**1. Introduction**

#### **1.1. What's unexplained infertility (UI)?**

Current definitions of infertility lack uniformity, rendering comparisons in prevalence between countries or over time difficult and inconclusive. The absence of an agreed definitions compromises clinical management and undermines the impact of research findings [1]. Idiopathic or unexplained infertility (UI) term is used whenever the cause remains unclear even after basic infertility work-up which usually includes semen analysis, detection of ovulation and fallopian tubal patency testing. The current diagnostic tools for intrauterine causes of infertility include transvaginal ultrasonograogy, hysterosalpingography (HSG) or saline infusion sonography (SIS) [2]. The levels of investigations to explain infertility are insufficient and require more intensive evaluation. In a previous open access free book chapter published by InTech [3], many explanations of UI utilizing endoscopic evaluation that were missed by many organizations were demonstrated.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
