Amniotic fluid levels of human chorionic gonadotropin and its alpha and beta subunits in second-trimester chromosomally abnormal pregnancies

Direct Reading of Bona Fide Barcode Assays for Diagnostics with Smartphone Apps

The desire to develop new point-of-care (POC) diagnostic tools has led to the adaptation of smartphones to tackle limitations in state-of-the-art instrumentation and centralized laboratory facilities. Today's smartphones possess the computer-like ability to image and process data using mobile apps; barcode scanners are one such type of apps. We demonstrate herein that a diagnostic assay can be performed by patterning immunoassay strips in a bona fide barcode format such that after target binding and signal enhancement, the linear barcode can be read directly with a standard smartphone app. Quantitative analysis can then be performed based on the grayscale intensities with a customized mobile app. This novel diagnostic concept has been validated for a real-world application, i.e., the detection of human chorionic gonadotropin, a pregnancy hormone. With the possibility of multiplex detection, the barcode assay protocol promises to boost POC diagnosis research by the direct adaptation of mobile devices and apps.

Chinese weight-correction model for maternal serum markers in Down syndrome prenatal screening

OBJECTIVE

To determine the best weight-correction model by means of analyzing the relationship between maternal weight and maternal serum markers when screening for Down syndrome in China.

METHODS

Serum levels of alpha-fetoprotein (AFP) and free beta-human chorionic gonadotropin (hCG) were measured in 35,917 Chinese women during the second semester of a normal singleton pregnancy and converted to multiple of median (MoM) values. Using 2 methods of statistical analysis, the all-point method and the median regression method, 4 weight-correction models were then tried, the simple linear, reciprocal, quadratic, and log-linear regression models.

RESULTS

The median regression method performed better than the all-point method, and the quadratic regression model showed the best fit for both AFP and hCG in the median regression method, with adjusted R(2)s of 0.987 and 0.988, respectively.

CONCLUSION

The quadratic regression model was found to be the most suitable for Chinese pregnant women.

Amniotic fluid human chorionic gonadotrophin and alpha-fetoprotein levels in pregnancies conceived after assisted reproduction

OBJECTIVES

To study the alteration in the second-trimester maternal serum levels of human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) in pregnancies conceived after assisted reproduction.

METHODS

We compared the amniotic fluid hCG and AFP concentrations of 45 pregnancies with fresh embryo transfer and 25 pregnancies with frozen-thawed embryo transfer with 269 spontaneous pregnancies. Wilcoxon rank-sum test was used for analysis.

RESULTS

The median amniotic fluid hCG MoM in pregnancies conceived after frozen-thawed embryo transfer was significantly increased to 1.41 compared to 1.00 (p = 0.01) in naturally occurring pregnancies and 0.96 (p = 0.049) in pregnancies after fresh embryo transfer. Further analysis showed that this was only observed in frozen embryos fertilized by conventional insemination with MoM of 1.59. The AFP MoMs were similar among the groups.

CONCLUSIONS

The observed raised amniotic fluid hCG level in IVF-FET pregnancies may reflect the elevated maternal serum level in these pregnancies. Further studies should be directed towards exploring the underlying pathophysiology.

The influence of fetal sex in screening for Down syndrome in the second trimester using AFP and free beta-hCG

In a study of 30 802 unaffected pregnancies and 90 cases of Down syndrome I have analysed second trimester maternal serum alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (beta-hCG) and grouped the data by fetal sex. In pregnancies with an unaffected female fetus maternal serum AFP was significantly lower (3%) than in the presence of a male fetus, whilst free beta-hCG was significantly raised (7%) in the presence of a female fetus. These differences led to a significantly higher false positive rate in women carrying a female fetus (5.78% versus 4.64%). In pregnancies affected by Down syndrome the median AFP in the presence of a female fetus was not significantly different to that with a male fetus (0. 72 versus 0.73); similarly for free beta-hCG the difference (2.37 versus 2.48) was not statistically significant. Although the detection rate amongst male fetuses was slightly higher than in females (74% versus 66%), this was not statistically significant. Although fetal gender does appear to have a significant effect on maternal serum marker levels, leading to a higher false positive rate in females, in cases of Down syndrome there is no evidence that such marker differences are significant and consequently little evidence for any fetal gender bias in detection rates.

Amniotic fluid biochemistry in second-trimester trisomic pregnancies: relationships to fetal organ maturation and dysfunction

Protein and enzyme patterns were investigated in amniotic fluid samples of 12 trisomy 21 and five trisomy 18, between 11 and 16 weeks and of a control group of 50 chromosomally and anatomically normal pregnancies at the same gestational age. Positive correlations were found between gestational age and the concentration of urea (P<0.05), creatinine (P<0.01), beta2-microglobulin (P < 0.0001), hCG (P < 0.01), ALP (P < 0.001), LAP (P < 0.0001) and GGT (P <0.0005) in the amniotic fluid of euploid pregnancies. There were also significant correlations between the concentrations of the different variables measured except for hCG and AFP. Different protein and enzyme patterns were found in the amniotic fluid of aneuploid pregnancies where only beta2-microglobulin concentration was significantly correlated with advancing gestational age. The beta2-microglobulin concentration was significantly (P <0.05) higher in aneuploid fetuses presenting with hydrops compared to those without. These findings suggest that the changes in amniotic composition found during the fourth month of normal pregnancies reflect mainly the maturation of the fetal renal glomerular function and the arrival of enzymes from the digestive and respiratory tract into the amniotic cavity. In trisomy 21, there is evidence of a delay in the maturation of these organs whereas in trisomy 18, there is a reduced production of most proteins and enzymes.

Zygosity and placental anatomy in 15 consecutive sets of spontaneously conceived triplets

Most triplets are trizygotic because they result from assisted reproduction. Prognosis is generally good. We analyzed 15 sets of triplets who were conceived spontaneously. Six sets were monozygotic, 7 were dizygotic, and only 2 sets were trizygotic. Considered as 45 twin pairs, 25 pairs (56%) were monozygotic. Twenty percent of these twins died as a result of twin-twin transfusion. Spontaneously conceived triplets have high risks compared with those resulting from assisted reproduction. These risks result from a high proportion of monozygotic embryos, many of whom have monochorionic placentas with vascular anastomoses, causing twin-to-twin transfusion.