Fetal Anal Atresia Presenting as Transient Bowel Dilatation at 16 Weeks of Gestation

Abstract

Congenital anal atresia is a rare abnormality which in two thirds of the cases is associated with other congenital abnormalities or syndromes. Prenatal diagnosis is usually achieved in cases with coexisting abnormalities. The diagnosis of isolated anal atresia is extremely difficult and can be suspected in the presence of colon dilatation. We present the case of a fetus in which marked dilatation of the colon was diagnosed at 16 weeks of gestation. Four weeks later the sonographic appearance of the bowel was normal and remained normal for the rest of the pregnancy. Anal atresia was diagnosed immediately after birth and corrected surgically. No other abnormalities were present. This case report illustrates that in anal atresia, bowel dilatation may be only transient.

Transient Distention of Right Posterior Located Sigma, a New Sonographic Sign for the Prenatal Diagnosis of Anal Atresia

“…Furthermore, in all three of the cases that did not terminate the pregnancy early, the distension was transient and had resolved by 19 weeks' gestation. Interestingly, transient distal colon distension has also been reported . In some cases, the apparent spontaneous resolution may be explained by the formation of a fistula decompressing the bowel.…”

“…Interestingly, transient distal colon distension has also been reported. 8,9 In some cases, the apparent spontaneous resolution may be explained by the formation of a fistula decompressing the bowel. The mentioned diagnostic signs of fetal anorectal malformations, distal colon and rectosigmoid distention, 2,3 a U-or V-shaped segment of dilated bowel, 4 enterolithiasis, 5 failure to visualize the anal ring, 6 or absence of the anal mucosa, 7 are not specific and false positives may occur.…”

Segmental colonic dilation is associated with premature termination of high‐amplitude propagating contractions in children with intractable functional constipation

“…Segmental colonic dilation is often encountered in children with severe constipation, both of functional and organic origin . In early life, this phenomenon is usually associated with congenital organic diseases such as Hirschsprung's disease, anorectal malformations or other birth defects such as intestinal atresia . However, segmental colonic dilation can also be observed in older children with long‐standing symptoms of functional constipation (FC), in whom underlying organic pathology has been ruled out .…”

“…[1][2][3][4][5][6][7] In early life, this phenomenon is usually associated with congenital organic diseases such as Hirschsprung's disease, anorectal malformations or other birth defects such as intestinal atresia. [8][9][10][11] However, segmental colonic dilation can also be observed in older children with long-standing symptoms of functional constipation (FC), in whom underlying organic pathology has been ruled out. 6,7,12 The phenomenon of segmental dilation has also been described in adults and this has led to the definitions of megacolon and megarectum, defined by Preston et al as a colonic/ rectal width of >6.5 cm.…”

Prenatal diagnosis of the VACTERL association using routine ultrasound examination

“…For example, the observation of a polyhydramnios associated with either a small or an absent stomach suggests the presence of an esophageal atresia (Choudhry et al, ). Also the detection of a dilated colon suggests the presence of an anal atresia (Kaponis et al, ). Finally some malformations remain undetectable on routine prenatal ultrasound examination.…”