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Disease Profile

Imperforate anus

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Anal atresia; Anal stenosis; Anorectal Malformations


Imperforate anus is a birth defect where the opening to the anus is missing or blocked. The anus, also known as the rectum, is the opening at the end of the intestines through which stool (bowel movement) leaves the body. Imperforate anus may end in a pouch, be too narrow (stenotic or atresic), or open into part of the urinary system, female or male reproductive system, or other system of body[1] Symptoms may include absence of the first stool within 24 to 48 hours after birth, no anal opening, anal opening in an abnormal place, stool coming out from the vagina, base of penis, scrotum, or urethra, and/or swollen belly. Although the exact cause of imperforate anus is not fully understood, it is believed to be due to the abnormal development of the rectum when the embryo is forming inside the womb. Many forms of imperforate anus occur with other birth defects. Imperforate anus may also be part of a syndrome with multiple birth defects. Treatment may include colostomy and surgery to correct the defect. Prognosis depends on the severity and type of imperforate anus and the severity and type of any other birth defects. [1][2]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Ectopic anus
Abnormal anus position
Hearing impairment
Hearing defect

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X-linked inheritance

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 


  1. Kaneshiro NK. Imperforate anus. MedlinePlus. May 14, 2017; https://medlineplus.gov/ency/article/001147.htm.
  2. Rosen NG. Pediatric Imperforate Anus. Medscape Reference. August 9, 2016; https://emedicine.medscape.com/article/929904-treatment#d6.