Obs And Gynae Flashcards
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?
Gestational age
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
Cervical dilatation
Uterine contractions
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?
Cyclooxygenase-2
Prostaglandin E2 (PGE2) and F2-alpha
Hyaluronic acid
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?
Prolonged pregnancy
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?
Prostaglandin E2
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?
0-12 weeks
When is the second trimester?
13-28 weeks
When is the third trimester?
29-40 weeks
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
vasorelaxing peptides
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?
7-10%
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
Indomethacin: NSAID
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 Post maturity
What is polyhydramnios? What increases the risk?
Twins/ multiple gestation Gestational diabetes Gastrointestinal atresia of foetus Rhesus disease in mother Chorioangioma 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 length
Bacterial vaginosis
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
What is actim partus?
Phosphorylated insulin like growth factor binding protein detected in cervical samples
Has high negative predictive value - negative result, labour will not begin in next 7 days so can be sent home with confidence
What risks are there to the foetus if delivered pre term?
Respiratory distress syndrome (hyaline membrane disease) Intraventricular haemorrhage Necrotising enterocolitis Patent ductus arteriosus Cerebral palsy
What treatment can be given in clinic for pre term labour?
Bed rest
Antibiotics
Cervical stitch
Progesterone
What effect does bacterial vaginosis have on inducing pre term labour? What can be done to treat it?
Good predictor of PTL in high risk women - 7 fold increased risk
Clindamycin can prevent preterm labour if BV positive
What length should a normal cervix be?
4-5cm when not pregnant
Average of 3.5cm in pregnancy
What is a primigravida?
Woman who is pregnant for the first time
What is a multiparous woman?
Has borne more than one child
What is the difference between a still birth and a miscarriage?
Miscarriage: foetus dies in utero before 24 weeks, not issued a death certificate
Still birth: foetus dies in utero after 24 weeks, issued a death certificate
What is the transformation zone of the cervix?
Inside glandular, outside stratified squamous epithelium
Most common place for abnormal cells to develop - Pap smear
Which hormone is responsible for maintaining a pregnancy in quiescence?
High levels Progesterone, low levels oestrogen - uterine quiescence and and cervical rigidity
What is pregnancy induced hypertension?
Increase in BP, no proteinuria, returns to normal after pregnancy
What is pre-eclampsia/eclampsia?
Increase in BP with proteinuria
What is essential hypertension in pregnancy?
Occurs before 20 weeks, >140/90 mmHg
What change in korotkoff sounds might you get in a pregnant lady?
Pregnancy increased blood volume, can hear softening and stopping of Korotkoff sounds
In some women can hear sounds at very low cuff inflation pressure
What happens to MAP, CO and plasma volume through a pregnancy?
CO and plasma volume increase dramatically up to 20/30 weeks and decrease back to normal after delivery
MAP decreases slightly to 20 weeks and then rises back to baseline again towards term
What medication changes might be required in essential hypertension in pregnancy?
Changing doses of anti-hypertensive medication throughout pregnancy
What happens to GFR and urea levels in pregnancy?
Renal changes in pregnancy: Increase blood flow to kidney
Increased GFR
Lower urea levels in pregnant women
What is the pathophysiology of pre-eclampsia?
Failed adaptation to pregnancy
Inadequate placentation
Foetal cells don’t adequately invade and so spiral artery dilation doesn’t occur sufficiently
High flow, high pressure system
Placenta signals to mother that it is not receiving enough supply so causes hypertension, proteinuria, liver dysfunction and if left untreated, cerebral oedema
What is the treatment for pre eclampsia?
Delivery of the foetus
What cardiac disease problems are made worse by pregnancy?
Increased blood flow: Normal to hear end diastolic flow murmur
Arrhythmia: Worse
If valvular heart disease: May not be able to increase CO, Heart failure
What respiratory change occur in pregnancy?
Rib cage and breast enlargement
Diaphragm pushed cranially: changes in lung vol
Increased mucosal engorgement: nasal – epistaxis
Asthma symptoms worse as lung capacity is decreased
Respiratory rate increases: normal
What happens to T cell levels in pregnancy? And what significance does this have in asthma and RA?
T helper 1 cell levels decrease: this means that RA symptoms are decreased in pregnancy as less interferon gamma is released
T helper 2 cell levels increase: this means that asthma is made worse as increased mast cell activation, B cells releasing IgE and eosinophils are released
Describe the functional flow of immunity following antigen detection
Antigen detected by antigen presenting cell
This signals to t helper cells which release cytokines to activate natural killer cells, macrophages and B cells
B cells release antibodies to opsonise the cell
T helper cells also directly activate cytotoxic T cells
How do t helper cells differentiate from naive to type 1 or 2?
Naive cells signalled by IL-6 from APCs and IL-4 from mast cells, eosinophils and NK cells cause differentiation to T helper 2 cells
Naive cells signalled by IL12 from APCs and IFNgamma from NK cells and t helper 1 cells cause differentiation to t helper 1 cells
What do t helper 1 cells do?
Fight viruses, cancer, yeast and intracellular pneumonia
Cell mediated immune responses
What do t helper 2 cells do?
Normal bacteria, Parasites, Toxins, Allergens
Humoral immune response
What change in immune balance must occur during pregnancy?
Pregnancy maternal and paternal antigens similar to tissue graft. Change in immune balance in pregnancy: decrease in t helper 1 cells which would lead to rejection. Decrease in IL-2 and IFNgamma
Increase in t helper 2 cells which lead to tolerance. Increase in IL-4, 5 and 10
Worsening of asthma, More susceptible to influenza (H1N1), Rheumatoid arthritis better
If the placenta in a pregnancy is small, what does this increase the risk of for the child in later life?
Increase in heart disease, diabetes,hypertension, obesity
If a foetus encounters starvation during pregnancy, what are they at increased risk of in later life?
Increase in heart disease, diabetes obesity
What factors can cause in utero programming of a foetus which can lead to problems later in life?
Maternal stress Infection Smoking Under nutrition Placental dysfunction Alcohol
What in utero programming can occur which affect vasculature and metabolism?
Thrifty phenotype hypothesis
Reduced pancreatic B cell mass
Insulin resistance in muscle liver and adipose tissue
Changes to HPA and neuroendocrine axis: results in over nutrition
Kidney glomerular number affected: hypertension and renal disease
All results in metabolic syndrome
Which bio marker measured antenatally is associated with failure of formation of the vertebral arches?
Raised maternal serum alpha feto protein (AFP)
Neural tube defects
What is genetic imprinting?
Certain genes are expressed in parent of origin specific manner
Involves methylation
Occurs in germline and maintained in all somatic cells
What is DNMT?
DNA methyl transferase
Catalyse transfer of methyl group to DNA
When located in a gene promoter, DNA methylation acts to repress gene transcription
What role does DNMT play in germ cells?
Immature gamete acted on by DNMT to convert to mature gamete
What role does DNMT play in silencing of the X chromosome and imprinted genes?
Acts on pluripotent stem cells to help them on an embryonic lineage
What placental features can affect nutrient supply to a foetus?
Hormone production and metabolism: oestrogen, progesterone, human placental lactogen and hCG Nutrient consumption and production Transporter abundance Blood flow Size and morphology
What is the function of hCG released by the placenta?
Prevents atrophy of the corpus luteum
Stimulates corpus luteum to release more progesterone and oestrogen
What is the role of progesterone released by the placenta?
Prevent spontaneous abortion as it prevents contractions of the uterus and is necessary for implantation
What is the role of oestrogen released by the placenta?
Proliferation of breasts and uterus
Also increases blood supply towards end of pregnancy through vasodilation
What is the role of human placental lactogen released from the placenta?
Develop foetal metabolism and general growth and development
Acts on lactogenic receptors to modulate embryonic development, metabolism, stimulate production of IGF, insulin, surfactant and adrenocortical hormones
When does oogenesis occur?
Oocytes are all formed in prior to birth
Imprinting occurs in mother uterus
Describe how adverse intrauterine environment for a foetus can have an effect on multiple generations
Adverse intrauterine environment can lead to poor placentation
This in turn results in adverse pregnancy outcomes which increases risk of early onset cardiovascular problems
This is exacerbated by poor socioeconomic status, deprivation and ethnicity which then increases the risk of adverse intrauterine environments in future generations
How is high maternal weight linked with childhood obesity?
Maternal obesity can lead to an adverse intrauterine environment and then an increased birth weight of the baby
This then predisposes to childhood obesity which is further exacerbated by low socioeconomic status, deprivation and ethnicity which then increases risk of developing into an obese adult and the cycle continues
What percentage of couples experience sub fertility in England and Wales?
15%
What percentage of couples experience recurrent miscarriages?
2%
What percent of pregnancies result in premature delivery?
10%