OB Test #1

An embryo should be seen with a MSD (Mean Sac Diameter) of >_____mm?

>25mm

YS should always be seen with an MSD of how many mm?

20mm

The embryo and gestational sac grow at a predictable rate of how many mm/day in early pregnancy/1st trimester?

1mm/day

Midgut herniation is normal between what weeks of gestation?

8-12 weeks gestation

Normal IUP HCG levels double every ______hours?

48-72hrs

A normal gestational sac is expected to be visible by sonography when hCG levels _________ mIU/mL (second international standard - milli-international units per milliliter)?

1000 to 2000 mIU/mL

Indications for Obstetric Sonography:

Estimation of Gestational (Menstrual) Age, what even is this all about?

This is for patients who are uncertain about their clinical dates. US can be used to verify dates for patients who have scheduled an elective cesarean delivery, as well as check when there is an indicated induction of labor and an elective termination of pregnancy.

Using obstetric sonography to estimate gestational (menstrual) age and confirm dating permits proper timing of cesarean delivery or labor induction to avoid what?

Premature delivery

Obstetric sonography can be used to evaluate fetal growth, especially when a patient has an identified cause for uteroplacental insufficiency.

What are some examples of uteroplacental insufficiencies?

Severe preeclampsia, chronic hypertension, chronic renal disease, or severe diabetes mellitus, or for other medical complication of pregnancy in which fetal malnutrition, like IUGR or macrosomia, is suspected

Measuring the fetal growth at 2 to 4 weeks intervals permits assessment of impact of what?

Complication conditions of fetus

What are some causes of bleeding in the first trimester?

1. Implantation bleed

2. Miscarriage

3. Ectopic pregnancy

What are cause of bleedings in the 2nd and 3rd trimesters?

1. Miscarriage

2. Placenta previa or abruption

3. Incompetent cervix

4. Preterm labor

OB sonography might be indicated for a serial evaluation of cervical length, especially in pregnant women with increased risk for what?

Recurrent or primary preterm birth; Check internal and external os

OB sonography can be used to evaluate abdominal or pelvic pain that could be associated with what?

1. Ectopic pregnancy

2. Placenta abruption

3. Maternal appendicitis

4. Renal stones

5. Pelvic mass or other conditions

T/F - Fetal presentation is variable in late pregnancy, so OB sonography can help determine fetal presentation?

True

OB sonography may be used if there are suspected multiple gestation based on what signs?

1. Detecting more than 1 fetal heartbeat

2. Fundal height that is larger than expected for dates

3. Prior use of fertility drugs

T/F - If multiple gestation is suspected, patient will automatically be pt in high risk pregnancy?

True

What is amniocentesis?

A prenatal diagnostic test in which a small amount of amniotic fluid is removed to determine any genetic abnormality. Can be OB US guided

When is a hydatidiform mole suspected?

When there are signs of

1. Hypertension

2. Proteinuria

3. Presence of ovarian cysts felt on pelvic examination

4. Failure to detect fetal heart tones with a Doppler US after 12 weeks

Which type of cyst is associated with trophoblastic disease aka hydatoform mole?

Theca lutein cysts

What is another name for trophoblastic disease?

Hydatoform mole

OB sonography can aid in timing and proper placement of a cerclage, which is used for what?

Patients with incompetent cervix, which is when they can't keep the baby in

OB sonography can check for suspected uterine abnormalities such as what?

1. Clinically significant leiomyoma

2. Congenital structural abnormalities

3. Serial surveillance of fetal growth

What is a Biophysical evaluation for a fetus?

An exam that checks the wellbeing of a fetus after 28 weeks of gestation and includes

1. Assessment of amniotic fluid

2. Fetal tone

3. Whole body movements

4. Breathing movements

5. Heart rate patterns

Elevated alpha feto-protein (AFP) increases the risk for?

Open spinal defects, exp. neural defects, spina bifida

Gravidity

The number of pregnancies, including present one; Twins and triplets count as one

Parity

Reports all possible pregnancy outcomes

What counts as a term birth?

Deliveries that are over 37 weeks and include alive and stillborn deliveries; Twins count as one

Premature births or stillborn fall under how many weeks?

20-37 weeks

Abortion/pregnancy loss/miscarriage fall under how many weeks?

<20 weeks

What is the standard way to date pregnancy in the US?

By using the last normal menstrual period (LMP or LNMP)

What are the weeks and days of the 1st trimester

13 weeks 6 days gestational age

What are the weeks and days of the second trimester?

14 weeks and 26 weeks 6 days GA

What are the weeks and days of the third trimester?

27 weeks GA and last until term (around 40 weeks)

Dates established by sonography performed in 1st or 2nd trimester typically take precedence over menstrual dates when the discrepancy is over 7 days in which trimester?

1st

Dates established by sonography performed in 1st or 2nd trimester typically take precedence over menstrual dates when the discrepancy is over 10 days in which trimester?

2nd

T/F - Dates can and should be changed after having been calculated from an early exam?

False

What is Nagele’s Rule use for?

To calculate expected date of delivery (EDD/EDC)

How to calculate EDD?

LMP - 3 months + 7 days

How to calculate LMP? Remember to add a year if LMP is April-December

EDC + 3 months - 7 days

A first trimester examination is performed before how many weeks and days of gestation?

13 weeks and 6 days of gestation

What does a first trimester examination look at?

Uterus, cervix, maternal adnexa as well as gestational sac and embryo; Chorionicity and amnionicity of multiple gestations should also be documented at this time

A pregnancy date is based on what?

Embryonic size and fetal heart motion documented, if it is present

Uterine anomalies and pelvic masses associated with pregnancy are more easily seen in which trimester examination?

1st trimester

What is a first trimester risk assessment examination aka Nuchal Translucency examination, and what does it look at?

It is only done whenever a patient chooses to do 1st trimester screening tests for aneuploidy. This screening tests includes measuring the fetal crown rump length as well as nuchal translucency using standard criteria

What is a standard examination and what does it include?

An anatomy scan that evaluates gestational age by fetal biometry, as well as checking fetal number, placental position, cardiac activity, amniotic fluid volume, and fetal anatomic survey including all of elements specified in guidelines

• could include the examination of maternal cervix and adnexa, but only when clinically appropriate and technically feasible

During what weeks is a standard examination exam done?

18-20 weeks

What is a repeat obstetric US and what does it include?

Done when there is previous standard obstetric examination recorded and is done for a REASON

Includes looking at biometry to evaluate fetal growth; Also reevaluates anatomy that may or may not have been well visualized on standard examination

What is a limited obstetric US and what is it used for?

Done when there is previous standard obstetric examination recorded and checks one little, specific thing

Used to answer a specific clinical question such as the presentation of the fetus, placental location, cervical length, amniotic fluid volume, and verification of fetal heart motion.

What is a specialized obstetric US aka TARGETED SONOGRAM

Anatomy scan on steroids; It is typically done when anomaly is suspected based on maternal history, biochemistry, and results of previous obstetric sonogram; Includes all the components of standard examination PLUS more in-depth view of fetal anatomy

What are the additional views in a specialized obstetric US that is looking at fetal anatomy?

Additional views of fetal heart (could use color), views of extremities, focus on areas of anomalous or expected findings associated with patient history

If you have a pregnant patient lying on their back and they note that they are starting to feel warm and dizzy, what is this a sign of?

Supine Hypotensive Syndrome

What is Supine Hypotensive Syndrome

When the pregnant woman lies flat on her back, the weight of the fetus and uterus can compress the aorta and vena cava against the spine. Consequently, the amount of blood returning to the heart is compromised, pressure falls, and supine hypotensive syndrome occurs

How do you help a patient with supine hypotensive syndrome

Lay the patient on their side as soon as you see something sus going on with them. This will help relieve the pressure, and the patient should start to feel better

What are some factors that may affect risk of producing fetus with congenital anomalies include

1. increased maternal age

2. 1st or 2nd trimester maternal serum biochemistry values

3. 1st trimester increased nuchal translucency,

4. maternal disease (diabetes mellitus and systemic lupus)

5. pregnant uterine cavity either too small or too large for dates

6. previous child born with chromosomal disorder

7. exposure to known teratogenic drug

8. infectious agent known to cause birth defects

Aneuploidie

Anomaly caused by reduced or increased number of fetal chromosomes; Most common is Down Syndrome aka Trisomy 21

T/F - there are potential biological effects that have not been documented

True

What are the major biologic effects of ultrasound

1. Thermal (rise in temperature)

2. Mechanical forces, including cavitation (production and collapse of gas-filled bubbles- CONTRAST AGENT

How can sonographers minimize the thermal effects of ultrasound?

1. Do not staying in one spot for long periods of time

2. Monitor output displays- keep Thermal Index (TI) & Mechanical Index (MI)- as low as possible (<1

T/F - Ultrasound equipment produces less energy today than it did in the past?

False

Nonmaleficience

directs sonographer to not cause harm

Beneficence

encourages sonographers to go beyond minimum standard protocol and to seek additional images and information if achievable and in best interests of patients

“Goods” that obstetric sonography should seek for patients

are:

• preventing early or premature death (not preventing death at all

• costs)

• preventing and managing disease, injury, handicapping

• conditions

• alleviating unnecessary pain and suffering

Autonomy

the patient’s right to self-determination; Respect for persons incorporates both respect for autonomy of individuals and requirement to protect those with diminished autonomy

Veracity

Means truthfulnesd

Integrity

adherence to moral and ethical principles; In terms of honesty, integrity means there is no difference between what you think, what you say, what you do: they all come together in ethical behavior

Justice

the ethical principle that requires fair distribution

of benefits and burdens injustice occurs when benefit to which person entitled is withheld or when burden is unfairly imposed; Justice means simply that sonographers must strive to treat all patients equally

Confidentiality

concerns obligation of caregivers to protect clinical information about patients from unauthorized access

Conceptual age aka Embryologic age

Embryologists basically say that this is when conception is from the first day of pregnancy

Gestational Age aka Menstrual Age

OB/GYN Drs and sonographers count the beginning of gestation as the 1st day of last menstrual period

How many weeks does gestational (menstrual) age add to conceptual age?

2 weeks

How is menstrual age calculated?

calculated from 1st day of last normal menstrual period (LMP), to point at which pregnancy being assessed

What is considered a zygote?

Until 12 days after conception, during implantation process, conceptus called a zygote

What is an embryo

From time of implantation (12 days after conception) until end of 10th week menstrual age, conceptus called an embryo

What is a fetus

After first 10 weeks, embryo called a fetus

Process of the zygotic phase

1. During 28-day menstrual cycle, mature ovum typically released on day 14

2. Ovum (egg) is swept into distal fallopian tube, via fimbria

3. Fertilization usually occurs within the AMPULLA 1 to 2 days after ovulation Fertilized egg/ovum is called zygote

4. Ruptured Graafien becomes a corpus luteum, which begins to secrete mostly progesterone and a small amount of estrogen

A zygote undergoes rapid cellular division to form what?

16-cell morula

After further cell proliferation, a 16-cell morula will enter which stage?

Blastocyst stage

A blastocyst contains trophoblastic cells and “inner cell mass” which forms what?

An embryo

Trophoblastic cells begin to secrete human chorionic gonadotrophin (hCG), which then leads to what?

hCG will be absorbed within the tubes and stimulates maternal pregnancy responses as well as causing uterine endometrium to convert to decidua

What is the decidua?

(a glycogen rich mucosa that nourishes early pregnancy)

A blastocyst usually enter the UTERUS how many days after fertilization?

4-5 days

During the zygote phase, implantation into the uterine decidua is completed within how many days after fertilization

12 days

During the implantation phase of the zygote phase, proteolytic enzymes produced by trophoblasts "eat into” decidual tissue creating what?

creating spaces for trophoblastic cell proliferation

Blood Pools aka Lacunae

Form as the enzymes also cause the maternal capillaries to erode; Also nourish proliferating trophoblastic cells

In the zygote phase, what cells develop into mature placental/maternal circulation complex that will sustain pregnancy?

Lacunae and trophoblastic cells

During the zygote phase, the primitive blood exchange network between mother and conceptus formed which provides what?

Provides nourishment for proliferating trophoblastic cells

When implantation is complete in the zygote phase, trophoblast has formed what?

Primary villi, which initially encircle early gestational sac

What causes implantation bleeding at the end of the implantation process?

zygote buries itself within one wall of uterus; sometimes results in light vaginal bleeding about same time as expected menstrual period

• Implantation bleeding only last a few hours or up to 1-2 days

Within blastocyst, the inner cell mass matures into what?

embryonic disc (future embryo) and primary yolk sac

At approximately how many days menstrual age is the primary yolk sac pinched off by extra embryonic celom, forming secondary yolk?

23 days

The secondary yolk sac is the yolk sac seen sonographically throughout which trimester?

1st trimester

In the zygote phase, around 23 days menstrual age, which cavities also develop and evolve?

Amniotic and chorionic cavities

During which phase do all major internal and external structures begin to develop?

Embryonic phase

During which phase does the embryo’s appearance changes from flat, disk- like configuration to C-shaped structure and start to develop a humanlike appearance?

Embryonic phase at the beginning of the 6th week of gestation

During what weeks of embryonic development can intrauterine pregnancy (IUP) can be visualized?

4th - 5th week

What does an IUP look like in the 4th to 5th week of embryonic development?

Appears as 1- to 2-mm sac with echogenic ring having sonolucent center; Anechoic center represents chorionic cavity

Circumferential echogenic rim seen surrounding gestational sac represents trophoblastic tissue and is associated with what?

Decidual reaction

What is the double decidual sac sign?

This sign demonstrates the interface between the decidua capsularis and the echogenic vascular endometrium; Echogenic ring around gestational sac divided embryologically into several components

• Reported to be reliable sign of early IUP

Decidua Basalis

Portion on myometrial (burrowing side of conceptus/gestational sac)

Decidua Capsularis

Villi covering developing embryo referred to as