Pregnancy and Prenatal Care Flashcards
define pregnancy
state of having products of conception implanted normally or abnormally in the uterus or occasionally elsewhere
terminated by spontaneous or elective abortion, or by delivery
how do you diagnose pregnancy
in a patient who has regular menstrual cycles and is sexually active, a period delayed more than a few days to a week is suggestive of pregnancy –> may already exhibit early signs and symptoms of pregnancy at this stage
can do urine or serum lab assay to test for pregnancy
can confirm a viable pregnancy by ultrasound which may show the gestational sac as early as 5 weeks on transvaginal US (or at bhcg of 1500-2000)
fetal heart motion can be seen on transvaginal US as soon as 6 weeks
what do urine and serum pregnancy tests measure
Bhcg (human chorionic gonadotropin)
this hormone is produced by the placenta and will rise to a peak of 100 000 mIU/mL by 10 weeks gestation, will decrease through second trimester and then level off at approc 20-30000 units in the third trimester
when can fetal heart motion be seen on transvaginal US
6 weeks
define an embryo
conceptus from conception to 8 weeks (10 weeks GA)
define a fetus
conceptus from 8 weeks (10 weeks GA) until birth
define infant
from delivery until 1 year
what are the timelines for the trimesters of pregnancy
1st–> up to 14 weeks GA (but is 12 weeks of pregnancy)
2nd–> 12-14 until 24-28 weeks GA
3rd–> 24-28 weeks until delivery
what is the GA limit of viability
born before 24 weeks
define preterm birth
between 24-37 weeks
define term birth
37-42 weeks l
define post term delivery
after 42 weeks
Define gravidity
number of times a woman has been pregnant
define parity
number of pregnancies that lead to a birth at or beyond 20 weeks GA or of an infant weighing more than 500 g
is a multiple gestation considered P1 or P2
P1–one pregnancy
what is gestational age
age in weeks and days measured from the LMP
what is developmental age
number of weeks and days since fertilization–usually about 14 days from LMP (therefore GA is usually 2 weeks before the DA)
what is the Nagele rule for calculating EDD
subtract 3 months from LMP, add 7 days, then add 1 year
how closely should US mirror EDD by dates
should not differ by more than 1 week in first trimester, by more than 2 weeks in second and by more than 3 in third
how accurate is crown-rump length dating in the first half of the first trimester?
within 3-5 days
when can you auscultate fetal heart sounds with doppler
10 weeks
when do fetal movements start
16-20 weeks
list signs of pregnancy
bluish discoloration of vagina and cervix–chadwick’s sign
softening and cyanosis of the cervix at or after 4 weeks–goodells sign
breast swelling and tenderness
development of the linea nigra (linea alba) from umbilicus to pubis
telangiectasias
palmar erythema
list symptoms of pregnancy
amenorrhea
nausea and vomiting
breast pain
quickening–fetal movements
by how much does cardiac output change in pregnancy
increases by 30-50%
most increases occur during the first trimester, with maximum being reached between 20-24 weeks gestation and maintained until delivery
what causes the increased cardiac output in pregnancy
first due to an increase in stroke volume and then is maintained by an increase in heart rate as stroke volume decreases to near pre-pregnancy levels at the end of the third trimester
how does SVR change during pregnancy
decreases
results in fall in arterial BP
why is there a fall is SVR during pregnancy
most likely due to elevated progesterone leading to smooth muscle relaxation
how does BP change in pregnancy
sBP decreases by about 5-10 mmHg and dBP decreases by about 10-15mmHg that nadirs at week 24
between 24 weeks GA and term, BP slowly returns to pre-pregnancy levels but should NEVER EXCEED them
how does tidal volume change in pregnancy? what are the implications of this for expiratory reserve volume?
increases by about 30-40% –> this is despite the fact that total lung capacity decreases by 5% due to elevation of the diaphragm
this increase in Vt decreases the expiratory reserve volume by about 20%
increase in Vt with constant respiratory rate leads to an increase in alveolar and arterial pO2 levels and a decrease in pCO2 levels
how does PaCO2 (arterial) change during pregnancy
decreases to approx 30 mmHg by 20 weeks (compared to normal 40mmHg)
leads to an increased CO2 gradient between mother and fetus and is likely caused by elevated progesterone that either increase the respiratory systems responsiveness to CO2 or act as a primary stimulant
this gradient facilitates oxygen delivery to the fetus and CO2 removal from the fetus
what % of women experience dyspnea of pregnancy
60-70%
possibly secondary to decreased PaCO2 levels, increased Vt or decreased TLC
what % of pregnant women experience nausea and vomiting
70%
“morning sickness” although can occur anytime throughout the day
caused by elevations in estrogen, progesterone and hCG
may also be due to hypoglycemia and can be treated with frequent snacking
typically resolves at 14-16 weeks gestation
define hyperemesis gravidarum
severe form of morning sickness associated with weight loss (more than or equal to 5% of pre pregnancy weight) and ketosis
why do you get reflux in pregnancy
delayed gastric emptying and decreased tone in gastroesophageal sphincter
why do you get decreased water absorption/diarrhea in pregnancy
decreased motility of large bowel
how do the kidneys change in pregnancy
increase in size and ureters dilate –> leads to increased rate of pyelonephritis
GFR increases by 50% early in pregnancy and is maintained until delivery –> BUN and Cr thus decrease by about 25% (above about 80 for Cr is abnormal)
increase in RAAS system leads to increased levels of aldosterone which results in increased sodium resorption –> BUT plasma levels of sodium do not increase as GFR also increases
how does plasma volume change in pregnancy
increases by 50%
how does RBC volume change in preganancy
increases by 20-30% –> thus, with the increase in plasma, you get a dilutional anemia
how does the WBC count change in pregnancy
increases to a mean of 10.5 with a range of 6-16 –> in labour this may increase to over 20
how do platelet counts change in pregnancy
decreases slightly, probably due to increased plasma volume and an increase in peripheral destruction
in 7-8% of patients the platelets may decrease to between 100-150, a drop below 100 over a short time is not normal and should be investigated
what hematologic event is more likely in pregnancy versus non pregnant women
thromboembolic events–> pregnancy is a hypercoagulable state
elevations in the levels of fibrinogen and factors VII-X–> however, actual bleeding and clotting times do not change
increased rates of thromboembolic events in pregnancy may also be secondary to the other elements of virchow’s triad (increase in venous stasis and vessel endothelial damage)
how do estrogen levels change in pregnancy and what is the implication of this
pregnancy is a hyperestrogenic state
produced by placenta with ovaries contributing a small amount
estrogen produced from the placenta is derived from circulating plasma-borne precursors produced by the maternal adrenal glands
fetal wellbeing has been correlated to maternal serum estrogen levels, with low estrogen levels being associated with conditions like fetal death and anencephaly
how do hCG levels change in pregnancy
double approximately every 48 hours in early pregnancy reaching a peak at about 10-12 weeks
then decline to reach steady state at about 15 weeks
where is hCG produced
placenta
what does hCG do
acts to preserve the corpus luteum during early pregnancy
what does the corpus luteum do
produces progesterone which maintains the endometrium–> eventually the placenta takes over progesterone production and the corpus luteum degrades into the corpus albicans
how do progesterone levels change in pregnancy
increase over course of pregnancy
what does progesterone do
causes relaxation of smooth muscle which has multiple effects on the GI, CV and GU systems
what is human placental lactogen
aka human chorionic somatomammotropin
hormone produced by the placenta which is important for ensuring a constant nutrient supply to the fetus
induces lipolysis with a concomitant increase in circulating FFAs
also acts as an insulin antagonist along with various other placental hormones which thus has a diabetogenic effect which leads to increased levels of insulin and protein synthesis
how do prolactin levels change during pregnancy
markedly increased
decrease after delivery but later increase in response to suckling
how do thyroid hormones change during pregnancy
- estrogen stimulates thyroid binding globulin (TBG) leading to elevation in total T3 and T4 –> but free T3 and T4 remain constant
- hCG has a weak stimulating effect on the thyroid likely because its alpha subgroup is similar to TSH –> slight increase in T3 and T4 and slight decrease in TSH during pregnancy
overall though-pregnancy considered a euthyroid state
what are the skin changes during pregnancy
spider angiomas and palmar erythema secondary to high estrogen
hyperpigmentation of the nipples, umbilicus, linea alba/nigra, perineum, and face (melasma) secondary to increased levels of melanocyte simulating hormones and steroid hormones
how does a womans daily caloric requirement change during pregnancy
increases by 300 kcal/day during pregnancy and 500 kcal/day during breastfeeding
most patients should gain between 20-30 pounds (overweight women should gain less, underweight women should gain more)
what nutrient requirements do women require more of in pregnancy
protein iron folate calcium other vitamins and minerals
what should be done at the first prenatal visit
complete history and physical
initial lab tests
address diet, weight gain goals and exercise should be discussed
occurs in first trimester around 6-10 weeks GA
what do ask on history at the first prenatal visit
present pregnancy LMP symptoms of pregnancy obstetric history--prior pregnancies, including date, outcome and mode of delivery, length of time in labour and second stage, birth weight, any complications complete medical and surgical history family history social history
what should you pay attention to on physical exam in the first prenatal visit
pap smear (unless one done in last 6 months)
cultures for gonorrhea and chlamydia
size of uterus on bimanual exam
dating US
what lab tests should be done in the first trimester
CBC
antibody screen, rapid plasma reagin or VDRL screening for syphilis, rubella antigen, hepatitis B surface antigen
UA and culture
titre for VZV if no history of chicken pox
PPD for TB
HIV testing
what screening tests should be done in the first trimester
screening tests for aneuploidy with nuchal translucency by US and serum markers
what should be done on routine prenatal follow up visits
BP weight urine dipstick measurement of SFH auscultation of FH
what do you worry about if you see protein on urine dipstick in pregnancy
pre-eclampsia
what are symptoms of complications of pregnancy
vaginal bleeding–> possible miscarriage or ectopic pregnancy in first trimester, or placental abruption or previa later in pregnancy
vaginal discharge or leaking of fluid–> sign of infection or cervical changes (discharge) or ruptured fetal membranes (leaking fluid)
urinary symptoms
what are braxton hicks contractions
irregular contractions, less than 5-6 per day, common in third trimester
(regular contractions more often than this may be sign of preterm labour and should be assessed)
how and when do you screen for aneuploidy
ultrasound for nuchal translucency and correlation with serum levels of pregnancy-associated protein A (PAPP-A) and free B-hCG
between 11-13 weeks
how and when do you screen for neural tube defects
maternal serum alpha fetoprotein (MSAFP) between 15-18 weeks (elevated means increased risk of NT defects)
use in conjunction with B-hCG and estriol for augmented screening (the triple screen)
addition of inhibin A further enhances it and it called the quad screen
when do you do the screening ultrasound
between 18-20 weeks
when do you usually feel the first fetal movement
between 16-20 weeks
how often are prenatal visits in the first and second trimesters
monthly
how often are prenatal visits in the third trimester
every 2-3 weeks between 28-36 weeks, and then weekly after 36 weeks
when should Rh- mothers receive rho gam
28 weeks
when do you order the third trimester lab tests
27-29 weeks
what are the third trimester lab tests
hematocrit–> patients with hematocrit lower than 32% or are started on iron supplementation
RPR/VDRL
glucose loading test –> screening for gestational diabetes (glucose tolerance test is actually diagnostic)
is active HSV an indication for cesarean delivery?
yes
when do you do GBS screening
36 weeks
how do you treat positive GBS screen
IV penicillin when they present in labour
list routine problems of pregnancy
back pain constipation contractions dehydration edema GERD hemorrhoids PICA round ligament pain urinary frequency varicose veins
why are laxatives generally avoided in the third trimester
theoretical risk of preterm labour
define braxton hicks contractions
occasional irregular contractions that do not lead to cervical change that can occur several times per day up to several times per hour
why do pregnant women get edema
compression of the IVC and pelvic veins by the uterus can lead to increased hydrostatic pressure in the lower extremities and edema in feet and ankles
should sleep on sides to decrease compression
severe edema of face and hands may indicate pre-eclampsia and warrants investigation
what genetic disorders may be screened for prior to conception
sickle cell
tay sachs
thalassemia
cystic fibrosis
how are fetal karyotypes and genetic screens done
amniocentesis or chorionic villus sampling
when is a dating US most accurate
first trimester
what does the biophysical profile look at
amniotic fluid volume fetal tone fetal activity fetal breathing movements non stress test
gives a score of either 0 or 2 for each
score of 8-10 is reassuring
what is considered formal antenatal testing for fetal wellbeing
NST
BPP
oxytocin challenge
when is an NST considered formally reactive (reassuring)
if there are two accelerations of the FHR in 20 min that are at least 15 beats above baseline HR and last for at least 15 sec
what is a oxytocin challenge test/contraction stress test (CST)
obtained by getting at least 3 contractions in 10 min and analyzing the FHR tracing during that time
reactivity criteria are the same as for NST
late decelerations with at least half of the contractions is a positive test and is worrisome
when do we start using NSTs
beginning 32-34 weeks in high risk and 40-41 in undelivered patients
what do you do if the NST is nonreactive
assess fetus with US
if there are any worrisome tracings on the NST or if BPP not reassuring, OCT is usually performed
what is percutaneous umbilical blood sampling, and why would you do it
“PUBS”
place a needle transabdominally into the uterus and phlebotimize the umbilical cord
may be used when fetal hematocrit needs to be obtained (i.e in case of Rh isoimmunization or other causes of fetal anemia, or hydrops)
also used for fetal transfusion, karyotype analysis and assessment of fetal platelet count in the setting of alloimmune thrombocytopenia
how do you test for fetal lung maturity
amniotic fluid sample obtained through amniocentesis
classically–> lecithin to sphingomyelin (L/S) ratio has been used as marker for fetal lung maturity
type II pneumocytes secrete surfactant that uses phospholipids in its synthesis
lecithin increases as lungs mature whereas sphingomyelin decreases around 32 weeks
L/S ratio above 2 is associated with only rare cases of respiratory distress syndrome (RDS)
can also use phosphatidylglycerol (PG), saturated phosphatidylcholine (SPC), the presence of lamellar body count, or surfactant to albumin ratio
how do you screen pregnant women with graves
TSH immunoglobins (can cause fetal disease)
how do you follow PPD+ women who are pregnant
CXR afer 16 weeks
what tests do you run in women with SLE who are pregnant
antiRho, antiLa antibodies –> can cause fetal complete heart block
why do we care when a pregnant woman has SLE
antibodies can cause complete fetal heart block
what groups are at high risk for sickle cell and should be screened
african americans
southeast asians
MCV less than 70
can do HgB electrophoresis or sickle cell prep for african americans
list the routine tests ordered in the first trimester
hematocrit
blood type and screen
RPR/VDRL
rubella antibody
HBsAg
gonorrhea and chlamydia cultures
PPD
pap smear
UA and culture
VZV titre in patients with no hx of exposure
HIV
NT plus serum markers
list the routine tests ordered in the second trimester
MSAFP/triple or quad screen
obstetric US
amniocentesis for women interested in prenatal dx
list the routine tests ordered in the third trimester
hematocrit
RPR/VDRL
GLT
GBS screen
