fundal or mid-uterus MSD grows about 1 mm per day NORMAL GESTATIONAL SAC SONOGRAPHIC SIGNS OF IUP • • • Intradecidual sac sign Double decidual sac sign Doppler: trophoblastic flow NORMAL GESTATIONAL SAC INTRADECIUAL SAC SIGN • • • Earliest sign of IUP Appears at 4.5 weeks Not very accurate NORMAL GESTATIONAL SAC INTRADECIDUAL SAC SIGN • Must differentiate from –Fluid in cavity –Endometrial, myometrial, decidual cysts –Degenerated fibroid • Follow-up to document development of yolk sac or embryo FALSE INTRADECIDUAL SAC SIGN Fluid in cavity Postmenopausal polyp FALSE INTRADECIDUAL SAC SIGN Decidual cyst, ectopic pregnancy Degenerated myoma NORMAL GESTATIONAL SAC DOUBLE DECIDUAL SAC SIGN • Sonographic sign of IUP • Later sign 5-6 wks • More useful with TAS • Two concentric echogenic rings around part of sac separated by a hypoechoic line NORMAL GESTATIONAL SAC DOUBLE DECIDUAL SAC SIGN • Differentiates an IUP from a pseudosac • Highly reliable but not absolute • Not needed after yolk sac or embryo appears • Follow-up is recommended DOPPLER IN EARLY PREGNANCY • Trophoblastic blood flow has a low resistance arterial waveform pattern • Do not use Doppler in normal first trimester without indication: higher energy Dillon, Radiology: 1990 and Dubinsky, JCU: 1997 NORMAL YOLK SAC SONOGRAPHIC FEATURES • Round sphere with echogenic rim • 3-6 mm diameter • One yolk sac per embryo • In chorionic cavity • Not seen after 10-12 weeks • Seen by MSD >13mm (TVS) EMBRYONIC YOLK SAC SIGNIFICANCE • Earliest embryonic landmark by TVS • Reliably identifies an IUP • Helps locate the embryo and heart beat • Estimates age of pregnancy at 5.5 weeks THE AMNION • Membrane surrounding the embryo • Grows with the embryo • Starts out smaller than chorionic cavity • Later overgrows the chorionic cavity • Thinner than yolk sac • Fuses with chorion 8-16 weeks MA NORMAL EMBRYO • • • • • • Exists between 5.1 and 10 weeks MA Not a fetus until after 10 weeks Earliest detection by TVS is 5.7 weeks Grows about 1mm per day in length (CRL) Should be seen in sac 20mm MSD (TVS) Should have visible heart beat with CRL > 5mm (TVS) EARLIEST EMBRYO DIAMOND RING SIGN Embryonic Heart Beat Do not use Doppler on a normal embryo NORMAL EMBRYONIC ANATOMY EMBRYONIC PERIOD Week 6 Weeks 6-10 Heart begins to beat Embryogenesis EMBRYO to FETUS Graduation Day is 10.0 weeks!! FETAL PERIOD Week 11 All organs present Week 12 Reduction of midgut hernia Week 14 Mature form of external genitalia 4 chamber heart TERMINOLOGY • EMBRYO, not fetal pole! • EMBRYONIC heartbeat, not fetal heartbeat! • EMBRYONIC demise, not fetal demise! NORMAL EMBRYONIC HEAD Two physiologic cystic spaces in the embryonic head (intracranial vesicles) 1. Anterior: precursor of cerebral ventricles 2. Posterior: rhombencephalon NORMAL ANATOMY Embryonic/Early Fetal Abdomen Physiologic umbilical herniation • Present <12 wks • Abdominal wall defect • Normal midgut herniation • Contents recede into abdominal cavity by 12 weeks MA PHYSIOLOGIC HERNIATION PHYSIOLOGIC HERNIATION EMBRYONIC HEART BEAT • • • • Seen by TVS around 6 weeks Should be seen in embryos CRL > 5mm May not be seen in embryos 4mm Rate increases between 5.5 & 10 weeks from 100 to 140-150 beats per minute • Bradycardia < 90 : poor prognosis 1st TRIMESTER DOPPLER • Do not use Doppler on a first trimester embryo!!!!!!!!!!!!!! THE ABNORMAL FIRST TRIMESTER EARLY PREGNANCY FAILURE TERMINOLOGY • Anembryonic pregnancy • Embryonic / fetal demise • Early pregnancy failure • Blighted ovum / sperm? • Empty sac • Missed abortion EARLY PREGNANCY FAILURE SONOGRAPHIC SIGNS Definitive or Primary (each sign stands alone in significance) Suggestive or Secondary (collective, cummulative significance) EARLY PREGNANCY FAILURE DEFINITE PRIMARY SIGNS 1. 2. 3. No heart beat No embryo No growth or shrinkage All signs depend on CRL or sac size EARLY PREGNANCY FAILURE DEFINITE PRIMARY SIGN No heartbeat in embryo CRL > 5mm (TVS) or > 9mm (TAS) Diagnosis: Embryonic demise N.B. Normal embryos 4mm may not have a heartbeat DEMISED ABNORMAL EMBRYOS EMBRYONIC DEMISE PRIOR TO DIAGNOSIS 1. Technically adequate exam 2. Locate embryo with certainty 3. Search embryo thoroughly EARLY PREGNANCY FAILURE DEFINITE PRIMARY SIGN (TVS) No embryo in gestational sac with MSD 20 mm TVS or 25 mm TAS Anembryonic Pregnancy ANEMBRYONIC PREGNANCY POSSIBILITIES FOR EMBRYO 1. Failure to develop 2. Very early demise, not visible 3. Resorption EARLY PREGNANCY FAILURE DEFINITE PRIMARY SIGN No growth or shrinkage of embryo or gestational sac on serial exams 10-14 days apart (Embryonic demise) (Anembryonic pregnancy) EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGNS • • • • • • • • Embryonic bradycardia First trimester oligohydramnios Subnormal growth of embryo or sac Perigestational bleed Abnormal sac border Abnormal yolk sac or amnion Low position of sac in uterus Absent living embryo in a sac of 12 –19 mm MSD • No yolk sac in a sac 10 mm TVS EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Embryonic bradycardia Heart rate <90 bpm Follow-up in 3-4 weeks EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN First trimester oligohydramnios • Small, tight sac relative to size of embryo • At least a 35% survival rate (Rowling et al 1997) • If MSD - CRL < 5mm, subsequent demise (Bromley et al 1981) FIRST TRIMESTER OLIGO SAGITTAL TRANSVERSE EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Subnormal growth of embryo or sac on serial examinations (less than 0.6 mm per day) EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Subchorionic bleed EARLY PREGNANCY FAILURE Subchorionic hemorrhage or twin? EARLY PREGNANCY FAILURE Subchorionic hemorrhage or triplet? EARLY PREGNANCY FAILURE BLOOD IN UTERINE CAVITY EARLY PREGNANCY FAILURE BLOOD IN UTERINE CAVITY SAGITTAL TRANSVERSE EARLY PREGNANCY FAILURE BLOOD IN UTERINE CAVITY EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Abnormal choriodecidual tissues • Thin rim < 2mm • Weakly echogenic • Irregular outline • Absent double decidual sac • Perigestational venous flow EARLY PREGNANCY FAILURE Abnormal Choriodecidual Tissues EARLY PREGNANCY FAILURE Abnormal Choriodecidual Tissues EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Yolk sac abnormalities Size: > 6mm Number: > one per embryo Shape: irregular Echogenicity: solid, calcified EARLY PREGNANCY FAILURE ABNORMAL AMNION • Large in relation to embryo • Thick amnion, approaches yolk sac thickness • Wavy outline • Empty amnion EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGN Low position of sac in uterus DDx: Low implantation site Abortion in progress Normal sac and contraction Nabothian cyst Cervical ectopic pregnancy EARLY PREGNANCY FAILURE Low position of sac in uterus EARLY PREGNANCY FAILURE Low position of sac in uterus EARLY PREGNANCY FAILURE SUGGESTIVE SECONDARY SIGNS Absent living embryo in a gestational sac of 12 -19mm in MSD No yolk sac in a gestational sac with MSD 13 mm TVS (Anembryonic Pregnancy) VANISHING TWIN RETAINED PRODUCTS OF CONCEPTION SPONTANEOUS OR INDUCED, INCOMPLETE ABORTION • Remnant of gestational sac embryo • Intracavitary complex fluid collection • Blood clots versus residual tissue – Thickened endometrial echoes 5 mm – Doppler blood flow • Air in cavity – normal versus endometritis SPONTANEOUS ABORTION • Complete or incomplete? • Blood or retained products of conception? SPONTANEOUS ABORTION • Complete or incomplete? • Blood or retained products of conception? Retained Products of Conception Doppler blood flow Retained Products of Conception Doppler blood flow Retained Products of Conception Doppler blood flow Retained Products of Conception Retained placenta Retained Products of Conception Gestational Trophoblastic Disease Differential Diagnosis Gestational trophoblastic disease Complete mole Partial mole Invasive mole Choriocarcinoma Hydropic placenta Degenerated fibroid MOLAR PREGNANCY • Gestational trophoblastic disease • Multiple small cysts within hyperechoic tissue expanding the endometrial cavity • Disproportionately elevated serum -HCG (>100,000 mIU/mL) • Invasive mole (5%) and choriocarcinoma (1-2%) look similar • Thecal lutein cysts MOLAR PREGNANCY Increased vascularity of molar tissue HYDROPIC PLACENTA • Low beta hCG PARTIAL MOLE • Coexistent abnormal or demised embryo or fetus -HCG 55,000 mIU/mL: Diagnosis? MULTIPLE EMBRYOS FIRST TRIMESTER • • • Establish # of embryos Confirm heartbeats Establish chorionicity & amnionicity –determine sac number –identify membranes • Amniotic fluid in each sac MULTIPLE EMBRYOS ESTABLISH CHORIONICITY AND AMNIONICITY EARLY • DC-DA: thick membrane around each sac • MC-DA: thick membrane around periphery, but thin membrane between sacs • MC-MA: thick membrane around periphery and no visible membrane between sacs DC-DA TWIN SACS R L DC-DA TWINS TRIPLETS SEPTUPLETS MC-DA TWINS MC-MA TWINS Twins or Blood Clot? Conclusion • Be familiar with the sonographic findings of normal first trimester pregnancy • Understand the significance between definite and suggestive signs of early pregnancy failure The End