Early Pregnancy

Dr S ChawlaDorma, GhanaNovember 2013

Role of US in Early pregnancy

Confirm:• Presence of live intra-uterine pregnancy• Gestational age• Number of fetuses

Exclude:• Early pregnancy failure• Ectopic pregnancy• Molar pregnancy• Other pathology

Technique

Transabdominal scan• 3.5 – 5 MHz• Full bladder• Entire pelvis visible

Transvaginal scan• 7.5 MHz• Empty bladder• 8 – 10 cm depth

only

Technique

• Begin in LS plane• Use wide FOV• Identify bladder• Look for gestation sac• Look for yolk sac or embryo• Check for heart pulsatations• Transverse• Scan out towards both adnexa

Anatomy

Bladder

Cervix

Body ofUterus

Gestation sac

Sac containing yolk sac andFetal pole

Estimating gestational age

1. Gestational sac size

Add 3 measurements, divide by 3, add 30, divide by 7

Estimating gestational age

2. Crown rump length (CRL)

• Zoom the image• Find the longest axis of the embryo• Measure from crown to rump

• If CRL > 85mm, measureHC instead

Early pregnancy abnormalities

• Embryonic demise• Multifetal pregnancy• Retained products of conception• Molar pregnancy • Ectopic pregnancy• Subchorionic haemorrhage• Some fetal abnormalities

Embryonic demise (EPF)

1. Empty sac sign• MSD > 20mm with no visible yolk sac

CAUSES:• Missed miscarriage• Anembryonic pregnancy• Pseudo sac from ectopic pregnancy

20mm

Embryonic demise (EPF)

2. Absent fetal heart pulsatation

• Embryo CRL > 10mm with no FH = EPF(Transabdominal)

If unsure:• Use M mode• Use Doppler• Get a second opinion

Ectopic pregnancy (1)

• Implantation of pregnancy outside endometrium• 0.3-1.6% of pregnancies, 10% of maternal deaths• Role of ultrasound is to locate pregnancy• Intra-uterine pregnancy = ectopic excluded

IMPORTANT FACTS:• Normal ultrasound does not exclude ectopic• Must be correlated with clinical findings• ß-hCG > 1000 iu = embryo should be visible• If the patient is collapsed, do not delay treatment

Ectopic pregnancy (2)Possible ultrasound features of ectopic

Intra-uterinepseudo sac

Solid adnexalmass with ‘doughnutappearance’

Ectopic pregnancy (3)

Possible ultrasound features of ectopic

Thickened echobright endometrium

Ectopic pregnancy (4)

Possible ultrasound features of ectopic

Solid adnexalmass

Bladder

Ectopic pregnancy (5)

Possible ultrasound features of ectopic

Molar pregnancy

• Present with bleeding and hyperemesis• Caused by excessive proliferation of

placental tissue• Occasionally fetal tissue forms (non-viable)• Elevated ßhCG levels• 10% develop into malignant choriocarcinoma

Molar pregnancyAppearance of molar pregnancy

Enlarged echobright endometrium Multiple cystic spaces

Retained products of conception

Echobright or heterogenous material within endometrial cavity

Multifetal pregnancy

• Assess viability of all fetuses

• Identify presence or absence of dividing septum

• Look for lambda sign

THICK DIVIDING MEMBRANE = DCDA

THIN DIVIDING MEMBRANE= MCDA

Associated findings• Intra-uterine fibroids

Associated findings

• Ovarian cysts

Early fetal abnormalities

• Anencephaly

Early fetal abnormalities

• Megacystic baldder

Early fetal abnormalities

• Gastroschisis/omphalocele

Troubleshooting

To improve image quality:1. Ensure patient has full bladder2. Use multiple focal zones3. Narrow FOV and use zoom4. Use M mode, Doppler and Transvaginal

scanning if available

TroubleshootingTo help visualise ovaries:• Use the bladder as a window

Scan right ovaryfrom the left

Scan left ovary from the right

Face

Nasal Bone

Heart

Kidneys

Spine

Limb

Calvarium, choroids and midline

Placenta

Troubleshooting

REMEMBER:Always consider the clinical picture and

not just the ultrasound picture!