Ultrasound Evaluation of First Trimester-b

Tuesday, April 11, 2023 Ultrasound evaluation of first trimester 1

ULTRASOUND EVALUATION OF FIRST TRIMESTER (cont.)


P/V bleeding in first trimesterSubchorionic bleeding

Spontaneous abortion

Ectopic pregnancy

Gestational trophoblastic

neoplasia(GTN)


Spontaneous abortionThreatened

cervix closedImpending/inevitable

open cervical OSIncomplete

retained tissuetrophoblastic flow

Completeusually endometrium is empty


Spontaneous abortion: ultrasound findingsSpectrum from threatened to complete

abortionnormalabnormal gestational sac:

o small, irregular, located in lower uterine segment or cervix

o movement of sac up and down canal withuterine contractions

large subchorionic hemorrhagefluid, debris within endometrial canalempty endometrial canal


Living embryoDead embryoEmpty gestational sac/blighted embryoSubchorionic haemorrhageMolar pregnancyCervix is closed

Threatened abortion: ultrasound


Inevitable/Impending abortionMay get any/some of the findings in

threatened abortion plus:Abnormal gestational sac:Small, irregular, located in lower uterine

segment or cervixMovement of sac up and down in cervical

canal with uterine contractionsOpen cervical canal


Deformed, irregular gestational sac


Open cervix: red arrow


Impending abortion Impending

abortion open cervix GS in

cervix

movement of sac


Incomplete abortionThickened, irregular endometrial stripe

Echogenic retained products of conception

Fetal parts

Open cervical canal


Retained products of conception: arrows



Complete abortion

Endometrium is usually empty and

endometrial stripe is usually normal

There may be some little fluid/hemorrhage

within the endometrium

Cervical canal is closed


Complete abortion: empty uterus


Gestational Trophoblastic Neoplasia (GTN)Spectrum including molar pregnancy, invasive

mole, choriocarcinoma, & placental-site

trophoblastic tumour (PSTT)

Paternal karyotype

fertilization of chromosomally empty egg

Pts present with markedly elevated β-HCG levels,

nausea


GTN: ultrasound findingsHeterogeneous, irregular endometrial mass

echogenicity variable“cluster of grapes” relatively late

appearancevascular: PSV, RI

+ Myometrial invasionFetus w/ a “thick placenta”Theca lutein cysts


Molar pregnancyComplete molar pregnancy:Chromosomal DNA exclusively paternal in originOvum with absent or inactive maternal

chromosomes is fertilized by a normal haploid sperm

Adiploid karyotype of 46,XX is produced (70-85%)

No fetal developmentPlacenta is entirely replaced by abnormal

hydropic chorionic villi with excessive trophoblastic proliferation


Complete molar pregnancy: ultrasound


Complete molar pregnancy: ultrasound


Molar pregnancy: theca lutein cysts


Partial molar pregnancyMost result from fertilization of a normal

ovum by 2 haploid spermsTriploid karyotype pf 69,XXX; 69,XXY; or

69,XYYWell developed but generally anomalous

(triploid) fetal tissuesHydropic degeneration of placental villi is

focal, interspersed with normal placental villiTrophoblastic proliferation is mildCoexisting embryo/fetus/GS


Partial molar pregnancy: ultrasound


Partial molar pregnancy: ultrasound


Fetal anatomy in the first trimester

Normal anatomy

Clear potential for early screening of

congenital anomalies

Developmental pitfalls

Nuchal translucency


Normal limb buds


Choroid plexus


Developmental pitfalls Developing

rhombencephalon normal finding contributes to

development of 4th ventricle, brainstem, cerebellum

cystic space in posterior fossa


Rhombencephalon


Developmental pitfallsFetal bowel normally

herniates into the base

of the umbilical cord in

the first trimester

echogenic mass near

cord insertion

< 7 mm across base

resolves by 12 wks


PHYSIOLOGIC HERNIATION OF BOWEL


Nuchal translucencyThin membrane found at approx 10 wks GA

along posterior neck

> 3 mm is abnormal, esp. if septated

Ass. with trisomy 21,18; Turner’s Syndrome

risk of congenital anomalies even if karyotype is normal

Regression is not reassuring


Normal nuchal translucency

2.6mm 2.7mm


Abnormal nuchal translucency

4.5mm


Nuchal translucencyShould make this measurement in all obs

ultrasound examinations between 10-14 wks

Measure in neutral position

Pitfalls

compression against uterine wall

extension or flexion of fetal neck


MATERNAL CAUSES OF PELVIC PAIN IN THE 1ST TRIMESTER

Hemorrhage / rupture of corpus luteum cyst

Ovarian hyperstimulation syndrome

Ovarian torsion


Haemorrhagic cysts

Changes over time - ultimately resolves

Thin wall (may be vascular)

Increased through transmission

No central blood flow


Haemorrhagic cystsDiffuse, low level

echoesLace-like or spider

web pattern of internal echoes/septations

Echogenic clot may be mobile or lenticular and adherent


Ruptured cyst

Crenated appearance

Adjacent free fluid

+/- internal debris


Ovarian hyperstimulation syndromeComplication of ovulation induction

incidence: pregnancy

estradiol > 4000 pg/ml

Bilaterally enlarged, multi-cystic ovaries

Complications include: cyst hemorrhage, cyst

rupture, ovarian torsion


Ovarian hyperstimulation syndrome: ultrasound evaluationAssess cysts for:

debris

irregular shape

adjacent free fluid

Document ovarian blood flow

Assess for ascites, pleural effusion


Ovarian hyperstimulation syndrome: ultrasound evaluation


Ovarian hyperstimulation syndrome: pleural effusion


Ovarian torsionClinical presentation: acute onset of severe pelvic

pain, usually no fever, normal WBC

More common on right

Differential diagnosis: hemorrhagic cyst, cyst

rupture, renal colic, appendicitis


Ovarian torsion: ultrasound featuresEnlarged ovary

check for underlying mass

heterogeneous central stroma

edema / infarct

peripheral cysts

+/- Free fluid

Appearance quite variable


Ovarian torsion: Doppler findingsVariable

varying degrees of torsionDecreased flowReversed diastolic flowDecreased or absent venous flowComplete absence of flow

Documents

Ultrasound Evaluation of First Trimester-b