The Effect of Perineal Wound Infection on the Anal Sphincter

Perineal injury following childbirth can result in complications such as wound infection. The perineum has closely related anatomical structures including the external genital organs and the anal triangle which contains the anal sphincter muscles. Therefore as wound infection can extend and as muscles of the perineum sit in such close proximity to each other, the anal sphincter muscles could potentially be affected. This could also potentially include cases of perineal injury where the anal sphincter was not injured. However ultrasound has never been used to investigate this. Endoanal ultrasound is the gold standard diagnostic tool in the assessment of obstetric anal sphincter injury. The anal sphincter can also be visualised using multiplanar transperineal ultrasound(three/four-dimensional. Therefore both modalities could be used. However, it has been shown that transperineal ultrasound has a high positive predictive value and therefore is able to correctly identify an intact anal sphincter, but low positive predictive value; meaning poor detection of sphincter defects. Therefore, although it cannot completely substitute endoanal ultrasound (the gold standard in investigating obstetric anal sphincter injuries), it provides and adjunct/alternative for women who cannot tolerate endoanal ultrasound. The investigators plan to perform an observational study to evaluate to the natural history of perineal wound infections. Patients will be assessed weekly with endoanal ultrasound and/or transperineal ultrasound until the wound infection has resolved and the wound has clinically healed. If a bacterial wound swab has not been taken prior to recruitment or wound swab results are not available, one will be taken to detect the causative organisms. Appropriate antibiotics will then be given to cover the detected organism. Bacterial burden and will also be measured weekly using the MolecuLight i:X; a bacterial autofluorescence camera which captures the presence and load of bacteria. In wounds that have superficially dehisced; exact wound measurements including wound surface area, depth, volume and healing progress will be precisely measured using the Silhouette® 3D camera