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Flashcards in OB - Exam One Deck (46)
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How is the sex of a fetus determined?

X and Y chromosomes

Y = male
X = female


What vessels are in umbilical cord?

2 arteries that carry deoxygenated blood away and 1 vein that carries oxygenated blood to the baby


Three Fetal Circulatory Shunts

1) Ductus venosus- diverts some blood away from liver as it returns from the placenta.
2) Foramen Ovale- diverts most blood from the right atrium directly to left atrium, rather than circulating in the lungs.
3) Ductus arteriosus- diverts most blood from the pulmonary artery into the aorta.


When does the fetal heart begin to beat?

Week 3 - primitive heart begins; heart has all four chambers


Week 3 Fetus Characteristics

Mesoderm and neural tube form, and primitive heart begins to pump. Some woman realize they missed their periods, and suspect they are pregnant.


Week 4 Fetus Characteristics

Esophagus and trachea separate, and the stomach forms. Neural tube closes, forebrain forms, upper and lower limb buds appear, ears and eyes begin to form.


Week 6 Fetus Characteristics

Auditory canal forms, eye is obvious. Heart has all 4 chambers, nasal cavity and upper lip form.


Week 8 Fetus Characteristics

Distinct human appearance, purposeful movements occur, tail has disappeared, sex organs form, most external and internal structures are formed, embryo enters fetal period.


Week 17 Fetus Characteristics

Genitalia and leg movements are visible on ultrasound and may be felt by the mother, bones are ossified, eye movements, sucks/swallows amniotic fluid, ovaries contain ova, no subcutaneous fat, blood vessels of scalp are visible.


Week 25 Fetus Characteristics

Wrinkled skin, lean body, eyes are open, fetus is now viable, Stronger movements, schedule of sleeping and moving, vernix caseosa is present on the skin, covers body, brown fat is formed, lungs begin to secrete surfactant, fingernails are present, respiratory movements begin.


Week 29 Fetus Characteristics

Fetus assumes cephalic position in utero, CNS functioning, skin less wrinkled, spleen stops forming blood cells and bone marrow start to form blood cells, ↑ surfactant is present in the lungs.


Week 36 Fetus Characteristics

Subcutaneous fat is present, skin is pink and smooth, grasp reflex is present, circumference of head and abdomen are equal, Surge in lung surfactant production occurs.


What complications can develop if respiratory distress is left untreated?

Increased pressure in the right ventricle causing reopening of the foramen ovale.

Possible death if severe.


What can folic acid help prevent during pregnancy?

 Reduces the incidence of neural tube defects such as spina bifida and anencephaly when taken at conception, and supplementation for 3 months before pregnancy may prevent autism.


What is the age of viability?

20 weeks - the lungs have matured enough functionally to survive outside the womb


Fetal Circulation

1. Blood enters fetal body through umbilical vein.
2. About half goes to the liver, remainder enters inferior vena cava through the ductus venosus, then goes through foramen ovale, then ductus arteriosus
3. Blood containing waste products is returned to placenta through umbilical arteries


Describe the sperm that is ejaculated into the cervix.

Sperm travel through the cervix and uterus into the fallopian tubes by means of flagellar activity. Can reach fallopian tubes within 5 minutes after sex. Remain capable of fertilizing the ovum for up to 5 days after being ejaculated into the area of the cervix


Functions of Amniotic Fluid

Maintains even temperature
Prevents the amniotic sac from adhering to fetal skin
Allows symmetrical growth
Allows buoyancy and fetal movement
Acts as a cushion to protect the fetus and umbilical cord from injury


How do you document obstetric hitory using the TPALM method?

TPALM is a standardized way to describe the detailed outcomes of a woman's pregnancies on her prenatal record.

T = number of term infants after 37 weeks
P = number of preterm infacts 20 - before 37 weeks
A= number of pregnancies aborted before 20 weeks
L = number of children now living
M = multiple birth number or multiple gestations



Any pregnancy (all; even one in progress)



Woman who is pregnant for the first time



A woman who has given birth to one or more children who reached the age of viability, regardless of the number of fetuses delivered and regardless of whether children are living now



A woman who has given birth to her first child (past age of viability) regardless of whether child was alive at birth or is now living. (term also used to describe a woman before the birth of her first child)



A woman that has given birth to two or more children past age of viability



A woman who has not given birth to a child who reached the age of viability



Termination of pregnancy before viability either spontaneous or induced


What is Chadwick's sign and what is the cause of it?

Purplish or bluish discoloration of the cervix, vagina, and vulva caused by increased vascular congestion. Hormonal imbalance or infection may also cause this.


What physiological changes occur with the woman during pregnancy?

Endocrine - produces estrogen and progesterone and hCG and Human placental lactogen, and increases maternal insulin resistance during pregnancy.

Uterus - grows from 10 mL to 5000 mL and reaches xiphoid process

Cervix - softens and thick mucous creates a mucous plug that is expelled after effacement and dilation

Ovaries - don't produce ova but produce progesterone to maintain uterine lining

Respiratory - O2 consumption increases by 15% Diaphragm rises 4 cm

Cardio - Blood volume increases by 45%


How can you determine a woman's expected delivery date using Nagel's rule?

Determine the first day of the last normal period. Count back 3 months and then add 7 days. Correct year if needed.

Example: LMP 1/27/17. Count back 3 months: 10/27. Add 7 days. EDD = 11/3/17.


What is the normal fetal heart rate?

110-160 bpm