Chapter 47 The Normal First Trimester Flashcards
12 days after conception, during the implantation process
zygote
From the time of implantation until the end of the 10th week menstrual age
embryo
After the first 10 weeks
fetus
conception as first day of pregnancy
conceptual age or embryologic age
First day of last menstrual period as the beginning of gestation
gestational or menstrual age
Fertilization occurs withing ______ days after ovulation.
1 to 2 days
At approximately _____ days menstrual age, the primary yolk sac is pinched off by the extraembryonic coelom, forming the secondary yolk sac. The amniotic chorionic cavities also develop and evolve during this period of gestation.
23
The embryonic phase occurs from week ______. During this phase all major internal and external structures begin to develop.
4 through week 10
The cardiovascular system undergoes rapid development, with the initial heartbeat occurring at between _______ weeks or ____ days.
5.5 to 6 weeks or 35 days
The crown-rump length measures _____ by the end of the 10th week.
35mm
The gestational sac is approximately ____ mean sac diameter at ten weeks.
45mm
hCG should double every _____ days
2-3 days
Gestational sac and hCG peaks at _____ weeks
8-10
1st trimester hCG is secreated by the _________ cells of the ________.
trophoblast, blastocyst
Transvaginal transducers are _____ MHz
5 to 8
Intrauterine pregnancy usually measures ___ at _____ weeks.
1cm, 5.5 weeks
normal sac grows ____ per day in first trimester
1mm
Gestational sac has a decidual wall thickness greater than ____.
3mm
Endovaginal at _____ weeks gestation and transabdominal at ___ weeks.
4.5, 5
failure to visualize the yolk sac, with a minimum of _____ MSD, using transvaginal sonography, should provoke suspicions of abnormal pregnancy.
12mm
The normal diameter of the yolk sac should not exceed ____.
6mm
The early embryo is often not identified until hear motion is detected at approximately ______, when the CRL is _____.
5.5, 2-3mm
The anechoic center of 5-6 week gestational sac represents the _______.
chorionic cavity
by week ____, three primary vesicles are seen within the feta brain: the prosencephalon, mesencephalon, and rhombencephalon.
8
The mid-gut herniation occurs and is normally seen between _____ weeks. Normally returns into the abdomen by ___ weeks.
8-12, 12
The embryonic heart starts beating at approximately ___ days (______ weeks). By the end of the ____ week of gestation, the has has reached its adult configuration.
35days, 5 to 5.5 weeks, 8th
Rates of ____ to ____ beats per minute at 6 weeks increases to rates of ____ to ____ beats at 9 weeks, with rates of approxmatly ____ beats the remainder of the the late first and second trimester.
90-115, 140-160, 140
As a rule, the gestational sac size remains accurate through the first ____ weeks of gestation.
8
Crown-Rump length is most accurate dating parameters for gestation dating. Deviations of plus or minus _____ days.
5 to 7
CRL measurements can be obtained as early as ____ weeks using transvaginal scanning. visualization of heart motion is a marker signifying the beginning of CRL measurements.
5.5
CRLs are considered the most accurate method for dating through ______ gestation.
12 week
