Prenatal Defects

Question 1

Mutation

Answer 1

Mutation is a change in DNA sequence, or anomalies resulting from a change in sequence

Question 2

Teratogenesis

Answer 2

Teratogenesis non-mutagenic development of a birt defect, produced by exposure to a factor that interferes with a developmental process without changing the DNA

Question 3

Malformation

Answer 3

Malformations are morphologic anomaly

Question 4

Deformation

Answer 4

Deformation is malformation produced over a prolonged period of time due to persistend molding forces, e.g. clubbed foot or abnormal cranium due to oligohydraminos (deficiency in amniotic fluid)

Question 5

Disruption

Answer 5

A disruption is a malformation produced after the initial formation of a normal structure, which occur in a relatively short period of time, due to the introduction of a destructive force, e.g. limb amputation due to amniotic band constriction

Question 6

Ectopic Pregnancy

• definition
• characteristics
• treatment

Answer 6

Ectopic Pregnancy- implantation in the wrong place. Most often in the Ampulla (95%) of the fallopian tube.

• most result in the death of the embryo during the second month leading to severe hemorrhaging and abdominal pain
• terminate ectopic pregnancy with methotrexate injection

Question 7

Tubal pregnancies

Answer 7

implantation anywhere along the uterine tube

-pregnancy must be terminated

Question 8

Most common site for abdominal implantation

Answer 8

peritoneal lining of the rectouterine cavity (Douglas’ pouch). Can also occur in the intestinal peritoneum or omentum

Question 9

Primary Ovarian Pregnancy

Answer 9

blastocyst implants on the surface of the ovary

Question 10

Hydatidiform Moles

• development
• outcomes

Answer 10

Hydatidiform Moles develop from implanted blastocysts that develop trophoblastic tissues (placenta) but no fetal tissue

• no fetal vasculature so maternal fluids remain in the placenta. Villi become swollen. They can expand to fill the whole uterus
• WORST CASE SCENARIO: they can develop into a metastatic malignancy called CHORIOCARCINOMA. The death rate for choriocarcinomas is still 10-20%

Question 11

Complete Hydatidiform mole

-how is it formed?

Answer 11

No fetal tissue.
The complete hydatidiform mole develops from an egg that has lot its nucleus and is fertilized by two sperm.

paternal genes are enough to support trophoblastic development, but maternal genes are necessary for emmbryonic development

Question 12

Partial hydatidiform mole

-how is it formed

Answer 12

A partial hydatidiform mole has less pronounced features with some fetal development.
It is one partial consequence of triploidy. Most of these spontaneously abort, but some can survive to term but have 100% neonatal mortality.

Question 13

Sacrococcygeal Teratomas

• why do they form
• what type of cells do they come from
• Treatment

Answer 13

Sacrococcygeal Teratomas are tumors that can develop at the anal region of the fetus

-they form if the primitive streak fails to regress completely

• Sarcococcygeal teratomas are derived from pluripotent cells and contain a mixture of different cell types
• in utero they can deprive the fetal brain of blood but can be removed after birth

Question 14

Caudal Dysgenesis

Answer 14

Caudal Dysgenesis is the underdevelopment of posterior features due to premature regression of the primitive streak and insufficient caudal mesoderm

Question 15

The pt presents with vertebral abnormalities, renal agenesis, imperforate anus and anomalies of the UG organs. The pt. may also have a clubbed foot.
what is the name of a more severe form?
-what is one teratogenic factor

Answer 15

caudal dysgenesis
sirenomelia- the fusion of the lower limbs that produces a mermaid like fetus
-a teratognic factor for caudal dysgenesis is maternal diabetes

Question 16

A pt comes in and has obvious mental retardation and a deficiency of midline craniofacial structures
what is one possible teratogenic cause?

Answer 16

Fetal Alcohol syndrome.

Obvious symptoms of FAS include mental retardation and holoprosencephaly

Question 17

spina bifida

Answer 17

open vertebral canal

Question 18

spina bifida occulta

Answer 18

spina bifida occulta is when the underlying meninges and spinal cord develop normally and do not protrude thru the opening

Question 19

Spina bifida systica

• meningocele
• myelomeningocele

Answer 19

spina bifida systica is when the meninges and spinal cord herniate thru the opening.

• meningocele a herniation that is only meninges without neural tissue. Require surgical correction
• myelomeningocele- herniation that is meninges AND neural tissue. Myelomeningoceles have a high mortality rate and symptoms include bowel/bladder incontinence, CSF leakage, flaccid paralysis, and hydrocephaly

Question 20

where are the most commom sites for dysraphism?

Answer 20

The most common sites of dysraphism are L5 or S1 but they can occur anywhere along the neural tube.
The general rule is that the farther away from L5 or S1 the greater the defects.
Hydrocephaly and neural deficits are more common with anterior defects while urinary incontinence is more common with posterior defects

Question 21

Anencephaly

-what develops?

Answer 21

Ancephaly results if the neural tub fails to close at the level of brain vesicles or when the neuropore fails to close

• instead of a brain, an undifferentiated mass of neural tissue develops, which is open on the dorsal surface of the head.
• neonatal mortality is 100%

Question 22

elevated levels of these proteins in the amniotic fluid or maternal blood suggest open defects

Answer 22

When fetal proteins such as a-fetoprotein and acetylcholinesterase are elevated in the amniotic fluid or the maternal blood it is suggestive of open defects like spina bifida cystica and gastrochisis

Question 23

Down Syndrome is suggested by elevated levels of what?

Answer 23

lower levels of a-fetoprotein, unconjugated estriol, and higher hCG and serum dimeric inhibin A
the quad screen

Question 24

Pregnant women are advised to supplement their diet with what to help reduce the chance of developing neural tube defects?

Answer 24

Pregnant women should supplement their diet with FOLIC ACID during the 3rd and 4th weeks of pregnancy (when the neural tube is closing) to help reduce the risk of neural tube defects.

Question 25

Monochorionic pregnancies

Answer 25

Monochorionic pregnancies are pregnancies where twins share one placenta and chorion

Question 26

Monoamniotic pregnancies

Answer 26

Monoamniotic pregnancies the twins share a common amniotic cavity as well as placenta and chorion

Question 27

Chorion

Answer 27

forms the fetal part of the placenta