Purpose:
The purpose of this review is to illustrate and discuss the seldom used technique of three-dimensional (3D) saline infusion sonohysterography (SIS) based on instillation of sterile saline through a catheter into the uterus under real-time vaginal transducer observation for assessment of the endometrial cavity.

Material and methods:
The cases for this pictorial review were selected from the imaging material collected at the Ultrasound Unit, Clinical Imaging Department, Women’s Hospital of Hamad Medical Corporation during a seven-year period from 2011 to 2017. This was a retrospective collection of 216 consecutive cases that underwent two-dimensional (2D) and 3D SIS for evaluation of the uterine cavity, followed by verification of results with histopathology. An open-sided speculum is inserted into the vagina. An intrauterine catheter is then threaded into the endometrial cavity. After that, the speculum is removed carefully, and a vaginal transducer is inserted. Using a 60-ml syringe attached to the catheter, saline solution is instilled under direct real-time observation (2D SIS). Subsequently, reconstruction of the three-dimensional anatomy of the intrauterine cavity is performed.

Pictorial review:
The review presents the most common indication for SIS, like abnormal bleeding in pre- and postmenopausal patients. SIS allows us to distinguish between focal lesions and global endometrial thickening. SIS should be supported as a second-line diagnostic procedure for abnormal uterine bleeding, when findings from transvaginal ultrasound are inconclusive.

Conclusions:
The addition of 3D techniques to SIS procedure helps in the distinction between endometrial and myometrial lesions, also it facilitates delineation of uterine anatomy, resulting in more precise and accurate diagnosis.