**4.1 History**

Diagnosis of duodenal disorder is challenging one, because of the non-specific signs. It requires invasive and noninvasive diagnostic modalities, viz., X-ray, ultrasound, and duodenoscopy, to identify the lesion localization. To confirm the root cause of the duodenal disorder, histopathology, cytology, and culture examination of duodenal aspirates through routine duodenoscopy examination are performed.
