Pregnancy Test

Embryology - 16 Apr 2024        Expand to Translate
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Educational Use Only - Embryology is an educational resource for learning concepts in embryological development, no clinical information is provided and content should not be used for any other purpose.

Introduction

File:Pregnancy test

The first of prenatal diagnostic tests. Through history there were a number of supposedly diagnostic tests to determine early pregnancy, the most obvious was the absence of an ongoing menstrual cycle in women of reproductive age. It was not until the early 20th century that the first clinical maternal urine test was developed. A complicated test requiring analysis of changes induced in the immature mouse genital system by hormones present in the maternal urine. The test was replaced by a urine test with either the rabbit (Friedman modification) showing similar changes or frog (Xenopus), that could be induced to lay eggs by similar urine effects. In the 1960's an immunological test for human chorionic gonadotropin (hCG) in either maternal urine or blood led to development in the late 1970's of home pregnancy kits that became simple one step tests in the late 1980's.

See the external link to 2003 online NIH summary, "The Thin Blue Line" and the 2004 review on the history of the home pregnancy test.

Note that there are a number of pathological conditions, such as endocrine tumours and hydatidiform moles, that can also mimic the detected hormonal changes.

Links: Menstrual Cycle | Week 2 | Implantation | Placenta Development | Pregnancy Test | Hydatidiform Mole | Human Chorionic Gonadotropin

Some Recent Findings

Use of a checklist to rule out pregnancy: a systematic review "Safe initiation of contraceptive methods requires that pregnancy be excluded. The World Health Organization has developed a list of criteria to assess pregnancy status. This review was conducted to evaluate the evidence regarding these criteria in excluding pregnancy. Four analyses of data from three studies met inclusion criteria as direct evidence. All were diagnostic accuracy studies of fair quality that evaluated the performance of a pregnancy checklist compared with urine pregnancy test to rule out pregnancy. The performance of the checklist varied, with sensitivity ranging from 55-100% and specificity ranging from 39-89%. The negative predictive value was consistent across studies at 99-100%." Checking pregnancy status in adolescent girls before procedures under general anaesthesia "Surgery, ionising radiation and anaesthesia in the presence of an undetected pregnancy could be harmful. British guidelines state that female patients of 'childbearing age' should have their pregnancy status established before surgery. Approaching this topic with an adolescent girl can be challenging. The authors conducted an observational study and a survey in their institution and a national survey of Association of Paediatric Anaesthetists (APA) linkmen. Both surveys demonstrate widespread concerns about inconsistent and informal practices. Only 45% of respondents in the authors' institution stated they ask adolescent girls if they could be pregnant. 40% of APA linkmen were unaware of national guidelines."

More recent papers

This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Pregnancy Test <pubmed limit=5>Pregnancy Test</pubmed>

History

• 1928 - Bernhard Zondek and Selman Aschheim procedure that measured the increase in gonadotrophic substance in the urine of a pregnant woman.
  • Immature mice injection with urine led to ovarian changes after a few days.
  • Xenopus clawed frog replaced mice, injection with urine stimulated the females to lay eggs that were easily seen the next day.
• 1960s - immunological tests for chorionic gonadotropin.
• 1972 - Research on hCG at NIH by Judith Vaitukaitis and Griff Ross.
• 1978 - USA first home pregnancy test kits available.
• 1988 - first “one step” test, Clearblue Easy, a blue stripe appeared to indicate pregnancy.

Aschheim-Zondek Test (1928) Page | Play

Rabbit Xenopus clawed frogs

Judith Vaitukaitis and Griff Ross (c1971)

Pregnancy Testing in Medicine

The urine test can be an indicator of an existing pregnancy, but does not exclude a pregnancy that has not reached the implantation stage, or even a very early adplantation stage (GA week 3). This test is often used in consultation with information on sexual history and the menstrual cycle, the last menstrual period (LMP).

There are a number of medical procedures and medications that are contraindicated for pregnant women. This can form part of a discussion or screening process prior to the procedure or prescription. This is also an issue in some medical procedures on women of reproductive age that require anaesthesia, see also UK NICE Guideline - section 5.18). A second issue relates to the preoperative pregnancy testing of minors, regulations for this circumstance may differ between countries.

A immunoradiometric assay for human chorionic gonadotropin (hCG) in urine identified that 10% of clinical pregnancies were undetectable on the first day of missed menses. The same test 1 week after the first day of the missed period, the test identified 97% of clinical pregnancies.

Links: Menstrual Cycle | Abnormal Development - Drugs | Australian Drug Categories | USA Drug Categories

References

Reviews

<pubmed></pubmed> <pubmed></pubmed> <pubmed>22149742</pubmed>

Articles

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Search Pubmed

Search Pubmed: Pregnancy Test | hCG

Search Bookshelf: Pregnancy Test | Human Chorionic Gonadotropin

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.

• USA - NIH A thin blue line - The History of the Pregnancy Test Kit | Timeline
• USA - Womens Health http://womenshealth.gov/publications/our-publications/fact-sheet/pregnancy-tests.cfm#a Pregnancy tests fact sheet]
• Australia - NSW Health Pregnancy
• UK - National Health Service (NHS) National Institute for Clinical Health and Excellence (NICE) Preoperative Tests The use of routine preoperative tests for elective surgery guidelines. PDF

Glossary Links

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Cite this page: Hill, M.A. (2024, April 16) Embryology Pregnancy Test. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Pregnancy_Test

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G