3D ULTRASOUND IN GYNAECOLOGY
Reading Time: 3 minutesToday, 2D ultrasound is the conventional method for the ultrasound study of anatomical structures of gynaecological interest, but the use of 3D ultrasound allows additional information to be gathered to improve the non-invasive diagnosis of certain pathological conditions.
3D ultrasound is based on the use of software that is able to recreate three-dimensional solid volumes on the screen from two-dimensional scans. There are different modes for displaying 3D images: the render mode shows a single image using colour gradients to recreate the sense of depth, while the multiplanar view allows the simultaneous evaluation of several section planes.
Data acquisition can be done manually, if the operator moves the probe while scanning the entire organ of interest, or automatically, if the probe must be held still while the ultrasound scanner scans. Subsequently, the images are processed and animated by the machine and can be manually optimised by the sonographer to obtain the final rendering of the structure under examination. A normal uterus in coronal section has a fundus with a slight upward convexity, an endometrium with a homogeneous ecostructure of varying appearance depending on the phase of the menstrual cycle and a myometrium that is more hypoechogenic than endometrium. The cervix must also be visualised in the coronal plane, taking into account the degree of flexion and version of the uterus.
The 3D ultrasound study is currently the gold standard technique for the diagnosis of possible congenital abnormalities of the uterus as it allows a sensitive, specific and non-invasive assessment of uterine morphology. Such congenital abnormalities are present in 24% of patients with recurrent miscarriages: the arched uterus is the most common form, followed by the subsecreted uterus and the bicornuate uterus.
In 2013, the ESHRE/ESGE classification of congenital anomalies of the female genital tract was published, which are numbered from 0 to 5 in ascending order of severity. This consensus represents a valuable tool to be able to discriminate and correctly report morphological changes found during a two- and three-dimensional ultrasound scan.
As far as the ovaries are concerned, 3D ultrasound can be used to calculate their volume more accurately than the estimate from the two-dimensional study. Despite this, it appears that ovarian volume is not an important predictor of gonadal response to IVF. The assessment of antral follicle count, on the other hand, seems to correlate better with IVF outcomes, but there are no significant differences between 2D and 3D.
Potentially, 3D ultrasound could improve the diagnostic accuracy of ovarian cysts and adnexal masses suspected for malignancy, however, further studies are needed before this type of study is introduced into clinical practice.
Bibliography
1. Coyne L, Jayaprakasan K, Raine-Fenning N. 3D ultrasound in gynecology and reproductive medicine. Womens Health Lond Engl. 2008 Sep;4(5):501-16.
2. Grimbizis GF, Gordts S, Di Spiezio Sardo A, Brucker S, De Angelis C, Gergolet M, et al. The ESHRE/ESGE consensus on the classification of female genital tract congenital anomalies. Hum Reprod Oxf Engl. 2013 Aug;28(8):2032-44.
