Fundamentals of Pregnancy

What is pregnancy?

the state of having product of conception implanted in the uterus or elsewhere, normally or abnormally

What type of pregnancy is more common and consistent with a viable birth?

intrauterine pregnancy

What is ectopic pregnancy?

the products of conception are implanted outside the uterus such as the tubes or adnexa

What is a molar pregnancy?

a non-viable pregnancy state with abnormal products of conception due to genetic anomaly (they are never viable)

What is the possible presentation of pregnancy?

- amenorrhea

- N/V

- Breast tenderness and swelling

- bluish coloration of the vagina/cervix (Chadwick's sign)

- widening and softening of the uterus

- Linea nigra

- Telangiectasias

- Palmar erythema

What is the most common symptom of pregnancy, and when does it begin and resolve?

- nausea and vomiting

- as early as 2 weeks

- resolves between 13 and 16 weeks

What is pregnancy-induced N/V treated with?

- frequent small meals

- emotional support

- antiemetics

What is hyperemesis gravidarum?

- extreme form of nausea and vomiting

- More than 3 episodes of vomiting per day with ketonuria and more than 5% weight loss

What is the clinical presentation of hyperemesis gravidarum?

- Severe dehydration fluid loss

- Hypokalemia

- Hyponatremia

- Ketosis/ketonuria

- Metabolic acidosis

- Weight loss

- Bleeding gums

What are non-pharmacological interventions for hyperemesis gravidarum?

- switching the patient's prenatal vitamins to folic acid supplementation only

- ginger supplementation

- acupuncture wristbands

What are first line pharmacological interventions for hyperemesis gravidarum?

- vitamin B6 (pyridoxine)

- doxylamine

What are second line pharmacological interventions for hyperemesis gravidarum?

- antihistamines

- dopamine antagonists

- dimenhydrinate/ diphenhydramine, prochlorperazine or promethazine

What does the uterus feel like during pregnancy during a bimanual exam?

- soft and elastic

- increase in size throughout pregnancy correlating with gestational age

What is fundal height?

the distance from the top of the pubic symphysis to the top of the fundus measured in centimeters

What is the fundal height at 20 weeks gestation?

at the umbillicus

What is the best initial test of diagnosing and ruling out pregnancy?

urine qualitative B hCG

Why is serum B hCG not used?

it is better, but it more expensive and considered invasive

What should a positive clinical hCG test be followed up with?

sonography to confirm pregnancy and locate gestational sack

How early can the gestational sac be located on a songogram?

5 weeks LMP

When can you first visualize the fetal heart?

6 weeks

When can you first hear the fetal heart?

10 weeks

What is the most common cause of abnormal hCG levels for the gestation date?

inaccurate dating

What are other causes of abnormal hCG levels for the gestation date?

- ectopic pregnancy

- threatened abortion

- missed abortion

- multiple pregnancies

- molar pregnancy

- choriocarcinoma

- embryonal carcinoma

When is the most accurate (higher) time to collect urine HCG?

1st morning specimens

How accurate is urine hCG?

they can diagnose pregnancy with 95% sensitivity by one week after the first missed menstrual period

When do false negatives occur during urine hCG?

the test is performed too early or the urine is very dilute

When do false positives occur during urine hCG?

- proteinuria

- UTI

When is plasma/serum hCG used?

- to aid in the diagnosis of an ectopic pregnancy

- monitoring trophoblastic tumors

- screening for fetal abnormalities

- serial levels to monitor accidents of pregnancy

What are the indications for a fetal ultrasound?

- confirm an intrauterine pregnancy

- document viability of the embryo

- diagnose multiple gestations

- estimate gestational age

- screen for fetal structure anomalies up to 12 weeks

What are the limitations to fetal ultrasound?

- dating becomes less accurate after 20 weeks gestation

- ultrasound will measure the size of the fetus not gestational age

- biological variation in size increases as gestation advances

When do limb buds appear on ultrasound, what about limb movements?

- limb buds: 7-8 weeks

- limb movements: 9-10 weeks

How do you determine gestational age on a fetal ultrasound?

crown rump length (until 13 weeks gestation then it becomes inaccurate)

How is pregnancy dated by a woman's menstrual cycle?

first day of bleeding of their last menstrual period

What is Naegele's rule?

- subtract 3 months from the LMP and add 7 days to estimate the day of delivery

- assume that a normal gestation is 280 days

- assume all patients have a 28 day menstrual cycle

If a woman has a 28-day cycle, when is ovulation?

day 14

If a woman has a 21-day cycle, when is ovulation?

day 7

If a woman has a 35-day cycle, when is ovulation?

day 21

What is gravida?

a woman who is pregnant

What is nulligravida?

a woman who has never been pregnant

What is primagravida?

a woman who has only been pregnant once

What is multigravida?

a woman who has had two or more pregnancies

What is parity?

the number of pregnancies in which fetuses have reached viability

What is nullipara?

a woman who has never completed a pregnancy beyond the stage of fetal viability

What is primapara?

a woman who has completed one pregnancy beyond the stage of fetal viability

What is a preterm?

a pregnancy that has reached 20 weeks LMP but before 37 weeks LMP

What is term?

a pregnancy from 37 weeks LMP to 42 weeks LMP

What is postterm?

a pregnancy after 42 LMP

What is G/TPAL?

- G - total number of pregnancies

- T - number of term pregnancies

- P - number of preterm pregnancies

- A - number of abortions, spontaneous or induced

- L - number of living children

What happens to the cardiac system during pregnancy?

- increase CO

- increase SV

- Increase PV

- Increase HR

- Decrease vascular resistance

- slight decrease in systolic BP

- decrease in diastolic BP

- no change in central venous pressure

- increase in femoral venous pressure

What is the saying for the cardiac system during pregnancy?

HIGH FLOW LOW RESISTANCE STATE

What is considered normal during pregnancy and can be heard along the left sternal border?

systolic ejection murmur

What type of murmur is never normal and should be investigated during pregnancy?

diastolic murmurs

What position elicits the highest cardiac output, and what about the lowest?

- highest: left lateral position

- lowest: supine

What happens to the respiratory system during pregnancy?

- tidal volume increases

- minute ventilation increases

- residual volume decreases

- PaCO2 decreases

- oxygen consumption increased

If pregnancy induces a state of respiratory alkalosis, what is it compensated by?

increased renal bicarbonate excretion

What happens to the hematologic system during pregnancy?

- Plasma volume: increases

- RBC volume: increases

- Hct: decreases

- WBC count: increases

- ESR: increases

- Coagulation factors: increases

- coagulability: increases

- Platelet count: unchanged

What kind of hematologic state is pregnancy?

hypercoagulable (likely owning to venous stasis and endothelial damage)

What does the hypercoagulable state increase the risk 5 fold for?

DVT

What does an increased RBC count highlight the need for?

iron and folate supplementation

What is folate supplementation useful for?

neural tube development

What is the most common cause of anemia in pregnancy?

iron deficiency

What kind of anemia NEVER occurs in pregnancy, and suggest alcohol consumption?

pernicious anemia (B12)

What happens to the renal system during pregnancy?

- kidney size: increases

- ureteral diameter: increases

- GFR: increases

- BUN/Cr/Uric acid: decreases

- Plasma Na: unchanged

- Plasma HCO3: decreases

- Blood pH: slight increase

- Urine glucose: increased

What are pregnant patients predisposed to as a result of these renal changes?

pyelonephritis and UTIs

What does lightening (in the late stage of pregnancy) do to the renal system?

makes it easier to breath, but increases urinary frequency and urgency

What happens to the endocrine system during pregnancy?

- Estrogen: increases

- Progesterone: increases

- Pituitary size: increases

- Adrenal size: unchanged

- Thyroid size: increases

What is pregnancy considered a state of in regards to the endocrine system, and what is it mediated by?

- hyperestrogenic

- placenta and fetal DHEAS production

What is the major form of estrogen produced in pregnancy?

estriol

The pituitary size increases during pregnancy; what does that predispose these patients to?

Sheehan's Syndrome

What happens to the gastrointestinal system during pregnancy?

- Gastric motility: decreases

- Gastric emptying time: increases

- GES tone: decreases

- Colonic motility: decreases

- Colonic transit time: increases

What do pregnant patients commonly develop due to these gastrointestinal changes?

- GERD

- Hemorrhoids

What is the hormone that is produced during pregnancy that is related to nausea?

hCG

What are the effects in pregnancy of the increase in progesterone on the gastrointestinal system?

- decrease the lower esophageal sphincter tone, causing heartburn

- decrease bowel peristalsis causing constipation

What are the dermatologic changes associated with pregnancy?

- Striae gravidarum

- Linea nigra

- Chloasma

- Spider angiomas

- Palmar erythema

- Chadwick sign

What is striae gravidarum?

"Stretch marks" along the abdomen because she is making more cortisol (reducing integrity of the skin) and stretching out her abdomen

What is line nigra?

increased pigmentation of the abdominal midline due to increased melanocyte-stimulating hormone levels

What is chloasma?

blotchy pigmentation of the nose and face

What is a spider angiomas and palmar erythema?

stigmata resulting from increased vascularity, high levels of estrogen

What is Chadwick sign?

blueish purplish discoloration of the vagina and cervix

What is considered normal weight gain for pregnancy?

25-35 ibs

What are the obstetric complications of multiple gestation?

- preterm labor

- placenta previa

- cord prolapse

- postpartum hemorrhage

- cervical incompetence

- gestational diabetes

- pre-eclampsia

- hyperemesis gravidarum

- iron deficiency anemia

- uterine atony

- thrombosis

- intrahepatic cholestasis of pregnancy

What are the fetal complications of multiple gestation?

- preterm delivery

- congenital abnormalities

- small for gestational age

- malpresentation

- death of a twin

- cerebral palsy

- mental retardation

What are the risk factors for multiple gestation?

- Infertility Therapies (clomiphene citrate)

- Advancing maternal age/delayed childbearing

- Race

- Heredity (maternal > paternal)

- Maternal size (taller/heavier)

What are the maternal adaptations to multiple gestation?

- Changes are more exaggerated compared to a singleton pregnancy

- Cardiac: increased heart rate, increased stroke volume, increased cardiac output secondary to increased myometrial contractility and blood volume

- Respiratory: increase in tidal volume and oxygen consumption

- Renal: increase GFR and increase in renal size

- Nutrition: increase calorie consumption to 3000 to 4000

- Weight gain average per week is 1 to 1.5 lbs with a total gain of 35 to 45 lbs

What are the two types of twins?

- Dizygotic

- Monozygotic

What are the three types of monozygotic twinning?

- Dichorionic-diamniotic

- Monochorionic-diamniotic

- Monochorionic-monoamniotic

What are dichorionic-diamniotic monozygotic twins?

- Separation occurs within first 72 hours or morula stage

- Resulting in separate chorion and separate amniotic sacs

- US: Lambda sign = inter twin membrane plus twin peak λ

What are monochorionic-diamniotic monozygotic twins?

- Separation during blastocyte stage (4-8 days)

- Resulting in shared chorion but separate amniotic sacs

- US: T-sign (intertwin membrane)

- Complication: twin-to-twin transfusion syndrome TTTS

What are monochorionic-monoamniotic monozygotic twins?

- Separation of embryonic disc (9-12 days)

- Resulting in a shared chorion and shared amniotic SAC

- Compilation: TTTS, umbilical cord entanglement

What is the most common kind of monozygotic twinning?

monochorionic-diamniotic

What is twin-to-twin transfusion syndrome (TTTS)?

- Results in a small, anemic twin and a large, plethoric, polycythemia twin

- Secondary to unequal flow within vascular communications between the twins and their shared placenta

- Results in one twin becoming a donor and the other a recipient of unequal blood flow

If twins are diagnosed with TTTS, how should they be monitored?

serial ultrasounds examining the amniotic fluid and fetal growth should be obtained every two weeks after diagnosis

How is TTTS managed?

serial amnio reduction

What are the prenatal requirements for multiple gestation?

- nutritional supplementation including one gram folate and 30 milligrams iron every day

- ideal weight gain ranges from 25 to 55 lbs or twin pregnancies

- 10-14 weeks: ultrasound to determine chorionicity and amnionicity

- 18-22 weeks: fetal anatomic ultrasound

- serial ultrasounds during second and third trimester

- 28 weeks: Antenatal steroids for mo-mo twins

When is induction of delivery done for monochorionic-diamniotic twins?

34-37 weeks (earlier for mono-mono)

When is induction of delivery done for dichorionic-diamniotic twins?

28 weeks

If the babies are preterm, what must you do or adminster?

assess fetal lung maturity if delivering prior to 38 weeks --> administer steroids

What are the four possibilities of twin presentation during birth?

- both vertex

- both breech

- vertex and breech

- breach then vertex

What do vertex/vertex twins undergo?

trial of labor --> reserve cesarean section

What do vertex/nonvertex twins undergo?

trial of labor