OB Flashcards
What is the difference between an embryo, fetus, and infant?
- embryos exist from fertilization to 8 weeks gestation
- from 8 weeks to birth the products of conception are referred to as a fetus
- infants are children less than 1 year old
How is amenorrhea defined?
- no menses for 3 months in someone with regular menses
- no menses for 6 months in someone with irregular menses
What defines the first, second, and third trimesters?
- the first trimester is from LMP to 14 weeks
- the second trimester is from 14 to 28 weeks
- the third trimester is from 28 weeks until delivery
How can you quickly estimate the due date?
LMP - 3 months + 7 days
What is a previable fetus and how is birth of a previable fetus managed?
a previable fetus is one born at less than 25 weeks gestation
- before 22 weeks resuscitation is not attempted
- between 22-25 weeks, the decision is made on a case-by-case basis after discussing risks and benefits with parents
- after 25 weeks, resuscitation is always initiated
What is considered a preterm birth? What is considered a post-term birth?
- preterm is birth before 37 weeks gestation
- post-term is birth after 42 weeks gestation
What are the Gs and Ps for a woman who is currently pregnant, has had 2 abortions, had two children born at term, and a set of twins born preterm?
G6P2124
Describe each of the following signs of pregnancy and when they are seen:
- Goodell sign
- Landin sign
- Chadwick sign
- Telangiectasias/Palmar Erythema
- Chloasma
- Linea Nigra
- Goodell sign: softening of the cervix felt at 4 weeks
- Landin sign: softening of the midline uterus at 6 weeks
- Chadwick sign: blue discoloration of the vagina and cervix at 6-8 weeks
- Telangiectasias/Palmar Erythema: first trimester
- Chloasma: the mask of pregnancy with hyperpigmentation of the face which worsens with sun exposure at 16 weeks
- Linea Nigra: hyperpigmentation extending from the xiphoid to the pubic symphysis seen in the second trimester
What is the first sign of pregnancy seen on physical exam?
Goodell sign, a softening of the cervix, which can be felt as early as 4 weeks gestation
What is chloasma?
also referred to as the mask of pregnancy, it is a hyperpigmentation of the face, worse with sun exposure, that is first seen around 16 weeks gestation
How should B-hCG levels change throughout the course of early pregnancy?
- the level should double approximately every 2 days for the first 4 weeks
- a level of 1500, seen around 5-6 weeks, suggests a gestational sac should be visible on ultrasound
- it should then peak around 10 weeks gestation
What are the first two steps in confirming pregnancy?
get a B-hCG level then perform an ultrasound to confirm an intrauterine pregnancy
At what point in pregnancy should a gestational and yolk sac be visible?
when B-hCG levels reach 1500 IU/mL
How do the following cardiac parameters change during pregnancy:
- blood volume
- hematocrit
- systemic vascular resistance
- heart rate
- cardiac output
- blood volume: increases
- hematocrit: decreases
- systemic vascular resistance: decreases
- heart rate: increases
- cardiac output: increases
How do the following respiratory parameters change during pregnancy:
- residual volume
- FEV1/FVC
- tidal volume
- respiratory rate
- minute ventilation
- PaCO2
- residual volume: decreased (upward pressure on diaphragm)
- FEV1/FVC: unchanged
- tidal volume: increased
- respiratory rate: unchanged
- minute ventilation: increased
- PaCO2: decreased
What are three common physiologic GI side effects of pregnancy and what causes these?
- morning sickness caused by increased estrogen and progesterone
- reflux caused by progesterone-induced LES relaxation
- constipation caused by reduced colonic motility
How do the following renal parameters change during pregnancy:
- GFR
- creatinine
- BUN/Cr
- kidney volume
- GFR: increases (greater blood volume and decreased SVR improves perfusion)
- creatinine: decreases (secondary to increased GFR)
- BUN/Cr: decreases
- kidney volume: increases due to increased vascular volume, increased interstitial volume, and dilation of renal pelvises
How do the following hematologic parameters change during pregnancy:
- WBC
- platelet count
- hematocrit
- PT
- PTT
- INR
- fibrinogen
- coagulability
- WBC: increased
- platelet count: decreased
- hematocrit: decreased
- PT: unchanged
- PTT: unchanged
- INR: unchanged
- fibrinogen: increased
- coagulability: increased
At what point should thrombocytopenia be investigated during pregnancy?
once platelet count is less than 80K
Describe the five options and timing of genetic testing available in the prenatal period.
- in the first trimester, between 9-13 weeks, a combined test of maternal B-hCG, maternal PAPP-A, and nuchal translucency can be performed as a screening tool
- in the first trimester, after 10 weeks, cell-free fetal DNA testing can be performed as a screening tool
- in the second trimester, between 15-20 weeks, a triple or quad screen can be performed with MSAFP, B-hCG, estriol, and (for the quad) inhibin A
- CVS is a confirmatory test performed at 10-13 weeks
- amniocentesis is a confirmatory test performed at 15-17 weeks
What routine prenatal testing is performed in each of the trimesters?
- in the first trimester, a dating ultrasound, pap smear, and G/C are performed along with routine blood tests
- in the second trimester, a routine ultrasound for anatomy is performed at 18-20 weeks
- in the third trimester a 1-hr GTT is performed at 24-28 weeks; a CBC for anemia at 27 weeks; and G/C, STD, and GBS testing at 36 weeks
When is glucose challenge testing performed during pregnancy?
at the end of the second trimester between 24-28 weeks gestation
What testing should be performed at 36 weeks gestation?
G/C, GBS culture, STD testing if patient was positive during pregnancy or has risk factors
What are Braxton-Hicks contractions and how should they be managed?
they are contractions that do not lead to cervical dilation; if they become regular or persist, the cervix should be checked to rule out preterm labor
When can CVS and amniocentesis be performed?
- CVS from 10-13 weeks
- amniocentesis from 15-17 weeks
What is the “combined test” during pregnancy?
it is a combination of maternal B-hCG, maternal PAPP-A, and nuchal translucency which serves as a screening for trisomy 21 and is performed at 9-13 weeks gestation
What is cell free DNA testing during pregnancy?
it is a screening test for aneuploidy that is performed in women over 35 after 10 weeks gestation
What are the triple and quad screening?
- triple is MSAFP, B-hCG, and estriol
- quad is the same plus inhibin A
- both are done between 15-18 weeks gestation
What does elevated maternal serum AFP indicate?
a dating error, neural tube defect, or abdominal wall defect
When should routine fetal US for anatomy be performed?
between 18-20 weeks of gestation
What is non stress testing, why is it performed, and how are the results interpreted?
- it is a noninvasive evaluation of the fetus in utero using fetal heart rate tracing
- a reactive test is defined by at least two accelerations within 30 minutes and this indicates adequate fetal oxygenation
- a nonreactive test does not necessarily indicate inadequate oxygenation however as the child may be sleeping
How is a fetal heart acceleration defined?
it is a more than 15 bpm abrupt increase in fetal heart rate that peaks within at least 30 seconds
How is the biophysical profile scored?
each category is worth 2 points and a score of 4 or less indicates fetal compromise:
- NST
- Amniotic fluid index: one pocket at least 2 cm in height
- Fetal breathing: at least 1 episode lasting 30 seconds
- Fetal movement: at least 4 counts
- Fetal muscle tone: at least 1 flexion and extension
What is a normal fetal heart rate? How are bradycardia and tachycardia defined?
- normal is 110-160
- bradycardia is a baseline (>10 minutes) less than 110
- tachycardia is a baseline (>10 minutes) more than 110
What causes variable, late, and early decelerations on fetal monitoring? Which is most serious?
V - Cord compression
E - Head compression
A - Okay!
L - Placental Insufficiency (most serious)
What are early decelerations?
- a decrease in HR that mirrors a contraction
- caused by head compression
What are late decelerations?
- a decrease in HR that comes after a contraction starts
- it is caused by placental insufficiency and fetal hypoxia
What are variable decelerations?
- decreases in HR that have no association with contractions
- caused by umbilical cord compression, which raises peripheral resistance and BP, triggering a reflexive bradycardia
What is meant by “lightening”?
this is a physiologic change that occurs before labor and describes fetal descent into the pelvic brim
What is meant by “bloody show”?
this is a physiologic change that occurs before labor and describe passage of blood-tinged mucus from the vagina that is released with cervical effacement
What do each of the following parts of labor involve:
- stage 1
- latent phase
- active phase
- stage 2
- stage 3
- stage 1: onset of labor to full cervical dilation
- latent phase: onset of labor to 6cm dilated
- active phase: 6cm dilated to full dilation
- stage 2: full dilation to child birth
- stage 3: child birth to delivery of placenta
What are the seven steps of stage 2 labor?
- engagement
- descent
- flexion
- internal rotation
- extension
- external rotation
- expulsion
Describe three methods of inducing labor and their mechanism of action.
- prostaglandin E2 is used for cervical ripening
- oxytocin is used for augmentation of uterine contractions
- amniotomy promotes engagement and effacement
Describe the following for ectopic pregnancy:
- risk factors
- presentation
- diagnosis
- most likely location
- management
- risk factors include prior ectopic, PID, IUD, and IVF
- it presents with pelvic pain and vaginal bleeding; patients may be hemodynamically compromised if it ruptures
- diagnosis is made with B-hCG and an ultrasound to identify the extrauterine pregnancy
- it most commonly occurs in the ampulla of the fallopian tube
- if it ruptures, patients require surgery, but if it has yet to rupture, patients can attempt medical management with methotrexate first (with some exceptions)
Describe the management of ectopic pregnancy.
- start by getting a B-hCG and US to make the diagnosis
- for ruptured ectopics, patients need hemodynamic support and surgery
- for unruptured ectopics less than 3.5 cm with no heartbeat and no other contraindications, methotrexate can be used for medical management
- after MTX, patients should have B-hCG monitored; if a decrease of 15% is not seen by day 7, an additional dose of MTX can be given
- surgery is indicated in these patients after 2 failed attempts at medical management
- in all patients, continue to follow B-hCG level to 0
Which patients with ectopic pregnancy are candidates for methotrexate?
must meet all of the following criteria:
- unruptured ectopic and hemodynamically stable
- no pre-existing immunodeficiency or liver disease
- ectopic is less than 3.5cm and without heart beat
- not breastfeeding or with a co-existing viable pregnancy
What is the most common cause of spontaneous abortion? What are other potential causes?
- the most common is chromosomal abnormality
- other causes include anatomic abnormalities, uncontrolled thyroid dysfunction or DM, SLE and antiphospholipid syndrome, infections, and trauma