- One in 4,000 newborns has an anorectal malformation.
- A total of 900 ultrasounds were performed on 372 study participants.
- Anal dimples were visualized in 58.6% of fetuses.
Research background: prenatal diagnosis of anorectal malformations
It is difficult to detect and diagnose anorectal malformations prenatally, especially less severe forms. Identifying less severe forms could be possible if an abnormal location or absence of an opening is detected, such as rectovestibular fistula, rectourethral bulbar or prostatic fistula, rectobladder neck fistula and anorectal malformation without fistula in males and females.
The identification and evaluation of an anal dimple (AD) during routine prenatal ultrasounds may be a feasible way to detect the presence of an AD and make a diagnosis of an anorectal malformation. The appearance of the AD is described as a “predominantly rounded area of echogenicity surrounded by a rim of hypoechogenicity posterior to the fetal genitalia, resembling a ‘target sign.’”
Researchers from the International Center for Colorectal and Urogenital Care and Colorado Fetal Care Center at Children’s Hospital Colorado hypothesized that visualizing the AD in prenatal ultrasounds may help detect less severe types of anorectal malformations and impact pregnancy management and family counseling.
Research methods: prenatal ultrasounds
Researchers performed a longitudinal study of 372 pregnant women who underwent prenatal ultrasounds at the Colorado Fetal Care Center between January 2019 and October 2020. Fetuses with suspected anorectal malformations were excluded. A total of 900 ultrasounds were performed, evaluating 1,044 fetuses, with a gestational age range of 16 to 38 weeks. The mean number of ultrasounds per participant was two.
Data collection on fetuses included:
- Gestational age
- Singleton vs. multiple pregnancies
- Visualization of AD
- Non-visualization of AD