After the vaginal probe is removed and an open-sided vaginal speculum is inserted, the cervix is inspected and is cleansed with an antiseptic solution. In the presence of severe discharge and acute pelvic pain, the procedure should be postponed.

An intrauterine catheter is placed into the cervical os under direct visualization with a sterile uterine packing forceps until the uterine fundus is reached. Catheters with different features are available (caliper 5–14 Fr, with or without balloon, rigid or flexible).

The speculum is carefully removed, and a 10–60 ml dedicated plastic syringe containing sterile contrast fluid (saline solution, SCSH, or gel, GIS) is attached to the catheter. After the ultrasound probe is reintroduced, the fluid is slowly infused into the uterus. Five to ten milliliters of fluid is required for proper uterine distention, but depending on intracavitary findings and/or problems with backflow, more fluid can be infused (in some cases almost continuously) to keep the cavity expanded during the examination. In the presence of submucous myomas, the slow injection and withdrawal of the fluid under direct sonographic control helps to observe the uterine walls and the myoma protrusion into the cavity. A second or third injection and withdrawal might be repeated when necessary, combined with histological and/or cytological analysis in doubtful cases. The great advantage of gel is that it lasts longer, with minimum backflow, while its disadvantages are its cost, due to the gel itself, and the need for a specific set (catheter, syringe).

The endometrial cavity should be meticulously and systematically scanned in sagittal and transverse sections, intracavitary lesions assessed (site and size), and endometrial thickness measured adding the two separate single layers.

The whole procedure might be digitally recorded for second opinion (video clips), and the selected diagnostic images stored and/or printed. Neither analgesic drugs nor prophylactic antibiotics should be administered.

In the last decades a large number of papers referred to the usefulness of three-dimensional transvaginal sonography (3D TVS) in gynecological investigations, mainly focused on uterine congenital anomalies [42]. More recently, 3D TVS showed to be effective to correctly diagnose adenomyosis [43, 44] and to properly evaluate intracavitary lesions (submucous myomas, endometrial polyp, and hyperplasia) [17, 45, 46].

In order to obtain a high-quality 3D image, it is of paramount importance to acquire an excellent volume by a high-quality 2D image. Therefore:

When using multiplanar display, having routinely the bladder on the right of the screen and acquired the volume from a sagittal scan, I usually suggest to rotate the sagittal scan of the uterus in plane A on the Y-axis, in order to move it in plane B, the transverse in A and the coronal in C, with correct corresponding uterine lateral walls in A and C (Fig. 4.2).

Volume rendering analysis is based on the selection of the region of interest (ROI) and of the observation plane of the acquired volume of the uterine corpus:

Volume contrast imaging (VCI) is a technology based on a volume acquisition technique that leads to contrast enhancement and speckle suppression in the two-dimensional ultrasound image, by offering to increase resolution and to reduce noise. Hence, the result of VCI is a thin surface-rendered image of the endometrium, in which thickness can be selected by the sonographer, usually settled at 2 mm (Fig. 4.4).

Tomographic ultrasound imaging (TUI) is a technology which leads to multiple planes displayed at the same time, with the option of concomitant use of VCI. Similarly, the number of images and the thickness might be selected by the sonographer, with differences depending on the plane used for analysis. I would suggest the option with three or seven images with distances of 1.5–2.5 mm when considering tomographic sagittal or transverse planes and 0.5 mm when considering coronal planes.

Similarly to the above-described techniques, 3D SHG by saline or gel instillation might benefit from the post-processing tools (Fig. 4.5).

3D volumes can be stored and analyzed later as many times as needed, permitting a second opinion by sending volumes by Internet, offering the possibility of studying an infinite number of sections through the uterine cavity. This latter feature is particularly relevant when analyzing submucous myoma, for which the rule is “myoma makes the uterus go around.”