CLINICAL APPLICATIONS OF

EARLY OBSTETRICAL ULTRASOUND

Photo here

Susan Rutherford, MDMedical Director, 3W Medical for Women

• First trimester ultrasound examination basics

• Establishing gestational age

• HCG testing and ultrasound results

• Early pregnancy loss

• Early ultrasound findings impacting clinical management

• How first trimester observations make a difference for patients

Content

Sagittal Plane

Transabdominal scan

FeetHead

Sagittal Plane

Transabdominal scan – anteverted, anteflexed

Sagittal Plane

Transabdominal scan – retroverted, retroflexed

Transverse Plane

Transabdominal scan

Right Left

Transverse Plane

Bicornuate uterus

Maternal

anterior this wayMaternal back

this way

Sagittal Plane

Transvaginal scan anteverted, anteflexed uterus

Sagittal Plane

Transvaginal scan – retroverted, retroflexed uterus

Maternal anterior

this way

Maternal back

this way

Transverse Plane

Transvaginal scan

Right Left

Overdistended Bladder

0.39 cm 6w1d 0.83 cm 6w5d

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Crown Rump Length - CRL

Fetal Heart Activity

• M-mode, not Doppler in first trimester• First seen in 90’s, soon >100

Establishing Gestational AgeRecommendations from ACOG/AIUM/SMFM

Date of Conception Compared to LMP

• Current tests measure intact hCG molecule

• Previous tests measured unique beta subunit

• Alpha subunit shared with TSH

• OTC home pregnancy tests sensitive at 30mIU/ml (time of missed period)

hCG Testing

• In general most IUP’s are visualized when serum hCG >1000mIU/ml

• Caution with a “discriminatory” cut-off to diagnose ectopic or pregnancy failure.

• Many instances of ultrasound-observed viability lagging for elevated hCG levels.

• Repeated hCG testing needed to look for increases in serum hCG levels.

hCG Level Accuracy

• Average increase in 48 hours = 2.24 fold

• Minimum increase in 48 hours = 1.53 fold (53% increase)

• Greatest increase in 48 hours = 3.28 fold

Barnhart, et al. Obstet Gynecol 2004, 104:50

hCG Rate of Increase in Patients with Pain & Bleeding

Multiple gestation and chorionicity

• Studied 221 women attempting to conceive with daily hCG.

• 22% of assay-detected pregnancies were lost prior to clinical recognition (“chemical pregnancy”).

• Of the chemical pregnancies:

• 35% became clinically pregnant by the next cycle• 65% clinically pregnant by the third cycle• 83% clinically pregnant by the sixth cycle• 95% clinically pregnant within 2 years

Wilcox et al NEJM 1988; 318:189

Incidence of Early Pregnancy Loss

Postulated Reasons for Loss Of Chemical Pregnancy

• Hormonal (Inadequate progesterone in luteal phase).

• Chromosomal? (Unknown compared to embryonic losses).

• Defective implantation.

Incidence of Early Pregnancy Loss

• Give it the benefit of the doubt• vs. failed pregnancy• vs. ectopic pregnancy

• Gestational Sac grows approximately 1mm/day

• Embryo grows approximately 1mm/day (6-11 wks)

• Mean Sac Diameter may be unreliable• Shape can vary due to external pressure, myometrial contractions, interobserver variations

Assessing Early Pregnancy Possible Failure

• CRL > 7mm with NO Cardiac Activity

• MSD > 25mm with NO Embryo

• Absence of embryo with cardiac activity > 2 weeks after scan showed gestational sac but no yolk sac

• Absence of embryo with cardiac activity > 11 days after a scan showed a yolk sac in a gestational sac

Assessing Early Pregnancy Failure, 2013 Statement

Doubilet et al. N Engl J Med 2013; 369:1443-1451

Anembryonic pregnancy

70% Chromosomal

• Trisomy 64%

• Abnormal number of

chromosomes

• Structural rearrangements

• Others

Early Pregnancy Loss

(numbers rounded)

30% Non-Chromosomal

• Hormonal

• Uterine shape

• Autoimmune

• Infection

• Alcohol, Smoking

• Molecular genetic abnormalities

Subchorionic hemorrhage

Subchorionic hemorrhage

Not Subchorionic hemorrhage

Also known as hydatidiform mole and gestational trophoblastic disease,

generally benign tumor of swollen chorionic villi.

• Complete molar pregnancy (no fetus) is from 1 or 2 sperm fertilizing an egg

missing maternal chromosomes.

• Partial molar pregnancy is from an egg fertilized by 2 sperm (69

chromosomes). The fetus does not survive.

Molar Pregnancy

Ectopic pregnancy

Ectopic pregnancy

Cystic hygroma

• Multiple gestation, establishing chorionicity

• Intrauterine subchorionic hematomas – increased

preterm birth

• Adnexal cysts larger than 5 cm

• Placenta localization >11 weeks

• Suspected anomalies

• Awareness of humanity of the unborn baby

How Incidental First TrimesterObservations May Help Patients