An imperforate anus or anorectal malformations (ARMs) are

birth defects A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

in which the

rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...

is malformed. ARMs are a spectrum of different congenital anomalies which vary from fairly minor lesions to complex anomalies. The cause of ARMs is unknown; the genetic basis of these anomalies is very complex because of their anatomical variability. In 8% of patients, genetic factors are clearly associated with ARMs. Anorectal malformation in

Currarino syndrome Currarino syndrome is an inherited congenital disorder where either the sacrum (the fused vertebrae forming the back of the pelvis) is not formed properly, or there is a mass in the presacral space in front of the sacrum, and there are malformatio ...

represents the only association for which the gene ''

HLXB9 Motor neuron and pancreas homeobox 1 (MNX1), also known as Homeobox HB9 (HLXB9), is a human protein encoded by the ''MNX1'' gene. Clinical significance Mutations in the ''MNX1'' gene are associated with Currarino syndrome Currarino syndrome ...

'' has been identified.

Types

There are other forms of anorectal malformations though imperforate anus is most common. Other variants include anterior ectopic anus. This form is more commonly seen in females and presents with constipation.

Presentation

There are several forms of imperforate anus and anorectal malformations. The new classification is in relation of the type of associated

fistula A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow or ...

. The classical Wingspread classification was in low and high anomalies: * A low

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...

, in which the colon remains close to the skin. In this case, there may be a

stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture). ''Stricture'' ...

(narrowing) of the anus, or the anus may be missing altogether, with the

ending in a blind pouch. * A high lesion, in which the colon is higher up in the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

and there is a

connecting the rectum and the

bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...

or the

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

. * A

persistent cloaca A persistent cloaca is a symptom of a complex anorectal congenital disorder, in which the rectum, vagina, and urinary tract meet and fuse, creating a cloaca, a single common channel. Signs and symptoms Cloacas appear in a wide spectrum of varia ...

(from the term

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

, an analogous orifice in birds,

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s and

amphibians Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...

), in which the rectum, vagina and urinary tract are joined into a single channel. Imperforate anus is usually present along with other birth defects— spinal problems,

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

problems,

tracheoesophageal fistula A tracheoesophageal fistula (TEF, or TOF; see spelling differences) is an abnormal connection (fistula) between the esophagus and the trachea. TEF is a common congenital abnormality, but when occurring late in life is usually the sequela of surgic ...

esophageal atresia Esophageal can refer to: * The esophagus * Esophageal arteries * Esophageal glands The esophageal glands are glands that are part of the digestive system of various animals, including humans. In humans Esophageal glands in humans are a part of a ...

renal The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

anomalies and

limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, ...

anomalies are among the possibilities, collectively being called the

VACTERL association The VACTERL association (also VATER association, and less accurately VACTERL syndrome) refers to a recognized group of birth defects which tend to co-occur (see below). This pattern is a recognized association, as opposed to a syndrome, because th ...

Associated anomalies

Imperforate anus is associated with an increased incidence of some other specific anomalies as well, together being called the

. Other entities associated with an imperforate anus are trisomies 18 and 21, the

cat-eye syndrome Cat eye syndrome (CES) or Schmid–Fraccaro syndrome is a rare condition caused by an abnormal extra chromosome, i.e. a small supernumerary marker chromosome. This chromosome consists of the entire short arm and a small section of the long arm o ...

(partial

trisomy A trisomy is a type of polysomy in which there are three instances of a particular chromosome, instead of the normal two. A trisomy is a type of aneuploidy (an abnormal number of chromosomes). Description and causes Most organisms that reprodu ...

tetrasomy A tetrasomy is a form of aneuploidy with the presence of four copies, instead of the normal two, of a particular chromosome. Causes Full Full tetrasomy of an individual occurs due to non-disjunction when the cell division, cells are dividing (mei ...

of a maternally derived

chromosome 22 Chromosome 22 is one of the 23 pairs of chromosomes in human cell (biology), cells. Humans normally have two copies of chromosome 22 in each cell. Chromosome 22 is the second smallest human chromosome, spanning about 49 million DNA base pairs and ...

Baller–Gerold syndrome Baller–Gerold syndrome (BGS) is a rare genetic syndrome that involves premature fusion of the skull bones and malformations of facial, forearm and hand bones. The symptoms of Baller–Gerold syndrome overlap with features of a few other genetics ...

, caudal regression syndrome,

FG syndrome FG syndrome (FGS) is a rare genetic syndrome caused by one or more recessive genes located on the X chromosome and causing physical anomalies and developmental delays. FG syndrome was named after the first letters of the surnames of the first pat ...

Johanson–Blizzard syndrome Johanson–Blizzard syndrome is a rare, sometimes fatal autosomal recessive multisystem congenital disorder featuring abnormal development of the pancreas, nose and scalp, with intellectual disability, hearing loss and growth failure. It is sometim ...

McKusick–Kaufman syndrome McKusick–Kaufman syndrome is a genetic condition associated with MKKS. The condition is named for Dr. Robert L. Kaufman and Victor McKusick. It is sometimes known by the abbreviation MKS. In infancy it can be difficult to distinguish between MK ...

Pallister–Hall syndrome Pallister–Hall syndrome (abbreviated PHS) is a disorder that affects the development of many parts of the body. It is named for Judith Goslin Hall, Judith Hall and Philip Pallister. Presentation Most people with this condition have extra fing ...

, short rib–polydactyly syndrome type 1,

Townes–Brocks syndrome Townes–Brocks syndrome (TBS) is a rare genetic disease that has been described in approximately 200 cases in the published literature. It affects both males and females equally.

13q deletion syndrome 13q deletion syndrome is a rare genetic disease caused by the deletion of some or all of the large arm of human chromosome 13. Depending upon the size and location of the deletion on chromosome 13, the physical and mental manifestations will vary. ...

, urorectal septum malformation sequence and the

OEIS complex Cloacal exstrophy (EC) is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of the bladder, genitalia, and the anus. It is sometimes called OEIS complex. Diagnosti ...

(

omphalocele Omphalocele or omphalocoele also called exomphalos, is a rare abdominal wall defect. Beginning at the 6th week of development, rapid elongation of the gut and increased liver size reduces intra abdominal space, which pushes intestinal loops out of ...

, exstrophy of the

, imperforate anus, spinal defects).

Diagnosis

When an infant is born with an anorectal malformation, it is usually detected quickly as it is a very obvious defect. Doctors will then determine the type of birth defect the child was born with and whether or not there are any associated malformations. It is important to determine the presence of any associated defects during the newborn period in order to treat them early and avoid further

sequela A sequela (, ; usually used in the plural, sequelae ) is a pathological condition resulting from a disease, injury, therapy, or other trauma. Derived from the Latin word, meaning “sequel”, it is used in the medical field to mean a complication ...

e. There are two main categories of anorectal malformations: those that require a protective

colostomy A colostomy is an opening ( stoma) in the large intestine (colon), or the surgical procedure that creates one. The opening is formed by drawing the healthy end of the colon through an incision in the anterior abdominal wall and suturing it int ...

and those that do not. The decision to open a colostomy is usually taken within the first 24 hours of birth.

Sonography Medical ultrasound includes diagnostic techniques (mainly medical imaging, imaging techniques) using ultrasound, as well as therapeutic ultrasound, therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal ...

can be used to determine the type of imperforate anus.

Treatment

Imperforate anus usually requires immediate

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

to open a passage for

feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...

unless a

can be relied on until corrective surgery takes place. Depending on the severity of the imperforate, it is treated either with a perineal anoplasty or with a

. While many surgical techniques to definitively repair anorectal malformations have been described, the posterior sagittal approach (PSARP) has become the most popular. It involves dissection of the perineum without entry into the abdomen and 90% of defects in boys can be repaired this way.

Prognosis

With a high lesion, many children have problems controlling bowel function and most also become

constipated Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The Human feces, stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bo ...

. With a low lesion, children generally have good bowel control, but they may still become constipated. For children who have a poor outcome for continence and constipation from the initial surgery, further surgery to better establish the angle between the anus and the rectum may improve continence and, for those with a large rectum, surgery to remove that dilated segment may significantly improve the bowel control for the patient. An antegrade enema mechanism can be established by joining the appendix to the skin (Malone stoma); however, establishing more normal anatomy is the priority.

Epidemiology

Imperforate anus has an estimated incidence of 1 in 5000 births. It affects boys and girls with similar frequency. However, imperforate anus will present as the low version 90% of the time in females and 50% of the time in males. Imperforate anus is an occasional complication of

sacrococcygeal teratoma Sacrococcygeal teratoma (SCT) is a type of tumor known as a teratoma that develops at the base of the coccyx (tailbone) and is thought to be primarily derived from remnants of the primitive streak. Sacrococcygeal teratomas are benign 75% of the ...

Society and culture

Ribbon

The ribbon to represent anorectal malformations/imperforate anus abnormalities is turquoise, which encapsulates hope, strength and a positive attitude. Zebra stripes were added to show the uniqueness and represent just how no two zebra markings are the same, nor are people living with ARM/IA. Anorecal Malformation Ribbon

Awareness day

The international awareness day for anorectal abnormalities is 1 May. The day aims to raise awareness about an abnormality many have not heard of by creating a human connection for an abnormality that often leaves people feeling alone. The day 1 May was chosen to represent the incidence of such malformations, which occur in roughly 1 in 5,000 babies.

History

Seventh-century

Byzantine The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...

physician

Paulus Aegineta Paul of Aegina or Paulus Aegineta ( el, Παῦλος Αἰγινήτης; Aegina, ) was a 7th-century Byzantine Greek physician best known for writing the medical encyclopedia '' Medical Compendium in Seven Books.'' He is considered the “Fathe ...

described a surgical treatment for imperforate anus for the first time. tenth-century

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

physician

Haly Abbas 'Ali ibn al-'Abbas al-Majusi ( fa, علی بن عباس مجوسی; died between 982 and 994), also known as Masoudi, or Latinized as Haly Abbas, was a Persian physician and psychologist from the Islamic Golden Age, most famous for the ''Kitab ...

was the first to highlight preserving the sphincter muscles throughout the surgery and the prevention of strictures with a

stent In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. A wide variety of stents are used for different purposes, from expandab ...

. He has reported the use of wine for wound care in this surgery. Some reports of children surviving this surgery are available from the early medieval Islamic era.

References

External links

Medline Plus Medical Encyclopedia: Imperforate anus
{{Congenital malformations and deformations of digestive system Congenital disorders of digestive system Colorectal surgery Rectum