Clinical: Imaging in Reproduction Flashcards
What week does implantation occur?
Week 3 (since LMP)
When does the gestation sac develop?
Week 4 (since LMP)
When does the gestation sac + yolk sac develop?
Week 5 (since LMP)
When does the gestation sac + yolk sac + embryo develop?
Week 6-7 (since LMP)
When is it an “embryo” and when is it a “Fetus”?
6-10 11-40
What is the thing the arrow is pointing at an what is the whiter stuff around it?
Arrow= Gestational sac
White = trophoblast
Why is the 1 side longer than the other?
One side- Placenta
Describe Growth (CRL)
4mm- 6 weeks
8mm- 7 weeks
15mm- 8 weeks
22mm - 9 weeks
(start to slow down between week 8 and week 9)
In all conditions, the growth must double every week. If it’s not growing, it is a failed pregnancy.
Failure during _______trimester is common
First trimester
What is a threatned abortion/miscarriage?
Defined as bleeding and cramping in the first 20 weeks of
Bleeding in the first tremester very common, although no normal
Sub Chorionic bleed
25-30% of first trimester pregnancy have some PV bleeding
(If it occurs away from the side of the embryo in the gestational sac, we can be relatively reassured. If the subchorionic bleed occurs at the side of the embryo, it can lead to fetal demise as it’s affecting the blood supply of the embryo)
What is an abnormal gestation sac?
- A true gestational sac can be distinguished from a pseudogestational sac by noting:
- its normal eccentric location: it is embedded in endometrium, rather than centrally within the uterine cavity
- presence of the double decidual sign (most helpful at 4.0-6.5 weeks)
- presence of a yolk sac: seen at approximately 5.5 weeks (unequivocal evidence of a gestational sac)
Abnormal:
Lac of yolk sac
Lack of double decidual reaction (lack of trophoblast)
Lack of embryo
What do you see on imaging when there is absent cardiac acitivty by the time the CRL is a certain size
CRL > 7 mm with no heart beat
(CRL= crown rub length- top to bottom)
What do you see if there is an absent embryo by the time the gestational sac is a certain size
MSD > 25mm with no embryo (mean sac dimester across 3 dimestions of gestation sac)
What is CRL?
From top to bottom length measurement
If you cannot see an embryo at 10 weeks, how can someone have pregnancy symtpoms?
Trophoblast
What are some high risk examples?
1) Low (near cervix)
2) Irregular trophoblast
3) If Sac is too small
What does a 8mm yolk sac suggest?
Not good- likely to fail
What HR should an early embryo have?
120-140bpm
When the gestation sac grows but the embryo doesn’t is called….
Anembryonic pregnancy
(Empty sac, afetal sac, blighted ovum)
Any fetuses over 7mm must have….
A heart beat.
(must check with colour, doppler, and another observer)
What are 2 common abnormal implantations
1) Fetal demise
2) Ectopic Pregnancy
Describe Ectopic Pregnancy
An ectopic pregnancy occurs when an embryo implants somewhere other than the uterus
~90% fallopian tube, ~10% ovary/pelvis/bowel
1/80 to 1/250 pregnancies increase in pelvic inflammatory disease
1) Gestational sac in pouch of douglas/behind the fallopian tube
2) Fluid in pouch of douglas
23 year old woman, bleeding in flank, in shock
what is this likely to be?
Ectopic pregnancy
What is a normal reasons for fluid in the pouch of douglas?
What is an abnormal reason?
Small normal reason: Menstruation and Ovulation
Abnormal reason: Ectopic
Describe gestational trophoblastic disease
= Molar Pregnancy
Is the trophoblast going bad/malignant?
They can proliferate (some are bengin and some ar malignant).
They have extreme morning sickness, and very very high BHCG
In the early week 4-8, BHCG doubles every 2-3 days.
Empty uterus, 5000units of BHCG indicates….. **EXAM
ECTOPIC PREGNANCY
When are ultrasound scans very helpful?
1) Dating (Estimated date of delivery- EDD)
- Accuracy diminishes with each trimester
- Go with the first trimester scan- don’t let people change it.
2) Twelve week nunchal translucency scan (for genosomal abnormalies e.g. trisomy 21)
3) Routine anatomy scan 20 weeks
4) Growth scan 3rd trimester
Do we need to know the serum BHCG value before we perform the ultrasound scan?
If you are scanning someone with good dates, you can just start scanning and you don’t need BHCG
If things don’t add up, you need the BHCG to interpret what you’re looking at. you want them to come in again in 2-3 days to see what’s going on.
The patient’s LMP was only 3 weeks ago. Why should we do an ultrasound scan when an ectopic pregnancy does not manifest until 5 weeks after the LMP?
Need a BHCG (to get a clear idea of what we expect to see)
-e.g. if it’s negative = no pregnancy
Need to scan her
The bleeding does not always indicate it was a normal period (we can even have periods once pregnant)
I am pregnant, by my dates- 6 weeks and 5 days. I turned up for my scan today and was told that they could not see the baby. They asked me to return for another scan in another week. What does this mean? I am very worried.
We’d ask her to do a BHCG test and come back in a week to clarify whether we are dealing with an early intrauterine preg
My wife is 9 weeks preg. She has had an on and off bleeding and spotting for the past 3 weeks. She has already had 3 ultrasound scans- always showing a strong heartbeat.
The doctor does not seem very worried. What is causing her bleeding Should we be worried?
Subchorionic bleed?
I had a scan when I was 8 weeks pregnant by dates.
The scan said the fetus was 7.5 weeks because of my irregulat menstrual cycle. I have just had naother scan at 34 weeks and my doc says the fetus is the size of a 31 weeks baby.
Should I change my due date?
No do not change the due date (1st trimester estimated due date is a lot more accurate)
Woman has had terrible mroning sickness,vomitting continuously, uable to eat, etc.
The scan shows an “empty scan” measuring 40mm
Failed pregnancy
Sickness is due to the trophoblasts
My girlfriend had a 12 week scan and a 20 week scan and was told everything was fine.
Now she has had our baby and there is a hole in the heart.
How could they have missed this?
Foramen ovale
The fetal circulation has not closed compeltely - this could not have been picked up in the scans
