Between one-third and one-half of the women who have third and fourth degree perineal obstetric injuries (anal sphincters injuries) suffer from symptoms of faecal incontinence. Endoanal ultrasound is considered the gold standard for assessing these types of injuries.
Some authors have used transperineal ultrasound to identify anal sphincter injuries (Figure 9).
Images of an injury of both anal sphincters as shown by endoanal ultrasound (image on the left) and by transperineal ultrasound using TUI (image on the right).
The transperineal approach provides several advantages, including the fact that it is more comfortable and less bothersome for the patient and that it can be conducted with the same probe that the gynaecologist usually uses (a convex probe). The three-dimensional transperineal approach is reproducible with endoanal ultrasound with high sensitivity in detecting residual defects in patients with anal sphincter injuries (11). This could be useful as a screening technique in order to select patients with a suspected injury and refer them for a more complete examination using the transanal approach, since the latter approach provides higher resolution and, as we have mentioned, continues to be considered the gold standard.
