A few weeks after surgery, the patient begins a program of anal dilations as part of the treatment of the ARM. Dilations are necessary to prevent fibrosis and consequently stenosis of the anus, which would otherwise result from the normal healing of the surgical wound.

Parents are trained to perform dilatations using Heagar dilators for their child according to the protocol determined by their treating surgeon.

When the desired size of Heagar dilator, determined by age, easily enters into the rectum, the closure of the colostomy can be performed. After the colostomy is closed, the dilatation program is continued according to a specified protocol.

As the size of Heagar dilatator increases, its entry into the anus may be slightly painful. However, dilatations must be continued to prevent stenosis of the anus and the subsequent consequences.

Furthermore, if the frequency or size of the dilations decreases prematurely, it may result is injury with the following dilation. This can gradually leas to the formation of fibrosis and stenosis of the anus. If for any reason the dilations stop, the process must be re-started from the beginning.