Chapter 31

Monozygotic twins result from:

A single zygote that splits

The inner membrane surrounding the fetus is referred to as the:

Amnion

The term that indicates the presence of two separate placentas is:

Dichorionic

Ovulation induction drugs not only increase the likelihood of multiple gestations, but also increase the likelihood of:

Heterotopic pregnancies

The abnormal twin in acardiac twinning is also referred to as the:

Parasitic twin

Factors that increase the likelihood of having multiple gestations include all of the following except:

Poor nutritional state

The twin that will appear larger in TTTS is the:

Recipient

Acardiac twinning may also be referred to as

TRAP syndrome or acardiac parabiotic twinning.

The shunting of blood from one twin to the other is termed:

TTTS

ovum?

an unfertilized egg

monozygotic?

coming from one fertilized ovum or zygote

placentation?

formation or structure of a placenta, structural organization, and mode of attachment of fetal to maternal tissues during placental formation

monoamniotic?

having one amniotic sac

craniopagus?

twins joined at the cranium

fraternal twins?

twins that result from the fertilization of two separate ova and have dissimilar characteristics

anastomoses?

vascular connections

SONOGRAPHIC FINDINGS OF TWIN-TWIN SYNDROME

1. Monochorionic twinning 2. Discordant fetal growth 3. Oligohydramnios around donor twin 4. Polyhydramnios around recipient twin 5. Recipient may be hydropic

SONOGRAPHIC FINDINGS OF ACARDIAC TWIN

1. Normal pump twin 2. Acardiac twin-absent upper body, absent heart, and hydrops

What factors what been shown to increase the probability of multiple gestations?

A maternal history of multiple gestations, ART, ovulation induction drugs, advanced maternal age, and maternal obesity

Acardiac twinning results from:

Abnormal links between the placental vessels

TRAP syndrome may also be referred to as:

Acardiac twinning

Which term relates the number of amniotic sacs?

Amnionicity

The outer membrane of the gestation is referred to as the:

Chorion

Which term relates the number of placentas?

Chorionicity

Twins whose bodies are connected at some point are said to be:

Conjoined

Dizygotic twinning Description, Result, amd Appearance

Description: Two separate fertilized ova Result: Dichorionic diamniotic Appearance: Fraternal

Monozygotic twinning Description, Result, and Appearance between 4 and 8 days, prior to 4 days, and zygote splitting late

Description: one zygote splits between 4 and 8 days Result:monochorionic diamniotic Appearance: identical Description: one zygote splits prior to day 4 Result: dichorionic diamniotic Appearance: identical Description:one zygote splits late Result: monochorionic monoamniotic Appearance: identical

The term that indicates the presence of two separate amniotic sacs is:

Diamniotic

Twins having two placentas and two amniotic sacs are referred to as:

Dichorionic diamniotic

The sonographic examination of twins reveals a triangular extension of the placenta at the base of the membrane. This finding is indicative of:

Dichorionic diamniotic twins

Which of the following can occur as a result of dizygotic twinning?

Dichorionic diamniotic twins

Which of the following can occur as a result of monozygotic twinning?

Dichorionic diamniotic twins, Monochorionic monoamniotic twins, Monochorionic diamniotic twins

Typically, the first sonographic manifestation of TTTS is:

Discordant fetal growth

Asymmetry in fetal weight between twins is indicative of:

Discordant growth

Twins that result from the fertilization of two separate ova are called:

Dizygotic

Fraternal twins result from:

Dizygotic twinning

the most common form of twinning is?

Dizygotic twinning, or fraternal twins

What is a treatment that separates abnormal placental vascular connections between twins that are suffering from TTTS?

Endoscopic-guided laser photocoagulation

conjoined twins Omphalopagus?

Joined at the abdomen

conjoined twins Ischiopagus?

Joined at the pelvis

conjoined twins Pyopagus?

Joined at the sacral region or back-to-back

Which of the following would increase the likelihood of multiple gestations?

Maternal age of >40 years, Maternal history of twins, ART

The most common form of monozygotic twins is:

Monochorionic diamniotic

What twins are the most common form of monozygotic twins?

Monochorionic diamniotic twins

Twins having one placenta and one amniotic sac are referred to as:

Monochorionic monoamniotic

Twins that have the threat of being conjoined are:

Monochorionic monoamniotic

Which form of monozygotic twinning is least common?

Monochorionic monoamniotic

Identical twins result from:

Monozygotic twinning

Monozygotic twins arise from ____ zygote, whereas dizygotic twins form from _____ zygotes.

Monozygotic twins arise from a single zygote, whereas dizygotic twins form from two separate zygotes.

Conjoined twins that are attached at the abdomen are referred to as:

Omphalopagus

What condition is pregnancy-induced maternal high blood pressure and excess protein in the urine after 20 weeks' gestation?

Preeclampsia

All of the following complications are associated with multiple gestations

Preterm delivery, Maternal anemia, Maternal preeclampsia

Which of the following would a newborn most likely suffer from if he or she were born prior to 32 weeks as a result of multiple gestation complications?

Pulmonary hypoplasia

What is the term for conjoined twins attached at the sacral region?

Pyopagus

What is it called when a twin fetus, suffering from TTTS, experiences severe oligohydramnios and becomes closely adhered to the uterine wall?

Stuck twin

Which of the following is a sonographic sign of dichorionic diamniotic gestation?

T sign

of one yolk sac and two The presence fetuses is indicative of a ____ gestation, of two yolk sacs is whereas the presence indicative of a _____ gestation.

The presence of one yolk sac and two fetuses is indicative of a monoamniotic gestation, of two yolk sacs is whereas the presence indicative of a diamniotic gestation.

The demise of a twin can lead to the development of neurologic complications in the living twin as a result of:

Twin embolization syndrome

The demise of a twin during the second or third trimester can lead to:

Twin embolization syndrome

There is no way Twins can have ___ placentas and ___ amniotic sac

Two, one

With TTTS, the twin that shunts blood to the other is called ____ and is often smaller than the twin receiving extra blood called?

With TTTS, the twin that shunts blood to the other is called the "donor" twin and is often smaller than the twin receiving extra blood, the "recipient" twin.

hydrops (fetal)?

abnormal accumulation of fluid in at least two fetal body cavities

acardiac twin?

abnormally developed twin that has an absent upper body and no heart

With a monochorionic diamniotic pregnancy, the membrane will be thin and seen, separating at the junction point with the placenta, a sonographic sign referred to as?

as the "T sign."

discordant fetal growth?

asymmetric fetal weight between twins

zygote?

cell formed by the union of two gametes; the first stage of a fertilized ovum

heterotopic pregnancy?

coexisting ectopic and intrauterine pregnancies

anemia?

condition of having a deficient number of red blood cells

Craniopagus?

conjoined twins Joined at the head

Thoracopagus?

conjoined twins Joined at the thorax (chest)

thoracopagus?

conjoined twins attached at the chest

stillborn?

dead at birth

vanishing twin?

death and reabsorption of a twin

fetus papyraceus?

death of one fetus in a twin preg- nancy that is maintained throughout the pregnancy; actually means paperlike fetus

monochorionic?

having one chorion

monochorionic diamniotic?

having one placenta and two amniotic sacs

amnion?

inner sac that contains the embryo and amniotic fluid; echogenic curvilinear structure that may be seen during the first trimester within the gestational sac

advanced maternal age?

maternal age of 35 years or older

conjoined twins?

monoamniotic, monochorionic twins that are attached at the head, thorax, abdomen, or lower body

Conjoined twins can result from

monochorionic monoamniotic twinning.

Twin embolization syndrome can result from the death of a

monochorionic twin.

chorion?

outer membrane of a gestation that surrounds the amnion and developing embryo

mortality?

rate of actual deaths

amnionicity?

relates to the number of amnions in a multiple gestation

chorionicity?

relates to the number of chorions and the type of placentation in a multiple gestation

zygosity?

relates to the number of zygotes (fertilized ova)

morbidity?

relative frequency of occurrence of a disease

amniotic sac?

sac-fluid-filled space, created by the amnion, surrounding the developing embryo or fetus

hypoxia?

shortage of oxygen or decreased oxygen in the blood

twin-twin transfusion syndrome?

shunting of venous or arterial blood from one twin to another through placental circulation

singleton pregnancy?

single developing fetus

assisted reproductive therapy?

techniques used to treat infertility

porencephaly?

the development of a cystic cavity within the cerebrum; may be the result of an intraparenchymal hemorrhage

cleavage?

the division of a cell

lambda sign?

triangular extension of the placenta at the base of the membrane is indicative of a dichorionic diamniotic pregnancy; also referred to as the delta sign or twin peak sign

identical twins?

twins that result from the split of a single zygote and share the same genetic structure

dizygotic?

two ova are fertilized by two sperms

therapeutic amniocentesis?

type of amniocentesis used to remove a large amount of amniotic fluid around a fetus suffering from polyhydramnios

pulmonary hypoplasia?

underdevelopment of the lungs

twin embolization syndrome?

when vascular products travel from a demised twin to the surviving twin by means of the common vascular channels within the shared placenta