In utero development of the fetal intestine: Sonographic evaluation and correlation with gestational age and fetal maturity in dogs.

Modern high-resolution ultrasound images enable earlier assessment of measures of fetal development, including identification of the bowel. The aim of this study was to describe the ultrasonographic development of fetal bowel and correlate this with gestational age; define whether ultrasonographic visualization of fetal intestinal peristalsis in utero is associated with fetal maturation and determine whether there is a difference in fetal intestinal peristalsis detection time between fetuses delivered by normal delivery and cesarean. A cohort study was conducted in pregnant bitches presented to a veterinary hospital, to assess fetal bowel development. Statistical analysis was used to establish the correlation of the stage of fetal bowel development, as recorded by ultrasound, with outcomes of normal delivery and cesarean section. The study was broken down into three stages: the first stage was a descriptive analysis of fetal bowel development by ultrasound; the second stage compared time (in days) of bowel development between groups (normal delivery vs. cesarean); and the third stage was correlated survival probability for fetuses born on any day after detection of intestinal peristalsis with fetal maturity. All statistical analyses were significant. It is possible to monitor pregnancy progression using ultrasonographic evaluation of bowel development and this can reliably identify the end of fetal organogenesis. However, ultrasonographic detection of bowel segments with visualization of wall layers and associated peristalsis should not be used as the sole indicator for cesarean section planning because it is not possible to determine ultrasonographically whether the bowel is functional (mature).