Extras Flashcards
What is a hydatidiform mole?
What causes it?
- “mole” refers to a clump of growing tissue
- it is an abnormal pregnancy that involves a non-viable fertilised egg implanting into the uterus and failing to come to term
- it is often caused by a sperm fertilising an “empty” oocyte that does not contain an original maternal nucleus
What type of tissue forms a hydatidiform mole?
- there is an overproduction of trophoblastic tissue
- this produces abnormal masses that are usually benign, but can turn cancerous
- the placenta contains grapelike vesicles that occur when the chorionic villi become distended by fluid
How does a hydatidiform mole usually present?
What can it cause false results for?
- usually presents with painless vaginal bleeding in the 4th-5th month of pregnancy
- there may also be:
- enlarged uterus and/or ovaries
- hyperemesis
- hypertension
- proteinuria
- blood tests will show very high levels of hCG and pregnancy tests will show a false positive result
What are the risk factors for hydatidiform mole?
- defects in the egg
- abnormalities within the uterus
- nutritional deficiencies (diet low in protein, folic acid & carotene)
- women <20 and >40 years of age
How can hydatidiform mole be detected prenatally?
- it has a characteristic “snowstorm” appearance on USS
- definitive diagnosis requires histopathological examination, which shows increased trophoblast proliferation and enlarging of the chorionic villi
What condition can hydatidiform mole potentially progress to?
- there is a risk that it can develop into choriocarcinoma** or an **invasive mole
- an invasive mole may invade so far into the uterine wall that it results in haemorrhage and other complications
- choriocarcinoma is a malignant, rapidly growing and metastatic form of cancer with a poor prognosis
What is the bleeding like in placenta praevia?
How does this condition typically present?
- this condition involves “revealed” bleeding, opposed to “concealed”
- this bleeding is bright red and is usually not painful
- it presents as antepartum haemorrhage (APH) or failure of the head to engage at delivery
What are the associations of placenta praevia?
- multiparity
- large placentae (twins)
- uterine abnormalities, such as fibroids
- previous uterine surgery
- previous C-section
What is meant by placental abruption?
What type of bleeding does this produce?
- this occurs when the placenta separates from the uterus before birth (usually 25 weeks)
- the maternal vessels tear away from the decidua basalis, causing a tear in the uterine tissue
- this produces bleeding that can be “revealed” or “concealed”
- it can be partial or complete
- once the placenta is fully separated from the uterus, it is unable to provide the exchange needed to keep the foetus alive
What are the potential causes of placental abruption?
- the cause is unknown, but potential associations include:
- pre-eclampsia
- smoking
- thrombophlebitis
- previous C-section
- multiple pregnancies
- short umbilical cord
How does placental abruption typically present?
- presents as antepartum haemorrhage (APH) or maternal shock without bleeding
- there may be associated pre-eclampsia, anuria and DIC
- coagulation abnormalities are usually present
- the uterus is tender and tense
- there is constant pain
- the shock is out of proportion to the visible loss
What is the management for a large and small placental abruption?
Small abruption:
- the mother is monitored in hospital until a change in condition or foetal maturity (whichever is first)
Large abruption:
- vaginal delivery can be attempted if the mother is stable
- if not, C-section is performed but this carries a greater risk of DIC
- if the mother is less than 36 weeks pregnant, corticosteroids are given to speed to development of foetal lungs
What is meant by velamentous insertion of the umbilical cord?
What condition is this associated with?
- this occurs when the umbilical cord does not insert into the centre of the placenta
- the unprotected umbilical vessels travel in foetal membranes (between amnion and chorion) to reach the placenta
- if the blood vessels lie close to the cervix, this is vasa previa, which carries a risk of rupture during delivery
- the foetus can exsanguinate (be drained of blood) before birth
What is vasa previa and how can it be detected prior to birth?
- the umbilical vessels are unprotected** and travel in foetal membranes **near or across the internal opening of the uterus
- the umbilical vessels are at risk of rupture when the supporting membranes rupture
- it is detected on USS - tubular structures are found overlying / in close proximity to the cervix and Doppler is used to confirm that these are foetal vessels
- foetal haemoglobin within vaginal bleeding is diagnostic of this condition
What is the treatment for vasa previa?
- women are recommended to have an elective C-section prior to rupture of the membranes (35-36 weeks)
- steroids are given to promote foetal lung development
- an emergency C-section is performed if the patient goes into labour or the membranes rupture
What are the risk factors for vasa previa?
- velamentous insertion of the umbilical cord
- multiple gestation
- accessory placental lobes / bilobed placenta
- IVF pregnancies
What is the classic triad of vasa praevia?
What happens if this condition goes undetected?
- membrane rupture
- painless vaginal bleeding
- foetal bradycardia / foetal death
- if it is undetected, the umbilical vessels rupture when the membranes rupture
- there is bleeding from the foetoplacental circulation, resulting in rapid exsanguination of the foetus and delivery of a stillbirth / neonatal death
What is pre-eclampsia?
How many pregnancies are affected by this condition?
- a disorder of pregnancy characterised by the onset of hypertension and significant proteinuria
- it begins after 20 weeks of pregnancy and symptoms resolve following delivery of the placenta
- mild pre-eclampsia affects 6% of pregnancies and severe pre-eclampsia affects 1-2%
What is thought to be the underlying cause of pre-eclampsia?
How does the appearance of the placenta differ in someone with this condition?
- cause is unknown but it is thought to involve formation of abnormal blood vessels in the placenta and poor trophoblastic invasion into the endometrium
- an abnormally implanted placenta is a significant predisposing factor to pre-eclampsia
- the placenta of a woman with this condition is often small with poor trophoblastic infiltration