Ch. 49 Normal First Trimester Flashcards
_______ refers to the timing of pregnancy dating from the first day of the last menstrual period
menstrual age
______ refers to the timing of pregnancy dating from the date of conception
embryologic age
The _____ yolk sac is the one seen on sonography
secondary
HCG levels generally peak at about the _____ week of pregnancy
8th
When a spontaneous abortion occurs, the HCG levels begin to fall _____ the conceptus is expelled from the uterus
before
If a patient presents with an HCG level consistent with at least a 5 week pregnancy and no gestational sac is seen in the uterus, a ______ must be considered
ectopic pregnancy
Which of the following patients is least likely to require a first trimester OB sonogram
patient with first time pregnancy
Which of the following best describes the sonographic appearance of a 4 week pregnancy
1-2mm sac with echogenic ring around the edge
Which of the following best describes the sonographic appearance of a 5 week pregnancy
8mm sac with thick echogenic ring and yolk sac
The gestational sac should be located near the _______ of the uterus
fundus
In early pregnancy, the gestational sac grows at a rate of about ______ per day
1mm
The yolk sac is found _____ the amniotic cavity
outside
The yolk sac usually disappears by ______ weeks
12
The fetal heart beat is seen at ______ weeks at the earliest
5.5
Transvaginally, the amniotic membrane is routinely seen after ______ weeks
5.5
During the 6th week (menstrual age) of pregnancy, the embryo folds, creating a constriction between the embryo and the yolk sac, called the
yolk stalk
The limb buds and tail are seen sonographically (TV) at about the ______ week of pregnancy
7th
Echogenic lines representing the spine are seen at _____ weeks
8
The yolk stalk, allantois and connecting stalk are brought together by the _____ creating the umbilical cord
amniotic membrane
The upper extremities develop ______ the lower extremities
before
Fingers and toes are sonographically recognizable at ______ with transvaginal sonography
11 weeks
Part of the embryo’s gut herniates into the base of the umbilical cord until about _____ weeks, when it returns to the abdomen
12
Sonographically, the bowel can be seen to be herniated into the umbilical cord from _____ to _____ weeks
8-10
A cystic structure in the posterior embryonic cranium from 8-11 weeks is
rhomboid fossa
The cerebral hemispheres and midline falx can be seen at about _____ weeks
9
The _____ is the first organ to function within the embryo
heart
When the embryonic heartbeat is first seen sonographically, it beats at a rate of about ____ bpm
90
In the second and third trimesters, the normal fetal heart rate is _____ bpm
120-160
High resolution, transvaginal sonography can demonstrate the development of the embryonic heart from a tube to its final 4 chamber configuration
false
Sonography is the most accurate method for determining gestational age in the _____ trimester
1st
CRL is the method of choice for measuring the fetus through the _____ week
12
CRL is accurate to +/- days
5
As a rule, the mean gestational sac size is an accurate way of determining gestational age through the _____ week
8th
When measuring the gestational sac size, the measurement should include the echogenic ring of the decidual reaction
false
Abnormally shaped or unusually large yolk sacs are associated with increased risk of spontaneous abortion
true
In ______ of cases, visualization of a normal yolk sac predicts a viable pregnancy
90%
The upper limit of normal size for the yolk sac is
5.6mm
Multiple pregnancies are always considered high risk pregnancies
true
Twins that occur as a result of two ova being fertilized are called _____ twins
fraternal
Twins that occur from a single fertilized ovum are called ____ twins
identical
A twin pregnancy with two chorions, two amnions and two placentas is called
dichorionic, diamniotic
A twin pregnancy with one chorion and two amnions is called
monochorionic, diamniotic
A twin pregnancy with one chorion and one amnion is called
monochorionic, monoamniotic
Monoamniotic twins have a ____% mortality rate
50
Transvaginal scanning enables the visualization of fetal anatomy about _______ earlier than transabdominal scanning
1 week
Gestational age=
fertilization age + 2 weeks
Embryologists use ______ age
fertilization
Sonographers use _______ age
gestational
When does the primary yolk sac pinch off forming the secondary yolk sac
23 days menstrual age
With EV, the secondary yolk sac is visible at _______ LMP and is almost always seen when the mean sac diameter (MSD) reaches ______
5.5 weeks, 8mm
Yolk sac is attached to the embryo by the
vitelline duct
Amniotic cavity develops from the ________ of the embryo, also known as the _____
dorsal side, epiblast
Which hCG is simply positive or negative
qualitative
Which test measure amount of hCG in maternal blood
quantitative
Normal hCG but normal uterus
ectopic pregnancy
Intrauterine pregnancy can be visualized at about _______ gestational age
5 weeks
Side of the endometrium where the conceptus is burrowing in. trophoblast is invading the endometrial tissue
decidua basalis
Endometrium that covers over the conceptus once it has burrowed into the endometrium
decidua capsularis
two layered echogenic ring around the gestational sac that is formed by the decidua capsularis
double sac sign
Which of the following best describes the sonographic appearance of a 6 week pregnancy
15mm sac with fetal pole and yolk sac
