Anatomical basis of digital rectal examination

Rectal examination is difficult to carry out by students because of their lack of knowledge and fear. It is therefore necessary to search for methods in order to facilitate its practice. This work mainly focuses on the palpation of the posterior lateral area of the rectum.

This work bases itself on the study of the average length of indexes and on the anatomical study of the dissection and prints of two pelvises. In the lithotomy position, we can identify three successive levels of exploration of the posterior and lateral area of the rectum. These three levels are defined by the extremity of the index, and the distal and proximal interphalangeal articulations placed successively on the tip of the coccyx. A 180° rotation of the hand enables at each level to identify the parietal structures that the pad of the index comes across, but excludes the palpation of genital organs and rectum.

The first level corresponds to the higher part of the anal canal, the ischioanal fossa and the ischium. The second level corresponds to the levator ani muscle, the ischioanal fossa and the pudendal canal. The third level corresponds to the sacrospinous ligament, the ischiatic spine and the internal obturator muscle.

In spite of the significant differences between the lengths of the indexes, the use of these landmarks will facilitate the identification of parietal anatomical structures. The internal organs' palpation will depend on the patient's position, his efforts in pushing, the length of the index, and the way the examiner presses on the perineum.