CH. 15 The use of ultrasound in the first trimester

gestational age (menstrual age)

duration of pregnancy counted from the first day of the last menstrual period, expressed in weeks and days or fractions of weeks

blastocyst

early gestation consisting of a thin outer layer of cells (trophoblast ), a fluid filled cavity, and an inner cell mass (embryo blast)

Fetal stage begins following ________ period after about ___________

embryonic 11 weeks

The blastocysts inner cell mass differentiates into two layers: thick __________ adjacent to the trophoblast, and thin __________ facing the blastocele

epiblast hypoblast

The placenta will mature from early pregnancy to release these 3 things

estrogen, hCG, progesterone

What 3 things assist the ova to move into and through the fallopian tube

fimbriae, cilia, contractile walls

LMP

first day of last menstrual period

The developing cluster of cells travels through the fallopian tube and reaches the uterus about _______ days after fertilization

four

estrogen

group of hormones, primarily produced in the ovaries, which effect secondary sex characteristics and the menstrual cycle

gametes are ________ cells with _________ chromosomes

haploid 23

progesterone

hormone produced by the corpus luteum in the ovary and the placenta of pregnant women

follicle stimulation hormone (FSH)

hormone produced in the anterior pituitary, which stimulates the maturation of ovarian follicles

The ________ hormone triggers ovulation

luteinizing

spermatozoon (pl. spermatozoa)

male gamete

crown-rump length

measurement of the lowest axis of an embryo determines gestational age

chorion

membrane around the chorionic cavity, made up of trophoblast cells and extra embryonic mesoderm

amnion

membrane enclosing the amniotic cavity and embryo or fetus

The whip like tails of sperm contain______

mitochondria

A cluster or ball of forming cells is a :

morula

gravidity

number of times a woman has been pregnant

fertilization

penetration of an oocyte by a sperm to form a diploid zygote

corpus luteum

progesterone-secreting structure formed by a follicle after releasing its oocyte

The five brain vesicles, which will become the lateral ventricles, third ventricle, and the upper and lower parts of the fourth ventricle, and the connections between them develop from :

prosencephalon and rhombencephalon

The first visualized structure within the gestational sac is the :

secondary yolk sac

zygote

single cell resulting from the fusion of two gametes

parity

summary of a woman pregnancy outcomes. The most common description of parity is expressed in 4 numbers. 1= term deliveries 2= preterm deliveries 3= abortions 4= living children

First blood cells to the embryo are produced by the ___________ and are transferred to and fro through the ___________ veins and arteries

umbilical vessel vitelline

What prevents more than one sperm entering an ovum?

zona pellucida

nourishment from the endometrial glands cross the ________ and enter the _______

zona pellucida morula

The head of the sperm cells contains ____________ which house enzymes allowing for penetration of the outer layer of the ovum

acrosome

At what age have the rudimentary forms of all embryonic organs and structures developed

almost 11 weeks menstrual/gestational age

fertilization generally occurs in the ______ portion of the fallopian tube

ampullary

The two endometrial layers are a thin __________ layer adjacent to the myometrium and a functional layer of __________

basal connective tissue

A blastocyst consists of what 3 things?

blastocele , trophoblast, embryoblast

The double sac sign is developed by two layers of deciduas, ________ and _________

capsularis parietals

decidualization

changes in the endometrium to allow implantation of blastocyst

The first structure seen sonographically within the uterus in early pregnancy is:

chorionic sac

fetal placenta occupies the _________ portion of the endometrium, leaving the basal layer intact

decidua basalis

The portion of the endometrium that surrounds the blastocyst

decidua capsularis

preparatory changes in the endometrium allowing for implantation

decidualization

The yolk sac becomes part of the embryonic gut and contributes to:

digestive, respiratory and urogenital development

Sonography may detect a blastocyst embedded in the decidua as early as __________ after conception:

11 days

The normal resting heart rate of a third trimester fetus is:

110-160 bpm

spontaneous pregnancy loss usually happens in the :

1st trimester

the primitive fetal heart begins beating about __________ days after conception

23

___________ hours after fertilization, rapid cell division occurs and is knows as __________

24-30 cleavage

A normal gestation last approx. :

280 days

The embryonic disc contains ________ germ cell layers from which all future organs and tissue is derived

3

acrosome

Area located in the head of the sperm containing enzymes to aid in penetration of the oocyte

Mean Sac Diameter (MSD)

Average diameter of the gestational sac, used to determine gestational age

The most accurate measurement for dating in early pregnancy is the:

CRL

conceptual age

Duration of pregnancy, counted from fertilization (conception), expressed in hours or days. Also called embryonic age or postovulatory age

Ultrasound in the first trimester is mostly performed to demonstrate :

EDD and GA

gestational sac

First sonographic evidence of an intrauterine pregnancy, the fluid-filled blastocyst

When the nuchal translucency measurement is combined with ___________, the detection rate for trisomy 21 increase to 86%

PAPP-A and free B-hCG

conceptus

Product of fertilization, including all stages from zygote to fetus

pregnancy associated plasma protein A (PAPP-A)

Protein produced by the trophoblasts; abnormal levels of PAPP-A may be associated with an increased risk of chromosomal abnormalities

morula

Solid cluster of undifferentiated cells formed by repeated cleavage of the single cell that resulted from the fusion of two gametes

The implantation window is _______ days after ovulation and lasts approx. _________ days

6-8 4

luteinizing hormone (LH)

A hormone produced by the anterior pituitary gland that triggers ovulation.

yolk sac (umbilical vesicle)

A structure within the cavity of the blastocyst that provides nourishment to the embryo and produces its first blood cells. The secondary umbilical vesicle (yolk sac) is the first structure to be sonographically identified within the gestational sac.

aneuploidy

Abnormal number of chromosomes.

chorionic villi

Budlike outward growths from the trophoblast, some of which give rise to the fetal portion of the placenta

estimated date of delivery (EDD)

Due date, calculated by adding 280 days to the first day of the last menstrual period; also called estimated date of confinement (EDC)

human chorionic gonadotropin (hCG)

Hormone produced by trophoblast cells of the blastocyst, which extends the life of the corpus luteum in the ovary; most pregnancy tests are based on detection of hCG

nuchal translucency (NT)

Subcutaneous fluid in the posterior region of the neck of embryos and fetuses up to 14 weeks' gestational age; abnormally large NTs have been associated with a higher risk of chromosomal and structural abnormalities