Saving changes...



Trisomy 18

Trisomy 18

Trisomy 18

Susan Riordan, RN, RDMS & Jonathan Weeks, M.D.
Susan Riordan, RN, RDMS & Jonathan Weeks, M.D.
on behalf of e-Ed Credits

$10.00 $ 10.00 $ 10.00

$10.00 $ 10.00 $ 10.00

$ 10.00 $ 10.00 $ 10.00
$ 10.00 $ 10.00 $ 10.00
Normal Price: $10.00 $10.00


Launch date: 09 Oct 2017
Expiry Date:

Last updated: 09 Oct 2019

Reference: 184918

This course is no longer available

Exam is embedded in the course
No preview available
No Exam Available

Latest User Comments

I would like to...


Trisomy 18 is a chromosomal disorder resulting in a syndrome characterized by specific dysmorphic features and organ malformations. Other names for Trisomy 18 include Edwards Syndrome, Trisomy E, or Trisomy 16/18. It was first recognized by Edwards et al in 1960 as a specific clinical entity by the discovery of an extra number 18 chromosome in babies with a particular pattern of malformation.

For explanation purposes, it is important to understand normal genetics. Chromosomes are long strands of deoxyribonucleic acid (DNA) that are found in the nucleus of every cell in the human body. There are two basic types of chromosomes, one group called autosomes (which are numbered 1 through 22) and the other group is the sex chromosomes (which are X and Y). The normal genetic makeup for humans is 23 pairs of chromosomes for an overall total of 46. Therefore, every cell in the body (except the egg and the sperm) should have twenty-two pairs of the autosomes (1 through 22) and one pair of sex chromosomes (as either XX for female or XY for male). This means that every cell (except the egg and the sperm) should have two number 1 chromosomes, two number 2 chromosomes, two number 3 chromosomes, and so on, up to two number 22 chromosomes, and two sex chromosomes. Thus, if a person has a genetic karyotype performed, a normal female karyotype would be written as 46 XX and a normal male karyotype would be written as 46 XY. Unfortunately with Trisomy 18, there is an ""extra"" number 18 chromosome, and the karyotype would be listed as 47 XY, +18 (for a male) or 47 XX, +18 (for a female).

To explain further, the autosomes are categorized into groups (designated by letters) based on size and appearance, which are:

Group A chromosomes 1, 2 and 3
Group B chromosome 4 and 5
Group C chromosomes 6 through 12
Group D chromosomes 13, 14 and 15
Group E chromosomes 16, 17, and 18
Group F chromosomes 19 and 20
Group G chromosomes 21 and 22

This helps to explain the other names for the syndrome, namely trisomy E or trisomy 16/18, based on their grouping category; whereas, the name Edwards Syndrome comes from the researcher that first discovered the anomaly.


Upon completion of this course, the learner will be able to:
1. Explain the normal chromosomal composition of humans.

2. Discuss what trisomy 18 is, the etiology behind its development, and its overall prognosis.

3. Describe the ultrasound findings that may be detected, if present, in a fetus with trisomy 18.

4. Discuss the prenatal diagnostic tests that are available for screening and how a definitive diagnosis is obtained.
Susan Riordan, RN, RDMS & Jonathan Weeks, M.D.

Author Information Play Video Bio

Susan Riordan, RN, RDMS & Jonathan Weeks, M.D.
on behalf of e-Ed Credits

Susan Riordan received her Bachelors degree in nursing in 1979 and has been a full time nurse for 21 years. She has worked in labor and delivery, postpartum, and the newborn nursery. She has been a high-risk obstetrical sonographer for the past 10 years and received her RDMS in Obstetrics and Gynecology in 1997. She currently works at Norton Suburban Hospital in Maternal-Fetal Medicine under the direction of Dr. Jonathan Weeks.

Jonathan Weeks, M.D. is a board certified Obstetrician / Gynecologist and Perinatologist. He is currently director of the Maternal Fetal Medicine Center at Norton Suburban Hospital. Dr. Weeks has several publications in peer-review medical journals and has lectured at numerous meetings across the country.

Current Accreditations

This course has been certified by or provided by the following Certified Organization/s:

  • American Nurses Credentialing Center (ANCC)
  • 1.00 Hours

Faculty and Disclosures

Additional Contributors

Conflicts Declared

Conflicts of Interest declaration by Author:


User Reviews (0)

Go Back


Saving changes...