Reproductive: Obstetrics Flashcards
Menstrual age (AKA gestational age)
Age counting from first day of last menses (embryological age + 14 days, because fertilization is assumed to occur during ovulation)
When does an embryo become a fetus?
After 10 weeks gestation
Menstrual age 0-10 weeks (embryo)
Menstrual age > 10 weeks (fetus)
Vaginal bleeding with a closed cervix in early pregnancy…
Threatened abortion
Cervical dilation in early pregnancy…
Inevitable abortion
Cervical dilation with passage of some products of conception…
Incomplete abortion
Cervix closed without intrauterine products of conception despite documented early pregnancy 1 week prior…
Complete abortion
Missed abortion
When the fetus is dead, but the body does not recognize it (does not try to pass the products of conception), cervix is closed
Positive pregnancy test
Intrauterine gestation
Note: This is the intradecidual sign (small fluid collection covered by echogenic decidua; look for the echogenic stripe of the uterine cavity to pass by the fluid and not stop at it which would suggest just some intracavitary fluid)
Positive pregnancy test
Intrauterine gestation
Note: This is the double decimal sac sign (visualization of both the decidua capsularis, light pink shading, and decidua parietalis, dark pink shading, with a small amount of fluid between, yellow shading)
How can you differentiate an early intrauterine gestation from a small collection of fluid in the endometrial cavity?
Look at the endometrial stripe (which should be continuous and pass right by an intrauterine gestation because those are buried within the endometrium)
Note: If the endometrial stripe stops at a fluid collection, its most likely within the endometrial cavity and not an intrauterine gestation.
What is the first structure visible within the gestational sac?
Yolk sac
What connects the old sac to the embryo?
Vitelline duct
What is the normal size of the yolk sac?
3-6 mm (not larger than 6 mm)
Note: It also shouldn’t be solid or calcified.
What are the layers of the gestational sac?
The embryo is located centrally in the amniotic sac (lined by amnion), which is surrounded by the chorionic space (lined by chorion)
Note: The amnion and chorion typically fuse around 14-16 weeks gestation.
Amniotic band syndrome
When the amnion gets disrupted in the first 10 weeks gestation, allowing the embryo to cross over to the chorionic space where it can get tangled up in fibrous bands resulting in deformities (e.g. limb amputation)
What are these structures?
Arrow: Amniotic sac
White arrowhead: Yolk sac
Black arrowhead: Placenta
Note: This is the “double bleb” sign and the earliest visualization of the embryo (which is flat between the yolk sac and amniotic sac).
When should an embryo be visible on ultrasound?
By 6 weeks gestation
Note: If an embryo isn’t visible by 6 weeks gestation, this is suspicious for pregnancy failure.
When should a yolk sac be visible on ultrasound?
A yolk sac is usually visible by the time the gestational sac reaches 8 mm (on transvaginal imaging)
Anembryonic pregnancy
A gestational sac without an embryo (think very early or non-viable pregnancy)
Pseudogestational sac
A small collection of blood/fluid in the endometrial cavity in the setting of an ectopic pregnancy
Note: This is not a gestational sac, but a fluid collection that looks like one because the ectopic pregnancy is stimulating the decidual endometrium.
What is the most important feature to grade the severity of a subchorionic hemorrhage
The percentage of placental detachment
Note: Hematomas greater than 2/3 the circumference of the chorion has a 2x increased risk of abortion.
Implantation bleeding
A small subchorionic hemorrhage that can cause trace vaginal bleeding when the chorion implants into the endometrium
What ultrasound findings are diagnostic of pregnancy failure?
- Crown-rump length of 7 mm or more and no heartbeat
- Mean sac diameter of 25 mm or more and no embryo
- No heartbeat 2 or more weeks after identifying a gestational sac
- No heartbeat 11 days or more after identifying a yolk sac
Differential for pregnancy of unknown location
- Normal early pregnancy
- Occult ectopic pregnancy
- Complete miscarriage
Note: Recommend serial beta-hCG and follow up ultrasound.