**1. Introduction**

One of the most common complications of pregnancy is early pregnancy failure, of which 25% result in miscarriages and 1-2% ends in ectopic pregnancy. Both these entities can present with similar symptoms of abdominal pain and/or vaginal bleeding [1]. The most common site of ectopic pregnancy is fallopian tube. As tubal ectopic pregnancy (EP) is associated with high morbidity and mortality, early and accurate diagnosis of this condi‐ tion is warranted. Present protocols for diagnosis of ectopic pregnancy utilize serial serum human chorionic gonadotropin (β-hCG) levels and pelvic ultrasound [2]. However, distinction between an intrauterine or extrauterine pregnancy may not be possible in 8-31% of cases at the first visit, even with sophisticated transvaginal ultrasound [3]. As a result, multiple visits for serial β-hCG and ultrasound monitoring are required before a diagno‐ sis can be established and management initiated. This interim period of uncertainty may lead to potential life threatening complications like intra-abdominal bleed and future infertility because of compromised tubal integrity. Therefore, early diagnosis of tubal ectopic not only prevents the added mortality in patients, but also plays an important role in preventing future infertility. Also, the optimal management strategies for ectopic pregnan‐ cy and other abnormal intrauterine pregnancy (IUP) like miscarriages differ, and these two distinct clinical entities need to be differentiated at the early stages of pregnancy. A circulating serum biomarker may aid in predicting early pregnancy outcome (viable intrauterine pregnancy, miscarriage or tubal ectopic pregnancy), and may guide in deciding the best management strategy (conservative, medical or surgical) for the patient. Numer‐ ous groups have focussed their attention on this issue, and have reported many potential candidate biomarkers. The present chapter discuss the recent status of these candidate biomarkers in diagnosing tubal ectopic pregnancy, along with our experience, and attempt to foresee the future diagnostic trend of this clinically significant entity.

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## **1.1. Problem statement**

Tubal ectopic pregnancy is an important cause of early pregnancy failure attributing signifi‐ cantly to morbidity and mortality, in absence of expeditious diagnosis. Currently, the diagnosis of ectopic pregnancy is based on combined ultrasonograhic findings and serial β-hCG levels. However, low positivity rates in early gestational age and a need for repeated testing are major limitations of these diagnostic procedures, leading to added risk of tubal rupture and intraabdominal bleed. Therefore, a circulating serum based biomarker, which could differentiate tubal ectopic from viable intrauterine pregnancy and other abnormal gestation (miscarriages) at the first visit of the patient, is the need of the hour.
