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 scanning
Abnormal 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 pregnancy
Embryo 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 = 2425/7 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, malignantchoriocarcinoma
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