Article by hi joiney
(1687, 'History 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 Records of attempts at pregnancy testing have been found as far back as the ancient Greek and ancient Egyptian 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 Early studies of hCG had concluded that it was produced by the pituitary gland In the 1930s Georgeanna Jones 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 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 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 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 antigens such as hCG was made possible with the invention of the radioimmunoassay in 1959 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 immunoassays such as agglutination inhibition based assays and sandwich ELISA used in modern home pregnancy tests Modern tests The test for pregnancy which can give the quickest result after fertilisation is a rosette inhibition assay for early pregnancy factor EPF EPF can be detected in blood within 48 hours of fertilization 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 Quantitative blood serum beta tests can detect hCG levels as low as 1 160 mIU mL while urine tests have published detection thresholds of 20 160 mIU mL to 100 160 mIU mL depending on the brand Qualitative blood tests generally have a threshold of 25 160 mIU mL and so are less sensitive than some available home pregnancy tests Most home pregnancy tests are based on lateral flow technology With obstetric ultrasonography the gestational sac sometimes can be visualized as early as four and a half weeks of gestation and the yolk sac at about five weeks gestation The 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 Accuracy Negative pregnancy test human subject 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 Timing of test 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 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 signs of 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 in the fallopian tubes waiting for ovulation to occur 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 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 35 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 Some diseases of the liver cancers and other medical conditions may produce elevated hCG and thus cause a false positive pregnancy test These include choriocarcinoma and other germ cell tumors IgA deficiencies heterophile antibodies enterocystoplasties gestational trophoblastic diseases 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 23 days apart Below an hCG level of 1 200 mIU ml the hCG usually doubles every 4872 hours though a rise of 5060 is still considered normal Between 1 200 and 6 000 mIU ml serum the hCG usually takes 7296 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 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 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 710 days later is reasonable practice References a b c Wilcox AJ Baird DD Weinberg CR 1999 Time of implantation of the conceptus and loss of pregnancy New England Journal of Medicine 340 23 17961799 doi 10 1056 NEJM199906103402304 PMID 10362823 160 Clark Stephanie Brown 2005 Jan Steen The Doctor s Visit Literature Arts and Medicine Database Retrieved 27 May 2007 Lubsen Brandsma M A 1997 Jan Steen s fire pot pregnancy test or gynecological therapeutic method in the 17th century Ned Tijdschr Geneeskd 141 51 25137 Retrieved 24 May 2006 The Doctor s Visit n d The Web Gallery of Art Retrieved 24 May 2006 Speert Harold 1973 Iconographia Gyniatrica Philadelphia F A Davis ISBN 978 0803680708 160 Damewood Marian D John A Rock August 2005 In memoriam Georgeanna Seegar Jones M D her legacy lives on PDF Fertility and Sterility American Society for Reproductive Medicine 84 2 5412 doi 10 1016 j fertnstert 2005 04 019 http www jonesinstitutefoundation org downloads GeorgeannaJones pdf Retrieved 2007 12 31 160 Yalow RS SA Berson July 1960 Immunoassay of endogenous plasma insulin in man Journal of Clinical Investigation 69 115775 doi 10 1172 JCI104130 PMID 13846364 160 Fan XG Zheng ZQ 1997 A study of early pregnancy factor activity in preimplantation Am J Reprod Immunol 37 5 35964 PMID 9196793 160 Waddell Rebecca Smith 2006 FertilityPlus org Home Pregnancy Test hCG Levels and FAQ http www fertilityplus org faq hpt html Retrieved 2006 06 17 160 a b Woo Joseph 2006 Why and when is Ultrasound used in Pregnancy Obstetric Ultrasound A Comprehensive Guide http www ob ultrasound net Retrieved 2007 05 27 160 a b Boschert Sherry 15 June 2001 Anxious Patients Often Want Very Early Ultrasound Exam OB GYN News FindArticles com http findarticles com p articles mi_m0CYD is_12_36 ai_76636730 Retrieved 2007 05 27 160 Bastian LA Nanda K Hasselblad V Simel DL 1998 Diagnostic efficiency of home pregnancy test kits A meta analysis Arch Fam Med 7 5 4659 doi 10 1001 archfami 7 5 465 PMID 9755740 http archfami ama assn org cgi pmidlookup view long amp pmid 9755740 Retrieved 2008 05 12 160 Weschler Toni 2002 Taking Charge of Your Fertility Revised ed New York HarperCollins pp 160 374 ISBN 0 06 093764 5 160 Ellington Joanna 2004 Sperm Transport to the Fallopian Tubes Frequently Asked Questions with Dr E INGfertility Inc http www ingfertility com FAQs html Sperm_Leaking_Out_After_Intercourse _Lessons_in_Sperm_Transport_Through_the_Cervix_ Retrieved 2006 08 13 160 Phillips Pat 2007 Early Pregnancy Tests Pregnancy Test FAQ http www early pregnancy tests com pregnancy tests html Retrieved 2007 03 04 160 External links Wikimedia Commons has media related to Pregnancy test A descriptive animation of the principle behind a lateral flow sandwich ELISA home pregnancy test v 160 160 d 160 160 e Pregnancy and Childbirth Planning Birth control 160 Pre conception counseling Conception Fertility awareness 160 Assisted reproductive technology IVF AI Fertility medication Testing Home testing 160 Obstetric ultrasonography 160 Prenatal diagnosis 160 3D ultrasound Prenatal Anatomy Endometrium 160 Placenta 160 Amniotic fluid 160 Amniotic sac 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