Garg Pankaj, Kaur Baljit, Yagnik Vipul D, Dawka Sushil
Indus Super Specialty Hospital, Mohali, India.
Department of Radiology, SSRD MRI Centre, Chandigarh, India.
Clin Exp Gastroenterol. 2021 Oct 7;14:397-404. doi: 10.2147/CEG.S335703. eCollection 2021.
In the anal sphincter complex, the intersphincteric space between the internal and external sphincters is the only conventionally recognized pathway for the spread of sepsis. However, there is another unrecognized space discovered on MRI, the "outer-sphincteric space", between the external anal sphincter and its lateral fascia along which pus can spread. An abscess in the intersphincteric space is easily drained into the rectum via the transanal route and is more likely to spread into the supralevator space. Conversely, an abscess in the outer-sphincteric space is difficult to drain transanally into the rectum and is more likely to become a transsphincteric abscess/fistula.
The MRIs of anal fistula patients operated over four years on intersphincteric abscesses were analyzed. The pattern of spread into the ischiorectal fossa and/or supralevator space and ease of drainage into the rectum through the transanal route were studied.
Thirty-six patients were operated on to drain their intersphincteric abscesses through the anal canal. Two distinct patterns were noted. Twenty patients had abscesses in the intersphincteric space, which were easily drained into the rectum. Of them, 6/20 had supralevator extension, while only 1/20 had spread to the ischiorectal fossa. In 16/36 patients, the abscess was in the outer-sphincteric space and could not be drained into the rectum. In 9/16 of these patients, pus spread into the ischiorectal fossa but supralevator spread did not happen in any patient.
Apart from the intersphincteric space, there is perhaps another unrecognized anatomical space - the outer-sphincteric space - discovered on MRI, through which pus can spread in anal fistulas or abscesses.
在肛门括约肌复合体中，内括约肌和外括约肌之间的括约肌间隙是传统上唯一公认的脓毒症扩散途径。然而，在磁共振成像（MRI）上发现了另一个未被认识的间隙，即肛门外括约肌与其外侧筋膜之间的“外括约肌间隙”，脓液可沿此间隙扩散。括约肌间隙脓肿很容易通过经肛门途径排入直肠，并且更有可能扩散到肛提肌上间隙。相反，外括约肌间隙脓肿经肛门很难排入直肠，并且更有可能形成经括约肌脓肿/肛瘘。
分析了4年间因括约肌间隙脓肿接受手术的肛瘘患者的MRI。研究了脓肿扩散至坐骨直肠窝和/或肛提肌上间隙的模式，以及经肛门途径排入直肠的难易程度。
36例患者通过肛管进行了括约肌间隙脓肿引流手术。观察到两种不同模式。20例患者的脓肿位于括约肌间隙，很容易排入直肠。其中，20例中有6例脓肿延伸至肛提肌上间隙，而只有1例扩散至坐骨直肠窝。在36例患者中的16例中，脓肿位于外括约肌间隙，无法排入直肠。在这些患者中的16例中有9例，脓液扩散至坐骨直肠窝，但没有患者的脓肿扩散至肛提肌上间隙。
除了括约肌间隙外，在MRI上可能还发现了另一个未被认识的解剖间隙——外括约肌间隙，肛瘘或脓肿中的脓液可沿此间隙扩散。
