Evaluation of a new rapid slide test for pregnancy THOMAS
A new latex-inhibition slide test for pregnancy, Gest 0 State, t with the use of polystyrene latex particles to which human chorionic gonadotropin (hCG) has been bound, is described. The sensitivity of this test was found to be 2 to 4 I.U. of hCG per milliliter of urine. Clinical trials with the Gest 9 State in urine samples from 328 patients (203 positive, 125 negative) showed one false negative and no false positive results. Urine containing drugs or high concentrations of various ingredients and abnormal urine did not result in interference with expected test results. The new test was comparable with or superior to other commercially available rapid slide tests for pregnancy. (AM. J. OBSTET. GYNECOL. 133:411, 1979.)
PRESENCE of human chorionic gonadotropin (hCG) in the urine of pregnant women has led to the development of immunologic methods for the detection of early pregnancy. I-3 Among these methods are the latex-agglutination-inhibition slide tests developed as a result of the work of Robbins and associates,4 who reported that polystyrene latex particles could serve as an agglutinable carrier for antigen-antibody systems. In most of these systems, the antigen (hCG) is either adsorbed onto the surface of the particle or covalently bound by amide linkages, for example, to an activated particle. Another method of attaching hCG to polystyrene particles, in which a polymerizing process is utilized, has been developed. This new hCG-latex complex was examined for sensitivity, specificity, and ease of interpretation in comparison with six other commercially available pregnancy tests. In a clinical setting, 328 urine specimens submitted for pregnancy diagTHE
From Fisher-Lederle Company.
Receizred for publication Rpclised June
Fisher Scient$c 6, 1978.
Accepted June 20, 1978. Reprint requesti: Dr. Gerald Diagnostics, Fisher Scientific York 10962.
E. Stiles, Fisher-Lederle Company, Orangeburg,
*Precent address: High Tor Medical St. New City, Near York 10956. **Present Cyanamid tFisher
Bldg. 345 N. Main
C. V. Mosby
Material and methods The following rapid slide tests for pregnancy were evaluated: Gest P State, DAP test,* Gravindex,? Pregnosticon,l: Pregnosticon Dri-Dot,$ Pregnosis,$ and UCG.” Only the reagent materials supplied by each manufacturer were employed. For qualitative and quantitative use of the slide tests, the recommended procedures outlined in the manufacturers’ circulars were used. Urine specimens. The Gest 0 State test was performed on normal urine, urine from pregnant women. and,.in addition, 25 urine samples with properties or substances reported to interfere with immunologic pregnancy tests, i.e., urine from subjects receiving psychotropic drug therapy, urine containing detergents, and urine with extremes of pH, high levels of protein. or abnormal levels of other urinary constituents. High-protein urine samples were obtained by adding various concentrations of human serum albumin to eight urine samples from pregnant women and nine urine samples from nonpregnant women. The effects of different levels of chlorpromazine were tested by adding this substance to urine from a nonpregnant woman and to urine from a pregnant woman. The Gest *Wampole Labs., Stamford, Connecticut. tOrtho Diagnostics, Raritan, New Jersey. *Organon, Inc., West Orange, New Jersey. §Roche Diagnostics, Div. Hoffmann-La Roche ley, New Jersey.
address: Lederle Laboratories, American Company, Pearl River, New York 10965. Scien+c
nosis were assayed, with the use of the Gest 0 State and three other similar pregnancy tests.
Sullivan, Barg, and Stiles
Table I. Relative hCG sensitivities tests for pregnancy
2-4 2-4 3.5 l-2 2 1.5-2.5 2
Gest P State DAP Gravindex Pregnosticon Pregnosticon Dri-D(>t Pregnosis UCG *United States Pharmacopeia pooled normal male urine.
of seven slide
2.5 I .5 6 2 3.5 3 4
standard (0870-F) diluted in
Table II. Results of seven latex slide pregnancy tests used on 25 selected urine samples* I Results Latex slide test
Gest P State DAP Gravindex Pregnosticon Pregnosticon Dri-Dot Pregnosis UCG
25 24 23 23 23 24 23
0 1t 1t 1* 1$ 0 0
0 0 19: 18 18
*Six confirmed positive, 19 confirmed negative. t Urine from a patient receiving psychotropic drugs. $ Urine contained detergent. $Urine obtained during the first trimester of pregnancy. ? State test was also performed on a reconstituted abnormal urine control* and on a reconstituted urine toxicology control (Drugs l*). The latter control was reconstituted and tested at a concentration five times higher than recommended. A group of 12 urine samples from nonpregnant women receiving drug therapy was also tested with Gest P State. Clinical studies. Gest PState and three other commercially available latex-inhibition slide tests (Pregnosis. Pregnosticon, and Gravindex) were used to assay 328 unfiltered urine specimens submitted for pregnancy testing at the offices of the senior author. A medical history was taken for each patient to obtain data on drug therapy and on the estimated date of the last menstrual period. Included in this clinical phase were urine samples from women who appeared to be menopausal. Urinalyses were carried out on all specimens to obtain sugar and protein levels. The pH, specific gravity, presence of blood cells, and any bacterial contamination of the urines were also recorded. *Lederle Diagnostics, American Cyanamid Company, Pearl River, New York.
Comparison of Gest V State with other latex slide tests. Table I shows that the sensitivity of the Gest 0 State was within the value claimed and that the new test compared favorably with six other rapid latex slide tests for pregnancy. The sensitivities found did not agree with the sensitivities reported by the manufacturers of four of the six kits examined. Lack of correlation of claimed and observed sensitivities was also reported by Porres and associates.’ The results of tests on 25 selected urine samples with seven different latex-type slide tests are given in Table II. These urine samples (six confirmed positive and 19 confirmed negative) were selected on the basis of their having properties known to interfere with the performance of immunologically based pregnancy tests. For example, the samples contained urine from nonpregnant patients receiving psychotropic drugs,:‘. ‘-’ urine with low or high pH, urine containing abnormally high levels of protein,“, *I’ urine containing detergent,‘! and commercially available abnormal urine* containing elevated levels of urinary constituents. The confirmed positive urines included several with low levels of hCG. The Gest ? State slide test correctly diagnosed all 25 urine samples. The DAP kit gave a false positive result with a urine sample from a patient receiving psychotropic drug therapy and three other kits (Gravindes, Pregnosticon. and Pregnosticon Dri-Dot) gave false positive results on a urine sample containing a detergent. Of the six urine samples confirmed positive at least one was missed (false negative) by five of the seven latex slide tests. Performance of Gest P State test on urine samples containing added constituents or urine samples with abnormal physical properties. Substances known to affect immunologically based latex-agglutination tests were examined in more detail with the Gest P State test. Concentrations of protein (human serum albumin) and chlorpromazine were added to a series of urine samples from pregnant and nonpregnant women at concentrations above normal or above pathologic levels. The resu1t.s obtained by the Gest P State test in the urine tv which protein or chlorpromazine was added did not differ from the results obtained in the same urines without the added constituents (Table III). In addition an abnormal urine control reconstituted as directed and a urine toxicology control (Drugs one) reconstituted five times concentrated had no effect on the agglutination of Gest 0 State. The high solids (specific gravity = 1.074) of the latter control did not *Abnormal
urine control, Lederle Diagnostics
New rapid slide test for pregnancy
Table III. The effect of high levels of protein Gest P State slide test for pregnancy
on the performance
1vo. of urinr
added to urine
4+ 4+ 4+ 4+ 4+ 4f -
9 9 9 8 8 8 8 I I I I
1 mg. HSA*/ml. 4 mg. HSA/ml. 20 mg. HSA/ml. 0 1 mg. HSA/ml. 4 mg. HSA/ml. 20 mg. HSA/ml. 10m3M Chlorpromazine 10e2M Chlorpromazine 1Oe3M Chlorpromazine 1Oe3M Chlorpromazine
Nonpregnant Nonpregnant Nongregnant Nonpregnant Pregnant Pregnant Pregnant Pregnant Nonpregnant Nonpregnant Pregnant Pregnant
*HSA = Human serum albumin. Table IV. Results of Gest P State slide tests on urine receiving drug therapy Urine specimen NO.
1 2 3 4 5 6 7 8 9 10 11 12
Age of patifnt (YrJ
25 17 54 54 31 48 Unknown 72 57 18 17 14
Fluphenazine, benztropine, chloral hydrate Thioridazine, duphenylhydantoin, benztropine, flurazepam Thioridazine, benztropine, chloral hydrate Benztropine, fluphenazine Thioridazine, phenylbutazone, doxepin Diazepam, thioridazine, amitriptyline, chloral hydrate No information Dioctyl sodium sulfosuccinate, nitrofurazone, erythromycin, chlorpromazine Thioridazine, amitriptyline, atropine, chlordiazepoxide. Rurazepam, phenobarbital, butabarbitat, glutethimide Fluphenazine Benztropine, haloperidol, thioridazine, chlorpromazine, butalbital Thioridazine
women Latex agglutination values *
4+ 4+ 4+ 4’ ;: t: 4+ 4+ 4+ 4+
*44+ = Strong agglutination. cause nonspecific agglutination of the Gest 0 State hCG-latex reagent. No false negative or false positive (nonspecific agglutination) results were obtained when Gest 4 State was used on eight urine samples that had a wide range of pH (5.06 to 8.63). Table IV shows that no false positive results were observed when Gest 0 State was tested on 12 urine specimens obtained from nonpregnant women who were receiving drug therapy. Clinical studies, A summary of the latex-inhibition slide test results and clinical impressions for 328 patients who submitted urine samples for pregnancy testing is given in Table V. The urine samples were tested with Gest Q State. Gravindex, Pregnosticon, and Pregnosis. All four slide tests gave similar results, i.e.,
for the 328 patients, there were 202 positive, tests and 125 negative ones. Of the 202 cases in which the pregnancy test was positive 199 pregnancies were confirmed by clinical impression and follow-up and three were either not confirmed or not followed up. Therefore, no false positive reactions were recorded. There was one, possibly two, false negative reactions. One of these was with a urine sample from a patient who appeared clinically to be six weeks pregnant, who had a positive subsequent Aschheim-Zondek test, and who was then lost to follow-up. The other false negative result involved a patient who eventually spontaneously aborted. The pH range of the urine samples tested was found to be 5.0 to 8.5, and the specific gravities ranged from 1.004 to 1.037. Five of the urine samples (three posi-
tebruar) .4m. ,I. 0bstet.
Table V. Comparison of clinical impression. latex-inhibition slide tests for pregnancy*
time of last menstrual
1.5, 1979 Gyecol.
and results of ~&II.
Pregnant O-14 15-28 29-42 43-56 57-70 7 1-84 85.98 99-112 113-126 127-140 141-154 >250
Not specified *Gest
37 43 28 72 63 47 20 2 2 3 2 4 .i
0 0 7 6; 58 43 20 I I
5 Positive Ascheim-Zondek
37 43 21 .5 5t 3 0
6; 58 44t 18 0
10 2 0 4 3
2 0 2
tone patient showed secretory endometrium *Urine assayed 72 days after after LMP was positive; patient
37 43 21 5 5 4 0
2 0 2
lb 2 0 4 3
and had a curettage.
at which time the patient lost to follow-up.
test at an earlier date; curettage revealed products of conception.
tive, two negative) were glucose positive. Some of the urine samples were from women using oral contraceptives, antibiotics, tranquilizers, and amphetamines. Several urine samples contained red or white blood cells, bacteria, casts, or sediment. None of these conditions interfered with the results of the C;est V State or other pregnancy tests. One urine sample (nonpregnant) that contained Azo Gantrisin* had a delayed negative reaction (Z+ agglutination at two minutes and 4+ at two and a half minutes).
Comment In the comparative clinical series studied, the results obtained with the Gest 0 State test were identical to those obtained with three other rapid slide tests for pregnancy. No false positive results occurred, and there was only one false negative reaction, which occurred in urine from a patient who was six weeks pregnant. No interference with the performance of the Gest ? State occurred when urine samples with pH *Roche Labs., Div. Hoffman-La
ranges of 5.0 to 8.5, with specific gravity ranges of 1.004 to 1.037. or with blood cells, bacteria. sediments, or casts were tested. Urines from patients using oral contraceptives, antibiotics, tranquilizers, amphetamines, or other drugs did not give false results in this series. In the laboratory studies of the Gest P State, elevated levels of the normal constituents of urine did not affect the results of the test. No interference with the performance of the Gest 0 State occurred in urine that had pH ranges of 5.0 to 8.6 or specific gravity ranges of 1.004 to 1.074. High levels of protein or chlorpromazine added to urine did not give false negative or false positive results. Accurate results with Gest 9 State were observed in urine from nonpregnant women receiving psychotropic drug therapy and in urine that contained detergents. Over all, Gest P State was found to compare favorably with other rapid slide tests for pregnancy. We are indebted assistance.
to Mrs. E. Haubenstein
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Tait, B.: Med. J. Aust. 2: 126, 1971. Ravel, R., Riekers, H. G., and Goldstein, B. J.: AM. J. OBSTET. GYNECOL. 105: 1222, 1969. 8. Marks, V., and Shackcloth, P.: Br. Med. J. 1: 517, 1966. 9. Bell, J.: J. Clin. Pathol. 22: 79. 1969. 10. Knight, R. A., Kilpatrick, L.. and Porter, M. M.: Am. J. 6. 7.
Horwitz, C. A., Sinykin. M.. Hill, D.. Jerome, E., and Burke, M. D.: Obstet. Gynecol. 40: 563, 1972.