4/14 D/O of implantation Flashcards
(41 cards)
What are trophoblasts?
Trophoblasts - cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta
Briefly describe the fetal:maternal circulation at the level of the placenta
- fetal venous blood is circulated back to mom via two umbilical arteries (remember they branch off the internal iliacs)
- fresh maternal blood goes to back to the fetus via a single umbilical vein (remember it connects to the IVC in the fetus)
- maternal blood comes in through the spiral arteries and bathes the terminal villi; exchange of nutrients, gases, etc occurs at the surface of the villous membrane
T/F fetal/maternal blood mixes at the level of the placenta.
FALSE. fetal/maternal blood does not mix!
What are the placental villi lined by?
syncytiotrophoblast
(remember these cells also produce hCG and
estriol)
What are the d/o of early pregnancy?
- SPONTANEOUS abortion
- ECTOPIC pregnancy
- ABNORMAL IMPLANTATION
- Hypertensive Disorders
- Gestational Trophoblastic Disease (GTD)
fetal causes of spontaneous abortion? maternal causes?
Fetal causes
- defective implantation
- genetic causes (aneuploidy, polyploidy, translocation accounts for 50% of early abortions)
Maternal causes
- inflammatory or infectious diseases (toxoplasma, mycoplasma, listeria, viruses)
- uterine abnormalities
- leiomyoma (fibroid, muscular growth in the wall of the uterus)
- polyps (glandular growth in the endometrium)
- anatomical defects
- Hormonal/metabolic abnormalities
What are the types of spontaneous abortions?
- complete - spontaneous expulsion of all fetal and placental tissue from the uterine cavity
- incomplete - passage of some but not all fetal or placental tissue through the cervix; have to surgically retrieve remaining tissue (D&C)
- threatened - uterine bleeding from a gestation without cervical dilation or effacement
- inevitable - uterine bleeding from a gestation with cervical dilation but without expulsion of any placental or fetal tissue through the cervix; cannot progress to a normal pregnancy
- missed - fetal death without expulsion of any fetal or maternal tissue for at least 8 weeks; have to surgically intervene via D&C
- septic - any type of abortion that is accompanied by uterine infection
difference between complete + incomplete abortion?
- complete - spontaneous expulsion of all fetal and placental tissue from the uterine cavity
- incomplete - passage of some but not all fetal or placental tissue through the cervix; have to surgically retrieve remaining tissue (D&C)
difference between threatened and inevitable spontaneous abortion?
- threatened - uterine bleeding from a gestation without cervical dilation or effacement
- inevitable - uterine bleeding from a gestation with cervical dilation but without expulsion of any placental or fetal tissue through the cervix; cannot progress to a normal pregnancy
why is a missed spontaneous abortion so disgusting?
fetal death without expulsion of any fetal or maternal tissue for at least 8 weeks; have to surgically intervene via D&C
definition of ectopic fallopian tube?
where does it commonly occur in naturally conceived births? IVF?
Implantation of the fetus in any site other than the normal uterine location (ie tubes, ovaries, omentum, cervix)
naturally conceived births: ampullary + tubal
IVF: heterotopic implantation (ampullary + tubal)
What is the greatest predisposing factor to ectopic pregnancy?
What other factors can cause it?
pelvic inflammatory disease with chronic salpingitis = greatest predisposing condition because it causes scarring
Other abdominal inflammatory processes = predisposing factors that also cause peritubal adhesions
- appendicitis
- abdominal inflammatory processes endometriosis
- failed tubal ligation
- previous abdominal / pelvic surgery
- assisted reproductive technologies (ART) - ex: IVF
Clinical presentation of ectopic pregnancy?
- typically occurs in first trimester
- Abdominal pain (none, mild or severe)
- Minimal vaginal bleeding - usually spotting or light bleeding
- **Intraperitoneal bleeding - no exit to outside world; ranges from none to life threatening hemorrhage (into intraperitoneal space)
What doest this patient have?
ectopic pregnancy - uterus does not surround gestational sac
Diagnostic tests (and findings) to establish ectopic pregnancy?
- US – uterus does not surround gestational sac
- Quantitative B-hCG
- Serum progesterone
- culdocentesis
How is US useful in diagnosing atopic pregnancies?
uterus does not surround gestational sac
How is Quantitative B-hCG useful in diagnosing atopic pregnancies?
- first detectable: at time of implantation
- typically doubles every two days (if it doesn’t, then the pregnancy is likely not viable)
- single value: helps to interpret US findings:
- ß-hCG >1500 w/ US findings in uterus = pregnant!
- ß-hCG >1500 w/o US findings in uterus = ectopic
- serial values: establish viability pregnancy too early for sonographic detection
How is serum progesterone useful in diagnosing an ectopic pregnancy?
- < 5 ng/ml: not consistent with normal intrauterine pregnancy; suggests ectopic
- > 15 ng/ml most consistent with viable intrauterine pregnancy
How is culdocentesis useful in diagnosing an ectopic pregnancy?
method to determine presence of peritoneal blood using a needle to extract fluid from the peritoneal blood from area behind cervix (pouch of Douglas), if any.
painful; not done anymore
How are ectopic pregnancies managed?
-
Methotrexate - stops the growth of rapidly dividing cells (embryonic, fetal, placenta cells)
- given every other day until hCG blood tests confirm that the pregnancy has ended
- Surgical - excise the ectopic pregnancy from the tube
What are the 3 main d/o of placental implantation?
- Placenta accreta
- Placenta increta
- Placenta percreta
What is placenta accretia?
placenta adheres to the superficial myometrium, but does not penetrate it, with partial or complete absence of decidua
- placenta usually detaches from the uterine wall relatively easily
- great risk of post-partem bleeding
What is placenta increta?
placenta invades the myometrium
- not all is removed after birth
What is placenta percreta?
placenta invades the entire myometrium to the uterine serosa
- greatest risk of placenta attaching to other organs such as the rectum or bladder
- usually happens after C-section, where implantation happens in the C-section scar
