Peculiarities of ultrasound diagnostics of paraurethral glands in women of fertile age

Determination of paraurethral glands during ultrasound study was conducted in the format of grey scale (B-mode) using the Doppler colour flow mapping and evaluation of Doppler indices of paraurethral glands both before and after sexual stimu­ lation. To optimize the paraurethral glands visual view at the beginning of examination urinary bladder was catheterized and a balloon, filled with gel, was inserted into vagina.

There are certain contradictions in the determination of homology of paraurethral glands with the anatomic body in a male organism and evaluation of its functional activity [11,[14][15][16][17][18].
Paraurethral glands' comparison of characteristics with the homologous men's organ shows that male prostate gland surrounds urethra, meanwhile the accumulation of women's paraurethral glands are located alongside urethra [11]. The thickness of walls and the length of female urethra limit the location of paraurethral glands, and that is why their size is smaller compared to the male prostate gland and constitutes in average 3.3 × 1.9 × 1.0 cm, while the average weight is 4 times smaller (3.9 and 23.7, respectively) [11,19].
Morphological research of the structure of paraurethral glands in women proves that in the stroma of this anatomic formation ducts similar to male prostate gland and smooth muscles are found, although their muscle component is more developed. A histological study of tissues of paraurethral glands by Rudolf Virchow gave grounds to reveal amyloid bodies, typical only for male organ [10].
In 1947, J. Huffman created threedimensional models of paraurethral glands. To perform that model, he filled anatomic structures of urethra with hot wax and received characteristic features of paraurethral glands' structure, size and number. The author noticed that this anatomic formation is similar to how a tree looks like. In his view, the urethra resembles a tree trunk, while tubes of paraurethral glands coming therefrom are similar to tree branches [20]. Taking anatomical data of Huffman's revolutionary wax model, M. Zaviacic (1999) found different types of paraurethral glands according to his pathoanatomic cross-sectional studies: anterior (meatal) type, posterior type, diffuse type, rudimentary type, rare middle tipe, dumbbell configuration [7,11]. According to the opinion of Huffman (1948), M. Zaviacic et al. (1985), Wernert et al. (1991), in 70 per cent of women the accumulation of glandular tissue is observed along the frontal distal part of urethra [20][21][22].
The system of outgoing ducts of paraurethral glands is presented by numerous channels, through which ejaculate, extracted during orgasm, comes to urethra. It should be mentioned that in some cases extractions from the female urethra are so abundant that they serve as a reason for comparison with the phenomenon of male ejaculation [9,[23][24][25]. A high amount of alkaline phosphatase was established, with variable PSA levels both in the vagina and in the female ejaculate [23][24][25][26][27].
Paraurethral glands as an active functioning organ in a female body have become the center of attention of clinicians and pathologists only in the second half of XX century. The data regarding the unified embryological origin of paraurethral glands and male prostate from the urogenital sinus have accumulated [28][29][30].
For a long time, the majority of skeptical scholars had not recognized embryological findings, as a confirmation of the existence of homology of two genitourinary structures and completely disagreed with the understanding of paraurethral glands as an actively functioning organ in a female body. The vestigial concept based on the macroscopic difference in the size of both sexes at that moment was the main one, while the difference in size of glands has been many times used to substantiate their functional inadequacy.
In the opinion of Wernert and coauthors the accumulation of paraurethral glandular tissue along urethra and also in the place between the wall of urethra and the frontal wall of vagina should be recognized as a rudimentary nonfunctional anatomic formation in a female body (vestigial concept) [22].
In these conditions M. Zaviacic and coauthors contrary to the traditional views and using the fundamental research persuasively proved the functional activity of paraurethral glands in a female body during all stages of life (nonvestigial concept) [18,22]. Vestigial theory was refuted by M.  on the basis that morphologically mature secretarial and basal cells were established in the tissues of paraurethral glands of women of reproductive and perimenopausal age during electronic microscope study. It was proved that paraurethral glands do not disappear in the process of embryological development (as it was regarded before), while in 90 per cent of cases they actively develop in a mature glandular tissue with fullfledged secretarial function (nonvestigial concept) [3].
In 2001 on the basis of studies of M. Zaviacic and coauthors the Federative International Committee on Anatomical Terminology (FICAT) during its meeting, which took place in Orlando (Florida, USA) included the concept of female prostate into the list of Histological Terminology, having prohibited the use of terms "Skene's paraurethral glands" or "paraurethral ducts" to mark female prostate.
In today's conditions the active study of anatomic and functional peculiarities of development of paraurethral glands continues [1]. In these circumstances the study of this anatomic formation in a female organism is related to great research difficulties, because paraurethral glands can constitute the object of research only in case of autopsy in women, which is by itself related to a list of legal prohibitions [16].
The optimization of diagnostics of paraurethral glands and the determination of their role in the formation of urogenital and sexual disorders in a female body remains an obvious problem of clinical medicine.
The presented work is based on the idea of revaluation of traditional approaches to the standards of identification of paraurethral glands in women of fertile age considering the types of their location.
As of today, in the world's clinical practice, these diagnostical criteria are not standardized and received little research.

Aim
Evaluation of diagnostics of ultrasound evaluation of paraurethral glands considering their types of location in women of fertile age.

Materials and methods
A gynecological, sexological and ultrasound study of 94 women in the age from 24 to 42 (average age 31.01 ± 6.60), was carried out.
An examination of women-volunteers, who consented to it, was carried out according to the rules of ethical committee and confidentiality requirements.
An examination of women-volunteers, who consented to it, was carried out according to the rules of ethical committee and confidentiality requirements.
It was suggested to use new methods of checkup to optimize ultrasound diagnostics of paraurethral glands. Before the examination bladder was catheterized and a 50.0 ml vessel, filled with gel, was introduced into the vagina. Implementation of these methods of ultrasound study, in our opinion, leads to alleviate visualization of paraurethral glands. In accordance with this research method, paraurethral glands were considered as a separate anatomic formation.
As previously established, the ultrasound study with Doppler method to investigate vessels of this anatomic formation permits the evaluation of indicators that describe blood flow with high accuracy. Under this scenario patients do not experience complications and consequences that are undesirable.
The ultrasound diagnostic expert class system XARIO of TOSHIBA in the format of grey scale (B-mode) was used in the study. Also, Doppler colour flow mapping (CFM) was employed during the examination of paraurethral zone and Doppler indices were determined.
The use of Advanced Dynamic Flow allows CFM re cei ving high dimensional image to see any vascularization, including insignificant one, and to establish even vague flows.
The program Panoramic View was thought to optimize view of largeformat picture having twodimension effect and optimization in research of topographic anatomy of paraurethral glands area.
In the format of CFM vascular angioarchitecture and characteristics of parenchymatous blood flow in paraurethral glands were assessed. The specific studied area included paraurethral glands and Gspot (their availability, characteristics of localization, intensity and symmetry).
In order to evaluate Doppler signals the selected scanning angle between ray and vessel (ranged between 0 and 40 degrees) was used.
We evaluated parameters of 3-4 complexes. Linear size was measured -diameters of vessels of the described formations and evaluation of Doppler parameters: peak systolic speed of blood flow (Vs cm/s), resistive index (IR), and pulsatility index (IP).
During the examination no one used contraceptives or hormone medicaments. The examination of women took place during the first phase of menstrual cycle (between the 5 th and 10 th days of cycle).
In course of visualization of the paraurethral glands, the patient was placed on the back. We introduced anesthetic (Cathejell) into urethra. Bladder was catheterized via Foley catheter No. 12 or No. 14, using the vessel, filled with gel, for 10-15 cm 3 . At the finish of the study, we removed the catheter and prescribed the 3-5 days antibacterial therapy. Our aim was to avoid potential complications after the examination [31].
The inspection was carried out in the state of calm as well as after 20-30 minutes of sexual stimulation using erotic video. The study was performed if convenience for the patient was ensured.
The ultrasound parameters data of women's paraurethral glands M ± SD, were analyzed using Wilcoxon signedrank test and Spearman correlation rtest. Stastically significant difference was considered for P < 0.05. Analysis was performed using SPSS 22.0 (IBM, Armonk, NY, 53595fc69139e7c88dec).
During ultrasound study of paraurethral glands using the mode of gray scale this anatomic formation was in the form of clear isoechogenic oval with the following dimensions: length -2.20 ± 0.60 cm, width -1.52 ± 0.40 cm, thickness -1.30 ± 0.30 cm, and volume -2.30 ± 0.70 cm 3 .
Sexual stimulation during 20-30 minutes (viewing erotic video) was accompanied by the increase in the diameter of paraurethral glands vessels, intensification of blood flow and brightness of sonographic image during CFM in the regime of energetic Doppler carding, and was characterized by the increase in the indices of blood flow of the studied zone elements (paraurethral glands and Gspot).
The diameter of vessels in the paraurethral glands zone was between 0.17 cm and 0.21 cm in calm, and 0.39-0.41 cm -during stimulation.
There were determined positive correlation and significant difference between changing of ultrasound parameters of women before and after sexual stimulation; increasing of diameter of vessels in the paraurethral zone (P < 0.001, r = 0.55), maximum systolic speed of blood flow (P < 0.001, r = 0.4) and pusatility index (P < 0.05, r = 0.2), while we didn't notice any correlation and statistically significant changes in resistance index (P > 0.05, r = -0.07).
In the conducted research the Gspot was found in 85 (90.4 %) of the examined. Gspot was visualized in the form of spheric thickening at the front wall of vagina at the distance 3.00-6.70 cm from introitus vaginae (Fig. 10).
We have noticed, that there is no correlation between paraurethral gland's location type and investigated ultrasound parameters (P > 0.05).
It should be noted that in every specific case the location of Gspot had its features. During ultrasound study the parameters of Gspot in calm (length -between 1.24 and 1.31 cm, width -between 0.68 cm and 0.76 cm, thickness -between 0.28 cm and 0.34 cm, volume -between 0.1 cm 3 and 0.2 cm 3 ) (Fig. 11,12,13) and at the background of videoerotic stimulation (length -between 1.34 cm and 1.38 cm, width -between 0.75 cm and 0.84 cm, thickness -between 0.38 cm and 0.54 cm, volume -between 0.20 cm 3 and 0.30 cm 3 ) (Fig. 14) were established.

Discussion
For a long time, medical academic community, adhering to the vestigial concept, had not recognized paraurethral glands in female body as a functionally active organ. The results of research by M. Zaviacic et al., complying to the principles of interdisciplinary approach, have persuasively demonstrated the fairness of recognition of non-vestigial concept on paraurethral glands with the confirmation of the peculiarities of anatomic structure and functional activity during the whole life of a woman [3,11,[14][15][16]18,19,21,23,26].
It should be once again stated that the assessment of anatomic structure of paraurethral glands is conditioned by the list of difficulties caused by legal aspects in making autopsies [16].
At the same time there are only occasional data about clinical and paraclinical evaluation of functional activity of paraurethral glands in women of different age groups.
Results of Magnetic Resonance Imaging of paraurethral zone and ultrasound studies of urethrovaginal space accumulate, but remain nonsystematic [32].
For instance, during magnetic resonance imaging of paraurethral glands in women F. Wimpissinger established the size of paraurethral glands without focusing on the types of their location [33].
The object of scientific discussion are not only anatomic and functional characteristics of paraurethral glands, but also the Grafenberg spot. In 1950 Ernst Grafenberg described an erogenous zone on the frontal wall of vagina, which for the first time was called Gspot by F. Addiego (1981) [34,35].
In the opinion of Crooks and Baur, "the Gspot contains a system of glands (Skene's glands) and ducts that surround the urethra" [40].
In 2008, G. L. Gravina et al. indicated that during ultrasound study of paraurethral zone the Grafenberg spot was established, but the image of this structure was not presented, which became the basis for debate [41].
In these circumstances the optimization of diagnostics of paraurethral glands and paraurethral zone is a demand of today. The methods of ultrasound study for vessels of paraurethral glands, using Doppler method, allow revealing the peculiarities of a separate anatomic formation considering the type of its localization and its character of development due to the individual features of paraurethral glands' bran ching. Gspot (projection of glandular tissue in relation to vagina) located in case of proximal and distal location of paraurethral glands was established in 80.4 % of the studied patients.
The methods of examination proposed above enhance visualization of paraurethral glands and all its parts. It gives us the opportunity to expand perception about the characteristics of this anatomic formation according to the paraurethral glands' description with different kinds of their placement, character of localization and view on Gspot.

Conclusions
1. The ultrasound research that includes the Doppler method of paraurethral zone vessels on earlier catheterized bladder allows determining paraurethral glands as a unique anatomic formation.             2. Ultrasound investigation of paraurethral glands vessels using Doppler method in accordance with the suggested above methodology gives opportunity to identify paraurethral glands and to determine their types; as a result, we can study blood flow in paraurethral glands, Gspot both in calm and after video-erotic stimulation.
3. Consequently, the "front type" of paraurethral glands location was established in the accumulation of glandular tissue in regard to distal part of urethra in 67 (71.2 %) of the examined women. "back type" of paraurethral glands location was found in the zone of proximal part of urethra in 19 (20.2 %) of the examined women, "diffuse type" -placed along urethra in 7 (7.5 %) of the examined women, and absence in 1 (1.1 %) of the examined women.
4. Colored Doppler examination marked an increase in vascular diameter of vessels and optimization of vessels image in the area of paraurethral glands on the background of sexual stimulation during the 20-30 minutes erotic video, what is confirmed by statistical difference between investigated parameters.
5. The results of the obtained observations and their clinical illustrations allow us to draw a conclusion that using of investigated ultrasound methodology optimizes the visualization of woman's prostate gland zone and allows reaching high quality image and also allows to reach clarity of the described structures; this method of examination also allows evaluating the characteristic of blood flow.