Sonography in the First Trimester Basic Embryology 1mm Sac G. William Shepherd PhD, RDMS, RVT 1 2 Embryonic Timeline Embryology Terms Gamete --------- Before fertilization Ovulation: Day 14-16 Zygote ---------- After fertilization Fertilization: Day 14-16 Morula --------- 16 -32 Cells (18 Days) Zygote to Morula: Day 16-18 Week 3 Blastocyst ---------- 20 Days Morula to Blastocyst: Day 18-19 Embryonic Disc --- 28 Days Implantation: Day 19-20 Ultrasound Detection --- 31 Days Earliest Heart Beat ------ 36 Days 3 4 Yolk Sac Formation: 4w1d Goals for a 1st Trimester Scan Visualization and localization of the gestational sac Determination of viability Determination of the # of embryos & viability Estimation of gestational age Determination of any detectable anomalies 5 6 1 Earliest Definite Ultrasound Visualization: 31days 4W6D coronal 7 Pre-embryonic (embryonic disc stage 4w4d or 32days)8 “Double Sac” Sign 9 10 “Double Sac” Sign Video Clip 11 12 2 Estimation of Gestational Age 5 weeks by LMP from the MSD (mean sac diameter) Age in Days (by LMP) = (L+W+H) + 30 3 13 14 5w0d by LMP 5 weeks 6 days by LMP 1cm 4mm + x x 6mm + xx 13mm Width (from trv image) = 6 ++ 11mm 6+6+4 divided by 3 = 5.3, +30 = 35.3d or 5w Width 15mm MSD 13 = 43d =6w1d 15 9.25 16 Human Chorionic Gonadotropin Beta Chorionic Gonadotropin Levels Made by trophoblastic cells MSD Age (weeks) HCG Level Detectable after implantation 2mm 5.0 1,164 5mm 5.4 1,932 Doubling time every 2-3 days 10mm 6.0 4,478 Correlates well with embryonic and sac size 15mm CRL 6.6 10,379 Level maximizes at about 8 weeks 20mm 7.3 24,060 Max level is about 50,000 -100,000 IU/L Declines after 10-12 weeks * Filly, in Ultrasonography in Obstetrics and Gynecology, ed Callen, W.B. Saunders, Philadelphia, 1994. 17 18 3 4-5mm Embryonic Timeline Week 6: Heartbeat will be detectable during this week. This is the neural tube stage x Weeks 6-10: Essentially all of the tissues and organs x of the embryo will form during this period. Week 11: All of the organs are present and all but a portion of the bowel and the external genitalia are in their final positions. Week 12: The bowel will reenter the fetal abdomen. 19 20 5w5d 6w1d CRL and Gestational Age CRL Gest. Age CRL Gest. Age 2mm 5.7 weeks 60mm 12.5 weeks 4 6.1 70 13.2 8 6.7 80 14.0 10 7.2 90 14.9 15 7.9 100 15.9 20 8.6 110 16.9 25 9.2 130 17.9 30 9.9 40 10.9 Hadlock et al 50 11.7 Radiology 18: 501, 1992 3 days development and growth 21 22 6w3d 2mm Yolk sac and the Early Embryo 23 24 4 Embryonic Period 8w CRL = 18mm 8w3d Oblique Scanning Plane Fluid? Fluid? 25 26 Don’t include the yolk sac in the CRL 13mm 7w2d 27 28 Be aware of fetal position 29 30 5 6w1d 7w4d 8w4d 10w3d 31 32 Manipulation of Transducer for CRL After 13 weeks use BPD, HC, AC, and FL 33 Video Clip 34 Skeletal Development 10w3d 8w2d 9w3d 35 36 6 Indications for a First Trimester Scan Significance of the Yolk Sac Vaginal bleeding Earliest landmark in the early gestational sac Size and date discrepancy Identifies an IUP No heart tones Helps to locate the embryo and heart beat Pelvic pain Should be round and “cystic” 3-6mm Accurate dating for future C-section 1 yolk sac per embryo, can help identify monoamnionic twins History of an anomaly Should disappear by 12 weeks Trauma 37 38 7 Week Embryo 7 Week Embryo Yolk Sac Amnion Chorionic Fluid Amniotic Fluid 39 40 Yolk Sac Too big Yolk Sac 1 cm 1.5 cm 41 42 7 Vaginal Bleeding (1st Trimester) Implantation Bleed Abortion Subchorionic Hemorrhage Placental Previa Ectopic Pregnancy Blighted Ovum Compressed Yolk Sac 43 44 The future Jen Shepherd Implantation Bleed Most common cause of 1st trimester vaginal bleeding Generally not significant Sonolucent area between the chorion and uterus (near the internal os) 45 46 Vaginal Bleeding (1st Trimester) Subchorionic Bleeds Can be behind the placenta Implantation Bleed Can be behind the chorion lavae Subchorionic Hemorrhage Can be behind the chorionic plate of the placenta Abortion Prognosis depends upon the cause and how much Placental Previa of the placenta is involved: >1/3 prognosis worsens Ectopic Pregnancy Blighted Ovum 47 48 8 1/4 of placenta is separated from uterus 49 50 8w2d 51 52 Blighted Ovum: Arrested or absent development of Vaginal Bleeding: 1st Trimester the embryonic pole (trophoblasts develop) Implantation Bleed Subchorionic Hemorrhage Blighted Ovum Placental Previa Ectopic Pregnancy Abortion 53 54 9 Growth will fall off No embryo HCG will level off or Yolk Sac Sac may move toward Cx 55 56 Trophoblastic ring may become irregular and thin < 2mm Video Clip 57 58 Placenta Previa Vaginal Bleeding: 1st Trimester 12w2d Implantation Bleed Abortion Subchorionic Hemorrhage Placental Previa Ectopic Pregnancy Blighted Ovum 59 60 10 Vaginal Bleeding: 1st Trimester Glossary of 1st Trimester Terms Abortion: Premature expulsion of the gestation Implantation Bleed from the uterus Abortion Incomplete Abortion: The expulsion of only a Subchorionic Hemorrhage portion of the gestational products from the uterus Placental Previa Ectopic Pregnancy Blighted Ovum 61 62 Retained Products of Conception Inevitable Abortion 63 64 Findings for Embryonic Demise Findings for Embryonic Demise Old Criteria No Sac Growth on Serial Exams The Findings Below Depend upon Body Habitus and Type of Transducer, Endovag or transabd A 7 -10 day interval between scans is recommended No Sac Growth on Serial Exams Give the embryo a chance No Cardiac Pulsations in a 5mm Embryo EV scanning is always best No Embryo Seen in a Sac 25mm MSD Abdallah et al US Obstet & Gynecol 2011 No Yolk Sac Seen in a 20mm MSD Sac Trophoblastic Ring is not Intact 65 66 11 The Gestational Sac Grows about 1mm/Day 1 Week Should Give a Statistically Significant Increase in MSD Findings for Embryonic Demise Jan 4 Jan 11 Slow Cardiac Pulsations in a 5 (now 7) mm Embryo in an endovaginal ultrasound examination MSD = 3mm MSD = 10mm 67 68 Reading an M-Mode Findings for Embryonic Demise No Cardiac Pulsations in a 9mm Embryo in a transabdominal ultrasound examination 1 second 1 second M-Mode No Heart-beat Heart rate only 60 bpm Heart rate 160 bpm 69 70 71 72 12 Video Clips 73 74 Video Clips Video Clips 75 76 Findings for Embryonic Demise No Embryo Seen in a Sac 18 (now 25) mm MSD in an endovaginal ultrasound examination 77 78 13 Findings for Embryonic Demise Findings for Embryonic Demise No Embryo Seen in a Sac 25mm MSD in an No Yolk Sac Seen in a 10mm MSD Gestational Sac transabdominal or EV ultrasound examination with endovaginal scanning Was 20mm 79 80 Findings for Embryonic Demise New Criteria for Embryonic Demise No Yolk Sac Seen in a 20mm No Sac Growth on Serial Exams MSD Gestational Sac with No Cardiac Pulsations in a 7 mm Embryo* transabdominal scanning No Cardiac Pulsations in a 9mm Embryo ** No Embryo Seen in a Sac 25 mm MSD* MSD 25mm No Embryo Seen in a Sac 25mm MSD** No Yolk Sac Seen in a 10mm MSD Sac * No Yolk Sac Seen in a 20mm MSD Sac** * endovaginal scanning ** transabdominal scan 10.0 81 82 Anembryonic Pregnancy Oligohydramnios Small for Dates S < D Normal Pregnancy / Wrong Dates Anembryonic Pregnancy (blighted ovum) Ectopic Pregnancy Embryonic Demise Fetal Demise Ectopic Pregnancy Oligohydramnios Intrauterine Growth Retardation (IUGR) 83 84 14 Pseudo-sac Ectopic Pregnancy 95% occur in the tube 5% are interstitial and are the most dangerous Cornual and cervical ectopics are increasing Transabdominal scans In vitro procedures increase the chance of ectopic pregnancy Heterotopic: IUP plus an ectopic Pseudo-sac 85 Endovaginal scans 86 Ruptured Ectopic 87 Live Ectopic Pregnancy in Right Fallopian Tube 88 Cervical Ectopic Pregnancy Ectopic Pregnancy in Right Cornu 89 90 15 Right & Left Horns of Ectopic? Bicornuate Uterus Uterus? 91 92 Hemorrhagic Corpus Luteum Can Look Like an Ectopic 93 94 Molar Pregnancy Large for Dates Vaginal Bleeding Very High HCG May be a live embryo 1 in 1200 pregnancies in the USA Risk is 20-40 fold higher if patient had a previous molar pregnancy (1 in 30-60) 95 96 16 Theca Lutein Cysts There may or may not be a sac. 97 98 The arrow heads point to the major portion of the mole. The white arrows point to echogenic invasive villi that extent almost to the serosal surface of the uterus (black arrows). Partial Mole at 12 weeks -Top, 14 weeks - Bottom 99 100 Video Clip Large for Dates Normal Pregnancy / Wrong Dates Molar Pregnancy Gestation with Mass / Masses Multiple Gestation 101 10.25 102 17 Bicornuate Uterus IUP Hydatidiform Mole Theca Lutien Cysts 103 104 Early Pregnancy with a Mass Multiple Gestation 105 106 Video Clip Triplets Bleeds 3 1 2 107 108 18 Anomalies: Detectable in the 1st Trimester (Endovaginal Scanning is Best) B A Anencephaly Conjoined twins E Acrania Large omphalocele C D Cystic hygroma Severe gastroschisis Hydrops Thanatophoric dwarf 109 110 Normal Head at 12 Weeks Video Clip Transverse Head at 12 Weeks Choriod Plexus Frontal Occipital 111 112 2mm Acrania at 10w2d Normal Nuchal Translucency 10w6d 113 114 19 Normal Herniation of the Gut Omphalocele into the Base of the Cord at 11w2d 12w4d 115 116 Questions? 117 20 .