L20 - Early pregnancy problems Flashcards
1. Briefly overview normal embryo transport and implantation within the uterus 2. Define the types of miscarriage 3. Define recurrent miscarriage and discuss the known genetic, immune and biochemical causes 4. Describe the normal anatomy of the Fallopian tubes and the common sites of implantation of ectopic pregnancies and clinical risk factors for this condition.
Recap the events that occur in the 2nd week of pregnancy? (4)
- Embryoblast, 2 layers: epiblast & hypoblast
- Trophoblast, 2 layers: cytotrophoblast & syncytiotrophoblast
- Yolk sac, 2: primary & secondary
- Cavities, 2: amniotic & chorionic
Describe when and how the blastocycst adheres to the uterine wall?
end of 1st week.
- Contact with uterine endometrium induces trophoblast at embryonic pole to proliferate.
- Some of these proliferating cells lose their cell membrane, coalesce to form the syncytium.
What is the synctiotrophoblast?
Mass of cytoplasm containing number of dispersed nuclei.
Describe the cytotrophoblast?
Cell of trophoblast that line the wall of the blastocyst retain their cell membrane.
What occurs between day 6-9 of pregnancy?
- Embryo fully implanted in endometrium.
- cytotrophoblast —secretes—> proteolytic enzymes
- to break down the ECM between endometrial cells.
How is the yolk sac formed?
Formed from the proliferation of hypoblast cell.
What layers must maternal and foetal blood flow through? (4)
- Endothelium of villus capillaries
- Loose connective tissue in core of the villus (extraembryonic mesoderm)
- Layer of cytotrophoblast
- Layer of synctiotrophoblast
Describe a hydatidiform mole?
signs / symptoms
- Pregnancy without embryo.
- Causes excessive nausea and vomitting
- due to excessively high levels of hCG.
Describe partial hydatidiform mole?
- Presence of typical nucleated embryonic erthryoblasts in molar villi
- presence of fetal BV indicate embryo was once present.
Define spontaneous miscarriage?
- Fetus dies or delivers dead
- before 24 completed weeks of pregnancy.
State the different types of miscarriage?
Threatened Inevitable Incomplete Complete Septic Missed
Threatened miscarraige
Bleeding, fetus still alive, os closed
Inevitable miscarriage
Heavier bleeding, fetus may be alive, os open, miscarriage about to occur.
Incomplete miscarriage
Some fetal part have been passed.
os usually open.
Complete miscarriage
All foetal tissue passed, bleeding has dimished, uterus no longer enlarged.
Cervical os is closed.
Septic miscarriage
Endometritis
Tender uterus
Infection
Missed miscarriage
Fetus not developed / died in utero, but not recognised until bleeding occurs.
Recurrent miscarriage
3 or more in succession.
Ectopic pregnancy
Embryo implants outside uterine cavity.
A patient with an ectopic pregnancy may present with…
- Lower abdominal pain.
- Dark vaginal bleeding.
What may be the medical management for an ectopic pregnancy?
- Ectopic unruptured, no cardiac activity: single does of methotrextate.
- Subsequent monitoring of hCG levels are important
Hyperemesis Gavidarum
Nausea, vomiting in early pregnancy.
Very severe.
Cause severe dehydration, weight loss of electrolyte imbalance.
What is gestational trophoblastic disease?
where does GTD begin?
- Normal development: trophoblastic cells form villi which grow into lining of uterus. This layer will develop into placenta.
- GTD begins in this layer of cells.
- HCG produced in excess
Briefly describe hydatidiform moles?
Complete - PATERNAL! - when one sperm fertilise an empty oocyte - diploid - no fetal tissue Partial - triploid usually - derived from two sperm entering one oocyte.
State different types of haemorrhage during pregnancy
- Threatened
- Antepartum
- Intrapartum
- Post-Partum
Threatened haemorrhage
Can occur up to 24 weeks gestation
Antepartum haemorrhage occurs…
24 weeks until onset of labor
Intrapartum haemorrhage occurs…
From onset of labour until end of second stage.
Post-partum haemorrhage occurs…
3rd stage of labour until end of puerperium.
- 6 weeks after child birth.
Placenta Praevia
Placenta encroachs upon lower segment of uterus.
Extending 5cm from internal os.
May occur during labour.
Often painless bleeding.
When might a women be advised not to deliver vaginally?
When their placental edge is not 2cm away from the internal os.
Placental abruption
When placenta separates from uterus before childbirth.
Retroplacental haemorrhage, bleeding between placenta and uterus.
What may placental abruption result in?
Retroplacental haemorrhage.
Reduced area for gas exchange between foetal and maternal circulation
- leading to foetal hypoxia and acidosis
Vasa Praevia
Umbilical cord vessels run in fetal membrane and cross internal os of cervis.
Vessels may spontaneously rupture in early labour.
Describe two types of post-partum haemorrhage?
PRIMARY (within 24hr)
1. Minor: Blood loss of <500mls, no hypovolemic shock
2. Major: >1000mls lost and hypovolemic shock
SECONDARY
1. (24hr to 12weeks post birth)
2. Infection? endometritis
What may be some causes of post-partum haemorrhage?
Trauma - perineal tear
Thrombin - coagulopathy
Tissue
What is the name given to the cartilaginous joint between the pubic joint?
Symphysis pubis.
Describe the broad ligament?
Fold in peritoneum.
Mesovarium - between uterus and ovary
Mesosalphinx - covers fallopian tube
What are the 3 parts of the fallopian tube?
Isthmus - closest to uterus Ampulla - commonest site of fertilization Infundibulum - fimbriae
What are the 3 layers of the fallopian tube and descirbe them ?
Mucosa
- simple columnar epithelium, ciliated and secretory
Muscularis
- inner circular and outer longitudinal fold
Serosa
- simple squamous epithlium
Blood supply to fallopian tubes
Branche sof ovarian and uterine arteries
Where is the fallopian tube situated and describe it?
10cm length, 1cm diameter.
Found in mesosalpinx (fold in broad ligament)
What symptoms may a patient with an ectopic pregnancy present wiht?
Usually asymptomatic until point of rupture.
- abdo pain
- abnormal vaginal bleeding
- shoulder tip pain (reffered pain)
- diarrhoea
State potential causes of recurrent miscarriage
Maternal age Genetic factors Structural uterine abnormalities Antiphospholipid syndrome Thrombophillia Cervical weakness endocrine causes Unexplained
How may maternal age contribute to mischarraige?
Aging oocyte smore likely to be abnormal
35-39 y/o : 25% risk
40-44 y/o : 51% risk
Give examples of structural uterine abnormalities that may lead to miscarriage
Septate / subseptate nucleus
Fibroids
Adhesions in uterine cavity
Fibroids
Benign growths in muscle layer of uterus.
Asherman’s syndrome
Acquired uterine condition when scar tissue forms inside the uterus and/ or the cervix.
- can cause infertility
What is antiphospholipid syndrome?
Maternal antibodies directed against phospholipid binding plasma proteins.
Causes increased risk of blood clots.
What is HbA1c?
Average blood glucose levels for the past 2/3 months.
High HbA1c In first trimester can cause increased risk of miscarriage and malformations.
