New Methods of Pregnancy Testing in Adolescent Girls

Abstract

The knowledge and use of newer, more sensitive, and reliable pregnancy tests which are easily accessible and of moderate cost are the 1st steps in the early diagnosis and management of pregnancy, especially in adolescent girls. Accurate diagnosis of pregnancy soon after conception offers the option of abortion by simple, effective, and inexpensive procedures or early initiation of prenatal maternity care. Discussion focuses on the symptoms of pregnancy and the historical development and basis of pregnancy tests as well as the specific types of pregnancy tests. The most familiar sign of pregnancy is the missed period. Other symptoms that provide presumptive evidence of pregnancy include fatigue and lassitude, increased body temperature, and breast fullness or pain. Feelings of nausea, vomiting, and weight gain may appear after 2 weeks. The diagnosis of pregnancy by the detection of the human chorionic gonadotropin was initially described 53 years ago by Selmar Aschheim and Bernhardt Zondek. Improvements in the techniques for the measurement of human chorionic gonadotropin (hCG) have been directly related to the progress in the purification and isolation of hCG and elucidation of the amino acid sequence of the hormone-nonspecific alpha subunit and hormone-specific beta subunit of hCG. The history, physical examination, and pregnancy tests will generally provide sufficient information for a definite diagnosis of pregnancy. The presence of hCG in the urine or blood is the most accurate of all the indications of pregnancy. During the last century, 4 different techniques for the determination of hCG in blood and/or urine have been developed. These include the following and are reviewed in detail: 1) bioassays in intact laboratory animals; 2) immunologic tube or slide methods with heme- or latex-agglutination inhibition, as well as the more recently developed competitive protein binding method such as 3) radioimmunoassay (RIA) for the use of radioisotope labeled hormone and the specific antiserum against hCG; and 4) radioreceptorassay by the use of radioisotope-labeled hormone with biological activity and the specific receptors as the binding proteins.