Substituting whole blood for urine in a bedside pregnancy test

BACKGROUND

Point-of-care testing for rapid detection of pregnancy in women of reproductive age is common practice in the emergency department. Commercially available rapid human chorionic gonadotropin (hCG) immunoassays are validated for use with urine and serum, but not whole blood.

STUDY OBJECTIVES

We assessed the validity of using whole blood to detect pregnancy using a point-of-care hCG assay by comparing it to a laboratory quantitative serum hCG assay as the criterion standard.

METHODS

A convenience sample of female patients of reproductive age (18-51 years) submitted 5mL of whole blood, from which two drops were immediately applied to a point-of-care hCG kit, with results recorded at 10min. The remainder of each whole blood specimen was sent to the hospital laboratory for the criterion-standard quantitative serum hCG assay. The criterion standard for a positive pregnancy test was defined as quantitative serum hCG≥5 mIU/mL. Investigators performing the whole blood test and laboratory technicians performing the quantitative serum assay were blinded to one another's results.

RESULTS

There were 633 patients enrolled, with a mean age of 30 years (± 7.7 years); 34% of the patients were pregnant. Overall, the whole blood pregnancy test was 95.8% sensitive (negative predictive value 97.9%), whereas the urine test was 95.3% sensitive (negative predictive value 97.6%); the specificity and positive predictive value of both tests was 100%.

CONCLUSION

Using a standard point-of-care qualitative hCG immunoassay kit, whole blood may be used for rapid detection of pregnancy with similar, or greater, accuracy than urine.

Concentration of bovine pregnancy associated glycoprotein in plasma and milk: its application for pregnancy diagnosis in cows

Pregnancy diagnosis is an important part in reproduction management of ruminants. The aim of the study was to use a new method for evaluating the bPAG and cPAG in milk and blood bPAG and compare this results with the other method for pregnancy diagnosis in the cows. The study was carried out in 220 Holstein Frisian cows. Heparinised blood samples were taken from the jugular vein and stored at -20 degrees C until PAG assay by RIA. For bPAG and cPAG, RIA test, milk samples were homogenized. Pure bPAG was used as a standard tracer described by Zoli et al. (1992). The cows were diagnosed as pregnant by means of USG (Aloka SSD 210) and by rectal palpation. bPAG and cPAG concentration in milk increased after 28 day of pregnancy and showed the rapid increase near the parturition. The same results of bPAG concentration we obtained in the blood samples. The decline of bPAG concentration was faster in the milk than in the blood. The data showed that the RIA method is precise enough to measure PAG concentrations in the maternal blood and milk of cows. The data indicate that milk samples can be used for pregnancy diagnosis in cows. The sensitivity and specificity of RIA measurement of PAG are very high.

Evaluation of early conception factor lateral flow test to determine nonpregnancy in dairy cattle

The early conception factor (ECF) lateral flow test was evaluated for its ability to accurately determine nonpregnant status in dairy cattle. Results of 2 field trials involving 191 cows and 832 tests indicated the probability that a cow can be correctly diagnosed as nonpregnant by using the ECF test is only about 50%. Agreement of test results between milk and serum obtained from the same cow was 57.5%. The ECF test was not consistent in identifying nonpregnancy when the same cows were tested repeatedly over a period of 4 weeks. We conclude that the ECF lateral flow test does not accurately identify nonpregnancy in dairy cattle.

Quantification of urinary chorionic gonadotropin in spontaneous abortion of pre-clinically recognized pregnancy: method development and analytical validation

Determination of environmental impacts on reproductive health and specifically on the incidence of early spontaneous abortion requires accurate estimates of the latter. This negative reproductive outcome can be detected by the pattern of elevation and decline of human chorionic gonadotropin (hCG) levels near and shortly beyond the expected time of implantation, requiring daily biomonitoring of hCG levels during the relevant period of the menstrual cycle. Prospective pregnancy studies to assess effects of potentially toxic exposures on human reproductive outcomes can involve up to three menstrual cycles and a huge number of samples in each, for the quantification of the inherently very low hCG levels usually can be determined only in serum. The invasive nature of blood collection, the number of samples needed for the development of prospective studies, and the lack of quantitative methods for the determination of low hCG levels in urine point to the need for collecting urine rather than blood and make it imperative to develop suitable quantitative methods for biomonitoring of very low levels of hCG in urine. This paper describes the development and validation procedures of an automated solid-phase two-site chemiluminescent immunometric assay for the quantification of urinary hCG in early pregnancy and early pregnancy loss. For the validation, both undiluted and diluted urine and control samples have been prepared. From the results, it can be concluded that the assay has a calibration range that extends to 5000 mIU/ml, with a detection limit of approximately 1.2 mIU/ml, practically identical to that found by the IMMULITE 2000 manufacturer's validation study. The intra- and inter-assay precision ranges up to a maximum of around 7%, meaning that the practical limit for functional sensitivity can be established as low as 10%. This means that the immunoassay from DPC can identify, with relatively high confidence, non-pregnant women and the typical "rise and fall" pattern of early pregnancy loss through analysis of urine samples. Results also lead to the conclusion that there is a very good agreement between expected and observed urinary hCG levels indicative of good immunoassay accuracy for the studied range of hCG concentrations. In terms of analyte stability, it can be concluded that urinary hCG is stable under the expected conditions required for ongoing investigations that include temperatures of 2-8 degrees C for up to 48 h and temperatures of around -20 degrees C for longer periods that can extend to over 3 months.

A single serum test for measuring early pregnancy outcome with high predictive value

OBJECTIVES

Current testing to determine a failing pregnancy requires two separate clinic visits to measure the hCG doubling rate. Diagnosing a failing pregnancy is often done in emergency departments where simplified and accelerated testing methods are needed. Here, we investigated hyperglycosylated hCG (hCG-H) for predicting pregnancy failure.

DESIGN AND METHODS

We studied two independent sets of patient samples collected in the early weeks of gestation. One set was urine samples, and the other was serum samples. In all cases, hCG and hCG-H were measured using automated chemiluminescence immunoassays. Concentrations of hCG and hCG-H were plotted on a scattergram, and levels in failing pregnancies were compared to those in continuing pregnancies.

RESULTS

Data indicated that a threshold level of hCG-H (13 microg/L) in both serum and urine samples defined the concentration below where pregnancies were likely to fail. This cut-off corresponded to 73% detection of failures at a 2.9% false positive rate using serum and 75% detection at a 15% false positive rate using urine. Using an hCG cut-off that corresponded to the same false positive rates, hCG detected only 42% of failures using serum and 43% of failures using urine.

CONCLUSIONS

Our data indicate that hCG-H provides a much more accurate single test than hCG for assessing pregnancy outcome. Compatible with the use of serum or urine samples, a single hCG-H test might provide simpler, faster, and more accurate results for predicting the progress of a pregnancy than standard hCG testing.

Frequent false positive beta human chorionic gonadotropin tests in immunoglobulin A deficiency

A patient with IgA deficiency had a series of positive serum pregnancy tests which led to medical and surgical procedures for suspected molar pregnancy. These tests were found to be falsely positive due to heterophile antibody. The aim of this study was to determine the frequency of false positive betahCG assays in sera of IgA deficient patients. Sera from a panel of IgA deficient (IgA < 7 mg/dl) patients were tested for the presence of betaHCG using three different assays, and also for IgG anti-goat and anti-mouse antibodies. Patients were seen at Mount Sinai Medical Center and included 54 patients (ages 1-80 years, 32 females, 22 males) with IgA deficiency. Thirty percent of 54 IgA deficient patient sera yielded positive pregnancy tests by one or more of the three betahCG assays, however, none of the patients were pregnant. In comparison to sera of normal controls, 39% of the patient sera contained significant amounts of anti-goat antibody and 18% contained significant amounts of anti-mouse antibody. While heterophile antibodies are common in IgA deficient serum, false positive assays for betahCG in IgA deficient serum have not been previously reported. The possibility of false positive test results should be considered prior to invasive procedures in IgA deficient patients.

Quantitative automated human chorionic gonadotropin measurement in urine using the Modular Analytics E170 module (Roche)

Ongoing demands on laboratory performance require optimization of processes. An obvious way to achieve this is to reduce manual labor in favor of automated methods. We describe the validation of an automated quantitative urine human chorionic gonadotropin (hCG) analysis on the Roche Modular E170 analyzer to replace the manual qualitative pregnancy test in urine. At urine hCG concentrations of 476, 45 and 11U/L, we found inter-assay variation of 4.3%, 4.3% and 6.8% and average intra-assay variation of 3.0%, 2.6% and 3.0%, respectively. The analytical detection limit was 0.7U/L. We did not detect any loss (due to degradation or adsorption) during a storage period of 5days at 4°C or at −20°C. Recoveries of hCG in urine of a pregnant woman diluted with urine of a pre-menopausal non-pregnant woman (concentration range between 6 and 800mU/L) were between 93% and 112% (y=0.997x−3.843, r

Hyperglycosylated hCG (invasive trophoblast antigen, ITA) a key antigen for early pregnancy detection

OBJECTIVES

Hyperglycosylated human chorionic gonadotrophin (hCG) is an hCG variant with extra-large O-linked oligosaccharides, produced by phenotypically invasive cytotrophoblast cells in choriocarcinoma and pregnancy. It is the principal form of hCG produced in the first weeks of gestation. We investigated the importance of hyperglycosylated hCG in pregnancy testing and its detection by current hCG tests.

DESIGN AND METHODS

We measured the concentration of hyperglycosylated hCG and total hCG in 512 pregnancies throughout gestation. We assessed and compared the abilities of 14 commonly used commercial laboratory hCG tests and 18 home pregnancy tests to detect regular and hyperglycosylated hCG.

RESULTS

Hyperglycosylated hCG is the principal source of hCG-related immunoreactivity in early pregnancy. In the week following missing menses, hyperglycosylated hCG measurements may be more sensitive than regular hCG measurements in detecting pregnancy. Of 14 commercial laboratory hCG tests, 3 appropriately detected hyperglycosylated hCG standard. Of 18 different home pregnancy products 11 poorly or very poorly detected this key antigen.

CONCLUSIONS

Hyperglycosylated hCG may be the key molecule in the detection of early pregnancy. However, the majority of tests poorly detected or failed to detect this key antigen. New pregnancy tests are needed that either solely detect hyperglycosylated hCG or equally detect regular hCG and hyperglycosylated hCG.

Early pregnancy diagnosis in swine by direct radioimmunoassay for progesterone in blood spotted on filter paper

A direct radioimmunoassay method for the measurement of progesterone in blood dried on filter paper has been developed for the early pregnancy diagnosis in sows, as well as for monitoring progesterone levels during the oestrous cycle. Pregnancy diagnosis was performed with 95 sows on Days 17-22 after artificial insemination (AI). The cut-off value for pregnancy diagnosis of 7.5 ng/ml was calculated (mean+/-2S.D.) from the progesterone concentrations measured on the same days from non-inseminated animals. There were 85 cases considered pregnant on the basis of progesterone concentration, leaving 10 animals non-pregnant. The accuracy for the positive cases was 98.8%. Two of the 10 sows considered as negative subsequently farrowed, giving an accuracy of 80%. The overall accuracy of the method was 96.8%. The blood-spot assay may be a useful tool for early pregnancy diagnosis in swine, with respect to sampling, simplicity, speed and accuracy.

Pregnancy-associated glycoproteins (PAG) detection in milk samples for pregnancy diagnosis in dairy goats

In ruminants, glycoproteins synthesized in the outer layers of the trophoblast enter the maternal bloodstream. The assay of their concentration in plasma or in serum can be used for pregnancy diagnosis and to indicate feto-placental health status. In this study, concentrations of the pregnancy-associated glycoprotein (PAG) were investigated in the milk of dairy goats. The mean concentrations of PAG in milk were significantly higher in pregnant than in non-pregnant goats throughout the sampling period. Positive milk PAG levels were found in all pregnant animals from Day 32 after breeding, but remained at negative values in nonpregnant ones. This study reports for the first time a pregnancy diagnosis based on milk concentrations of PAG, that could be of great use on the farm.

Evaluation of the early conception factor (ECF) test for the detection of nonpregnancy in dairy cattle

The ability to detect conception and/or conception failure in cattle would be beneficial to producers in formulating reproductive management plans. A new diagnostic test, the early conception factor (ECF) test, has been developed forthis application yetthe accuracy of this test has not been adequately determined. The objectives of this study were to evaluate the effectiveness of the ECF test for detecting the nonpregnant cow, and to compare the reliability of serum versus milk ECF tests relative to actual pregnancy rates. In Trial 1, Holstein heifers were synchronized, the animals were bred (timed-AI), and serum ECF tests were performed 72 h later. Heifers exhibiting a negative ECF test after AI were re-synchronized, bred again, and re-tested for ECF for up to three services. Relative to actual pregnancy rates, a negative ECF test was correct (i.e., true negative) 38.5% of the time over the three services. In Trial II, Holstein heifers were bred (AI) after observed estrus and serum ECF tests conducted between Days 1 and 3 and Days 7 and 9 after AI. In this trial, only 44.4% and 55.6% of the confirmed nonpregnant heifers were identified correctly by serum ECF analysis at Days 1 to 3 and Days 7 to 9 post-AI respectively. In Trial III, 40 lactating cows were synchronized, the animals were bred (AI), and serum and milk ECF tests were performed on Days 3, 9, 15, 21 and 30 after AI. Pregnancy diagnosis (ultrasound on Day 30 and palpation on Day 51) confirmed that 50% of the cows were pregnant to AI, while serum and milk ECF analysis indicated a 100% and 37.5% predicted pregnancy rate, respectively, at 30 d post-AI. Moreover, results of the serum and milk ECF tests disagreed with one another 36.9% of the time overall, while agreement between ECF and actual pregnancy rates were 50.6% and 45.6% for milk and serum respectively. Additionally in Trial III, a negative ECF result only identified 5% and 28.8% of nonpregnant cows overall for serum and milk tests respectively (i.e., true negatives), with a high incidence of false positive ECF results noted (47.5% and 31.3% for serum and milk, respectively). Collectively, these data indicate that the current ECF test cannot accurately identify the nonpregnant cow with the precision needed by the dairy producer.

Noninstrumented enzyme-linked immunosorbant assay for detection of early pregnancy in macaques

A practical, noninstrumented enzyme-linked immunosorbant assay (NELISA) for the measurement of urinary monkey chorionic gonadotropin (mCG) has been developed for the detection of early pregnancy in macaque monkeys for use in both the laboratory and the field. Five rhesus monkeys (Macaca mulatta) and six crab-eating monkeys (Macaca fascicularis) were tested for the presence of mCG in urine on gestational days (GDs) 12 to 35. The mCG NELISA detected pregnancy as early as GD 14, with an average earliest detection at GD 16.5 +/- 1.4 (n = 11). Out of 90 tests, 27 false-negative and zero false-positive tests were obtained, for an accuracy of 70.0%. Without the aid of a spectrophotometer, the presence of mCG in pregnant monkey samples was indicated by a dark green color change. Nonpregnant monkey urine samples, on the other hand, exhibited no color change. These findings suggest that the simple, economical, and reliable urinary mCG NELISA may be useful for diagnosing early pregnancy in these and related species. Because capture and restraint are unnecessary for collecting urine samples, the mCG NELISA has widespread potential for confined and free-ranging animals.

A commercial pregnancy test modified for field studies of fetal loss

We describe simple modifications to the ICON II hCG (URINE) pregnancy test to provide a sensitive and specific urinary assay for hCG in field studies of fetal loss. The modified assay had a qualitative lower limit of detection of 0.30 IU/l, a 50% qualitative limit of 0.61 IU/l, a 100% qualitative limit of 1.16 IU/l, and a quantitative limit of 0.80 IU/l. Coefficients of variation ranged from 9.9% to 21.1%. Parallelism was observed among serially diluted subject samples. We used the assay in an 11-month prospective study of fetal loss in rural Bangladesh in which urine samples were collected twice-weekly from 494 women; 330 pregnancies and 93 fetal losses were detected. The median time to a positive pregnancy diagnosis was day 26 from last menses. The modified assay provided qualitative detection of early pregnancy comparable to laboratory assays, and appears to be well suited for use in epidemiologic or rural-population fetal loss studies.

[Clinical trial of 2 highly sensitive pregnancy tests--Tandem ICON HCG-urine and OPCO One-step Pacific Biotech]

The highly sensitive pregnancy test, Tandem ICON HCG-urine, was compared with OPCO "One-step" Pacific Biotech in the gynecological and obstetrical department of Randers Hospital. The purpose was to determine the test specificity and sensitivity of the pregnancy tests in women with possible pregnancies. The test sensitivities were found to be 0.83 and 0.63 for ICON and ONE, respectively. We experienced one and four cases of negative pregnancy tests and ectopic pregnancies with ICON and ONE, respectively. In all cases, the diagnosis of ectopic pregnancy was suspected by other means and the patients submitted to operation. The ICON test showed its supremacy in diagnosis while ONE was easier and cheaper.

[Immunogold dot assay for diagnosis of early pregnancy]

Two monoclonal antibodies anti-HCG were prepared. One anti-alpha HCG was directly labeled with colloidal gold, and the other, anti-beta HCG was coated on nitrocellulose membrane as dot. After determination of optimal conditions of the system, an immunogold dot blot assay for testing HCG in urine sample was established. The sensitivity of the assay was 50 mIU HCG/ml, corresponding to the content of HCG in the urine of women about 30 days after last menstruation. The assay has been evaluated in clinical trial. All the testing results accorded with clinical diagnosis. No false positive results appeared. This simple, rapid and stable assay is ideal for women to diagnose early pregnancy at home.

Radioimmunoassay of a bovine pregnancy-associated glycoprotein in serum: its application for pregnancy diagnosis

A sensitive and specific double-antibody RIA for a bovine pregnancy-associated glycoprotein (bPAG) is described. The limit of detection was 0.2 ng/ml. The assay was specific for bPAG in that pituitary and placental gonadotropic hormones and other placental or serum proteins assayed in serial dilutions did not cross-react. The RIA allowed measurement of bPAG in placental extracts, fetal serum, fetal fluids, and serum or plasma of pregnant cows. About 20% of unbred heifers and nonpregnant cows had detectable levels ranging from 0.30 +/- 0.09 to 0.50 +/- 0.17 ng/ml (mean +/- SD), and 15% of bull sera showed higher concentrations (3.01 +/- 1.73 ng/ml) of bPAG or bPAG-like protein. Variations among animals was observed in fetal serum bPAG concentrations. Bovine PAG was detected in maternal peripheral blood at Day 22 of pregnancy (mean +/- SD, 0.38 +/- 0.13 ng/ml) in some animals and at Day 30 in all pregnant cows. Peripheral serum bPAG levels increased progressively to 3.60 +/- 1.73 ng/ml (mean +/- SD) at Day 30 of pregnancy, to 24.53 +/- 8.81 ng/ml at Day 120, and to 1551.91 +/- 589.68 ng/ml at Day 270. Peak concentration of bPAG was 2462.42 +/- 1017.88 ng/ml and it occurred 1-5 days prior to parturition. After delivery, bPAG concentrations decreased steadily to 499.63 +/- 267.20 ng/ml at Day 14 postpartum (pp), 10.12 +/- 7.84 ng/ml at Day 60 pp, and 1.44 +/- 1.08 ng/ml at Day 90 pp. The undetectable concentration (less than 0.20 ng/ml) was reached by Day 100 +/- 20 pp. An investigation undertaken in Holstein heifers, Holstein cows, and Hereford cows used as recipients for purebred Holstein embryos supplied evidence of the influence of breed of recipient and sex of fetuses on peripheral concentrations of bPAG. A herd of 430 Holstein-Friesian heifers that had received transferred embryos were bled at Day 35 postestrus (pe) for measurement of bPAG. The bPAG was detected in 287 of 430 serum samples analyzed. By rectal palpation performed at Day 45 pe, 267 heifers with detectable levels of bPAG at Day 35 pe were confirmed to be pregnant as were 3 of 143 heifers previously diagnosed as not pregnant by RIA. These results suggest that detection of this placental-specific antigen in the serum could be used as a specific serological method for early pregnancy diagnosis in cattle from 28 days after breeding.

Monoclonal antibody pregnancy tests

Urine and serum monoclonal antibody pregnancy tests are easier to use than latex agglutination-inhibition slide tests. Their more selective binding properties allow detection of low levels of human chorionic gonadotropin (HCG) in the urine and serum. These tests approach the accuracy of serum beta-HCG radioimmunoassays for confirmation of normal pregnancy or evaluation of possible abnormal pregnancy.

Evaluation of methods for the prospective identification of early fetal losses in environmental epidemiology studies

A major problem in the epidemiologic investigation of early fetal losses has been incomplete or biased ascertainment. In order to assess early fetal losses more accurately, one must first develop a simple method to identify early pregnancy. This study, conducted at the University of Pittsburgh from October 1985 through October 1986, has developed such a method through the use of monoclonal antibody urine pregnancy testing kits. A total of 88 volunteers collected urine samples beginning on the seventh postovulatory day and continued until either menses occurred or a serum radioimmunoassay pregnancy test was performed on day 16. If pregnancy was diagnosed, all of the participants' urine specimens from that menstrual cycle were analyzed by five monoclonal antibody tests. A total of 34 pregnancies were diagnosed, six (18%) of which resulted in early fetal losses. Pregnancy was first detectable between eight and 18 days postovulation. The mean time to the first positive test was 14 days for all five kits. The results indicate that it is possible to diagnose early pregnancy with urine testing and that this method is likely to prove acceptable for use in large-scale prospective studies.

Early pregnancy factor as a marker for the earliest stages of pregnancy in infertile women

Early pregnancy factor (EPF) is known to be detectable in sera of pregnant women within 24 to 48 h after conception. To examine the incidence of early embryonic loss after hormonal treatment and homologous artificial insemination, we screened the sera of our patients for the presence of EPF by means of a rosette inhibition test. Our results show a considerably lower conception rate as described in appropriate studies on fertile women. If reduced sperm quality is the indication for insemination, the abortion rate in the first 2 weeks of gestation is significantly increased in relation to the rest of our patients. Infertility because of an impaired development of the embryo, especially if repeated EPF-positive cycles do not result in a pregnancy, may be due to chromosomal defects or malformations and a chromosomal analysis is recommended. In patients in whom EPF is never found to be positive, indicating a disorder of conception, we regard IVF/ET to be the treatment of choice.

Assessment of pregnancy in sheep by analysis of plasma progesterone using an amplified enzyme immunoassay technique

An amplified enzyme immunoassay kit for progesterone analysis was used to diagnose pregnancy in a flock of 130 mule ewes. An accuracy of 100 per cent was obtained after the analysis of progesterone in plasma samples taken 15 to 16 days after mating. In mule ewes a plasma progesterone level greater than 5.9 nmol/litre was indicative of pregnancy. In the validation of the technique, duplicate ewe plasma samples and progesterone standards were compared with a radio immunoassay technique; the regression coefficient between the two techniques was r = 0.82.

Utility of a sensitive bedside serum pregnancy test

We compared the performance characteristics of a rapid qualitative serum pregnancy test with a standardized quantitative assay for human chorionic gonadotropin in the evaluation of women with suspected ectopic pregnancy. At a threshold value of 25 mIU/mL, the rapid assay demonstrated a sensitivity of 100% and a specificity of 96%.

Enzyme-linked immunosorbent urine pregnancy tests. Clinical specificity studies

The performance of six recently introduced highly sensitive enzyme-linked immunosorbent (ELISA) urine pregnancy test reagent kits was evaluated for false positive results using 100 male and 100 postmenopausal female urine specimens and the findings were compared with those of a qualitative radioimmunoassay (RIA) procedure. Based on the findings, the most suitable pregnancy test reagent kit was then selected for doing routine pregnancy testing of urine samples of premenopausal patients. The less sensitive PregnaSTICK ELISA method and Concept RIA procedure did not give any positive results. Positive results for postmenopausal female and male urine samples were obtained as follows: Testpack, 2 and 0 (greater than 50 mIU/mL [IU/L]); Icon, 2 and 0 (greater than 50 mIU/mL [IU/L]); Quest, 4 and 2 (greater than 50 mIU/mL [IU/L]); Nimbus, 17 and 4 (greater than 25 mIU/mL [IU/L]); and Sensi-Chrome, 33 and 19 (greater than 50 mIU/mL [IU/L]), respectively. The medical records of the patients whose urine samples gave positive results were examined for information that would have explained the positive results, but no clear-cut reasons were found. Comparison of the routine urinalysis findings showed that there was a correlation between the mucus content of female (but not of male) urine samples and the incidence of false positive human chorionic gonadotropin results. During 12 months of routine use of the Icon reagents for pregnancy testing of premenopausal urine samples, the University of Texas Medical Branch staff has not reported any suspected false positive findings to the authors.

Verification of early pregnancy tests in a multicenter trial

Tests for the diagnosis of early pregnancy have been available since 1974. However, no studies have systematically verified the accuracy of routine clinical laboratories in measuring human chorionic gonadotropin (hCG) prior to the time that pregnancy is clinically evident. We have conducted such a study in association with the NICHD-funded Diabetes in Early Pregnancy Study (DIEP). The purpose of this study was to elucidate the etiology of malformations in pregnancies complicated by diabetes mellitus, which probably occurs within the first few weeks of pregnancy, and therefore uniformity of pregnancy testing was necessary among the five centers to find an association of a teratogen at the time of organogenesis. We confirmed that routine clinical laboratories, in fact, could measure accurately hCG at the time of the missed menses; however, detection was not necessarily possible prior to that time. We conclude that in order to assure accurate diagnosis of early pregnancy, tests should ordinarily be delayed until time of the missed menses. When the test is used at this time, it is a reliable tool for early pregnancy testing and thus can be used to resolve questions relating to early pregnancy pathophysiology.

Monoclonal antibodies based sandwich erythro-immunoassay and 'dot' enzyme immunoassay for human chorionic gonadotropin in urine

Two simple solid-phase sandwich immunoassays for human chorionic gonadotropin (hCG) employing monoclonal antibodies have been described. One is a sandwich erythro-immunoassay employing V-shaped well microtitration plates coated with monoclonal anti-beta-hCG antibody and monoclonal anti-alpha-hCG antibody labelled sheep erythrocytes. The second is a 'dot' enzyme immuno-assay employing dip-stick (plastic strips pasted with nitrocellulose pads) coated with monoclonal anti-beta-hCG antibody. Anti-alpha-hCG monoclonal-alkaline phosphatase conjugate was used to reveal hCG bound to solid surface. The assays can be performed by 'one-step' or 'two-step' procedures. Erythro-immunoassay as well as 'dot' enzyme immunoassay was able to detect in urine as low as 10 mIU hCG/ml. A good correlation was observed between the values obtained by these two methods as well as 'two-step' sandwich enzyme immunoassay on 47 urine samples.

Performance of a new enzyme-linked immunoassay urine pregnancy test for the detection of ectopic gestation

An enzyme-linked immunoassay urine pregnancy test was used on a group of patients suspected of having an ectopic pregnancy. Patients were seen in the county hospital emergency department and had the urine test correlated with a serum beta-hCG level determined by radioimmunoassay. There were 884 patients with urine ICON-serum beta-hCG correlations. The ICON was positive in each of the 247 patients whose serum value was over 50 mIU/mL, and was negative in each of the 619 patients whose serum level was below 5 mIU/mL. Eighteen patients had a serum level between 10 and 50 mIU/mL and the ICON was positive in 13. The five patients with a low serum beta-hCG level and a negative ICON had dilute urine when tested. Using a modified testing procedure, each of these produced a positive ICON. Of the 27 patients with an ectopic pregnancy the urine ICON was positive in 26. The urine ICON is an improved assay for hCG in patients suspected of having an ectopic pregnancy, and is ideally suited for ED use.

Evaluation of new serum and urine tests in cases of suspected pathologic early pregnancy

Two pregnancy tests, ModEL serum hCG Assay and ModEL Urine hCG Assay, were evaluated using sera and urine from 46 patients suspected of pathologic early pregnancy, of whom 22 patients had spontaneous abortion and 9 an ectopic pregnancy. ModEL Serum hCG Assay had a 100% sensitivity and specificity, thus demonstrating its value in these cases. With a sensitivity of 94% and a specificity of 87%, ModEL Urine hCG Assay gave poorer results. Both tests have a relative high "detection limit" of 25 U/l (serum) and 50 U/l (urine) which may impair their ability to distinguish between presence and absence of pregnancy by very low levels of hCG.

Reliability of urinary pregnancy tests in the diagnosis of ectopic pregnancy

Recently a new generation of urinary pregnancy tests with increased sensitivity and specificity for beta-human chorionic gonadotropin (beta-HCG) was introduced. The clinical sensitivity of seven of these tests was evaluated in patients with surgically proven ectopic pregnancy. Two enzyme-linked immunosorbent assays (Tandem Visual, Hybritech; Mod C1, Monoclonal Antibodies), with a sensitivity of 50 mIU of beta-HCG, were positive in 90% of ectopic pregnancies. The three-tube tests (Sensitex, Roche; UCG Beta Stat, Wampole; beta-Neocept, Organon), with a sensitivity of 150-250 mIU of beta-HCG, were positive in 81-85% of ectopic pregnancies. Two slide tests (UCG Beta Slide, Wampole, and Sensislide, Roche), with a sensitivity of 500-800 mIU of beta-HCG, were positive in 51-61% of ectopic pregnancies. Both the immunosorbent assays and the tube tests were statistically more sensitive than the slide tests (P less than .001). There was no statistically significant increase in sensitivity between the tube tests and the immunosorbent assays. The sensitivities of these tube tests in ectopic pregnancy are similar to those of tube tests from other manufacturers previously reported on.

Evaluation of a rosette inhibition test for pregnancy diagnosis in pigs

A rosette inhibition test was developed using pig lymphocytes and sheep red blood cells. Antilymphocyte serum (ALS) in the presence of complement inhibited rosette formation by greater than 95% at 1/250 declining to no inhibition at 1/8000. Sera obtained from a total of 14 pregnant sows before and 1, 2, 3 and 4 wk after mating were tested for their ability to augment the rosette depression caused by ALS. In one experiment in which the responses of 4 pregnant sows were compared to 4 non-pregnant sows by discriminant analysis, sera were classified correctly in 83% of the samples taken from either pregnant or non-pregnant sows. When the more usual method of calculating the rosette inhibition titre was used, the responses of sera from pregnant pigs were classified with 31% accuracy and those from non-pregnant pigs with 80% accuracy. In a second experiment, sera from 10 pregnant sows were classified with 25% accuracy using the rosette inhibition titre. Thus 4 of these pigs were classified as non-pregnant by this method. Data from the second experiment were not suitable for discriminant analysis. It was concluded that there was some factor present in the sera of pregnant pigs, particularly by 3 or 4 wk post-mating, which could be detected by the rosette inhibition test. However, the test is not sensitive enough to allow specific diagnosis of early pregnancy in pigs.

Early detection of pregnancy by new beta-hCG monoclonal urine test

1,066 urine samples were assayed by beta-human chorionic gonadotrophin (beta-hCG) monoclonal pregnancy test with a sensitivity of 150 IU hCG/l. Tests were performed in 5 independent laboratories and results were compared with those of pregnancy tests which were used routinely. Urine samples which showed discordant results under evaluation were reassayed for beta-hCG using radioimmunoassay. 569 urine samples were from nonpregnant women, and a consistent result with comparison pregnancy tests was achieved in 97.19% of urine samples. The trial test from 389 urine samples of pregnant women was 99.49% in accordance with routine pregnancy tests. Results from 108 urine samples of women over 40 years of age indicate the high specificity of the new beta-hCG monoclonal pregnancy test. Titration experiments showed 63% positive tests at 150 IU beta-hCG/l. Data presented combine to suggest that this new monoclonal pregnancy test is a valuable aid in diagnosing early pregnancy. It may also be used in the diagnosis of tubal pregnancy and in other ectopic processes.

Clinical evaluation of two urine tests for the early diagnosis of pregnancy

We compared the performance of two immunologic tests for hCG in urine with a qualitative serum hCG assay. The latex agglutination assay ( Sensi -Tex) was found to be superior to a hemagglutination assay (Beta-Stat) in that fewer equivocal results were obtained with it. Excluding equivocal results, both urine tests agreed well with the results of the serum qualitative hCG assay. Interference by human menopausal gonadotropins occurred at higher concentrations with Sensi -Tex than with Beta-Stat, suggesting that the Sensi -Tex reagents have greater specificity. We recommend that laboratories examine the performance of available urine pregnancy tests on site before selecting a reagent system for routine use.

[Studies of early pregnancy factor by rosette inhibition test using monoclonal antibody]

We established a new stable rosette inhibition test using anti-human T-cell and anti-mouse Thy-1 monoclonal antibody, instead of antilymphocyte serum for the testing of immunosuppressive early pregnancy factor (EPF). The results obtained with this experimental system are as follows. Serum of pregnant mouse and woman indicated the immunosuppressive activity as inhibition of rosette formation. Serum of pregnant mouse inhibited rosette formation between human lymphocytes and heterologous erythrocytes as well as mouse spleen cells. It indicated that EPF, at least partially, is species-independent. In mouse serum, EPF became evident within 8 hours after mating, and declined at 4 days before term. In human pregnancy, EPF was detected in the 1st and 2nd trimesters but the rosette inhibition declined to the nonpregnant range in the 3rd trimester. In patients with threatened miscarriage and poor prognosis, the rosette inhibition declined. Surgical abortion led to normalization of the rosette formation within 18 to 24 hours. To investigate the origin of EPF, an in vitro fertilization system for mouse was employed. Immunosuppression was demonstrated in the culture medium of a two cell-stage embryo.

Enzyme immunoassay of the glycoprotein tropic hormones--choriogonadotropin, lutropin, thyrotropin--with solid-phase monoclonal antibody for the alpha-subunit and enzyme-coupled monoclonal antibody specific for the beta-subunit

Monoclonal antibody technology has made it possible to produce homogeneous populations of antibodies to discrete determinants on an antigen surface. We have produced monoclonal antibodies to the alpha-subunit and beta-subunits of the glycoprotein hormones choriogonadotropin, thyrotropin, and lutropin, and developed two-site simultaneous enzyme-linked immunospecific assays for these hormones. The anti-alpha-subunit monoclonal antibody was used as the solid-phase (coated tube) capture antibody for all three hormones; the anti-beta-subunit monoclonal antibodies were coupled to horseradish peroxidase (EC 1.11.1.7). Cross reactions between the closely related choriogonadotropin and lutropin were apparently greater in this method than in RIA, with use of the same antibodies. Ka of the antibodies did not appear to be as critical to sensitivity of the sandwich assay as it was for RIA. The lower limit of detection was 0.2 microgram/L after a 2-h incubation with serum sample at room temperature and a 30-min incubation with enzyme substrate at room temperature after washing away excess enzyme conjugate. Within-assay precision (CV) was very good, less than 6%.

Home testing for pregnancy--can it be recommended?

A kit for home testing for pregnancy (Predictor) was tested by 201 volunteers with a menstrual delay of eight days or more who had requested a pregnancy test at a pharmacy. This number corresponds to two-thirds of the women attending the pharmacy for this purpose during the study period. The same urine sample was also tested by experienced analysts with Pregnosticon All-In--an essentially identical method with a guaranteed sensitivity of 1000 U/1 (2nd IS)--as well as assayed for choriogonadotrophin (CG) content by a sensitive and specific radioimmunoassay. Of 101 samples with a CG concentration of more than 1000 U/1 all were positive with the home test. Of 95 samples with a CG concentration below 1000 U/1, 91 were recorded as negative, two as equivocal and two as positive. The figures for sensitivity and predictive values of positive and negative test results were thus 98-100%, and those for Pregnosticon All-In were 99-100%. We conclude that home testing for pregnancy with suitable reagents may offer acceptable sensitivity and efficiency.

Validation of the rosette inhibition test for the detection of early pregnancy in women

The authors validated use of the rosette inhibition test for the detection of early pregnancy factor (EPF) in human pregnancy, first by optimizing conditions for the assay, using known pregnant and nonpregnant sera, and second, by examining the performance of this assay in three clinical situations: a "blind" study involving coded first-trimester sera showed 80% correlation with pregnancy status; serial assay of EPF activity in sera collected from normal women attempting to conceive, correlated with human chorionic gonadotropin beta-subunit (beta-hCG) levels and pregnancy status; a longitudinal study of serial serum samples through two normal pregnancies showing the continued presence of EPF until the early third trimester in each case. It was concluded that with the rosette inhibition assay, consistent demonstration of a pregnancy-associated substance (EPF) could be obtained.