The most basic treatment for anal fistula is surgery. However, the high recurrence rate of anal fistulas is a common problem, especially in recurrent and complex anal fistulas. For effective surgical management, prior knowledge of the site of the fistula, the main types of perianal fistulas, and the anatomy of the internal orifice is essential to the success rate of a single operation. important for increasing. The most common imaging evaluation techniques include fistulography, endoscopic ultrasound, CT, MRI, and B-ultrasound.
Fistulography has its limitations due to low diagnostic accuracy [10]cannot see the anal sphincter or establish the relationship between the anal sphincter and the fistula. [11]. Extensions away from the primary track can also be difficult. Endoscopy allows visualization of detailed anal anatomy with high spatial resolution and can be used to classify fistula types. [12]. However, due to the narrow field of view of endoscopy, suprasphincteric and secondary tracts cannot be detected. [11]. Traditional 2D CT images are still insufficient for detailed analysis and accurate classification of fistula anatomy. Additionally, the delicate distribution of fistulas cannot be completely depicted due to the low soft tissue differentiation ability. [13, 14]. Additionally, CT exposes the patient to ionizing radiation. [15].
MRI is a highly accurate, noninvasive modality for detecting and characterizing the presence and location of the primary fistula track, secondary extensions, and associated abscesses, as well as delineating their extent. [16, 17]. MRI has become the preferred imaging modality for evaluating perianal fistulas due to its high spatial resolution and soft tissue contrast in the perianal region. [18]. Preoperative MRI has been shown to influence subsequent surgery, thereby significantly reducing the risk of recurrence. [12].However, cost and accessibility constraints still remain [19]. It is also time-consuming to acquire multiple sequences to depict the fistula in detail. [6]. The activity of the fistula or abscess is also believed to play a role in determining the surgical treatment strategy.
Recently, DW-MRI has been recommended as a diagnostic aid because it can detect the presence and extent of fistulas. Additionally, it is a useful tool to assess anal fistula activity. However, due to the low spatial resolution, it is not possible to assess the course of the fistula with respect to adjacent structures. [20].
Ultrasound examination of anal fistulas is a real-time, high-resolution, effective and safe evaluation method and has been developed as an alternative imaging technique. Unlike MRI, ultrasound is better tolerated by the patient and provides dynamic anatomy and orientation of the fistula tract. Additionally, it can be used intraoperatively to aid in surgical management. Because of the limitations of viewing images in only one plane, three-dimensional ultrasound has recently been introduced to image the anal canal and anal sphincter anatomy at high resolution in multiple planes. I am. The number and location of fistulas and internal openings, as well as the communication between local defects in anal canal mucus and large superficial abscesses, can be accurately depicted. Three-dimensional anorectal ultrasound has improved the diagnosis of anal fistulas by more accurately showing the relationship between the anal sphincter and the fistula canal and providing a detailed multiplanar reconstruction of the anal canal. It also improves the sensitivity of detecting fistula scars, internal openings, and anal sphincter defects. This is important in surgical planning to minimize damage to the anal sphincter complex. However, evaluating the patient with a three-dimensional intracavitary probe may worsen the patient’s pain. Therefore, three-dimensional pelvic ultrasound can be used to reduce pain and perform surgery around subcutaneous abscesses without the need for anal dilatation.
This study provides a multifaceted preoperative mapping of perianal fistulas by evaluating anal fistulas using 3-dimensional pelvic ultrasound, identifying all components (location and type of primary and secondary canals; We demonstrate that it is possible to identify the internal opening (e.g., internal opening) and quantify the length of the anal fistula. Displays sphincter muscle damage, the relationship between sphincter muscle and fistula, and classifies anal fistulas. This method is well tolerated and minimally invasive. The results showed the accuracy of pelvic 3D US and MRI for evaluating internal orifice (97.92%, 94.79%), perianal fistula (97.01%, 94.03%), and Parks classification (97.53%, 93.83%), respectively. . There is no statistically significant difference (P> 0.05). This suggests that the two diagnostic methods are equally effective in diagnosing anal fistulas.
This study has a small sample size. Ultrasound has limitations in detecting and imaging deep lesions due to transmission limitations of the transonic beam and potential for air interference. [21]. Elevator fistulas are the most complex and rare type of anal fistula. A larger sample size could be used to evaluate the utility of pelvic 3D US imaging in the diagnosis of high-grade anal fistulas. Furthermore, a follow-up period is required to reasonably assess the fistula healing rate.