Lecture 13: Pathological Pregnancies Flashcards
In a broad sense what are the changes that occur in pregnancy?
- Changes occur to most body systems
- Maternal CV
- Heamotological system
- Maternal immune system
- Genital system
What are the heamotological changes for mum in pregnancy?
- Increased blood volume
- Plasma and blood volume increase at differing rates
= Heamatocrit falls as plasma increases at a higher rate than cell mass. - Plasma increases around 1250mls by 30 weeks and thereafter remains stable
What are the cardiovascular changes of pregnancy?
Most important:
- Increased CO
- > ~10% inc. SV, 10-15% inc HR
- 50% increase Blood volume
= Reduced peripheral vascular resistance (i.e pre-eclampsia = higher than normal PVR)
How can estrogen cause CV adaptations?
Potentially oestrogen
- Can reduce vascular resistance mainly in reproductive tissues
- Can alter the ratio of type 1 : 3 collagen in the vessel wall
- High levels of estrogen are not reached until 9 weeks when fetal adrenals induce synthesis
How can progesterone cause CV adaptations?
- Progesterone may induce vascular relaxation in the uteroplacental circulation but DOES NOT appear to ahve a systemic effect
- Progesterone is alos not markedly elevated until 10 weeks pregnant.
What is the role of angiotensin in CV adaptations?
- ANG2 (vasocon) increases in pregnancy…
- The uteroplacental unit produces a large amount of RAS
BUT the effects of ANG2 appear to be blunted in pregnancy - Potentially due to changes in receptors.
What is the role of NO in CV adaptations of pregnancy?
- No is produced by vascular endothelial cells by NO synthetase in response to shear stress of blood flowing over the vessel surface.
- T1/2 of six seconds and causes art. wall relaxation and dilation
- The activity of NO synthetase is some tissues is increased in pregnancy
What is preeclampsia?
Pre-eclampsia is a multi system disorder unique to human pregnancy
Characterised by hypertension and involvement of one or more other organ systems and/or the fetus.
Raised BP commonly but not always first manifestation.
Proteinuria is commonly recognised additional feature after hypertension. but not considered mandatory to make clinical diagnosis.
What is the clinical profile of preeclampsia?
- Hypertension arises 20+ weeks gestation \accompanied by one or more of:
- Renal involvement
- Disseminated intravascular coagulation
- Severe epigastric and/or right upper quadrant pain
- Neurological involvement headache, visual disturbances
- Stroke
- Pulmonary oedema
- FGR/IUGR
What is believed to trigger preeclampsia?
Preeclampsia is a failed maternal adaptation
- Triggered by something from the placenta
- An exaggerated inflam response leading to vascular dysfunction
- Failure of the normal CV adaptations to pregnancy
- Loss of the normal decrease in maternal peripheral vascular resistance
What are the subgroups of pre-eclampsia?
Early onset; 20-30 weeks at diagnosis
late onset; 34+ weeks
Distinction important - usually but NOt always late onset is less severe.
Probably different causes and potentially treatments may differ
What is the cure for pre-eclampsia?
- Delivery of the fetus to prevent progression of maternal signs/symptoms
- Hypertension can be managed pharmacologically
What does pre-eclampsia dispose the mother to?
Early CV mortality
What are some of the risk factors for pre-eclampsia that can be addressed prior to pregnancy?
Just generic CV risk factors
- Smoking, hypertension, obesity, dyslipidemia
Define SGA:
Small for gestational age
- Compared to averages usually <10 centile
- Includes constitutionally small babies
- Easy and consistent to measure
