Flashcards in Obs And Gynae Deck (191)
Which hormones are actively involved in transforming a pregnancy into the labour phase?
Progesterone levels decrease and oxytocin increases which increase uterine contractions
Prostaglandin levels increase which lead to cervical ripening and increase uterine contractions
Oestrogen and relaxin also contribute to this
When is a foetus considered mature?
Maintain an independent existence outside the uterus
Breathe / maintain oxygenation
Feed / Maintain blood sugars
Maintain body temperature
When is a foetus considered viable?
Can survive extra-uterine
Usually 23-24 weeks depending on neonatal intensive care facilities
When is a foetus considered term?
37 completed weeks till 42 weeks
When is a foetus considered pre term?
Earlier than 37 completed weeks and after accepted age of viability (23-24 weeks)
When is a foetus considered post mature?
After 42 weeks
What processes have to occur in the process of parturition?
Cervical ripening / effacement
Foetal membrane rupture
What is cervical effacement?
Cervix shortens and thins
What is a bloody show?
Mucus plug loosened and released from cervix as it starts to efface
What is the latent phase of labour?
Once cervix effacement starts to dilation of 4cm and regular contractions have begun
What factors contribute to cervical ripening?
Prostaglandin E2 (PGE2) and F2-alpha
Chemotaxis for leukocytes, causes increased collagen degradation
Stimulation of interleukin (IL)–8 release
Activity of matrix metalloproteinases 2 and 9
Cervical collagenase and elastase
Why can infection or inflammation lead to pre term labour?
Cytokines: interleukins 1 and 6 released as inflammatory response can trigger the process of cervical ripening and uterine contractions as they lead to the production of prostaglandins E2 and F2a
What are indications for inducing labour using prostaglandins?
Pre labour rupture of membranes
Concerns about health of mother: pre eclampsia
Concerns about health of baby: poor growth
What can be used to induce labour?
Propess and cervidil: controlled release vaginal insert
Prostin and glandin: vaginal suppositories
What are the names of the foetal membranes?
Chorion: outermost membrane, contributes to placenta formation
Amnion: when first formed, closely covers embryo, fills with amniotic fluid to become protective sac
What cellular changes occur to allow growth of the uterus?
Smooth muscle hyperplasia and hypertrophy
When is the first trimester?
When is the second trimester?
When is the third trimester?
What are the layers of the uterus?
Endometrium: highly vascular mucosa, stratum functionalis (shed during menstruation), stratum basalis (permanent, gives rise to new functionalis after each cycle)
Myometrium: three layers of muscle
Perimetrium/serosa: visceral peritoneum
What happens to the Myometrium prior to parturition?
Increased expression of contraction-associated proteins,
including oxytocin receptors, connexin-43, and prostaglandin F2alpha receptors
Down-regulation of the nitric oxide (NO) pathway and other
What happens to the myometrium during labour?
Prostaglandins and oxytocin act in synergy to trigger contractility through an increase in intracellular Ca2+ concentration
What percentage of deliveries are pre term?
What factors could cause pre term labour?
Increasing maternal age, stress (domestic abuse)
Pre term rupture of membranes: infection, smoking, drug use, previous PROM, polyhydramnios, multiple gestation, amniocentesis, poor nutrition, cervical insufficiency, low SES, underweight
Pre term contractions
Cervical insufficiency: previous cervical biopsy, uterine abnormalities, trauma to cervix
What are tocolytics? Give examples
Used to suppress premature labour, buy time for administration of betamethasone
Terbutaline/salbutamol: B2 agonist
Nifedipine: ca channel blocker
Atosiban: oxytocin antagonist
Magnesium sulfate: myosin light chain inhibitor, reduce risk of cerebral palsy
What is Oligohydramnios? What increases the risk of this?
Foetal chromosomal abnormalities
Intra uterine infections
PG inhibitors, ACE inhibitors
Obstruction of foetal urinary tract
Intra uterine growth restriction
Amnion nodosum: failure of secretion by amnion cells covering placenta
What is polyhydramnios? What increases the risk?
Twins/ multiple gestation
Gastrointestinal atresia of foetus
Rhesus disease in mother
Chromosomal abnormality of foetus
Hydrous fetalis: fluid build up in foetus' abdomen or thorax
What factors can be used to predict the risk of pre term labour?
Past obstetric history
Cervical factors: Fetal fibronectin, actim partus
What is foetal fibronectin?
Found at interface of chorion and decidua: "glue" that binds foetal sac to uterine lining
Leaks info vagina if pre term delivery is likely to occur so can be measured as a screening test