What is the difference between endoanal and endorectal ultrasound?

23/10/2017

Ultrasound: Definition

First, we need to define ultrasonography. Ultrasonography is a complementary examination through which we obtain images of structures inside the body by means of sound waves emitted and captured by a transducer, which generates a different perspective as they reflect in certain tissues and cross others. This way, we have a “photograph”, which allows us to analyze in detail the structure of parts of the body, allowing the identification of various changes and diseases, directing different types of treatment.

Ultrasonography, specifically in regards to coloproctology, aims at the detailed visualization of the structures of the anal canal and rectum. The transducer, in this case, allows the capture of radial images along the entire circumference of the rectum and anal canal.

In cases where only visualization and investigation of the anal canal is desired, endoanal ultrasonography is performed. When an evaluation of the rectum is necessary, endorectal ultrasound is done. There are still situations where we want to study the two structures together, both the anal canal and the rectal canal. In this case, anorectal ultrasound is the right choice.

Endoanal Ultrasonography vs Endorectal Ultrasonography

The fundamental difference between both exams is the assessed structures and indications.

In the case of examination of the anal canal, the transducer is inserted into the rectum and then pulled back into the anal canal, and it stays there during the capture of the images for study. It evaluates the muscles that make up the anal sphincters and surrounding structures. In the case of investigation of the rectum, the transducer is introduced up to the rectum, which is the final part of the large intestine and is located in the pelvis just above the anal canal.

In the case of anorectal ultrasonography, anal and rectum images are collected in the same procedure.

In most cases, endoanal ultrasound is used, but in cases of suspected rectum tumors or anal canal tumors extending into the rectum, rectal examination or a combination of the two should be performed.

Main indications of endoanal, endorectal and anorectal ultrasonography

Indications of this technique will depend on the goals and structures to be studied, and include:

  • Study of the musculature responsible for the maintenance of fecal continence and evacuation movements, for diagnosis of fecal incontinence and definition of treatment;
  • Verification of the presence or absence of inflammatory or tumor lesions;
  • Identification of tumors, evaluation of structures involved and definition of stage of lesion development;
  • Definition of the form of treatment in several types of tumors: be it conservative treatment, open, or minimally invasive surgeries, for example;
  • Evaluation of response to radiotherapy or chemotherapy;
  • Evaluation of anal abscess, with or without anal fistula;
  • Evaluation of undetermined causes of anal pain;
  • Preoperative evaluation of orifice procedures;
  • Diagnosis and further investigation of various neoplastic or inflammatory anorectal diseases;
  • Investigation of some causes of intestinal constipation, among others.

General characteristics of the exam

There is no need for sedation in most cases, because the examination usually does not cause pain, except in specific cases and some preconditions. In these cases, sedation or anesthesia is used.

It’s a quick run exam. The release of the report usually occurs until the business day subsequent to that of its accomplishment.

Preparation for the exam is simple. The patient does not need to fast, only a bowel cleansing is performed previously, already in the clinic (except in cases that require sedation, as mentioned). The patient usually is released soon after the exam, for his daily activities.

In Colono, we perform a simple and safe routine ultrasonography. Come check it out!

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