Hi. I recently found a small hole just above my anus and I'm worried that it could be something serious. The hole itself is about 1mm wide and has recently started to weep and bleed a small amount. I've looked on the Internet to see if I can find out what it is and I think it could be a polinodal. Anorectal Malformations / Imperforate Anus Anorectal malformations, also known as imperforate anus, are defects that occur during the fifth to seventh weeks of fetal development. With these defects, the anus (opening at the end of the large intestine through which stool passes) and the rectum (area of the large intestine just above the . The embryological origin of the mouth and anus is an important characteristic, and forms the morphological basis for separating bilaterian animals into two natural groupings: the protostomes and deuterostomes. In animals at least as complex as an earthworm, a dent forms in one side of the early, spheroidal embryo.