Obstetric Flashcards
Define:
Embryo and Fetus
Embryo: 0-10 weeks (menstrual age)
Fetus: > 10 weeks
Menstrual age: Embryological age + 14 days
Define
Threatened vs inevitable vs incomplete vs complete vs missed abortion:
- Threatened: Bleeding with closed cervix.
- Inevitable: Cervical dilation +/- placental +/- fetal tissue protruding out.
- Incomplete: Residual products in uterus
- Complete: All products out
- Missed abortion: Fetus is dead but still in uterus.
What is the name of the early gestational sac sign?
Intradecidual sign- when seen covered by echogenic decidua is an early sign of early pregnancy (4.5 weeks)
Double decidual sac sign: It is produced by visualising the layers of decider
When should you be able to see the yolk sac?
Yolk sac is the first thing visible within the GS. It should be visible when GS is 8mm in diameter.
The appearance of yolk sac
Should not be too big > 6mm, or too small < 3mm
Should not be solid or calcified.
What is an amniotic band syndrome?
The amnion and chorion are separated by a thin layer of fluid, until 14-16 weeks at which point, they fuse.
If the amnion gets disrupted before 10 weeks, the fetus might get trapped across the fibrous bands- can cause limb amputation.
What is the name of the earliest visualisation of the embryo?
Double bleb sign: this is two fluid filled sacs (yolk and amniotic) with the flat embryo in the middle.
When is embryo usually visible?
Usually at 6 weeks
What is usually used to estimate gestational age in first trimester?
How about in 2 or 3rd trimester?
1st trimester: CRL ( Crown Rump Length)
2nd and 3rd trimester: Composite GA: BPD, AC, HC, and FL
What does anembryonic pregnancy mean?
This is GS without embryo:
- Very early pregnancy
- Non viable pregnancy
You should see yolk sac at 8mm
When would you see a pseudogestational sac?
This is seen in ectopic pregnancy: blood in the uterine cavity with bright decidual endometrium.
What are the diagnostic features of failed pregnancy: (4)
- CRL > 7mm with no heart beat
- Mean sac diameter > 25mm and no embryo
- No embryo with heartbeat > 11 days after a scan that showed GS with a YS
- No embryo with heartbeat > 14 days after a scan that showed GS without a YS
What does subchorionic haemorrhage mean?
These are very common. The % of placental detachment is the prognostic factor associated with fetal demise.
Haematoma > 2/3 of the circumference of chorion has x2 increased risk of abortion.
RF for ectopic pregnancy:
PID Tubal surgery Endometriosis Ovulation induction Previous ectopic IUD
Where is the most common location for ectopic?
The isthmus portion of fallopian tube
What would be suspicious for ectopic pregnancy?
Positive BhCG: At around 2000 IU/L you should see a GS
A normal doubling time makes ectopic less likely
Name a sign that is associated with ectopic pregnancy:
Tubal ring sign: echogenic ring which surrounds un ruptured ectopic. 95% specific.
Other signs include: pseudo gestation sac, trilaminar endometrium, thin-walled decimal sac.
What is heterotropic pregnancy?
A baby in uterus and a baby in the tube or other ectopic locations. Rare. Can happen in women with previous bad PID or those that are taking ovulation drugs.
Where would the biparietal diameter is measured from
This is recorded at the level of the thalamus. It is affected by the shape of the skull.
What is the difference between BPD and HC measurement?
Both recorded at the same level. HD does not include the skin, therefore, less affected by the head shape.
Where would the abdominal circumference measured from?
This is recorded at the level of junction of the umbilical vein and left Portal vein.
How is fetal weight estimated?
This is based on:
- BPD and AC or
- AC and FL
What would be indicative of IUGR?
- Estimated fatal weight below 10th percentile
- FL:AC > 23.5
- Umbilical artery systolic: diastolic > 4
If normal doppler - then he is little guy!
What is the most common cause of oligohydramnios during the third trimester?
Fetal growth restriction associated with placental insufficiency
What are the two different types of IUGR?
- symmetrical: this is global growth restriction. It is seen throughout the pregnancy including first-trimester. Has a much worse prognosis because the brain does not develop.
- asymmetrical: normal head with small body (sparing head). This is seen during the 3rd trimester as a result of extrinsic factor.
What are the causes of asymmetrical IUGR?
High BP,
Severe malnutrition
Euler Danlos
What are the causes of symmetrical IUGR?
TORCH infection
Fetal alcohol syndrome/Drug abuse
Chromosome abnormalities
Anaemia
What is biophysical profile used for?
This is used to look for acute and chronic hypoxia
What should happen to the resistance in the umbilical artery as the gestation age increases?
(Umbilical artery systolic /diastolic ratio)
The resistance in the umbilical artery should decrease with the gestational age.
The general rule is 2 - 3 at 32 weeks.
The ratio should not be more than 3 at 34 weeks.
An elevated systolic to diastolic ratio means there is……….. resistance.
HIGH
High resistance patterns are seen in pre-eclampsia and IUGR.
What is Erb’s palsy?
This is injury to the upper trunk of the brachial plexus (C5-C6), most commonly seen in shoulder dystocia ( which kids with macrosomia are higher risk for)
What is an amniotic fluid index?
This is made by measuring the vertical height of the deepest fluid pocket inch quadrant of the uterus then summing the 4 quadrants. Normal is 5- 20.
What is oliogohydramnios?
This is defined as AFI < 5 cm
Define polyhydramnios?
This is defined as AFI > 20 m or a single fluid pocket > 8 cm.
What does an artery adjacent to the bladder mean?
Two vessel cord