1st trimester scan

Basic ultrasound in O&G

Why scan?

Pregnancy

Mass per abdomen

Screening procedure - Pap smear, abd scan

Liver/gallbladder

Kidney/ bladder

Pregnancy scanning

Confirmation of pregnancy:

POA

UPT

Scan

Pregnancy scanning

Dating of pregnancy:

4-5th week: GS

6th week: GS, Fetal echo, FH

7-12th week: CRL

12-24th week: BPD/HC/AC/FL +/- 2/52

After 24 weeks: 3/52 error

To change EDD???

Pregnancy scanning

No. of fetuses/ sacs

Viability of fetuses:

Out of sync

Wrong dates

Missed abortion

Incomplete abortion

Molar pregnancy

Pregnancy scanning

Ectopic pregnancy:

History

UPT

Complaints- symptoms

Signs- classical, silent, leaking

USS-by exclusion, vaginal probe, fluid in POD

Pregnancy scanning

Abnormality scan:

1st trimester

2nd trimester

3rd trimester

Placenta:

Error in localisation

Probe

Wait > 34/52

Pregnancy scanning

Sex

Growth scan:

BPD/AC/HC/wt

Liquor volume-AFI

Charts

Pregnancy scanningAbnormal lie/ presentation:

Breech

Transverse

Unstable

Post-partum:

Hemorrhage/retained placenta

Sepsis

Uterus = 12/52 at 12/7

Gynaecological scanning

Uterus: uterine fibroid, adenomyosis, polyp

Cervix: fibroid, polyp

Ovarian: cyst, mass

Infertility work up: vaginal probe

1st trimester u/s

Confirmation of pregnancy:

Earliest by scan:

4w3d-vaginal probe (2-3mm)

5w3d -abdominal probe

Presence of GS with fetal echo

FH + by 6/52

1st trimester u/s

Viability:

size and shape of GS

CRL

FH

1st trimester u/s

No. of fetuses

Nuchal translucency

Dating of pregnancy

Dating of pregnancy

Abdominal method:

Full bladder in early pregnancy:

Pushes uterus out of pelvis

Acoustic window

Displaces bowel superiorly

Dating of pregnancy

Holding of probe (alignment):

Maternal bladder on the right

Fundus on the left

Dating of pregnancyEmbryo 37 days

Dating of pregnancy

Head discriminated against torso:

7w+3d

8 weeks:

Movements with limbs

Dating of pregnancy

Accuracy of dating- When biological variability is minimal:

CRL is more accurate than BPD

But can be the most difficult measurement to obtain

Dependant on operator

Dating of pregnancy

Eg: between 5-7 weeks can be inaccurate

Full length of embryo not obtained

End points not separate from yolk sac or not included

From 9w: any flexion- can underestimate

Dating of pregnancy

After 12w ++flexion --> delay after 15w

Nuchal translucency

Between 11-14w

For chromosomal abnormalities-principally trisomy 21

An increased collection of subcutaneous fluid (NT) behind the neck

Structural abnormalities, genetic cond, cardiac abnormalities

Numerical cut off in relation to gestational age

Adjusted to maternal age, CRL and NT

Nuchal translucency

Measurement

Problems of early pregnancy

Miscarriage

Ectopic pregnancy

Abdominal pregnancy

Trophoblastic disease

Ovarian probs in early pregnancy

Uterine fibroids

Pregnancy with IUCD

Problems of early pregnancy

Hormonal measurement (HCG)

Monoclonal antibody based UPT can detect >25 iu/L = 24-25/7 of a normal 28/7 cycle (i.e before one misses the period)

Serum HCG doubles every 2/7

Combine w USS: no intrauterine preg, no doubling Of HCG in 2-3/7, or cut off point of 1000iu/L

Miscarriage

20% incidence

Threatened

Missed

Complete

Incomplete

Problems of early pregnancy

Threatened miscarriage :

PV bleed with live embryo

15% proceed to miscarriage

Subchorionic haematoma # poor outcome

Problems of early pregnancy

Missed miscarriage:

Early featal death but retained GS

RCOG: absence of cardiac activity when CRL > 6mm

Absence of yolk sac or embryo when CTS > 20mm

If less than above, repeat after 1/52

Missed miscarriage

Problems of early pregnancy

Complete miscarriage:

Thin endometrium

Same as non pregnant uterus

Complete miscarriage

Problems of early pregnancy

Incomplete miscarriage:

Endometrial thickness between 5-15mm

Combine diagnosis with clinical situation e.g VE

Incomplete miscarriage

Problems of early pregnancy

Ectopic pregnancy:

Implantation outside uterine cavity:93% tubal

Incidence around 1%

Presentation: classical, abd pain with PV bleeding, silent

Problems of early pregnancy

Ectopic pregnancy:

Ultrasound findings:

UPT positive with empty uterus

With vaginal probe 85% can be visualised

Pseudo sac--> 10-30% of ectopic

Presence of fluid in POD--> 20-25% of ectopic

Problems of early pregnancy

Trophoblastic disease:

Spectrum: benign- hydatidifom mole, malignant- choriocarcinoma

Complete hydatidifom mole- snow storm appearance, no fetal tissue, serum HCG high

Partial hydatidifom mole- trophoblastic hyperplasia w fetal tissue

Problems of early pregnancy

Ovarian:

Mostly corpus luteum cyst- resolves <12w, usually < 5mm, single but can be complex

Theca lutein cyst

Dermoid cyst

Benign cystadenoma

Endometriomas