L16 Early Pregnancy Disorders and Miscarriage Flashcards
Time point of 4-cell stage and morula:
- 4-cell at 2dpf
- 16-cell i.e. morula at 4dpf
At what point does the germ disc form?
- During 3rd week of gestation
What are the 4 processes during germinal stage?
- Fertilisation
- Cleavage
- Blastulation
- Implantation
Embryonic stage:
- Formation of embryonic disc
- Gastrulation
- Neurulation (begins at 15dpf with folding of neural plate, resulting in neural tube formation by 23dpf with notochord beneath)
- Embryonic folding and organogenesis
What is the basic pathophysiology of preeclampsia?
- Invasion of spiral arteries does not successfully remodel low resistance environment
What is miscarriage vs stillbirth?
- Around 20 -24 weeks is border of viability
- Below this is a miscarriage, and above is stillbirth
- If death occurs within the window, categorisation can depend on developmental progress
Miscarriage statistics: How common, types
- Defined as spontaneous loss of pregnancy before the fetus reaches viability
- 1 in 5 pregnancies will end in a loss before 12 weeks
- Biochemical (pregnancy hormone but no USS confirmation)
- Early (before 12 weeks, late after this point
6 risk factors for miscarriage:
- GA
- Chromosomal abnormality (50% of miscarriage)
- Maternal and paternal age
- Previous miscarriage
- Pre-pregnancy weight
- Substances: alcohol, smoking, excessive caffeine
What is inevitable miscarriage?
- Impending miscarriage due to cervical bleeding or open cervical os
What is an anembryonic miscarriage?
- Aka: Blighted ovum
- Empty gestational sac with no fetus
USS criteria for miscarriage:
- Crown-rump length beyond 7mm with no heartbeat
- Gestational sac diameter over 25mm with no embryo
- Absence of an embryo with a heartbeat a certain period following USS found a gestational sac
What is the significance of the yolk sac on USS?
- Confirms presence of intrauterine pregnancy
What is a subchorionic hematoma?
- Fluid between uterine wall and sac
- Most patients with SCH will not have a miscarriage but patients should be warned to expect discharge
Clinical pathways for patients presenting with early pregnancy problems:
- Patient presents -> Clinical assessment
- A: Clinical features of ectopic/miscarriage -> admit, BHCG, USS -> Diagnosis
- B: Stable/minimal symptoms -> USS offered in early pregnancy unit -> Diagnosis
- Key diagnoses: Pregnancy of undetermined location, miscarriage, ectopic, ongoing pregnancy
Ectopic pregnancy incidence:
- 11.1/1000 pregnancies
Types of ectopic pregnancy:
- Tubal (ampullary, cornucal)
- Ovarian
- Cervical
- Abdominal
- Rarer: Caesarian scar ectopic
- Very rarely viable
Pharmacological approach to ectopic pregnancy:
- Methotrexane -> stops growth (blocking inflammatory signalling)
- KCl -> fetal cardiac arrest
Common symptoms of ectopic pregnancy:
- Abdominal or pelvic pain
- Amenorrhoea or missed period
- Vaginal bleeding with or without clots
- Other less common symptoms include dizziness and fainting, shoulder tip pain, urinary symptoms and rectal pressure/pain
How can ectopic pregnancies mimic the USS presentation of a normal pregnancy?
- Decidual secretions can form a pseudo-sac
- Mimics the gestational sac
What qualifies as recurrent miscarriage?
- 3 or more consecutive miscarriages
- Affects 1% of couples trying to conceive
List some groups of risk factors for recurrent miscarriage: (8x)
- Environmental (maternal age, previous miscarriages, obesity, alcohol etc)
- Antiphospholipid antibody (inhibits trophoblast function)
- Genetic (balanced translocation/chromosomal)
- Anatomical (uterine malformations, cervical weakness)
- Endocrine (uncontrolled diabetes, thyroid, PCOS)
- Immune (uNKs?)
- Infection
- Thrombophilia (excess clotting -> placental insufficiency)
What are the key investigations for recurrent miscarriage?
- APL test
- Cytogenetic analysis
- Pelvic USS
- Thrombophilia test
What is gestational trophoblastic disease?
- Abnormal growth of trophoblast (placental precursor)
- Abnormal cells or tumour -> grape like vesicles, no fetus present
- One key example is molar pregnancies/hydratidiform mole
What is a molar pregnancy? (balance of benign and malignant)
- Type of GTD
- Arises from an abnormality at the point of fertilisation (e.g. complete molar pregnancy is fertilisation of an egg with no maternal genes)
- Begins as benign tissue
- 80% remain benign, 10-15% become invasive and 2-3% become choriocarcinoma
Types of hydratidiform mole:
- Complete (2 sets paternal genes, no maternal genes and no fetus as a result)
- Partial (2 sets of paternal from 2 sperm, 1 set of maternal genes resulting in a non-viable fetus)
Risk factors for molar pregnancy:
- Ethnicity (higher incidence in asian women)
- Advance age
- Previous molar pregnancy
- Diets low in protein, folic acid and carotene
- Defects in the egg, abnormalities of uterus etc
- Women in blood group a
How is molar pregnancy diagnosed?
- Clinical: vaginal bleeding after amenorrhea, hyperemesis gravidarum, passing of grape-like vesicles
- Radiological: absent GS in complete mole, complex intrauterine mass with cystic space -> snow storm
- Ovaries may also develop theca lutein cysts
Types of partial mole:
- Diandric (two sperm)
- Digynic (diploid ovum)
- Note that 90% of partial moles have triploidy
How is partial mole diagnosed?
- Cystic spaces in placenta (USS)
- Transverse/A-P ratio of G.sac >1.5
- Disturbed organogenesis and restricted growth
- Foetal defects in >90% cases
- Maternal serum proteins and foetal cytogenetics aid diagnosis
Presentation of twin gestation with one complete hydratidiform mole?
- High risk of persistent disease
- Vaginal bleeding in >90% cases
- Pregnancy-induced hypertension in 50-60% cases
- Usually diagnosed in 1st/2nd trimester
