Examine individual changes

'{{Diagnostic infobox | Name = {{PAGENAME}} | Image = Test de grossesse ouvert.jpg | Caption = A modern pregnancy test | ICD10 = | ICD9 = | MeshID = D011258 | OPS301 = | OtherCodes = | }} A '''pregnancy test''' attempts to determine whether a woman is [[pregnancy|pregnant]].These markers are found in urine and blood, and pregnancy tests require sampling one of these substances. The first of these markers to be discovered, [[human chorionic gonadotropin]] (hCG), was discovered in 1930 to be produced by the trophoblast cells of the fertilised ovum (blastocyst). While hCG is a reliable marker of pregnancy, it cannot be detected until after implantation:<ref name="wilcox"/> this results in false negatives if the test is performed during the very early stages of pregnancy. [[Obstetric ultrasonography]] may also be used to detect pregnancy. Obstetric ultrasonography was first practiced in the 1960s; the first home test kit for hCG was released in the mid-1970s. If you wanna know how the fuck to use it. PISS ON THE SHIT!!! God damn. why the hell do you look this up anyways?! ==History== [[Image:JanSteen-Doctor'sVisit(1658-1662).jpg|thumb|right|220px||[[Jan Steen]]'s ''The Doctor's Visit''. Included in this 17th century painting is a depiction of a dubious pregnancy test: a ribbon dipped in the patient's urine and then burned.<ref>Clark, Stephanie Brown. (2005). [http://litmed.med.nyu.edu/Annotation?action=view&annid=10398 Jan Steen: The Doctor's Visit]. ''Literature, Arts, and Medicine Database.'' Retrieved 27 May 2007.<br /> Lubsen-Brandsma, M.A. (1997). [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9555144&dopt=Abstract Jan Steen's fire pot; pregnancy test or gynecological therapeutic method in the 17th century?]. ''Ned Tijdschr Geneeskd, 141(51),'' 2513–7. Retrieved 24 May 2006.<br /> "[http://www.wga.hu/frames-e.html?/html/s/steen/page1/doctor_v.html The Doctor's Visit]." (n.d.). ''The Web Gallery of Art.'' Retrieved 24 May 2006.</ref>]] Records of attempts at pregnancy testing have been found as far back as the [[Ancient Greece|ancient Greek]] and [[ancient Egypt]]ian cultures. The ancient Egyptians watered bags of wheat and barley with the urine of a possibly pregnant woman. Germination indicated pregnancy. The type of grain that sprouted was taken as an indicator of the fetus's sex. [[Hippocrates]] suggested that a woman who had missed her period should drink a solution of honey in water at bedtime: resulting abdominal distention and cramps would indicate the presence of a pregnancy. [[Avicenna]] and many physicians after him in the [[Middle Ages]] performed ''[[uroscopy]]'', a nonscientific method to evaluate urine. [[Selmar Aschheim]] and [[Bernhard Zondek]] introduced testing based on the presence of human chorionic gonadotropin (hCG) in 1928.<ref>{{cite book | last = Speert | first = Harold | title = Iconographia Gyniatrica | publisher = F. A. Davis | year = 1973 | location = Philadelphia | isbn = 978-0803680708 }}</ref> Early studies of hCG had concluded that it was produced by the pituitary gland. In the 1930s, Georgeanna Joness discovered that hCG was produced not by the pituitary gland, but by the placenta. This discovery was important in relying on hCG as an early marker of pregnancy.<ref name="jones obit">{{cite journal | last = Damewood | first = Marian D. | coauthors = John A. Rock | title = In memoriam: Georgeanna Seegar Jones, M.D.: her legacy lives on | journal = Fertility and Sterility | volume = 84 | issue = 2 | pages = 541–2 | publisher = American Society for Reproductive Medicine | month = August | year = 2005 | url = http://www.jonesinstitutefoundation.org/downloads/GeorgeannaJones.pdf | accessdate = 2007-12-31 | doi = 10.1016/j.fertnstert.2005.04.019 |format=PDF| pmid = 16363033}}</ref> In the Aschheim and Zondek test, an infantile female [[mouse]] was injected subcutaneously with urine of the person to be tested, and the mouse later was killed and dissected. Presence of [[ovulation]] indicated that the urine contained hCG and meant that the person was pregnant. A similar test was developed [[Rabbit Test|using immature rabbits]]. Here, too, killing the animal to check her ovaries was necessary. An improvement arrived with the frog test, introduced by [[Lancelot Hogben]], which still was used in the 1950s and allowed the frog to remain alive and be used repeatedly: a female [[frog]] was injected with serum or urine of the patient; if the frog produced [[Egg (biology)|eggs]] within the next 24 hours, the test was positive. This was called the Bufo test, named after the toad genus [[Bufo]], which was originally used for the test. Other species of toads and frogs have been used later on. Direct measurement of [[antigen]]s, such as hCG, was made possible with the invention of the [[radioimmunoassay]] in 1959.<ref>{{cite journal | last = Yalow | first = RS | coauthors = SA Berson | title = Immunoassay of endogenous plasma insulin in man | journal = Journal of Clinical Investigation | volume = 39 | pages = 1157–75 | month = July | year = 1960 | pmid = 13846364 | doi = 10.1172/JCI104130 | pmc = 441860 | issue = 7 }}</ref> Radioimmunoassays require sophisticated apparatus and special radiation precautions and are expensive. In the 1970s, the discovery of [[monoclonal antibodies]] led to the development of the relatively simple and cheap [[immunoassay]]s, such as [[agglutination-inhibition]]-based assays and [[ELISA#Sandwich_ELISA|sandwich ELISA]], used in modern home pregnancy tests. ==Modern tests== The test for pregnancy which can give the quickest result after fertilisation is a [[Enzyme assay|rosette inhibition assay]] for [[early pregnancy factor]] (EPF). EPF can be detected in blood within 48 hours of [[Human fertilization|fertilization]].<ref>{{cite journal |author=Fan XG, Zheng ZQ |title=A study of early pregnancy factor activity in preimplantation |journal=Am. J. Reprod. Immunol. |volume=37 |issue=5 |pages=359–64 |year=1997 |pmid=9196793 }}</ref> However, testing for EPF is expensive and time-consuming. Most chemical tests for pregnancy look for the presence of the beta subunit of '''hCG''' or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to twelve days after fertilization.<ref name="wilcox">{{cite journal | author=Wilcox AJ, Baird DD, Weinberg CR | title=Time of implantation of the conceptus and loss of pregnancy | journal=New England Journal of Medicine | volume=340 | issue=23 | pages=1796–1799 | year=1999 | pmid=10362823 | doi=10.1056/NEJM199906103402304}}</ref> Quantitative blood (serum beta) tests can detect hCG levels as low as 1&nbsp;mIU/mL, while [[urine test strip]]s have published detection thresholds of 20&nbsp;mIU/mL to 100&nbsp;mIU/mL, depending on the brand.<ref>{{cite web | author=Waddell, Rebecca Smith| year=2006| title=FertilityPlus.org | work=Home Pregnancy Test hCG Levels and FAQ | url=http://www.fertilityplus.org/faq/hpt.html | accessdate=2006-06-17}}</ref> Qualitative blood tests generally have a threshold of 25&nbsp;mIU/mL, and so are less sensitive than some available home pregnancy tests. Most home pregnancy tests are based on [[Lateral flow test|lateral-flow]] technology. With [[obstetric ultrasonography]] the [[gestational sac]] sometimes can be visualized as early as four and a half weeks of [[gestational age|gestation]] (approximately two and a half weeks after ovulation) and the [[yolk sac]] at about five weeks' gestation. The [[Embryo#The human embryo|embryo]] can be observed and measured by about five and a half weeks. The heartbeat may be seen as early as six weeks, and is usually visible by seven weeks' gestation.<ref name="woo">{{cite web | last = Woo | first = Joseph | title = Why and when is Ultrasound used in Pregnancy? | work = Obstetric Ultrasound: A Comprehensive Guide | year = 2006 | url = http://www.ob-ultrasound.net/ | accessdate = 2007-05-27 }}</ref><ref name="boschert">{{cite journal |author=Boschert, Sherry |title=Anxious Patients Often Want Very Early Ultrasound Exam |journal=OB/GYN News |publisher=FindArticles.com |date=15 June 2001 |url=http://findarticles.com/p/articles/mi_m0CYD/is_12_36/ai_76636730 |accessdate=2007-05-27}}</ref> ==Accuracy== [[File:Negative Pregnancy Test.JPG|thumb|200px|The control line of this pregnancy test is blank, making the test invalid]] A systematic review published in 1998 showed that home pregnancy test kits, when used by experienced technicians, are almost as accurate as professional laboratory testing (97.4%). When used by consumers, however, the accuracy fell to 75%: the review authors noted that many users misunderstood or failed to follow the instructions included in the kits. Improper usage may cause both false negatives and false positives.<ref>{{cite journal |author=Bastian LA, Nanda K, Hasselblad V, Simel DL |title=Diagnostic efficiency of home pregnancy test kits. A meta-analysis |journal=Arch Fam Med |volume=7 |issue=5 |pages=465–9 |year=1998 |pmid=9755740 |doi= 10.1001/archfami.7.5.465|url=http://archfami.ama-assn.org/cgi/pmidlookup?view=long&pmid=9755740 |accessdate=2008-05-12}}</ref> ===Timing of test=== [[Type I and type II errors|False negative]] readings can occur when testing is done too early. Quantitative blood tests and the most sensitive urine tests usually detect hCG shortly after implantation, which can occur anywhere from 6 to 12 days after [[ovulation]].<!-- --><ref name="wilcox" /> Less sensitive urine tests and qualitative blood tests may not detect pregnancy until three or four days after implantation. [[Menstruation]] occurs on average 14 days after ovulation, so the likelihood of a false negative is low once a menstrual period is late. Ovulation may not occur at a predictable time in the [[menstrual cycle]], however. A number of factors may cause an unexpectedly early or late ovulation, even for women with a history of regular menstrual cycles. Using ovulation predictor kits (OPKs), or charting the [[fertility awareness|fertility signs]] of [[cervix|cervical]] mucus or [[basal body temperature]] give a more accurate idea of when to test than day-counting alone. The accuracy of a pregnancy test is most closely related to the day of ovulation, not of the act of intercourse or insemination that caused the pregnancy. It is normal for sperm to live up to five days<!-- --><ref name="tcoyf">{{cite book | first=Toni | last=Weschler | year=2002 | title=Taking Charge of Your Fertility | pages=374 | edition=Revised | publisher=HarperCollins | location=New York | isbn=0-06-093764-5 }}</ref> in the fallopian tubes, waiting for ovulation to occur.<!-- --><ref>{{cite web | last = Ellington | first = Joanna | title = Sperm Transport to the Fallopian Tubes | work = Frequently Asked Questions with Dr. E | publisher = INGfertility Inc | year = 2004 | url = http://www.ingfertility.com/FAQs.html#Sperm_Leaking_Out_After_Intercourse-_Lessons_in_Sperm_Transport_Through_the_Cervix_ | accessdate = 2006-08-13 |archiveurl = http://web.archive.org/web/20060713234557/http://www.ingfertility.com/FAQs.html#Sperm_Leaking_Out_After_Intercourse-_Lessons_in_Sperm_Transport_Through_the_Cervix_ |archivedate = 2006-07-13}}</ref> It could take up to twelve further days for implantation to occur, meaning even the most sensitive pregnancy tests may give false negatives up to seventeen days after the act that caused the pregnancy. Because some home pregnancy tests have high hCG detection thresholds (up to 100 mIU/mL), it may take an additional three or four days for hCG to rise to levels detectable by these tests — meaning false negatives may occur up to three weeks after the act of intercourse or insemination that causes pregnancy. ===False positives=== [[Type I and type II errors|False positive]] test results may occur for several reasons. These include: errors of test application, use of drugs containing the assay molecule, and non-pregnant production of the assay molecule. Spurious ''evaporation lines'' may appear on many home pregnancy tests if read after the suggested 3–5 minute window or reaction time, independent of an actual pregnancy. False positives may also appear on tests used past their expiration date. A woman who has been given an hCG injection as part of [[infertility]] treatment will test positive on pregnancy tests that assay hCG, regardless of her actual pregnancy status. However, some infertility drugs (e.g., [[clomid]]) do not contain the hCG hormone.<ref>{{cite web | author=Phillips, Pat| year=2007| title=Early Pregnancy Tests | work= Pregnancy Test FAQ | url=http://www.early-pregnancy-tests.com/pregnancy-tests.html | accessdate=2007-03-04}}</ref> Some diseases of the [[liver]], [[cancer]]s, and other medical conditions may produce elevated Human chorionic gonadotropin|hCG and thus cause a false positive pregnancy test. These include [[choriocarcinoma]] and other [[germ cell tumor]]s, [[Selective immunoglobulin A deficiency|IgA deficiencies]], [[Heterophile|heterophile antibodies]], enterocystoplasties, [[gestational trophoblastic disease]]s (GTD), and gestational trophoblastic neoplasms (GTN). ==Viability== Pregnancy tests may be used to determine the viability of a pregnancy. Serial quantitative blood tests may be done, usually 2–3 days apart. Below an hCG level of 1,200 mIU/ml the hCG usually doubles every 48–72 hours, though a rise of 50–60% is still considered normal. Between 1,200 and 6,000 mIU/ml serum the hCG usually takes 72–96 hours to double, and above 6,000 mIU/ml, the hCG often takes more than four days to double. Failure to increase normally may indicate an increased risk of [[miscarriage]] or a possible [[ectopic pregnancy]]. [[Obstetric ultrasonography|Ultrasound]] is also a common tool for determining viability. A lower than expected heart rate or missed development milestones may indicate a problem with the pregnancy.<ref name="boschert" /> Diagnosis should not be made from a single ultrasound, however. Inaccurate estimations of fetal age and inaccuracies inherent in ultrasonic examination may cause a scan to be interpreted negatively. If results from the first ultrasound scan indicate a problem, repeating the scan 7–10 days later is reasonable practice.<ref name="woo" /> ==References== {{reflist|2}} ==External links== {{commons}} * [http://www.whfreeman.com/kuby/content/anm/kb07an01.htm A descriptive animation] of the principle behind a lateral-flow [[ELISA#Sandwich_ELISA|sandwich-ELISA]] home pregnancy test. * [http://baby-parenting.com/pregnancy/pregnancy_due_date_chart.html A detailed pregnancy due date chart] {{Pregnancy}} {{Urine tests}} {{DEFAULTSORT:Pregnancy Test}} [[Category:Obstetrics]] [[Category:Pregnancy tests| ]] [[ar:اختبار الحمل]] [[de:Schwangerschaftstest]] [[el:Τεστ εγκυμοσύνης]] [[es:Pruebas de embarazo]] [[fa:آزمایش حاملگی]] [[fr:Test de grossesse]] [[it:Test di gravidanza]] [[he:בדיקת היריון]] [[nl:Zwangerschapstest]] [[ja:妊娠検査薬]] [[pl:Test ciążowy]] [[pt:Teste de gravidez]] [[ru:Тест на беременность]] [[fi:Raskaustesti]] [[sv:Graviditetstest]] [[zh:妊娠试验]]'