Key Terms: Test2

Question 1

Indications for 1st trimester exams

Answer 1

confirm presence of an intrauterine pregnancy, evaluate a suspected ectopic pregnancy, define the cause of vaginal bleeding, evaluate pelvic pain, estimate gestational(menstrual) age, diagnose or evaluate multiple pregnancy, confirm cardiac activity, an adjunct to chorionic villous sampling, embryo transfer, assess for certain fetal anomalies, evaluate maternal pelvic or adnexal mass, screen for fetal aneuploidy, evaluate suspected hydatidiform mole

Question 2

indications for 2nd and 3rd trimesters

Answer 2

evaluation of gestational age, fetal growth, vaginal bleeding, cervical insufficiency, abdominal and pelvic pain, determination of fetal presentation, eval of suspected multiple gestation, adjunct to amniocentesis, significant discrepancy between uterine size and clinical dates, eval of pelvic mass, exam of suspected hydatidiform mole, adjunct to cervical cerclage placement, eval suspected ectopic preg, fetal death, uterine abnormality, fetal well-being

Question 3

types of OB exams

Answer 3

1st trimester exam

1st trimester nuchal translucency

standard obstetric exam

repeat obstetric exam

limited obstetric exam

specialty obstetric exam

Question 4

patient history

Answer 4

information obtained before exam

Question 5

nageles rule

Answer 5

EDD = LNMP - 3mo + 7days

LMP = EDD - 3mo + 7 days

(EDD-estimated date of delivery)

(LNMP-last normal menstrual period)

Question 6

maternal risk factors

Answer 6

latex allergies

supine hypotension

taking any meds

pain, bleeding, decreased fetal movement

congenital anomalies-maternal age, 1st or 2nd maternal serum biochem values, maternal disease, pregnant uterine cavity too big or too small, previous child born with chromosomal disorder, exposure to known teratogenic drug or infectious agent known to cause birth defects

Question 7

fetal anatomy

Answer 7

head, face, and neck: cerebellum, choroid plexus, cisterna magna, lateral cerebral ventricles, midline falx, cavum septi pellucidi, upper lip

chest: four chamber view of the fetal heart
abdomen: stomach(presence, size, and situs), kidneys, bladder, umbilical cord, number of vessels
spine: cervical thoracic, lumbar, and sacral spine
extremities: presence or absence of arms and/or legs
gender: medically indicated in low-risk pregnancy, only for eval of multiple gestations

Question 8

morality and ethics in OB sonography

Answer 8

morality-the protection of cherished values that relate to how persons interact and live in peace (concerns right and wrong conduct-what we ought not to do, the good and bad character-the kinds of persons we should become and the virtues we should cultivate in doing so)

ethics-the study of what is good and bad of moral duty and obligation; systematic reflection on and analysis of morality

Question 9

nonmaleficence

Answer 9

refraining from harming oneself or others

appliation of the principle of nonmaleficence requires the sonographer to obtain appropriate education and clinical skills to ensure competence in performing each required examination

Question 10

conceptual age

Answer 10

(embryonic age)

age of embryo stated as time from date of conception

embryologists state time in conceptual age, with conception as the first day of pregnancy

Question 11

menstrual age

Answer 11

(gestational age)

length of pregnancy defined in the U.S. as the number of weeks from first day of last menstrual period (LNMP)

clinicians and sonographers use gestational age to date the pregnancy

Question 12

zygote stage from conception through implantation

Answer 12

mature ovum-released at day 14

fertilization-occurs 1-2 days after ovulation

zygote-fertilized conceptus, 12 days after conception

morula-16 cell (zygote forms 16 cell morula)

blastocyst-further cell proliferation brings the morula to this stage, enters uterus 4-5 days after ovulation

implantation-completed within 12 days post fertilization

time of iimplantation until end of 10th wk-embryo

after 10wks-fetus

Question 13

maternal serum biochemistry

Answer 13

at 9-10wks, hCG levels plateau and decline

increased levels-screening marker for Down’s during 1st and 2nd trimesters

component of risk assessment(1st trimester), triple screen and quad test (2nd trimester)

PAPP-A-low levels may be a marker for Down’s during 1st trimester

Question 14

decidua basalis

Answer 14

uterine decidual surface on the maternal side of the placenta

the part of the decidua that unites with the chorion to form the placenta

Question 15

decidua capsularis

Answer 15

uterine decidua on the surface of the implantation site

the part of the decidua that surrounds the chorionic sac

Question 16

double decidual sac sign

Answer 16

interface between the decidua capsularis and the echogenic, highly vascular endometrium

highly vascular surface on th opposite side of the endometrial cavity

Question 17

features of a normal gestational sac

Answer 17

round or oval shape

fundal position in uterus

eccentrically placed position in middle portion of uterus

smooth contours

decidual wall thickness > 3mm

embryo should be seen with MSD> 18mm

gestational sac grows at rate of 1mm/day

Question 18

yolk sac

Answer 18

earliest intragestational sac anatomy seen

normally seen from 5wks of gestation

functions of secondary, or sonographic, yolk sac in embryonic development-provide nutrients to developing embryo, hematopoiesis, development of embryonic endoderm, which forms primitive gut

typically reabsorbs by 12wks

Question 19

embryo

Answer 19

beginning of 5th wk, bilaminar embryonic disk undergoes gastrulation and converts into trilaminar (three germ layer) embryonic disk

early embryo not often identified until heart motion detected at approx 5 1/2wks

embryo seen between yolk sac and immediate gestational sac

embryonic folding continues-creating yolk stalk, which later forms into umbilical cord

beginning of 6th wk, trilaminar embryonic disk folds into C-shaped embryo

Question 20

rhomboencephalon

Answer 20

1 of 3 primary vesicles are seen within the fetal brain(prosencephalon, mesencephalon, rhomboencephalon)

rhomboencephalon- divides into two segments: cephalic portion-mesencephalon, caudal component- myelencephalon

once it divides with its corresponding flexure, the cystic rhomboid fossa forms

Question 21

hCG levels in 1st trimester

Answer 21

direct relationship exists in early pregnancy between sonographic findings and quantitative serum hCG levels

gestational sac size and hCG levels increase proportionately until 10wks

ectopic pregnancy hCG levels are lower than normal

hCG levels fall before spontaneous expulsion of nonviable gestations

Question 22

limb development

Answer 22

limb buds embryologically recognizable during 6th wk of gestation, as is embryonic tail, which is not unlike that of a tadpole

upper limbs form first, then lower limbs

hands and feet develop later in 1st trimester (completely formed by end of 10th wk)

sonographically, limb buds may be seen from 7th wk on

limbs not routinely detected til calcification of long bones begins at 10wks

fingers and toes have been identified using transvaginal sonography at 10wks

Question 23

skeletal ossification

Answer 23

calcification of clavicle begins at approx 8wks

followed by ossification of mandible, palate, vertebral column, neural arches

frontal cranial bones begin to calcify at 9wks, followed by long bones

palate fusion occurs late in 1st trimester

sonographically, embryonic face cannot typically be seen with diagnostic detail

by 9th wk, maxilla and mandible noted as brightly echogenic structures

further bony palate development may be visualized from 10th wk

Question 24

physiologic herniation of bowel

Answer 24

anterior abdominal wall developed by 6wks gestation from fusion of four ectomesodermal body folds

primitive gut formed simultaneously as dorsal yolk sac incorporated into the embryo

midgut, derived from primitive gut, develops

forms majority of small bowel, cecum, ascending colon, proximal transverse colon

midgut herniates into base of umbilical cord until approx 11th wk when it begins to descend back into abdomen

Question 25

gestational sac size

Answer 25

mean gestational sac size correlates closely with menstrual age during early pregnancy, size remains accurate through 1st 8wks

gestational sac size (mean sac diameter) determined by average sum of length, width, and height of gestational sac

MSD = length(mm) + width(mm) + height(mm)/3

MSD(mm) + 30 = menstrual age (days)

menstrual age (days)/7 = menstrual age (weeks)

Question 26

crown rump length (CRL)

Answer 26

determination of 1st trimester gestational dates by direct measurement of embryo using CRL 1st reported in 1975

produced gestational dating standard deviations of +/- 5-7 days, by far the most accurate dating parameters within obstetric biometry

CRL measurements can be obtained as early as 5 1/2wks using transvaginal sonography

visualization of embryonic heart motion is marker signifying beginning of CRL measurements

CRLs considered most accurate method for dating through 12wks gestation

after 12 wks, fetus begins to curl, making measurement of length more difficult