Can endometrial cancer be diagnosed using ultrasound alone?

Author: Yang Yueming, deputy chief physician of Foshan First People's Hospital

Reviewer: Wang Gang, Chief Physician, Sichuan Provincial Maternal and Child Health Hospital

Xiaoli suspected that she had endometrial cancer, and the doctor asked her to do a B-ultrasound. Before, Xiaoli only heard that a curettage was needed to diagnose endometrial cancer, but she didn't know that a B-ultrasound could also be done. So, can B-ultrasound really diagnose endometrial cancer?

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1. Conventional gynecological B-ultrasound method

B-ultrasound is actually a B-type ultrasound examination. Ultrasound is the abbreviation of ultrasound, which refers to sound waves that exceed the human hearing threshold. It has no radiation and can propagate in any tissue and in the human body [1].

Ultrasound examination refers to the process in which an ultrasound scanner emits weak ultrasonic waves into the human body through an ultrasonic probe, and the reflected waves of the human body tissue are processed into images by the instrument. The images formed by the instrument are the same as the organs and tissues in the body. Doctors can judge the characteristics of human tissues by observing and analyzing these images. Ultrasound examination uses the principle of mechanical waves and has no radiation, no trauma, no noise, and no time limit for examination. Even if continuous examination is required, it will not harm the human body[1]. It is recognized as the preferred method for screening gynecological diseases in women, and has a very high detection rate for tumors[1].

Ultrasound is divided into type A and type B. Type A ultrasound was invented first, and it uses the changes in a line to analyze whether there are problems with human organs. Type B ultrasound (B-ultrasound) that appeared later uses different changes in black and white images to analyze and diagnose various diseases of human organs [1].

B-ultrasound is widely used in gynecological examinations. There are three types of conventional gynecological B-ultrasound.

1. Transabdominal ultrasound

The ultrasound probe slides across the abdomen to examine the uterus and pelvic cavity through the abdominal wall. It is often used in routine physical examinations and is especially suitable for unmarried women or women with no sexual history. However, before the examination, the patient needs to hold back urine (about 300 to 500 ml), and the amount of urine held back and the thickness of the abdominal wall may affect the clarity of the image, and some minor lesions may be missed [1].

2. Transvaginal B-ultrasound

The ultrasound probe is inserted into the body through the vagina. The closer it is to the organs and tissues being observed, the clearer the image is, and the observation of endometrial lesions is more intuitive, and tiny lesions can be identified. In addition, there is no need to hold urine before the examination, and the accuracy of the diagnosis will not be affected by factors such as abdominal wall thickness, multiple reflections, and intestinal gas. It is suitable for all women who have had sex, especially obese or older women.

3. Transrectal ultrasound

The ultrasound probe is inserted into the rectum through the anus, and the effect is basically the same as that of transvaginal examination. It is suitable for patients who have no sexual history but need to observe the lesion closely, as well as women who cannot be diagnosed through abdominal examination [1].

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II. Diagnosis and evaluation of endometrial cancer by transvaginal B-ultrasound

Among the above three examination methods, transvaginal B-ultrasound can observe the thickness of the endometrium more clearly, and can also be combined with the morphological changes of the endometrium for analysis, which is more advantageous in detecting tiny lesions. Therefore, transvaginal B-ultrasound has a high diagnosis rate and lesion detection rate, and is the preferred method for clinical screening of endometrial cancer. In addition to monitoring endometrial cancer, transvaginal B-ultrasound can also preliminarily determine the degree of endometrial cancer lesions.

The myometrial invasion of endometrial cancer, that is, the degree of invasion of cancer cells into the muscle layer, is one of the indicators for clinical evaluation and prediction of disease development and outcome, and is also an important basis for selecting treatment options. Transvaginal B-ultrasound can observe the endometrium, myometrium and serosa, and judge whether infiltration has occurred, the depth of infiltration and whether it has spread to the cervical canal based on whether the low echo halo between the endometrium and myometrium is broken.

In early-stage endometrial cancer, the hypoechoic halo surrounding the lesion in the uterine cavity is complete, and the boundary between the lesion and the myometrium is clear. In mid- and late-stage endometrial cancer, there are irregular areas of strong echo or weakened echo in the uterine cavity, and some also have irregular liquid dark areas. The boundary between the lesion in the uterine cavity and the myometrium is not clear, the surrounding hypoechoic halo is incomplete, and myometrial infiltration can be seen.

In addition, the strength of the endometrial echo is also related to the degree of differentiation of the tumor. If the cancer cells are highly differentiated and there are many glands in the tissue, the ultrasound will show high echoes; otherwise, it will show uneven or low echoes. Therefore, transvaginal B-ultrasound helps clinically determine the degree of differentiation of endometrial cancer cells and has a guiding role in the treatment and prognosis of the disease.

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It can be seen that transvaginal B-ultrasound can not only diagnose endometrial cancer, but also evaluate it. In particular, transvaginal color Doppler ultrasound, based on black and white ultrasound, adds observation of blood in blood vessels and determines the direction and velocity of blood flow by the color of the image. The organs in the human body (including lesions) need blood supply. When most organs are diseased, the blood vessels will undergo corresponding changes. The application of color Doppler ultrasound technology can obtain more diagnostic information [1].

If color Doppler ultrasound is used as the initial screening method for endometrial lesions, it will provide more basis for the prevention, evaluation and treatment of endometrial cancer.

In summary, following the doctor's advice to perform B-ultrasound examination is helpful in evaluating and diagnosing endometrial lesions and tumors.

References

[1] Dong Xiaoqiu, Tang Qin. Ultrasound doctors talk about health. Beijing: People's Medical Publishing House, 2020.