Ultrasonography is an exam performed by acoustic waves that generate images when reflecting or passing through tissues, reproducing in detail the physical structure of an organ and its different tissues. In colorectal surgery, ultrasonography is performed in the anal canal and rectum through the use of a rotational transducer that allows us to visualize the structures that form them and peripheral regions, generating radial images along their entire circumference.
In the anal canal it is possible to visualize the submucosal layer, the superficial layer and the muscles responsible for preserving the anal continence and the coordination of the evacuation movements: the internal and the external sphincters of the anus and the puborectalis muscle. In the case of the exam performed on the rectum, its layers can be individualized and the mesorectum, the fatty layer containing the lymph nodes surrounding the rectum, can be visualized.
The exam provides visual information of these structures, detecting whether there are lesions on them or not.
Anorectal Ultrasonography identifies tumours and allows the evaluation of the compromised structures and their stage of development, that is, whether they are early or advanced. Thus, it allows the doctors to define the best form of treatment and select the patients who can benefit from minimally invasive procedures. It is also useful for evaluating the late response to radiochemotherapy.
Other common indications are anal abscess, with or without anal fistula, in which all the elements of the fistulous complex can be identified. That is: the fistulous tract and its relations with the muscular structures of the anal canal, its internal opening, which, if unidentified and not addressed at the time of surgery, may lead to recurrence of symptoms and the necessity of further surgeries, and associated cavities and collections (abscesses).
Abscesses can be detected even in their early stages or when deep (and difficult to detect by physical examination) by Endoanal Ultrasonography combined or not with Endorectal Ultrasonography.
Anal fistulas, due to abscesses in the anal canal after spontaneous or surgical drainage, tend to develop as fistulas in up to 35% of the cases. It can be perceived by the patient as a small orifice or lump around the anus, from which there is continuous or intermittent discharge of a yellowish or brownish coloured secretion (pus, with or without blood). There may be pain or itching and bad smell.
The treatment is surgical in these cases and the exam is important to guide the procedure and the choice of the most appropriate technique, avoiding unwanted lesions to the anal muscles and consequent fecal incontinence after surgery.
At Colono we use the modern ERISON ER12 equipment, which consists of a 360º portable transducer with adjustable frequencies. Because it is a portable device, we can use it in any environment of the clinic and even in the operating room (during a surgery), as an important aid in the making of operative decisions, like in the case of hidden abscesses.
Another condition in which this exam is essential is fecal incontinence, especially in women who have already delivered or people who have experienced anal injuries (such as surgeries or traumatic lesions of the anus), because this exam will provide accurate diagnosis and the best treatment for each case.
In some cases, an ultrasonography can be complemented by an anorectal electromanometry, which provides specific functional information for the anorectum. The information from both exams are interpreted together for a more accurate diagnosis and a proper treatment plan for each case.
The exam is painless most of the time and the discomfort caused by it resembles that of the rectal examination performed during a physical exam. In selected cases, sedation or anesthesia may be required.
The exam is fast, lasting for about 10 minutes, and the report is released up to a day after. The patient usually does not receive sedation and does not need any preparation or fasting, and can return to his usual activities right after the exam.