Serum biomarkers of tubal ectopic pregnancy: current candidates and future possibilities

Conventional and modern markers of pregnancy of unknown location: Update and narrative review

Pregnancy of unknown location (PUL) is a temporary pathologic or physiologic phenomenon of early pregnancy that requires follow up to determine the final pregnancy outcome. Evidence indicated that PUL patients suffer a remarkably higher rate of adverse pregnancy outcomes, represented by ectopic gestation and early pregnancy loss, than the general population. In the past few decades, discussion about PUL has never stopped, and a variety of markers have been widely investigated for the early and accurate evaluation of PUL, including serum biomarkers, ultrasound imaging features, multivariate analysis, and the diagnosis of ectopic pregnancy based on risk stratification. So far, machine learning (ML) methods represented by M4 and M6 logistic regression have gained a level of recognition and are continually improving. Nevertheless, the heterogeneity of PUL markers, mainly caused by the limited sample size, the differences in population and technical maturity, etc., have hampered the management of PUL. With the advancement of multidisciplinary integration and cutting-edge technologies (e.g. artificial intelligence, prediction model development, and telemedicine), novel markers, and strategies for the management of PUL are expected to be developed. In this review, we summarize both conventional and novel markers (represented by artificial intelligence) for PUL assessment and management, investigate their advancements, limitations and challenges, and propose insights on future research direction and clinical application.

Comparisons of Fertility Outcomes Following a Salpingectomy and a Salpingotomy with or Without Suturing for a Tubal Ectopic Pregnancy

Objective

This study aimed to compare fertility outcomes in patients who underwent different laparoscopic surgeries and to determine the most beneficial surgical treatment for tubal ectopic pregnancy (EP) patients who wished to become pregnant in the future.

Methods

In this retrospective study, patients aged 18–36 years, who had been diagnosed with a tubal EP in our hospital, were enrolled. Based on the treatment methods, the patients were divided into three groups, ie a salpingectomy group, a salpingotomy with suturing group and a salpingotomy without suturing group. The follow-up time for the enrolled patients was more than three years. Serum beta (β)-human chorionic gonadotropin (β-HCG) levels were monitored after surgery. The intrauterine pregnancy (IUP) rate at 12, 24 and 36 months postoperatively, and recurrent EP rate were compared.

Results

The median time for β-HCG level returning to normal in the salpingectomy group was much shorter than in the salpingotomy with suturing or salpingotomy without suturing groups (P < 0.001). The 12, 24 and 36-month IUP rates among the three groups were not significantly different. A recurrent EP was found in only one patient in the salpingotomy with suturing group and two patients in the salpingotomy without suturing group.

Conclusion

In this study, we found that salpingectomy and salpingotomy with or without suturing methods reflected no significant differences in fertility outcomes for tubal EP patients.

Progesterone and Inflammatory Response in the Oviduct during Physiological and Pathological Conditions

Progesterone has been shown to be a potent suppressor of several inflammatory pathways. During pregnancy, progesterone levels increase, allowing for normal pregnancy establishment and maintenance. The dysregulation of progesterone, as well as inflammation, leads to poor pregnancy outcomes. However, it is unclear how progesterone imbalance could impact inflammatory responses in the oviduct and subsequently result in early pregnancy loss. Therefore, in this review, we describe the role of progesterone signaling in regulating the inflammatory response, with a focus on the oviduct and pathological conditions in the Fallopian tubes.

The Role of Interleukin in Ectopic Pregnancy: A Systematic Review

BACKGROUND: Ectopic pregnancy (EP) is the implantation of an embryo outside the eutopic cavity with the most location of EP is in the fallopian tube (FT), known as tubal EP (TEP). The FT of TEP expresses higher levels of pro-inflammatory cytokines such as interleukin-1 (IL-1), IL-6, and IL-8. AIM: The study aimed to look systematically into the current literature and carefully analyze the results to explore the role of IL in EP. METHODS: Three independent reviewers conducted the literature search through some electronic databases searching for articles fulfilling inclusion and exclusion criteria. The lead author independently assessed the risk of bias of each of the 313 articles identified in database searching, 12 articles met the criteria for this review. CONCLUSION: IL-6 and IL-8 have diagnostic significance in predicting EP with the cutoff levels of IL-6 and IL-8 which were 26.48 and 40 pg/mL. Further, research is needed for the role of other interleukins in EP.

Serum calponin 2 is a novel biomarker of tubal ectopic pregnancy

OBJECTIVE

To evaluate serum protein calponin 2 (CNN2) as a candidate biomarker for tubal ectopic pregnancy (EP).

DESIGN

Retrospective study.

SETTING

Single University affiliated tertiary hospital.

PATIENT(S)

Serum samples were obtained from 84 patients with EP, 39 with viable intrauterine pregnancy (vIUP), and 42 with miscarriage. Moreover, 10 fallopian tube and corresponding villous tissue samples from patients with EP, 6 villous tissue samples from patients with vIUP, and 10 villous tissue samples from patients with miscarriage were collected.

INTERVENTION(S)

Serum CNN2 concentrations were measured using enzyme-linked immunosorbent assay; CNN2 expression in tissues was evaluated via immunohistochemistry and quantitative real-time polymerase chain reaction analysis.

MAIN OUTCOME MEASURE(S)

The diagnostic performance of serum CNN2 to discriminate an EP from vIUP and miscarriage.

RESULT(S)

CNN2 was highly expressed in villous stromal cells isolated from patients with EP, and CNN2 messenger ribonucleic acid expression was upregulated in villous tissues from women with EP compared with that in women with vIUPs and miscarriages. Serum CNN2 concentration was higher in women with EP than that in women with vIUP and miscarriage. The serum CNN2 predicted EP from vIUP and miscarriage with areas under the curve (AUCs) of 0.931 (95% confidence interval: 0.889-0.975). For discriminating EP from miscarriage only, the AUC was 0.906 (95% confidence interval: 0.835-0.977). In contrast, the AUCs for serum human chorionic gonadotropin were 0.809 and 0.637, respectively.

CONCLUSION(S)

Our data highlight the possibility of serum CNN2 as a single biomarker for the diagnosis of EP.

CLINICAL TRIAL REGISTRATION NUMBER

ChiCTR 1900020483.

The relationship between serum thiol levels and thiol/disulfide homeostasis in women with tubal ectopic pregnancy

OBJECTIVE

The aim of this study was to investigate the thiol/disulfide homeostasis in tubal ectopic pregnancies in terms of early diagnosis of the disease.

DESIGN

A prospective case-control study was carried out between June 2017-February 2018 in the Gynaecology Department of Umraniye Medical and Research Hospital.

MATERIALS AND METHODS

A total of 42 women with ectopic pregnancy were compared with 44 healthy women who have intrauterine first trimester pregnancies. The thiol/disulfide homeostasis is evaluated with the spectrophotometric measurement method that was recently developed by Erel&Neselioglu.

RESULTS

Disulfide/native thiol and disulfide/total thiol ratios were increased (p = 0.018 and p = 0.023 respectively), while native thiol/total thiol ratios and native thiol levels were decreased in tubal ectopic pregnancy group according to control group (p = 0.023). Between control and tubal ectopic pregnancy groups no differences were measured in disulfide levels (p = 0.350). The area under curve for native thiol and total thiol were 0.937 and 0.927, respectively. The optimum cut off value for native thiol was 379.95 μmol/l with a sensitivity of 90% and specificity of 81%. The optimum cut off value for total thiol was 432.5 μmol/l had 92% sensitivity and 79% specificity.

LIMITATIONS

In the study, whether intrauterine pregnancies resulted in miscarriage or delivery can be examined.

CONCLUSION

Increased disulfide/native thiol levels, disulfide/total-thiol ratio and decreased native/total thiol ratio were found to be significantly associated with the presence of tubal ectopic pregnancy which can be useful for the early diagnosis of the disease.

Alteration of the immune cell profiles in the pathophysiology of tubal ectopic pregnancy

Tubal ectopic pregnancy (TEP) refers to implantation of conceptus in the fallopian tube. It makes up over 98% of ectopic pregnancy (EP), which is the leading cause of maternal morbidity and mortality in the first trimester of pregnancy. Immune cells at the maternal-fetal interface play important roles in the process of embryo implantation, stroma decidualization, and early placental development. Alterations in the composition, phenotype, and activity of the immune cells in the fallopian tubes contribute toward the onset of TEP. In this review, we compare the leukocytic proportions in decidua of normal pregnancy, and in decidua and fallopian tubes of TEP. The possible functions of these immune cells in the pathophysiology of TEP are also discussed.

Evaluation of maternal serum ischemia modified albumin and total antioxidant status in ectopic pregnancy

BACKGROUND

Ectopic pregnancies constitute about 2% of all pregnancies which are the leading cause of pregnancy-related deaths and a considerable cause of maternal morbidity. Oxidative stress can lead to a number of pregnancy related diseases including miscarriage, eclampsia and preterm labor. Ischemia modified albumin (IMA) which reflects the oxidative stress may be used as a marker for ectopic pregnancy. Our aim was to compare the levels of IMA and total antioxidant status (TAS) in ectopic and normal pregnancies and to understand if IMA can be used as a marker to diagnose ectopic pregnancy.

MATERIALS AND METHODS

Our case-control study consisted of 38 women with ectopic and 42 women with normal pregnancy. IMA and TAS levels were determined in serum samples with an albumin-cobalt binding test and by commercially available kits, respectively. IMA levels were adjusted according to serum albumin levels. Index of oxidation (IOS) was calculated by dividing adjusted IMA (A-IMA) levels with TAS. A receiver operating characteristics (ROC) curve analysis was made and cut-off values for the biomarkers were investigated in SPSS 21.0 program (SPSS, Chicago, IL). Data were presented as mean ± standard deviation and a p value < .05 was accepted as statistically significant.

RESULTS

There was a statistically significant difference in IMA, A-IMA, and IOS levels between ectopic and normal pregnancies. Although TAS level was not different statistically, it was lower in ectopic pregnancy. According to ROC curve analysis, IOS had the largest area under curve. A cut-off value of 0.545 for IOS had 81.6% sensitivity and 59.5% specificity.

CONCLUSIONS

According to our study, oxidative stress plays an important role in ectopic pregnancy and either A-IMA or IOS can be evaluated as a marker of ectopic pregnancy after further studies.

Developing a deeper insight into reproductive biomarkers

The development of biomarkers of reproductive medicine is still in its infancy because many black boxes are still present in reproductive medicine. Novel approaches to human infertility diagnostics and treatment must be developed because reproductive medicine has lagged behind in the implementation of biomarkers in clinical medicine. Despite the dearth of the available literature, the current rapid pace of publications suggests that this gap will soon be filled therefore; this review is a précis of the research that has been done so far and will provide a basis for the development of biomarkers in reproductive medicine.

Factors to consider in pregnancy of unknown location

The management of women with a pregnancy of unknown location (PUL) can vary significantly and often lacks a clear evidence base. Intensive follow-up is usually required for women with a final outcome of an ectopic pregnancy. This, however, only accounts for a small proportion of women with a pregnancy of unknown PUL location. There remains a clear clinical need to rationalize the follow-up of PUL so women at high risk of having a final outcome of an ectopic pregnancy are followed up more intensively and those PUL at low risk of having an ectopic pregnancy have their follow-up streamlined. This review covers the main management strategies published in the current literature and aims to give clinicians an overview of the most up-to-date evidence that they can take away into their everyday clinical practice when caring for women with a PUL.

Circulating MicroRNAs as Potential Molecular Biomarkers in Pathophysiological Evolution of Pregnancy

MicroRNAs represent nonprotein coding small RNA molecules that are very stable to degradation and responsible for gene silencing in most eukaryotic cells. Increased evidence has been accumulating over the years about their potential value as biomarkers for several diseases. MicroRNAs were predicted to be involved in nearly all biological processes from development to oncogenesis. In this review, we address the importance of circulating microRNAs in different conditions associated with pregnancy starting with the implantation period to preeclampsia and we shortly describe the correlation between placental circulating miRNAs and pregnancy status. We also discuss the importance of microRNAs in recurrent abortion and ectopic pregnancy.

The Role of Serum Beta hCG in Early Diagnosis and Management Strategy of Ectopic Pregnancy

INTRODUCTION

The presentation of Ectopic Pregnancy (EP) can be highly variable and serum Beta hCG estimation plays an important role in early diagnosis.

AIM

Aim of the study was to determine the trends of hCG levels in EP and to explore the role of hCG in decisions related to management and follow-up of EPs.

MATERIALS AND METHODS

A retrospective study of women who had EPs from January 2006 to December 2012 at an advanced tertiary care centre in southern India was carried out. These women had undergone treatment based on the hospital protocol.

RESULTS

The study identified 337 women with EP. Thirty one surgically confirmed cases were diagnosed below the discriminatory zone of 1500 mIU/ml. Among women who had Beta hCG estimations 48 hours apart, plateauing was observed in 22.5% while decrease >15% was noted in 26.8%. Almost half (47.9%) of the cases had an increase >15% and a few (2.8%) demonstrated an initial fall followed by a rise in titres. In 23.9% of these women, there was a rise >53% similar to intrauterine pregnancy. The average pre-treatment Beta hCG was 429.8, 3866.2 and 12961.5 mIU/ml for those who received expectant, medical and direct surgical treatment respectively. 43 women with relative contraindications received medical management and 39 were lost to follow-up after medical and expectant management. Excluding them, the success rate of these two modalities was 76.6% and 85.0% respectively.

CONCLUSION

No single level of Beta hCG is diagnostic of EP and serial levels can demonstrate atypical trends in some cases. Hence, interpretation of these results should be done in conjunction with clinical and sonographic findings to arrive at a correct diagnosis.

Evaluation of mean platelet volume in unruptured ectopic pregnancy: A retrospective analysis

We aimed to investigate and compare the mean platelet volume (MPV) levels in ectopic and viable intrauterine pregnancy (IUP). The medical records of 78 unruptured tubal ectopic pregnancy patients (TEP, Group 1) and 150 patients with viable IUP (Group 2) served as control group between May 2014 and February 2015 in our clinic were retrospectively analysed. The demographic characteristics including age, parity, gravida, abortus, haemoglobin levels and leucocyte counts showed no statistically difference between two groups. The mean MPV level was significantly lower in TEP group compared to IUP group (8.69 ± 1.14 and 10.06 ± 1.46, p < 0.001). The platelet (PLT) distribution width was higher in TEP group, however, there was no statistical difference between the two groups (p = 0.078). The early diagnosis of TEP is crucial in order to prevent maternal morbidity and mortality. Our results showed that MPV is lower in TEP than IUP and it seems to be related with the possible inflammation at implantation site of tuba uterina. However, there is need for further studies for employing PLT indices in the diagnosis of TEP.

Does adenosine deaminase activity play a role in the early diagnosis of ectopic pregnancy?

Early diagnosis of ectopic pregnancy (EP) is important due to life-threatening consequences in the first trimester of pregnancy. In this study we aimed to investigate the role of adenosine deaminase (ADA) activity in the prediction of EP. Forty-one patients with unruptured ectopic pregnancy comprised the case group and forty-two first trimester pregnant women with shown foetal heart beating in ultrasound comprised the control group. The mean ADA level in EP (10.9 ± 3.0 IU/L) was higher than that in control group (9.2 ± 3.6 IU/L) (p = 0.018). Receiver operating characteristics or ROC curve identified ADA value of 10.95 IU/L as optimal threshold for the prediction of EP with 56% sensitivity and 67% specificity. High ADA levels are valuable in the early diagnosis of EP. However more comprehensive studies are required.

Role of activins in embryo implantation and diagnosis of ectopic pregnancy: a review

Embryo implantation is a major prerequisite for the successful establishment of pregnancy. Ectopic implantation outside the intrauterine cavity and the development of ectopic pregnancy (EP) is a major cause of maternal morbidity and occasionally mortality during the first trimester. EP may be induced by failure of tubal transport and/or increased tubal receptivity. Activins, their type II receptors and follistatin have been localised in the human endometrial and tubal epithelium and they are major regulators of endometrial and tubal physiology during the menstrual cycle. Pathological expression of activins and their binding protein, follistatin, was observed in tissue and serum samples collected from EP. Several studies with different designs investigated the diagnostic value of a single measurement of serum activin-A in the differentiation between normal intrauterine and failing early pregnancy and the results are controversial. Nevertheless, the diagnostic value of activins in EP, including the other activin isoforms (activin-B and -AB) and follistatin, merits further research. This review appraises the data to date researching the role of activins in the establishment of normal pregnancy and, pathogenesis and diagnosis of tubal EP.

MicroRNA and implantation

We provide a review of microRNA (miRNA) related to human implantation which shows the potential diagnostic role of miRNAs in impaired endometrial receptivity, altered embryo development, implantation failure after assisted reproduction technology, and in ectopic pregnancy and pregnancies of unknown location. MicroRNAs may be emerging diagnostic markers and potential therapeutic tools for understanding implantation disorders. However, further research is needed before miRNAs can be used in clinical practice for identifying and treating implantation failure.

Can Mean Platelet Volume and Platelet Distrubition Width be Possible Markers for Ectopic Pregnancy and Tubal Rupture? (MPV and PDW in Ectopic Pregnancy)

OBJECTIVE

We aimed to evaluate the alterations in serum levels of platelet indices such as mean platelet volume (MPV) and platelet distribution width (PDW) in ectopic pregnancy (EP) and discuss the mechanism of the alterations in MPV and PDW.

METHODS

This retrospective evaluation of 153 tubal EP patients (39 ruptured and 114 non-ruptured) admitted to our clinic between 2009 and 2013 and 67 healthy pregnancies was conducted. The data regarding the maternal age, hemoglobin level, platelet level, MPV, PDW was analyzed.

RESULTS

MPV was lower in the EP, especially in ruptured EP, compared to control group. However, no significant difference could be found between the groups (p=0.616). PDW was higher in the EP, especially in ruptured EP, compared to control group, however there was no statistical difference between the three groups (p=0.451). Platelet counts were significantly lower in ruptured EP compared to non-ruptured ectopic pregnancies and control groups (p=0.005).

CONCLUSIONS

MPV seems to be lower in ruptured EP suggesting the possible high grade inflammation in pathology. Platelet counts tend to be lower in ruptured EP suggesting the consumption of the platelets at the inflammation site. However, further studies are needed to describe the usefulness of the platelet indices in the diagnosis and clinical follow-up of EP. Our preliminary results show that MPV levels may decrease in the ruptured EP cases. At the same time, PDW levels may increase.

Activin A and follistatin as biomarkers for ectopic pregnancy and missed abortion

Activin A as a predictor of pregnancy failure has been the focus of heated debate, but the value of a combined activin A and follistatin (FS) measurement in serum to predict pregnancy failure has not been reported yet. We assessed whether a single serum measurement of the two physiological antagonists at 6–8 weeks gestation could differentiate ectopic pregnancies (EP) or missed abortions (MA) from healthy intrauterine pregnancies (IUP). activin A concentrations were significantly lower in women with EP (n = 30, median value of 264 pg/mL) and women with MA (n = 30, median value of 350 pg/mL) compared to IUP (n = 33, median value of 788 pg/mL); P < 0.001. At a threshold value of 505 pg/mL, activin A had 87.9% sensitivity and 100% specificity and negative predictive value of 0.974 for discriminating an ectopic pregnancy from viable pregnancies. FS was able to discriminate IUP from EP (ROC curve P < 0.001) as was their ratio (ROC curve P = 0.008), but was unable to discriminate a MA from an EP. In EP, activin A did not correlate with beta HCG levels. The present findings support the thesis that activin A or FS could be considered promising biomarkers for the discrimination between an IUP and a failed pregnancy (MA or EP).

Comparison of the diagnostic values of circulating steroid hormones, VEGF-A, PIGF, and ADAM12 in women with ectopic pregnancy

Background

Several peripheral proteins that might be useful for detecting the presence of ectopic pregnancy (EP) have been evaluated, but none have been proven entirely useful in the clinic. We investigated the presence and the possible changes in circulating molecules that distinguish between normal intrauterine pregnancy (IUP) and tubal ectopic pregnancy.

Methods

Non-pregnant women during the menstrual cycle, women with IUP, and women with tubal EP after informed consent. Serum levels of 17β-estradiol (E2), progesterone (P4), testosterone (T), beta-human chorionic gonadotropin (β-hCG), vascular endothelial growth factor-A (VEGF-A), placental growth factor (PIGF), and a distintegrin and metalloprotease protein 12 (ADAM12) were analyzed. Receiver operating characteristic analysis was used to assess the diagnostic discrimination of EP and gestational age-matched IUP.

Results

E2, P4, PIGF, and ADAM12 levels increased and β-hCG decreased throughout IUP. E2 and VEGF-A levels were significantly different between women with tubal EP and IUP. However, using a serum β-hCG cut-off of less than 1000 mIU/mL, P4 was significantly lower in women with tubal EP compared to IUP. Although E2 was inversely correlated with VEGF-A in women in the early stages of IUP, E2 was not correlated with VEGF-A in women with EP prior to tubal surgery. There were no significant differences in either PIGF or ADAM12 alone between women with tubal EP or IUP. Although no significant correlations were seen between E2 and PIGF or P4 and ADAM12 in women in the early stages of IUP, E2 was positively correlated with PIGF and P4 was positively correlated with ADAM12 in women with EP prior to tubal surgery. Our studies defined associations but not causality.

Conclusions

Individual measurements of serum E2 or VEGF-A levels are strongly related to early pregnancy outcomes for women with IUP and EP, and pregnancy-associated E2 and VEGF-A levels provide diagnostic accuracy for the presence of tubal EP. This study demonstrates that correlation analysis of E2/VEGF-A and E2/PIGF serum levels may be able to distinguish a tubal EP from a normal IUP.

Serum biomarkers for detecting ectopic pregnancy

Unless an ectopic pregnancy is visible by ultrasound, diagnosis can be a challenge. Differentiating ectopic pregnancies from intrauterine pregnancies can be impossible without intervention or follow-up. This poses a clinical dilemma to the practitioner given the inherent danger to the mother of tubal rupture of an ectopic pregnancy versus the fear of intervening in the case of a desired pregnancy without certainty of diagnosis. Early diagnostic modalities are clearly lacking, and serum biomarkers are currently being investigated as a solution to need for a rapid and accurate test for ectopic pregnancy.

Diagnostic applications for inhibin and activins

Inhibin and activins play major roles as paracrine and autocrine signaling molecules in reproduction and development where the main emphasis has been placed in developing potential diagnostic applications. While a role for activin assays in diagnostics has so far been unfounded, ELISAs specific for the biologically active inhibin A and B dimers, and for free inhibin alpha subunits, alone or in combination have found some specific diagnostic applications. Addition of inhibin A to the triple test for Down syndrome in the second trimester of pregnancy, measurement of total inhibin as a marker of certain forms of ovarian cancer in specific circumstances, and inhibin B for male fertility are useful diagnostics. A review of the evidence so far suggests that other applications for inhibin and activin assays have yet to be confirmed, or translated into reliable tools for clinical practice.

The Values of CA-125, Progesterone, ß-HCG and Estradiol in the Early Prediction of Ectopic Pregnancy

OBJECTIVE

To explore the diagnostic value and measurement of serum CA-125, the single measurement of progesterone (P), ß-HCG, and estradiol (E2) in the early diagnosis of ectopic pregnancy.

METHODS

Serum levels of CA-125, progesterone, ß-HCG and estradiol were measured by Enzyme Linked Immuno Sorbent Assay (ELISA) techniques in 40 symptomatic women with ectopic pregnancy and 24 women with normal intrauterine pregnancy during gestational age of 4-10 weeks at Al-Kadhmiya Teaching Hospital, Baghdad, Iraq, between November 2010 and June 2011.

RESULTS

The mean ±SEM serum levels of CA-125, progesterone, ß-HCG, and estradiol in patients with ectopic pregnancies (16.51±2.39U/ml; 2.54±0.47ng/ml; 72.75±12.27mIU/ml; 13.4±2.14pg/ml; respectively) were significantly lower than the levels in normal intrauterine pregnancies (74.25±18.5U/ml; 28.36±3.7ng/ml; 249.54±18.0mIU/ml; 112.7±23.6pg/ml; respectively). When using a CA-125 concentration of 20.5 U/ml as a cut-off value for the diagnosis of ectopic pregnancy, sensitivity was 75.7%, specificity 100%, the positive predictive value was 100% and the negative predictive value 71.4%.

CONCLUSION

The measurement of CA-125 and progesterone levels is useful in discriminating ectopic from normal gestations.

Circulating microRNA miR-323-3p as a biomarker of ectopic pregnancy

BACKGROUND

The use of serum human chorionic gonadotropin (hCG) and progesterone to identify patients with ectopic pregnancy (EP) has been shown to have poor clinical utility. Pregnancy-associated circulating microRNAs (miRNAs) have been proposed as potential biomarkers for the diagnosis of pregnancy-associated complications. This proof-of-concept study examined the diagnostic accuracy of various miRNAs to detect EP in an emergency department (ED) setting.

METHODS

This study was a retrospective case-control analysis of 89 women who presented to the ED with vaginal bleeding and/or abdominal pain/cramping and received a diagnosis of viable intrauterine pregnancy (VIP), spontaneous abortion (SA), or EP. Serum hCG and progesterone concentrations were measured by immunoassays. The serum concentrations of miRNAs miR-323-3p, miR-517a, miR-519d, and miR-525-3p were measured with TaqMan real-time PCR. Statistical analysis was performed to determine the clinical utility of these biomarkers, both as single markers and as multimarker panels for EP.

RESULTS

Concentrations of serum hCG, progesterone, miR-517a, miR-519d, and miR-525-3p were significantly lower in EP and SA cases than in VIP cases (P < 0.01). In contrast, the concentration of miR-323-3p was significantly increased in EP cases, compared with SA and VIP cases (P < 0.01). As a single marker, miR-323-3p had the highest sensitivity of 37.0% (at a fixed specificity of 90%). In comparison, the combined panel of hCG, progesterone, and miR-323-3p yielded the highest sensitivity (77.8%, at a fixed specificity of 90%). A stepwise analysis that used hCG first, added progesterone, and then added miR-323-3p yielded a 96.3% sensitivity and a 72.6% specificity.

CONCLUSIONS

Pregnancy-associated miRNAs, especially miR-323-3p, added substantial diagnostic accuracy to a panel including hCG and progesterone for the diagnosis of EP.

Mechanisms of disease: the endocrinology of ectopic pregnancy

Ectopic pregnancy is defined as a pregnancy implanted outside the uterus, and >98% implant in the Fallopian tube. It has a major clinical and socioeconomic impact worldwide. The diagnosis of ectopic pregnancy is often difficult and resource intensive owing to a lack of accurate biomarkers, and there is a need for improved medical management of ectopic pregnancy using new or adjuvant treatments. The aetiology of ectopic pregnancy is uncertain, but tubal implantation is probably due to retention of the embryo in the Fallopian tube owing to impaired embryo-tubal transport and alterations in the tubal microenvironment. This comprehensive review of the literature supporting current understanding of the endocrinology of Fallopian tube biology and tubal implantation focuses on genes expressed in the Fallopian tube regulated by oestrogen and progesterone and discusses their potential functions. It concludes with a discussion of how advances in this field are enabling the development of novel biomarkers and could lead to the identification of potential new treatments for ectopic pregnancy.

Development of a multiple marker test for ectopic pregnancy

OBJECTIVE

Many serum markers have been proposed to aid in the identification of an ectopic pregnancy, but few have been validated. Most studies have been limited by sample size and design. The goal of this study was to assess putative markers to identify which can be optimally combined.

METHODS

We conducted a case-control study using sera from 100 patients with ectopic pregnancy and 100 patients with intrauterine pregnancy who presented to three urban academic centers between September 2000 and April 2009 with first-trimester pain or bleeding. Samples were analyzed for 12 promising biomarkers. Classification tree analysis was used to examine markers simultaneously with the goal of optimizing the accuracy of ectopic pregnancy diagnosis, and validation was performed using bootstrapping.

RESULTS

Six of the 12 markers were differentially expressed between those with ectopic pregnancy and intrauterine pregnancy (P<.001) with fair diagnostic properties (area under the curve greater than 0.6) when examined individually (inhibin A, progesterone, activin A, vascular endothelial growth factor [VEGF], pregnancy-specific β-1-glycoprotein, and pregnancy-associated plasma protein-A). Six additional markers were found to have limited value. Using a two-step diagnostic algorithm with four markers (progesterone, VEGF, inhibin A, activin A), we diagnosed 42% of the sample with perfect specificity and 98% (93-100%) sensitivity. Overall, a single ectopic pregnancy was misclassified, achieving 99% (96-100%) accuracy.

CONCLUSION

Evaluating a large number of biomarkers simultaneously demonstrates that most of the putative markers of ectopic pregnancy are not useful. However, a select few can distinguish ectopic pregnancy from intrauterine pregnancy with superior accuracy as part of a multiple marker test.

CLINICAL TRIAL REGISTRATION

: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00194168.

A disintegrin and metalloprotease protein-12 as a novel marker for the diagnosis of ectopic pregnancy

OBJECTIVE

To evaluate the performance of a novel biomarker, a disintegrin and metalloprotease-12 (ADAM-12), to differentiate an ectopic pregnancy (EP) from normal intrauterine pregnancies (IUPs).

DESIGN

Case-control study.

SETTING

Three urban academic centers.

PATIENT(S)

Women who were seen in the emergency department with pain or bleeding in the first trimester of pregnancy.

INTERVENTION(S)

Sera from women with diagnosed EP or IUP were evaluated via proteomics and an ADAM-12 dissociation-enhanced lanthanide fluoroimmunoassay.

MAIN OUTCOME MEASURE(S)

Differences between groups, area under the receiver operating curve, sensitivity, and specificity.

RESULT(S)

Via a proteomics evaluation, we found a statistically significant decrease in ADAM-12 in the sera of patients with EP, which we confirmed in a larger group of 199 patients (median IUP 18.6 ng/mL versus median EP 2.5 ng/mL with good discrimination between the groups as assessed by receiver operating characteristics [area under the curve = 0.82]). At a low cut-point, the sensitivity was 70% and specificity 84%, but, at a higher cut-point optimizing sensitivity, the ADAM-12 test demonstrated a sensitivity of 97%.

CONCLUSION(S)

ADAM-12 is a promising marker for the diagnosis of EP in women with symptoms in the first trimester, validating the proteomics findings. Further studies in additional patient populations and in combination with other biomarkers are needed.

Attenuated tubal and endometrial urocortin 1 and corticotropin-releasing hormone receptor expression in ectopic pregnancy

Fallopian tube (FT) and endometrial urocortin 1 (Ucn1) and corticotropin-releasing hormone (CRH)-receptor (CRH-R1/CRH-R2) expression were examined using quantitative real-time polymerase chain reaction (RT-PCR) and immunohistochemistry in nonpregnant and pregnant women (intrauterine, IUP; ectopic pregnancy, EP). Tubal Ucn1 messenger RNA (mRNA) expression was higher in luteal compared to follicular phase (P < .01) and equivalent to follicular phase in FT from EP. Tubal CRH-R1/CRH-R2 mRNA was lower in luteal phase (P < .05) and in FT from EP compared to follicular phase (P < .01). Ucn1 mRNA was lower in endometrium from EP compared to IUP (P < .05). Corticotropin-releasing hormone-R1 mRNA was higher in endometrium from EP compared to viable IUP (P < .05). No differences were observed in CRH-R2 expression. Corticotropin-releasing hormone-R1 protein was primarily localized to epithelium of FT and endometrium. Quantitative analysis of tubal CRH-R1 protein expression reflected that seen at the mRNA level but endometrial expression was equivocal. The demonstration of attenuated tubal/endometrial Ucn1/CRH-R expression in EP further supports a role of the CRH-family in embryo implantation.

Systematic discovery of ectopic pregnancy serum biomarkers using 3-D protein profiling coupled with label-free quantitation

Ectopic pregnancy (EP) and normal intrauterine pregnancy (IUP) serum proteomes were quantitatively compared to systematically identify candidate biomarkers. A 3-D biomarker discovery strategy consisting of abundant protein immunodepletion, SDS gels, LC-MS/MS, and label-free quantitation of MS signal intensities identified 70 candidate biomarkers with differences between groups greater than 2.5-fold. Further statistical analyses of peptide quantities were used to select the most promising 12 biomarkers for further study, which included known EP biomarkers, novel EP biomarkers (ADAM12 and ISM2), and five specific isoforms of the pregnancy specific beta-1-glycoprotein family. Technical replicates showed good reproducibility and protein intensities from the label-free discovery analysis compared favorably with reported abundance levels of several known reference serum proteins over at least 3 orders of magnitude. Similarly, relative abundances of candidate biomarkers from the label-free discovery analysis were consistent with relative abundances from pilot validation assays performed for five of the 12 most promising biomarkers using label-free multiple reaction monitoring of both the patient serum pools used for discovery and the individual samples that constituted these pools. These results demonstrate robust, reproducible, in-depth 3-D serum proteome discovery, and subsequent pilot-scale validation studies can be achieved readily using label-free quantitation strategies.

Placental growth factor: a promising diagnostic biomarker for tubal ectopic pregnancy

CONTEXT

Tubal ectopic pregnancy is common, but accurate diagnosis is difficult and costly. There is currently no serum test to differentiate tubal from intrauterine implantation, and an effective biomarker of ectopic pregnancy would be a major clinical advance.

OBJECTIVE

A key feature of successful intrauterine implantation is the establishment of a supportive vascular network, and this has been associated with the activity of placental growth factor (PIGF). We hypothesized that the local decidual environment facilitates PIGF-dependent angiogenesis and that this pathway is not active in tubal implantation. We aimed to determine whether tubal implantation is manifest by an attenuation of the normal trophoblast PIGF response and whether serum PIGF levels are different in ectopic compared with intrauterine pregnancy.

DESIGN AND SETTING

Tissue and serum analysis was done at a large United Kingdom teaching hospital.

PATIENTS

Tissue and sera were collected from gestation-matched pregnant women undergoing surgical termination of pregnancy (viable intrauterine) (n = 15), evacuation of uterus for embryonic missed miscarriage (nonviable intrauterine) (n = 10) and surgery for tubal ectopic pregnancy (n = 15).

INTERVENTIONS

Trophoblast was examined by immunohistochemistry and quantitative RT-PCR, and serum was analyzed by ELISA.

RESULTS

PIGF was localized to the cytotrophoblast cells. Expression of PIGF mRNA was reduced in trophoblast isolated from women with ectopic compared with intrauterine pregnancies (P < 0.05). Serum PIGF was undetectable in women with tubal ectopic pregnancies and reduced, or undetectable, in miscarriage compared with viable intrauterine pregnancies (P < 0.01).

CONCLUSIONS

Serum PIGF is a promising novel diagnostic biomarker for early pregnancy location and outcome, and large-scale studies are now required to determine its clinical utility.

Economic evaluation of diagnosing and excluding ectopic pregnancy

BACKGROUND

The diagnosis of ectopic pregnancy in women presenting in early pregnancy is often protracted, relying on costly investigations that are psychologically burdensome to the patient. The aim of this study was to evaluate the financial costs to the health services in Scotland of the current methods used to diagnose and exclude ectopic pregnancy, and compare these with that of a theoretical single diagnostic serum biomarker.

METHODS

We conducted a retrospective cost-description analysis (with and without costs of diagnostic laparoscopy) of the health-care costs incurred by all patients presenting to a large Scottish teaching hospital between June and September 2006 with pain and bleeding in early pregnancy, where ectopic pregnancy was not excluded. Additionally, a cost minimization analysis was performed for the costs of current ectopic pregnancy investigations versus those of a theoretical single diagnostic serum biomarker. This included sensitivity analyses where the biomarker was priced at increasing values and assumed to have less than 100% diagnostic sensitivity and specificity.

RESULTS

About 175 patients were eligible to be included in the analysis. Forty-seven per cent of patients required more than three visits to diagnose or exclude ectopic pregnancy. The total yearly cost for diagnosing and excluding ectopic pregnancy was 197K pound sterling for the hospital stated, and was estimated to be 1364K pound sterling for Scotland overall. Using a theoretical diagnostic serum biomarker we calculated that we could save health services up to 976K pound sterling (lowest saving 251K pound sterling after subanalysis) every year in Scotland.

CONCLUSIONS

Ectopic pregnancy is expensive to diagnose and exclude, and the investigation process is often long and might involve significant psychological morbidity. The development of a single diagnostic serum biomarker would minimize this morbidity and lead to significant savings of up to 1 million pounds per year in Scotland.