Abnormal Implantation Flashcards
What is an ectopic pregnancy?
Occurs outside the uterus
Where is the most common place for an ectopic pregnancy to occur and what % occur here?
Majority occur in uterine tube with 80% occurring in the ampulla
What are the dangers of a tubal implantation?
Can rupture the uterine tube once the embryo grows too big. Danger of mother haemorrhaging due to connection of blood supplies. Can also affect future pregnancies
What can an implantation in the right uterine tube be confused with?
Appendicitis
Patients suffering with an ectopic pregnancy can be prescribed methotrexate. What is the result of this?
Inhibits the enzyme dihydrofolate reductase which is essential for the synthesis of purines and pyrimidines. This inhibits the production of DNA, preventing the growth of the embryo before a rupture occurs. The pregnancy is resorbed.
Patients suffering with an ectopic pregnancy can be offered a laparoscopic salpingectomy. What does this involve and what is the outcome?
Small incisions in the lower abdomen are made and a laparoscope is inserted into the pelvis –> keyhole surgery. The camera guides the surgeon and the Fallopian tube/tissue is removed
What is job of the fimbriae?
There is a gap between the ovary and the uterine tube. In normal pregnancies, the fimbriae (at end of uterine tube) sweep the fertilised egg into the uterine tube.
What causes an abdominal implantation to occur?
The fimbiae fail to sweep the fertilised egg into the tube and it drops out of this gap and enters the abdominal cavity
If the egg implants between the uterus and the rectum, what is this called?
The rectouterine pouch
What happens if it implants into the mesentery?
Usually wouldn’t survive and body resorbs the pregnancy (mother unaware)
When is a lithopaedion formed?
When the pregnancy is too big for the body to resorb. Instead, it calcifies it, forming a lithopaedion.
What is purpose of lithopaedion?
Thought to protect mother from neurotic tissue of foetus (usually remains uncovered for years)
What happens if implantation occurs in place with good blood supply e.g. liver?
Embryo can develop and grow to almost full term, C-section is required.
What is placenta previa?
When implantation occurs in the uterus but near the cervix (i.e. not ectopic)
What has happened during placenta previa?
Placenta lies low in the uterus and partially or completely covers the cervix
What is the problem with placenta previa during late pregnancy if it doesn’t resolve?
Can cause severe bleeding or blood supply loss to the baby
How can placenta previa be picked up and what is solution?
Normally picked up during screening. A C-section is suggested if the baby grows to full-term
What is a hydatidiform mole? What does it suggest?
Development of trophoblast without an embryonic tissue. Only contains paternal genes.
Suggests that paternal genes are mainly concerned with the formation of trophoblasts (support structures)
How does a hydatidiform mole occur
A sperm fertilises an empty egg without a nucleus
Why would a hydatidiform mole give a false positive pregnancy?
Syncytiotrophoblasts produce hCG
