ART&Twinning

Question 1

___ _ ___ (____) describe clinical and laboratory techniques used to achieve pregnancy in infertile couples for whom direct corrections of underlying causes are not feasible.

Answer 1

Assisted reproductive technologies (ART)

Question 2

ART procedures are those that at some point require ____ & ____ of an ____

Answer 2

extraction and isolation of an oocyte

Question 3

What are the 6 ARTs you should know? What are the main two (bolded)

Answer 3

- in vitro fertilization (IVF),

- intracytoplasmic sperm injection (ICSI),

• egg donation,
• gestational carrier surrogacy,
• gamete intrafallopian transfer (GIFT),
• zygote intrafallopian transfer (ZIFT).

Question 4

During IVF, ____ ____ from stimulated ovaries are retrieved _____ with ____ ____. Prior to the procedure, _____ is induced with specific medication, using specific protocols (_____ ____ ____ (COH)), and ____ maturation is monitored over several days sonographically. Near ovulation, a transvaginal approach is used to ____ ___ from the ____.

These oocytes are fertilized _ ___ and fertilized eggs develop to the ____ ___. Blastocysts are then drawn up into a ____ and transferred_____ into the ____ ____using ____ ____.

Answer 4

Mature oocytes

transvaginally

Sonographic guidance

Superovulation

controlled ovarian hyperstimulation (COH

follicle

harvest eggs

ovaries

in vitro

blastocyst stage

syringe

transcervically

endometrial cavity

sonograpgic guidance

Question 5

Many ___ are genetically or functionally abnormal, and thus in IVF, exposure of several ova to sperm results in an increased chance of a healthy embryo. Optimally, ____ to __ ova are harvested, and from these, ideally ___ healthy embryo is transferred.

Unfortunately, methods to determine embryo’s health are imperfect. Therefore, to maximize the probability of pregnancy, more than one embryo is typically transferred, thus resulting in increased risk of ____ ____.

Answer 5

ova

10 to 20

1

multifetal gestation

Question 6

_____ ____ ____ (___) is a variation on IVF and is most applicable to male factor infertility. During the micromanipulation technique of ICSI,_____ ____surrounding the ova are _____ digested, and a single sperm is directly injected through the_____ _____ and ____ ___ ____. Pregnancy rates with ICSI are comparable with those achieved with IVF for other causes of infertility.

Answer 6

Intracytoplasmic Sperm Injection (ICSI)

cumulus cells

enzymatically

zona pellucida

oocyte cell membrane

Question 7

PREIMPLANTATION GENETIC DIAGNOSIS (PGD) is a procedure that is used to detect ____ ____ ____, _____ ______, or to identify the ___of the embryo in cases in which a male embryo would be at risk of a serious X-linked disorder. The sex of the embryo can be determined by ___ and ___ techniques targeting the __ chromosome.

Answer 7

single gene defects

chormosomal abnormalities

sex

PCR

fluorescence in situ hybridization (FISH)

y chromosome

Question 8

PGD may be performed at three different embryonic developmental stages:

1. The first involves biopsy of the polar bodies just prior to _____ (first polar body) and after ____ (second polar body). This method is thought to be the ____ for the embryo. The limitations of this approach are that no information on the ____ ____ contribution can be deduced.
2. The second methos is ___ _ ____ cell biopsy & involves _____ removal at the __-__ cell embryonic stage.

One or two blastomeres are removed from the embryo known to be at risk and analyzed before fertilization.

3. The third method is _____ or ___ ___ that occurs on day 5-6 when the embryo has around ___ cells. 5-8 of these cells will be removed from the ____ as it “hatches” through the zona pellucida.

Answer 8

prior to conception

fertilization

safest

paternal

Day 3 cleavage

blastomere

5-8

trophectoderm or blastocyst biopsy

trophectoderm

Question 9

As of now, most PGD is done at which stage?

Why mught this change?

Answer 9

Day 3 cleavage-cell stage

The tropoectoderm (blastocyst) biopsy was seems to be safe for the embryo

Question 10

Assisted reproductive technologies in most cases lead to successful delivery of healthy singleton pregnancies. However, there are complications of pregnancy that may develop more frequently in those conceived using ART. Of these, risk of ____ ___ is the most common. However, risks of ____ or ___ ___ ___, that is independent of maternal age and fetal number, are also increased. In addition, increased rates of major congenital defects and ____ ____ have been noted in IVF-conceived pregnancies . Accordingly, in view of the above increased risks, it is reasonable to consider more intensive prenatal assessment in pregnancies conceived by IVF.

Answer 10

multifetal gestation

prematurity or fetal growth restriction

placenta previa

Question 11

Twinning occurs naturally in about __-__% of births.

If pregnancy occurs by ART the incidence of twins is ___%. The incidence of natural multiples remained relatively unchanged over the decades, but the actual number of multiple pregnancies increased due to increased use of assisted reproductive technologies.

The risks of _____ ____ and fetal ____ &______ are higher in multiple gestations than in single gestations.The risk of ____ is higher in multiple pregnancies.

Answer 11

1-3%

37%.

chromosomal anomalies

Morbidity and mortality

prematurity

Question 12

Describe Hellin’s Law

Answer 12

In North America, twins normally occur about once in every 89 pregnancies, triplets about once in 89^2 pregnancies, quadruplets once in 89^3 pregnancies, and quintuplets approximately once in every 89^4 pregnancies (in general, the approximate number of multiple births occurs in 1: 89^n-1 pregnancies, where n is the number of fetuses

NEVER BEEN PROVEN MATHEMATICALLY

Question 13

____ ____ are twins that form by the splitting of a single original embryo and are also called identical, twins. This type of twinning occurs infrequently (about ____% naturally). The monozygotic twins share an identical ___ ___ and, therefore, look alike as they grow up.

Monozygotic twins may share none, some, or all of their ___ ___, depending on how late in development the original embryo splits to form twins.

Answer 13

Monozygotic Twins

.4%

genetic makeup

fetal membranes

Question 14

For monozygotic twins, If the splitting occurs at the___ __ stage to the ____ stage (approximately 0-4 days), the twins will be ____ and _____ (25 -35% of monozygotic twins). They will behave like _____ ____. They will also have two _____ even though they may be ____.

Answer 14

two cell stage to morula stage

dichorionic, diamniotic

dizygotic twins.

placentas

fused

Question 15

For monozygotic twins, if the splitting occurs at the ___ ____ ____(approximately 4-8 days) then the embryos will share a single ____&____ but occupy separate ____.

This may result in ____.

Answer 15

Early blastocyst stage

chorion and placenta

amnions

TTTS (twin-twin transfusion syndrome)

Question 16

For monozygotic twins, if the splitting occurs after the formation of the ___ with ____ ___ ___ (late blastocyst stage - approximately 8-12 days), the embryos will have a common ____and occupy a single ____.

Answer 16

blastocyst with inner cell mass

chorion

amnion

Question 17

For monozygotic twins, if the twins are formed by splitting of a ____ ___ ____ after the _____ ____ has started to form, they will occupy the same amnion. In rare cases, such twins may not fully separate, resulting in the birth of conjoined twins (after 12-13 days - after the primitive streak started to form).

Answer 17

bilaminar embryonic disc

the primitive streak

amnion

conjoined twins

Question 18

So what are the types of monozygotic twins?

Answer 18

Diamniotic, dichorionic

monochorionic, dioamniotic

monochorionic monoamniotic

monochorionic monoamniotic conjoint twins

Question 19

____ _____ ___ twins will always have separate amnions, a single chorionic sac, and a common placenta. If there is_____ of the _____ ____, one twin may receive most of the nutrition from the _____ and additional _____ _____ from the ___ ____. This is called TTTS.

Answer 19

Monozygotic monochorionic diamniotic twins

anastomosis of the placental vessels

placenta

additional blood flow from the other twin

Question 20

Dizygotic (____) twins arise from two separate ____ produced during the same ____ ___, that are fertilised by two ___ _____. This type of twinning is by far the more frequent and increases with increased ____ ___; it seems to have a ___basis. Dizygotic twin embryos implant separately and develop separate ___, _____, and _____.

Answer 20

fraternal

oocytes

menstrual

different sperm

maternal age

genetic

amnions, chorions, placentas

Question 21

Dizygotic twins twinning shows a _____ tendency. Recurrence in families is approximately_____ times that of the general population. The incidence of DZ twinning shows considerable variation, being approximately 1 in 500 in Asians, 1 in 125 in whites, and as high as 1 in 20 in some African populations. If the DZ embryos implant close together, then the _____ may be _____

Answer 21

hereditary

3x

placents

fused.

Question 22

In twin pregnancies, ______ can form between vessels supplying the two placentae. This shared circulation usually poses no problem, but there are several complications that may occur. Name 4 complications that may occur, one does not have to do with anastomoses:

1.

2.

3.

4.

Answer 22

anastomoses

1. In utero death of one twin
2. twin-twin transfusion syndrome (TTTS)
3. twin-reversed arterial perfusion (TRAP sequence, less common).
4. Cord entanglement (not related to the intra-placental anastomosis)

Question 23

If in utero death of one twin occurs late in gestation, the___ ___ of the dead twin drops significantly, and the remaining twin is at risk. If the blood pressure of one twin falls sharply, the other twin may suffer ___ ___, as its heart attempts to fill both ___ ___ at once

If one twin dies, the other twin may be killed by an ____ caused by bits of tissue that break off in the dead twin and enter the ____ ____,

Answer 23

blood pressure

heart failure

circulatory systems

embolism embolism

shared circulation

Question 24

Twin-to-twin transfusion syndrome occurs in 10% to 20% of all _____ ______ twins and is responsible for about 15% of all perinatal deaths in twins, ___ ____ occur between vessels in the two ____ that result in unbalanced blood flow between the twins. One twin, the so-called ___ ___, exhibits ______, ____ ___, and ____ ____, whereas the other, the so-called recipient twin, exhibits _____ and ____ ____ and eventually ___ ___.

Answer 24

monochorionic, diamniotic

vascular anastomoses

placentas

donor twin

oligohydramnios

growth restriction

renal insufficiency

polyhydramnios

cardiac enlargement

cardiac failure.

Question 25

In TRAP sequence (incidence of about 1 in 35,000 births), one twin, the so-called ___ ___ , provides all of the ____ ___ to a second ____/____ twin through ____ ___ ____. Because of the additional stress placed on the pump twin’s heart, ____ ____ and the pump twin’s subsequent demise can occur in 50% to 75% of the cases (the ___ twin cannot survive without the pump twin, and it dies either with death of the ___ twin or at birth).

In the past, the only treatment for these situations was to wait until the healthy twin was old enough to have a chance of surviving outside the womb and then to perform a cesarean section. However, surgical techniques are being developed that may provide in utero treatment of these serious conditions. Currently, ____ of the ____ ____ in utero is a routine prenatal approach.

Answer 25

pump twin

blood flow

acardiac/acephalic

placental vascular anastomoses

cardiac failure

acardiac

pump

ablation of the placental anastomosis

Question 26

In the case of ______ _____ twins, the most comon complication is cord entanglement. This complication usually occurs after ___ ____ gestation.

This can cause death of one twin or both, if the entanglement interrupts the ___ ___ through the ____ ____. Overall risk of demise in this case is 10-15%, depending on the time of delivery

Answer 26

monochorionic, monoamnionic

20 weeks

blood supply

umbilical cord

Question 27

Triplets may be derived from:

• One zygote and be ____
• Two zygotes and consist of ____ ___ and a ____
• Three zygotes and be as similiar or different if as it were ____ _____ ____

Answer 27

identical

Identical twins and singleton

three different pregnancies