Diagnostic ultrasound ( PDFDrive )

CHAPTER
30
The First Trimester
Elizabeth Lazarus and Deborah Levine
SUMMARY OF KEY POINTS
• First-trimester development follows a predictable pattern
on irst-trimester ultrasound.
• Some ultrasound indings are deinitive for early pregnancy
failure, whereas others are suggestive and require
follow-up.
• Ultrasound is vital in the diagnosis of ectopic pregnancy in
typical and atypical locations.
• Gestational trophoblastic disease is composed of four
entities, and ultrasound is helpful in their diagnosis and
management.
CHAPTER OUTLINE
MATERNAL PHYSIOLOGY AND
EMBRYOLOGY
SONOGRAPHIC APPEARANCE OF
NORMAL INTRAUTERINE
PREGNANCY
Gestational Sac
β-hCG and Early Pregnancy
Ultrasound
Yolk Sac
Embryo and Amnion
Embryonic Cardiac Activity
Umbilical Cord and Cord Cyst
ESTIMATION OF GESTATIONAL AGE
Gestational Sac Size
Crown-Rump Length
EARLY PREGNANCY FAILURE
Diagnostic Findings of Early Pregnancy
Failure
Crown-Rump Length 7 mm or
Greater and No Heartbeat
Gestational Sac Mean Sac Diameter
25 mm or Greater and No
Embryo
Worrisome Findings of Early Pregnancy
Failure
Embryos With Crown-Rump Length
Less Than 7 mm and No
Heartbeat
Gestational Sac With Mean Sac
Diameter 16 to 24 mm and No
Embryo
Gestational Sac Appearance
Small Mean Sac Diameter in
Relationship to Crown-Rump
Length
Abnormally Large Amnion With
Respect to Embryo Size
Yolk Sac Size and Shape
Embryonic Bradycardia
Subchorionic Hemorrhage
ECTOPIC PREGNANCY
Clinical Presentation
Sonographic Diagnosis
Heterotopic Gestation
Serum β-hCG Levels
Speciic Sonographic Findings
Nonspeciic Sonographic Findings
Adnexal Mass
Free Fluid
Endometrium
Implantation Sites
Pregnancy of Unknown Location
Management
EVALUATION OF THE EMBRYO
Normal Embryologic Findings
Mimicking Pathology
Rhombencephalon
Physiologic Anterior Abdominal Wall
Herniation
Abnormal Embryos
GESTATIONAL TROPHOBLASTIC
DISEASE
Hydatidiform Molar Pregnancy
Complete Molar Pregnancy
Partial Molar Pregnancy
Coexistent Hydatidiform Mole and
Normal Fetus
Persistent Trophoblastic Neoplasia
Invasive Mole
Choriocarcinoma
Placental-Site Trophoblastic Tumor
Sonographic Features of Persistent
Trophoblastic Neoplasia
Diagnosis and Treatment
CONCLUSION
The irst trimester of pregnancy is a period of rapid change
that spans fertilization, formation of the blastocyst, implantation,
gastrulation, neurulation, the embryonic period (weeks
6-10), and early fetal life. 1 First-trimester sonographic diagnosis
traditionally focused on evaluation of growth by serial examination
to diferentiate normal from abnormal gestations. his has changed
since the advent of transvaginal sonography (TVS), which afords
enhanced resolution over transabdominal sonography (TAS),
with earlier visualization of the gestational sac and its contents, 2
earlier identiication of embryonic cardiac activity, 3 and improved
visualization of embryonic and fetal structures.
Despite these technologic improvements, it is important to
set clinically relevant and realistic goals for irst-trimester
sonographic diagnosis. Most examinations are requested because
the patient has vaginal bleeding or pain, or a palpable mass has
been identiied on physical examination. Ultrasound in the irst
trimester is oten requested to diagnose early pregnancy failure
or an ectopic pregnancy.
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