End-scan Convex Array Probe Is Used To Locate The Internal Orifice Of Female Anal Fistula Via Vaginal Or Perineal Ultrasound

Objective:This study mainly discusses the diagnostic value of locating the internal orifice of female anal fistula by transvaginal or perineal ultrasound with end-scan convex array probe.End-scan convex array intracavity probe and high-frequency linear array probe were used to examine and locate the internal orifice of anal fistula,and the results were compared with those of surgery and pathology.It shows the position of anal fistula internal orifice and the relationship between fistula and sphincter,analyzes the characteristics of the obtained ultrasonic images,and discusses the consistency between the two probes in examining anal fistula internal orifice and surgical pathology results.Comparing the two different probes shows the value of the end-scanning convex intracavity probe in locating anal fistula internal orifice before operation,which provides another effective imaging examination method for clinicians in diagnosing and treating anal fistula diseases,and popularizes this examination method in future work.Method:This study observed 39 female patients with anal fistula in our hospital from January,2016 to June,2020.Before operation,the patients were examined by end scanning convex array intracavity probe(transvaginal ultrasound examination for married women and transperineal ultrasound examination for unmarried women).Record the position and size of anal fistula according to the 12 o’clock method of lithotomy position,and show the number and shape of fistula.The sensitivity,specificity and consistency test results of this examination method were analyzed as reference standard.The ultrasonic frequency of the end-scanning convex array intracavity probe is 3～10 MHz.The inclusion criteria of the subjects are:(1)women with anal fistula after clinical diagnosis;(2)Patients with normal anal morphology and function;(3)Patients who have no obvious respiratory diseases,blood diseases and circulatory diseases,and whose liver and kidney functions meet the treatment standards;(4)Patients need and are allowed to use ultrasound for examination and diagnosis;(5)Patients with anal fistula to be operated in our hospital.The criteria for ultrasonic diagnosis of anal fistula:(1)There is a hypoechoic fissure in the anorectal mucosa.(2)Partial defect of annular muscle of internal anal sphincter;(3)The echo of the external anal sphincter with strong echo was interrupted and the muscular layer was damaged,showing a hypoechoic image.If it meets one of the above criteria,it can be diagnosed as anal fistulaResult:All patients can be examined,and the anal canal can be divided into three sections.There is no obvious boundary between external anal sphincter and puborectalis muscle during ultrasound examination.Cross-sectional images are used to distinguish the shape of external anal sphincter from puborectalis muscle,which shows that the hyperechoic pubic muscle is U-shaped,while the internal sphincter is annular,while the hypoechoic one is the upper section.Female internal and external anal sphincter are in the middle section of closed hyperechoic and hypoechoic,while female external anal sphincter hypoechoic one is the lower section.The longitudinal section of female anal canal divides the anal canal into different structures:hyperechoic mucosa layer,hypoechoic internal sphincter and hyperechoic external sphincter,which clearly shows the anorectal angle.Dynamic ultrasound can be used to observe the gas-liquid flow in patients’ rectal ampulla in real time.All 39 patients were found to have different degrees of perianal abscess,of which 36 patients could observe the flowing liquid echo with two probes;51 internal anal fistula and 58 fistulas were found in 39 patients.Before operation,46 internal orifices of anal fistula and 52 fistulas were diagnosed with end-scan convex array intracavitary probeA total of 46 anal fistulas were detected before ultrasound,among which 28 were located at 5～6 o’clock,7 at 1～2 o’clock,6 at 10～11 o’clock,3 at 7～8 o’clock and 2 at 4～5 o’clock.Among the 46 internal orifices,the echo interruption range of external anal sphincter was 1.8～7.6 mm,with an average of(3.8±1.2)mm.The end-scan convex array probe was consistent with the pathological results of the operation(Kappa value 0.521).3 internal fistulas were missed and 5 internal fistulas were misdiagnosed.The end-scan convex array probe is consistent with the pathological results of surgery(Kappa value 0.449).The sensitivity and specificity of anal fistula are 90.2%and 66.7%,and the sensitivity and specificity are 89.6%and specificity.62.5%.The diagnosis of female anal fistula with end-scanning convex array intracavity probe is consistent with the results of surgery and pathology.Conclusion:The diagnosis of female anal fistula with end-scanning convex array intracavity probe is consistent with the results of surgery and pathology.The value of transvaginal or perineal end-scanning convex array intracavity probe in locating the internal orifice of female anal fistula before operation:①The accuracy of locating the internal orifice of anal fistula before operation is high,which has high diagnostic value.② The probe is not placed at the lesion,especially for those patients who can’t tolerate acute inflammation through anal canal examination.③ End-scanning intracavity probe is very popular,economical and convenient.To sum up,transvaginal or perineal ultrasound with end-scan convex array intracavity probe has high clinical value in preoperative diagnosis and localization of female anal fistula,which is worth popularizing.