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physiology of pregnancy clinical
R-GU
58
Medical
Graduate
10/13/2010

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Term
how does the uterus change in terms of size, weight and capacity in a female?
Definition
non-pregnant: 70 g, 10 mL capacity, 6-8 cm. pregnant: 1100 g, 5-20 L capacity. (increase in capacity 500-1000x)
Term
what is distention in the uterus due to?
Definition
the products of conception as well as the effects of estrogen
Term
what characterizes enlargement of the uterus? when is this important?
Definition
enlargement of the uterus is not symmetrical and is most marked in the *fundus* (the portion of the uterus surrounding the placenta enlarges more rapidly than the rest). this is important w/cesareans b/c if the incision is made at the lower portion, there will be less tension on the scar and a subsequent vaginal birth will be possible.
Term
where is the uterus by 12 wks? why is this important?
Definition
outside the pelvis - meaning that high impact exercise is possible/encouraged in the first trimester
Term
does blood flow increase throughout the gestational period? how does perfusion redistribute during gestation?
Definition
yes blood flow increases throughout the gestation. by the end of the the first trimester the endometrium receives 50% of the blood flow.
Term
what is chadwick's sign? how does the cervix change over pregnancy?
Definition
pronounced softening and cyanosis of the cervix seen in pregnancy (due to increased vascularity and edema of the vagina and hypertrophy and hyperplasia of the cervical glands). by term, the cervix will undergo a 12x reduction in mechanical strength.
Term
what happens to the ovaries, fallopian tubes, and vagina during pregnancy?
Definition
ovulation ceases, maturation of the follicles is suspended, musculature of the fallopian tubes undergoes hypertrophy, and the vagina undergoes hyperemia (takes on characteristic violet color) and its secretions are 3.6-6 pH (increased lactic acid due to lactobacillus).
Term
what is leukorrhea pregnancy?
Definition
a creamy/milky discharge from the vagina that is normal during pregnancy
Term
what is the linea nigra?
Definition
pigmentation of the midline abdomen seen in some pregnant women
Term
what are chloasma/melasma gravidarum?
Definition
irregular brown patches on the face/neck due to high estrogen levels. (more common in summer)
Term
who do angiomas and palmar erythema occur more commonly in?
Definition
2/3 of pregnant white women - but only 10% of african american women
Term
what characterizes changes to the breasts during pregnancy?
Definition
in the first trimester - the breasts become enlarged, very tender and may tingle. the nipples become considerably larger, more dark, and more erectile. after the first few months - colostrum (high protein discharge w/IgA - not milk) can be expressed w/gentle massage.
Term
does breast size correlate w/milk production?
Definition
no - unless the woman has undergone augmentation
Term
what is most wt gain in pregnancy attributable to?
Definition
the uterus and its contents, the breasts, and an increase in intracellular 3rd space fluid (avg wt gain: 25-30 lbs, obese pts should gain less/tiny pts should gain more). a small part of wt gain is due to maternal reserves (deposition of new fat and protein, and increase in cellular water)
Term
what is the necessary increase in calories for a pregnant woman?
Definition
300 more calories from baseline
Term
what is the normal level of increased water retention in pregnancy?
Definition
6.5 L extra - which will cause plasma osmolality to fall (and 3rd spacing to increase).
Term
what characterizes the normal metabolic changes in pregnancy?
Definition
normal pregnancy is characterized by fasting hypoglycemia, post prandial hyperglycemia, and hyperinsulinemia - which all ensure there is a continuous flow of glucose available for transfer to the fetus (glucose transfers across the placenta, *maternal insulin does not*).
Term
how does the fact that glucose transfers across the placenta but maternal insulin does not affect infants w/diabetic mothers?
Definition
since the baby is receiving glucose, but not insulin, its pancreas has to rev up to make more insulin - which is androgenic and if they have to make more insulin (due to more glucose from a diabetic mother) they will be larger.
Term
what happens when fasting is prolonged in a pregnant woman?
Definition
ketonemia (in the mother) rapidly appears b/c the baby gets metabolic priority.
Term
how do concentrations of lipids, lipoproteins, and apolipoproteins change in a pregnant woman's plasma?
Definition
maternal serum concentrations of lipids, lipoproteins, and apolipoproteins will all increase. LDLs peak at 36 wks, HDLs peak at wk 25, decrease at 32, then remain constant.
Term
how do Fe/Ca/Mg concentrations change in pregnancy?
Definition
they will all decrease - Fe levels need to be checked in the first trimester and @ 28 wks
Term
what characterizes hematologic changes during pregnancy? what are the 3 important reasons for this change?
Definition
maternal blood volume increases by 40-45% for 3 reasons: 1) to meet the demands of the enlarged uterus (w/a greatly hypertrophied vascular system). 2) to protect the mother/fetus from impaired venous return in the supine/erect position. 3) to safeguard the mother against the adverse effects of blood loss w/parturition.
Term
what is the increase in blood volume in pregnant women due to? how are hemoglobin and hematocrit affected?
Definition
increased plasma and RBCs - accompanied by erythroid hyperplasia and elevated retic count. hemoglobin/hematocrit decrease slightly, which is usually thought to be due to iron deficiency (but a hemoglobin below 11g/dl should be considered abnormal).
Term
how do WBC levels change in pregnancy?
Definition
yes, the WBC count varies from 5,000-12,000 and there is a neutrophilia of *predominately mature forms. leukocyte alanine phosphatase, c-reactive protein, ESR, C3, and C4 are all elevated during pregnancy.
Term
how are chemotaxis and the adherence function of WBCs changed during pregnancy?
Definition
chemotaxis and adherence function of leukocytes are depressed in the *second trimester onward. this is important b/c you *do not want the body's immune system to be revved up at this point* (b/c of this herpes, hpv, etc outbreaks may occur)
Term
what characterizes the coagulation cascade during pregnancy?
Definition
the coagulation cascade is in an active state during pregnancy - all factors are elevated except XI and XIII. this is important b/c this raises the risk of DVTs/PEs.
Term
does platelet count increase in pregnancy?
Definition
no - just width/volume
Term
when do the most important changes occur to the heart during pregnancy? what are these changes?
Definition
the most important changes to the heart occur during the first 8 weeks of pregnancy, where the resting pulse rate *increases by about 10 bpm, the heart becomes displaced L and upward (by the diaphragm), which appears as a shift to the L on an EKG. the heart will appear larger on a radiograph, and there is a normal level of benign pericardial effusion in pregnancy. the L ventricular wall mass and end diastolic dimensions also increase in pregnancy.
Term
is there a change in the inotropic state of the myocardium during pregnancy?
Definition
no
Term
how are the cardiac sounds altered in pregnancy?
Definition
there is an exaggerated splitting of the 1st heart sound w/an increase in loudness of both components, the 2nd sound is unchanged, and the 3rd sound is loud and easily heard. a systolic murmur is noted in 90% of pregnant pts (goes away after delivery) and a soft diastolic murmur in 20% of pts. 10% of pts have a continuous murmur arising from breast vasculature.
Term
what factors contribute to a rise in cardiac output during pregnancy?
Definition
arterial blood pressure and vascular resistance decrease while maternal blood volume, maternal wt, and basal metabolic rate increase.
Term
how is blood pressure changed during pregnancy? how is HTN defined?
Definition
the posture of a pregnant woman affects blood pressure - by mid-term the blood pressure is lowest, then it slowly rises w/diastolic pressure being more affected than systolic. *HTN in a pregnant pt is defined as > 140/90*.
Term
how is the diaphragm affected by pregnancy?
Definition
the diaphragm rises (4 cm) and its diameter increases (2 cm). thoracic circumference increases (6 cm), but this does not keep *residual volume from being decreased. *excursion is actually greater during pregnancy.
Term
do tidal volume, minute volume and minute oxygen uptake increase during pregnancy?
Definition
yes
Term
what happens to functional residual capacity (FRC) and residual volume in pregnancy?
Definition
functional residual capacity (FRC) and residual volume are decreased
Term
what happens to lung compliance in pregnancy?
Definition
lung compliance is decreased
Term
what is increased respiratory effort in pregnancy linked to? what does this increase cause?
Definition
*progesterone causes increased minute ventilation/respiratory effort which causes a respiratory alkalosis. this alkalosis is partially compensated for by a *moderate reduction in plasma bicarb. this increase in pH causes the O2 dissociation curve to shift to the L and increases the maternal affinity for O2 - however the maternal erythrocytes produce 2,3 DPG which shifts this curve back to the R. (conclusion: blood gases may be slightly alkalotic b/c they breathe faster and blow off more CO2 - doesn't always mean a PE)
Term
how is kidney size affected by pregnancy?
Definition
kidney size will increase slightly during pregnancy (b/c they are working harder). dilation of the pelvis, calyces, and ureters can resemble hydronephrosis on US (more marked on R where the uterus usually lies). this physiologic hydronephrosis can leave pts more susceptible to UTIs due to increased stasis.
Term
how are GFR/renal plasma flow affected by pregnancy? renal bicarb threshold?
Definition
GFR and renal plasma flow increase by ~ 50%. the renal bicarb threshold decreases.
Term
what characterizes a pregnant pt's urinanalysis?
Definition
glucosuria is not abnormal (but might still need to r/o DM), proteinuria may be seen in *small amounts (may need to r/o preeclampsia), hematuria may be present in amounts otherwise compatible w/a UTI.
Term
are hydronephrosis/hydroureter common in pregnancy?
Definition
yes. ureteric distention is greater on the R, secondary to the protective effect of the sigmoid colon on the L. the ureter lengthens during pregnancy and can twist/bend - causing more distention. *progesterone levels do cause ureteric dilation.
Term
why is pregnancy associated w/an increase in urinary incontinence? what is one compensation for this?
Definition
b/c the uterus will compress the bladder - the pressure of which will increase from 8 cm H20 to 20 cm H20 (3x increase). overall bladder capacity thus decreases and to compensate, functional urethral lengths increase. towards the end of pregnancy the head of the baby will also compress the bladder.
Term
as pregnancy progresses, how are the stomach and intestines affected?
Definition
they are displaced by the enlarging uterus
Term
why are gastric emptying and transit time decreased in pregnant pts?
Definition
increased progesterone and decreased levels of motilin.
Term
why is pyrosis/GE reflux common in pregnancy?
Definition
b/c of stomach position alteration and loss of LES tone
Term
why are hemorrhoids common in pregnancy?
Definition
hemorrhoids in pregnancy are a result of constipation and increased venous pressure below the level of the enlarged uterus.
Term
why are LFT's altered in pregnancy?
Definition
*alk phos nearly doubles*, AST/ALT/GGT and bilirubin levels are *slightly lower. plasma albumin is decreased, but *total albumin is still higher (greater volume of distribution). cholinesterase activity is reduced during pregnancy and leucine aminopeptidase activity is markedly elevated.
Term
how is the gall bladder affected by pregnancy?
Definition
*progesterone impairs gallbladder contraction by *inhibiting CCK and increased stasis can lead to an *increase in stone formation (women who have been pregnant several times have an increased risk of cholelithiasis).
Term
how is the pituitary gland affected by pregnancy?
Definition
the pituitary gland enlarges (may impinge on the optic chiasma = vision changes) and GnRH production starts to increase at 10 wks, then peaks at 28. prolactin production increases 10x then decreases post-partum. (prolactin is found in high concentrations in the placenta and it is theorized that it is also produced in the decidua)
Term
how is the thyroid gland affected by pregnancy?
Definition
there is a marked increase in *thyroxine transport protein and thyroxine binding globulin in response to high estrogen levels and several thyroidal stimulatory factors of placental origin are produced in excess. pregnancy is accompanied by a decrease in the availability of iodide for the maternal thyroid.
Term
how are thyroid hormones affected by pregnancy?
Definition
*TSH may be decreased due to beta-hCG (look at free T4). TBG increases during the 1st trimester, then stabilizes at 2x the baseline. T4 increases sharply between 8-9 wks and plateaus after 18 wks (free T4 levels return to normal after the 1st trimester). T3 is more pronounced up until 18 wks, which it plateaus after.
Term
why is it important for a pregnant pt to have adequate Ca++ intake?
Definition
b/c there is a physiologic hyperparathyroidism
Term
why are calcitonin levels higher in pregnant pts?
Definition
b/c pregnancy causes stress
Term
how does pregnancy affect 1,25 dihydroxyvitamin D3 levels?
Definition
they are increased
Term
why are serum cortisol levels higher in pregnant pts?
Definition
b/c of decreased clearance
Term
what does increased maternal adrenal gland secretion of aldosterone counteract?
Definition
the natriuretic effect of progesterone and ANP
Term
is steroid production increased in pregnancy?
Definition
yes
Term
how is the musculoskeletal system affected by pregnancy?
Definition
increased lordosis, increased mobility o the sacroilliac, sacrococcugeal, and pubic joints. during late pregnancy, aching, numbness and weakness are experienced in the upper extremities - thought to be due to marked lordosis of the neck/slumping of shoulder girdle impinging on the ulnar/median nerves (C4-C8) -*all due to increased fluid retention*-
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