8.2 Maternal problems in pregnancy (lecture) Flashcards
what is carried out an antenatal screening?
history + examination
blood test
urinalysis
what do you check for in history + examination in antenatal screening?
risk factors e.g. gestational diabetes
what do you check for in blood tests in antenatal screening?
- blood group (mother and foetus) - blood transfusion e.g. C-section, haemorrhage
- haemoglobin
- infection
why do you check for maternal haemoglobin within a blood test?
the demand on the maternal iron store - baseline measurement of maternal haemoglobin
(check if mother has become anaemic)
what do you check for in urinalysis within a blood test at antenatal screening?
protein
baseline measurement, check of proteinuria - for pre-eclampsia
which systems undergo physiological changes in pregnancy?
CVS urinary respiratory metabolic GI immune
what are the metabolic changes that occur during pregnancies?
carbohydrate
thyroid hormones
what are the changes undergone by the CVS during pregnancies?
blood volume increases (CO = SV x HR)
therefore CO, SV, HR all increase
what are the CVS changes from the first trimester (T1)?
CO: increase 40%
SV: increase 35%
HR: increase 15%
(CO = SV x HR, therefore changes in CO most significant if the other 2 increase)
Systemic vascular resistance decrease 25-30%
why does Systemic Vascular Resistance decrease 25-30% from the first trimester (T1)?
release of prostaglandins causes relaxation of SM - including vascular SM
what are the changes to blood pressure throughout pregnancy?
T1 + T2: BP decrease (vascular resistance decrease - SM)
T3: BP returns to normal
what effects will pregnancy have on pre-load and after-load? why?
pregnancy will increase pre-load and after-load because of increase CO (and HR, SV)
what is never increased in pregnancy normally?
SYSTOLIC BP
why can pregnancy result in hypotension in T1 + T2?
progesterone effects on SVR
why can pregnancy result in hypotension in T3?
aortocaval compression by gravid uterus (pregnant, enlarged uterus)
what is aortocaval compression syndrome by gravid uterus? (resulting in hypotension in T3)
compression of the abdominal aorta and inferior vena cava by the gravid uterus when a pregnant woman lies on her back, i.e. in the supine position
function of the endothelium within pregnancy?
controls vascular permeability
contributes to the vascular tone
vasodilation in pregnancy
how would endothelium in a normal pregnancy appear?
vasodilated (prostaglandins, vascular permeability)
plasma-expanded (increase BV)
how does epithelium appear in pre-eclamptic pregnancy?
vasoconstricted
plasma-contracted
what is pre-eclampsia?
pregnancy-induced hypertension in association with proteinuria (>0.3 g in 24 hours) with or without oedema. Virtually any organ system may be affected
what can cause pre-eclampsia?
- defect in placentation
- poor uteroplacental circulation
- widespread endothelial dysfunction
what can pre-eclampsia lead to?
eclampsia
seizures during pregnancy - impact mother and baby
what are the effects of pregnancy on the urinary system?
GFR increases
renal plasma flow increases
filtration capacity intact
functional renal reserve decreases as GFR increases
(increase CO, therefore increase GFR (from increase in renal plasma flow))
what is the functional renal reserve?
the reserve of glomerular filtration rate (GFR) and renal blood flow
within the urinary system, which variables increase during pregnancy?
RPF - 60-80%
GFR - 55%
creatinine clearance - 40-50%
protein excretion: up to 300mg/24 hours
within the urinary system, which variables decrease during pregnancy?
urea - 50%
uric acid - 33%, but rises with gestation (before birth)
bicarbonate: 18-22mmol/L
creatinine: 25-75 micromol/L
what are the consequences of changes to the urinary system?
- urinary stasis:
- progesterone effect on urinary collecting system –> hydroureter
- obstruction - UTI: pyelonephritis –> pre-term labour
(Compression of uterus on bladder (with hydroureter) can lead to hydronephrosis)
what are the anatomical changes to the respiratory system during pregnancy?
- diaphragm displaced
2. A-P and transverse diameters of thorax increase (to compensate for the displaced diaphragm)
what are the consequences of anatomical and physiological changes to the respiratory system?
- decreased functional residual capacity (decrease residual volume)
- vital capacity unchanged (largest in + out), total lung capacity ~ unchanged
- increased minute + alveolar ventilation
- increased tidal volume (resting), RR unchanged
what are the 2 overall physiological changes to the respiratory system?
- physiological hyperventilation
2. ‘physiological’ dyspnoea (SoB)
why does physiological hyperventilation occur?
- increased metabolic CO2 production (has to excrete foetus CO2 in maternal blood)
- increased respiratory drive effect of progesterone (stimulate respiration, breath off more CO2)
- resulting in respiratory alkalosis (high pH), compensated by increased renal bicarbonate excretion (partially)
why does ‘physiological’ dyspnoea occur?
due to progesterone-driven hypERventilation
physiological SoB normal, harder to take in a large breath
which variables increase in the respiratory system during pregnancies?
O2 consumption increase 20%
resting minute ventilation: 15% (ventilate more, different from RR)
tidal volume increase: resting breath breathe in more air
PaO2 results in increase
which variables decrease in the respiratory system during pregnancies?
functional residual capacity in T3
PaCO2 decrease - physiological hyperventilation
which variables remain unchanged in the respiratory system during pregnancies?
respiratory rate (RR) vital capacity (max in and out) FEV1 (breath out in first second)
why is vital capacity unchanged during pregnancy?
although pulmonary function is altered during pregnancy, it is not compromised. Therefore, in the absence of any respiratory condition (ie, asthma), does not induce any mechanical stress on the respiratory efficiency of the pregnant patient
what are the carbohydrate metabolism changes during pregnancy?
- placental transport of glucose: facilitated diffusion (GLUT)
- pregnancy increases maternal peripheral insulin resistance
why does pregnancy increase maternal peripheral insulin resistance?
switches to gluconeogenesis and alternative fuels e.g. fatty A
(save glucose for foetus)
how are changes to carbohydrate metabolism achieved?
human placental lactogen (like growth hormone)
also prolactin, oestrogen / progesterone, cortisol
how does blood glucose change in pregnancy?
- decrease in fasting blood glucose (to foetus)
2. increase in post-prandial blood glucose (post meal glucose - prolong in circulation for longer for foetus)
