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89 Cards in this Set

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what is aneuploidy?
abnormal number of chromosomes
what are the normal number of chromosomes?
46: 23 from the female, 23 from the male.
when should chorionic villi sampling (CVS) be done?
between 11 and 13 weeks
what is conceptual age also known as?
embryologic age, with conception as the first day of pregnancy.
what iss gestational age also known as?
menstrual age, which dates the pregnancy with the first day of the last menstrual perio as the beginning of gestation.
How far ahead is gestational age from conceptual age?
two weeks
From the time of implantation until thhe end of the 10th week the conceptus is called?
an embryo
what is an embryo called after the first 10 weeks?
a fetus
Fertilization usually occurs how many days after ovulation?
1-2 days
what cyst persists throughout the first 12 weeks of gestation releasing progesterone?
corpus luteum cyst
after fertilization, the ovum is known as a?
zygote
what is the progression of the zygote after division?
blastomere, morula, blastocyst
thee blastocyst typically entersth uterus how many days after fertilization?
4-5 days
Implantation into the uterine deidua is complete within how many days after fertilization?
12 days
which cells produce hCG?
trophoblastic cells
what is a decidua?
a glycogen-rich mucossa that nourishes the early pregnancy.
what are lacunae?
blood pools that from as maternal capillaries erode nourish the proliferating trophoblastic cells, forming a primitive blood exchange between conceptus and mother.
when is the primary yolk sac pinched off?
23 menstrual days
what is the secondary yolk sac?
a membranous sac attached to an embryo, providing early nourishment.
when is the initial heart flicker seen sonographically?
51/2 to 6 weeks
during embryogenesis, the CRL, develops rapidly and by the end of the 10th week measures?
35 mm
what time constitutes the beginning of the fetal period?
11/12th weeks. end of the 10th week.
at 10 menstrual weeks, what is the mean sac diameter of the gestational sac and wht should you see?
45mm and an embryo transabdominally or transvaginally
what should be suspected when the patient's hCG levels are over 1000 and no gestational sac is seen in thhe fundus of the uterus?
ectopic pregnancy
ectopic pregnancies normally demonstrate what kind of hCG level?
lower, perhaps owing to limited absorption outside the uterus.
a normal inter uterine pregnancy demonstrates a doubling of what hormone every 48 hours in the first 7 weeks?
hCG
when do hCG levels plateau and subsequently decline?
9 to 10 weeks
how does the hCG level behave for pregnancies carrying trisomy 21?
hCG levels plateau later and fall slower.
what is PAPP-A
aka pappalysin-1, an insulin-like growth factor produced by trophoblastic cells during pregnancy. It is involved in bone and tissue growth.
at what week should an IUP be visualized?
week 5
what is the sonographic appearance of a gestational sac at 5weeks?
1-2mm sac with an echogenic ring having a sonolucent center.
what is a decidual basalis?
the part of the conceptus that burrows into the endometrium.
what is the decidua capsularis?
th villi covering the developing embryo
what is the double decidual sac sign?
the interface between the decidua capsularis and the echogenic, highly vascularized decidua on the opposite wall of the endometrial cavity, this is considered a reliable sign of an early IUP.
what are the features of a normal gestational sac?
round or oval shape
fundal or middle uterus position
double decidual sign
smooth contour
echogenic wall
yolk sac( when MSD is > 12 mm)
embryo (when MSD is > 18mm)
a yolk sac is normally seen when the MSD is what size and at what gestational week?
MSD > 12mm and at week 5-51/2 weeks.
an embryo should be visualized when the MSD is what size and at what gestational week?
MSD > 18mm and at week 6
what are the three essential functions of the secondary yolk sac?
1. provide nutrients
2. hematopoiesis
3. development of the embryonic endoderm, which forms the primitive gut.
at what week does the yolk sac detatch from the yolk stalk?
8th week
transabdominally, the yolk sac should be visible at what MSD? at what MSD must it be visible to be viable?
MSD > 10-15mm
must be seen @ MSD>20mm
a yolk sac should not exceed a diameter of what size?
6mm
when is the secondary yolk sac reabsorbed and no longer seen sonographically?
12 weeks
what is chorion laeve?
it is where the villi degenerate and the chorion becomes smooth. at these locations no exchange between the maternal and fetal bolo circulation takes place.
what is a cytotrophoblast?
the inner layer of the trophoblaast, interior to the syncytiotrophoblast in an embryo. It is considered to be the trophobastic stem cell.
what is a syncytiotrophoblast?
the outer layer of the trophoblasts and actively invades the uterine wall.
at what week does the bilaminar embryonic disk undergo gastrulation and is converted to a trilaminar embryonic disk?
5th week
the CRL measures what size when fetal cardiac activity is identified??
3mm
what is the chorionic cavity?
the initial dumping ground for embryonic waste.
what is chorioamniotic fusion?
when the chorion and amniotic cavities form at week 14-15. this must be completed by week 16.
what is an allantois?
an extra-embryonic membrane emerging as a sac from the hind gut's ventral wall
what does the spine develop from?
the ectoderm, and initially evolves from the primitive neural tube, which close by the 6th week.
the brain by appear to have a single fluid filled vesicle at what week?
7th
at 8 weeks how many primary vesicles are seen in the fetal brain?
3: the prosencephalon, the mesencephalon, and the rhombencephalon
what are the two segments of the rhombencephalon?
metencephalon or the cephalic portion and myelencephalon or caudal component
what forms the cystic rhomboid fossa?
the division of the rhombencephalon and the corresponding flexure.
at what week can the cystic rhomboid fossa be seen sonographically?
8-10th week
by the 9th week what is seen in the brain?
the midline flax and the echogenic choroid plexus tissue in the lateral ventricles
what surrounds the choroid plexus at the 9th week gestation?
cerebrospinal fluid.
from 4-6 weeks gestation what should be seen sonographically in order?
gestational sac (4-5)
yolk sac (51/2)
Fetal heartbeat (51/2-6)
Fetal pole (6)
from 7-8 weeks gestation what should be seen sonographically in order?
single ventricle (7)
spine (71/2)
Lower Limbs (71/2)
Upper limbs (8)
what should be seen sonographically between 9-10 weeks?
falx (9)
body movement (9)
limb movement (9.2)
midgut herniation (9.5)
choroid plexus (9.5)
hindbrain (9.5)
what should be seen sonographically between 12-12.5 weeks?
fingers (12)
jaw (12)
toes (12.5)
what forms the primitive 4th ventricle?
cerebellum, medulla, medulla oblongata enclose the rhomboid fossa.
at what week are limb buds recognizable?
6th week
when does calcification of the long bones begin?
10th week
when does ossification of the clavicle begin?
8th week followed by the mandible, palate, vertebral column and the neural arches.
what ossifies at the beginning of the 9th week?
frontal cranial bones.
what forms the primitive gut?
the incorporation of the dorsal yolk sac into the embryo
what forms the midgut?
the midgut is derivived from the primitive gut and develops the majority of the small bowel, cecum, ascending colon and proximal transverse colon.
what causes the herniation of the gut?
as amniotic expansion occurs, the midgut elongates faster than the embryo is growing, causing the mid gut to herniate into the base of the umbilical cord. it regresses by the 11th week.
what is the first organ functioning within the embryo?
heart
when does the embryonic heart begin beating?
day 35 or 5-51/2 weeks. the heart reaches its adult configuration by the 8th week of gestation.
at what CRL size should the heart beat be seen?
4mm
what is the most reliable and accurate pregnancy dating method?
crown rump length (CRL) within 4-5 days
what is the formula for measuring mean sac diameter?
length(mm) + width(mm) + height(mm)/3 = MSD
what is the formula for measuring menstrual age (days)?
MSD (mm) + 30= menstrual days
what is the formula for menstraul age (weeks)?
Menstrual age (days)/7=Menstraul age in weeks
when is CRL measuring no longer practical and why?
at 12 weeks the fetus begins to curl into the fetal position akin measurement of length more difficult.
what is the risk for Downs syndrome for a woman 35 or over?
1:200
what is nuchal translucency? (NT)
the small pocket of fluid along its back that is normally found in the first trimester.
what is the measurement that the nuchal translucency should not exceed?
3mm
what facial feature is typically missing in the first trimester that is associated with trisomy 21?
the nasal bone
what are the three risk assessment sonography techniques?
nuchal translucency, nasal bone, and tricuspid regurgitation.
what is included in the triple screen test?
hCG measurement, estriol and alpha-fetoprotein.
what is included in the quad screen?
hCG measurement, estriol, AFP & inhibin.
what is the decidua parietals
aka decidua vera, is the decidua of the endometrium lining the uterus, except for those areas beneath and aboveth implanted and developing ovuum.
what is dichorionic and diamniotic?
twins that appearr as two separate gestational sacs with individual trophoblastic tissue, which allows the appearance of a thick dividing membrane. each sac has an individual yolk sac, amniotic membrane and embryo.
what are monochorionic-diamniotic twins?
twins that appear t be contained within a sinle gestational/chorionic sac, two amnions, two yolk sacs, to embryos identified.
what are mono amniotic-monochorionic twins?
one gestational sac, one yolk sac, one amniotic membrane and two embryos within a single amniotic cavity. Poor prognosis (50%) *can cause twin to twin transfusion*