Early Pregnancy and Implantation
Where does fertilisation usually happen?
In the ampulla of the fallopian tube.
What does the inner cell mass develop into?
The embryo
What is the most common cause of bleeding in the first trimester?
miscarriage
Name two common causes of bleeding after 20 weeks.
Placenta previa and placental abruption.
What is the first vital sign you would check in a woman with bleeding?
Blood pressure and pulse.
What is the morula?
A solid ball of cells formed after cleavage of the zygote
What does the trophoblast become?
The placenta
What is an ectopic pregnancy?
When the embryo implants outside the uterus, most often in the fallopian tube.
What is placenta previa?
When the placenta implants low in the uterus and covers part or all of the cervix.
Why is it important to take a history of gestational age?
Because the likely causes of bleeding differ in early vs late pregnancy.
What is the blastocyst made up of?
The inner cell mass (embryoblast) and the outer cell layer (trophoblast).
What is the function of the syncytiotrophoblast?
It invades the uterine lining and produces hCG.
Why might molar pregnancy cause bleeding?
Abnormal trophoblastic growth disrupts the uterus.
What is placental abruption?
When the placenta separates early from the uterine wall.
What simple test can confirm an ongoing pregnancy in the first trimester?
A urine pregnancy test (detects hCG).
What role does progesterone play in implantation?
It prepares and maintains the endometrium so the blastocyst can implant.
Why is hCG important in early pregnancy?
It maintains the corpus luteum so progesterone continues to be made.
What is a threatened miscarriage?
Vaginal bleeding occurs, but the cervix is closed and the pregnancy may continue.
Which cause of late pregnancy bleeding is usually painless?
Placenta previa.
Why should a vaginal examination be avoided if placenta previa is suspected?
It can cause severe bleeding by disturbing the placenta.