Abstract
Endometrial pathology includes hyperplasia, polyps, cancer and infection. Intracavitary fibroids are sensu stricto not endometrial lesions, but should be included in the differential diagnosis.
Although intracavitary pathology may be found incidentally while scanning for an unrelated reason, most patients will be diagnosed during the evaluation of abnormal uterine bleeding. Ultrasound examination is the test of choice to triage patients for further management. If a thin and regular endometrium is seen after menopause, endometrial atrophy is the most likely diagnosis, while the risk for malignancy is very low (Figure 6.1).
Introduction
Endometrial pathology includes hyperplasia, polyps, cancer and infection. Intracavitary fibroids are sensu stricto not endometrial lesions, but should be included in the differential diagnosis.
Although intracavitary pathology may be found incidentally while scanning for an unrelated reason, most patients will be diagnosed during the evaluation of abnormal uterine bleeding. Ultrasound examination is the test of choice to triage patients for further management. If a thin and regular endometrium is seen after menopause, endometrial atrophy is the most likely diagnosis, while the risk for malignancy is very low [1,2] (Figure 6.1).
In those cases there is no need for further investigations. If a focal intracavitary lesion (e.g. an endometrial polyp or an intracavitary fibroid) is evidenced, the patient can be scheduled for an operative hysteroscopy. If the ultrasound image is suspicious for endometrial cancer or atypical hyperplasia, immediate endometrial sampling is indicated. If physiological endometrial changes or simple endometrial hyperplasia are anticipated, the clinician may choose endometrial sampling, hormonal therapy or expectant management.
This chapter gives an overview on how to assess the endometrium and the uterine cavity using ultrasonography.
Unenhanced Ultrasound Examination
The ultrasound scan starts with the visualization of the endometrium. The entire endometrium should be scanned from right to left and from fundus to isthmus. If the endometrium is clearly visible, it is measured in the sagittal plane, where it appears at its thickest (see Chapter 2). This is not necessarily the most fundal part of the endometrium.
If the endometrium cannot clearly be delineated, it must be recorded as ‘not measurable’. A not measurable endometrium must be considered as potentially abnormal and warrants further testing (e.g. hydrosonography). In a series of 1220 women presenting with abnormal bleeding, almost 20 per cent of cancer cases had a non-measurable endometrium [3].
Merely reporting endometrial thickness is not enough. The ultrasonographic features should also be described [4]. The echogenicity of the endometrium may be uniform or non-uniform. During the menstrual cycle the endometrium in the follicular phase is typically uniform and hypoechogenic (three-layer type), and hyperechogenic in the secretory phase. The endometrium is reported as non-uniform if the background is heterogeneous (Figure 6.2) and/or in the presence of internal cysts (Figure 6.3).
The endometrial midline is reported as linear, non-linear, irregular or not visible. The endometrial–myometrial junction or junctional zone (JZ) is the hypoechogenic rim surrounding the endometrium. The JZ is the inner myometrium and is not part of the endometrium [5]. The JZ may be regular, irregular, interrupted or not defined. It is not always easy to see the JZ. The JZ visualization can be optimized using volume contrast imaging (VCI) set at 2 mm using 3D ultrasound [6].
Colour Doppler and power Doppler imaging to visualize the vascularization of the endometrium and of endometrial lesions may help in the diagnosis. While in most of the normal menstrual cycle no vessels can be seen in the endometrium, multiple peripheral vessels become visible at the end of the secretory phase. Intracavitary lesions have typical vascular patterns: a polyp has a single dominant vessel with or without branching [7], a fibroid circumferential flow and endometrial cancer multiple vessels from multifocal origins.
Polyp, Fibroid, Cancer or Clot?
An intracavitary lesion seen using hydrosonography may be an endometrial polyp, an intracavitary fibroid, a focal malignant lesion, a blood clot or caused by polypoid endometrial growth. The outline of the lesion, its echogenicity and colour Doppler features may lead to the exact diagnosis. The outline of a polyp or an intracavitary fibroid is regular, as opposed to a clot or a focal malignant lesion. A polyp tends to be more hyperechogenic, occasionally with small internal cysts. A fibroid is habitually less echogenic and the overlying, more echogenic endometrium may be visible. The echogenicity of endometrial cancer varies according to the tumour type, a well-differentiated endometrioid cancer often being hyperechogenic. The endo-myometrial junction is typically interrupted in a FIGO type 1 or 2 fibroid as is often the case in endometrial cancer, while both an endometrial polyp and a clot are entirely intracavitary without affecting the JZ. The findings at colour Doppler are often helpful. A polyp (Figure 6.4) has typically a feeding vessel (pedicle), a fibroid (Figure 6.5) has circumferential flow, endometrial cancer (Figure 6.6) has multiple vessels from multifocal origin, while in a clot no flow can be detected. During fluid instillation a clot may move freely and its shape may even change during the examination. It is easier to visualize this using saline instillation. If a blood clot is suspected, it might be considered to aspirate the clot, e.g. using a pipelle sampler, and to check the cavity and the disappearance of the clot after aspiration.
