The role of multimodal ultrasound in diagnosis of fetal bowel dilatation and prediction of adverse neonatal outcomes: A study of 86 cases in a series of 43,562 births

Abstract

Objective: To investigate the diagnostic utility of multimodal ultrasound for fetal bowel dilatation (FBD) in different parts of the bowel and to examine its prognostic potential in FBD.

Methods: This retrospective study analyzed 86 fetuses with a dilated bowel identified via ultrasound in a 10-month postnatal follow-up. Both two- and three dimensional (2D and 3D, respectively) ultrasound volume imaging were used to characterize dilation across different bowel sections. The optimal intestinal diameter cut-off values for pathological bowel dilatation were determined and a predictive model for neonatal surgery was developed.

Results: The 86 cases of dilatation were distributed as follows: duodenal (n = 36); jejunum/ileum (n = 35); and colonic (n = 15). Duodenal dilatations presented the earliest during pregnancy compared to the other 2 groups (24.4 versus [vs.] 29 vs. 33.7 weeks respectively; p < 0.05). Cases with small intestinal dilatation were delivered earlier than those with colonic dilatation (p < 0.05). Infants with duodenal dilatation had the lowest birth weight and the highest rate of multi-system abnormalities (30.6% vs. 5.7% vs. 20%; p < 0.001). More than one-half of the multi-system abnormalities had chromosomal abnormalities (multiple, 54% vs. single, 12.5%; p = 0.015). There were 2 stillbirths, 24 induced labors, 44 postnatal surgeries, and 18 normal cases after birth. In predicting adverse neonatal outcomes of jejunum/ileum dilatation using a cut-off value of 15.5 mm small intestine diameter, sensitivity was 81.5%, specificity was 62.5%, and the area under the receiver operating characteristic curve (AUC) was 0.762 (p < 0.05). For colonic dilatation, using a cut-off value of 21.5 mm colon diameter: sensitivity was 83.3%, specificity was 77.8%, and AUC was 0.861 (p < 0.05). In detecting jejunum/ileum and colonic obstruction, 3D ultrasound demonstrated significantly better diagnostic efficiency than 2D ultrasound (p < 0.05). Using the backward stepwise selection method, a predictive model for neonatal surgery in patients with jejunum/ileum and colonic dilatation was established: logit (P) = -1.58 + (2.32 × polyhydramnios) +(2.0 × ascites) +(1.14 × hyperechogenic bowel). The AUC for the prediction model was 0.874 (p < 0.05), with 76% sensitivity and 94.1% specificity.

Conclusions: Duodenal dilatation occurred earlier, with a higher incidence of chromosomal abnormalities and multi-system abnormalities than dilatation of other parts of the bowel. 3D ultrasound played an important role in the detection of jejunum/ileum and colon obstructions. Clinical signs, including polyhydramnios, ascites, and strong echoes in the intestine, can be used to predict neonatal surgery.

Keywords: 3D ultrasound volume imaging; Fetal bowel dilatation; Multimodal ultrasound; Prediction model; Prenatal diagnosis.

Fig. 1

Flowchart of selection process of included patients.

Fig. 2

Fetus at 22 weeks and 2 days of gestation with proximal duodenal dilation. Postnatal surgery confirmed proximal narrowing of the descending part of the duodenum. A. 2D ultrasound shows the “double-bubble sign” in the upper abdomen. B. In 3D inversion mode, a clear connection is seen between the esophagus and the gastric bubble, and the proximal duodenal dilation appears as a “crescent moon” shape.

Fig. 3

Fetus at 24 weeks of gestation with distal duodenal obstruction. Postnatal surgery confirmed horizontal duodenal atresia. A. 2D ultrasound shows the “double-bubble sign” in the upper abdomen. B. 3D volume imaging demonstrates the connection between the gastric bubble and the duodenum through the pylorus, with proximal dilation of the descending and horizontal parts of the duodenum forming a “C” shape.

Fig. 4

Fetus at 28 weeks and 5 days of gestation with small intestinal dilatation. Postnatal surgery confirmed distal jejunal atresia. A. 2D ultrasound shows dilated intestine with clear acoustic transmission through the intestinal contents. B. 3D imaging inversion mode demonstrates changes in the morphology of the dilated intestine. C. 3D imaging grayscale mode confirms the dilated intestinal segment as the small intestine with the smooth inner wall and the absence of haustra of colon.

Fig. 5

Fetus at 27 weeks and 3 days of gestation with small intestinal dilatation. Postnatal surgery confirmed ileal atresia. A. 2D ultrasound shows intestinal dilatation, with localized distribution of small bright spots within the intestinal lumen. During peristalsis, the walls of two adjacent intestines come into contact and protrude into the intestinal lumen. B. In 3D volume imaging in grayscale mode, the dilated intestinal segment is identified as the small intestine with the smooth inner wall.

Fig. 6

Fetus at 29 weeks and 4 days of gestation with small intestinal dilatation. Postnatal surgery confirmed terminal ileum torsion necrosis and mesenteric dysplasia. A. 2D ultrasound shows dilated intestine with the intestinal contents appearing densely packed with tiny light spots. B. In 3D imaging inversion mode, the dilated intestinal segment shows a “spiral sign”. C. 3D imaging in grayscale mode shows a smooth inner wall in the dilated intestine, indicating it is the small intestine with single-layer changes in the intestinal wall.

Fig. 7

ROC curve of dilated small intestine diameter in predicting adverse pregnancy outcome in fetuses with jejunal or ileal dilatation.

Fig. 8

Fetus at 32 weeks of gestation with colonic dilatation. Postnatal surgery confirmed distal atresia of ascending colon. A. 2D ultrasound shows dilated intestine with dense, small bright spots within the intestinal lumen. B. In the grayscale mode of 3D ultrasound, the presence of haustra on the inner wall of the intestine is well displayed.

Fig. 9

Urorectal septum sequence at 31 weeks and 6 days of gestation: A. 2D ultrasound shows absence of the “target sign” in the anal area; B. 2D ultrasound shows strong echo spots within the bowel, uterine distension with fluid accumulation, and local deposition of small echogenic spots; C. 3D imaging in grayscale mode demonstrates strong echogenic spots suspended within the dilated bowel; D. 3D imaging in inversion mode shows the spatial relationship between the bladder, uterus, and dilated colon, with the uterus appearing as a unicompartimental shape.

Fig. 10

Urorectal septum sequence at 33 weeks and 3 days of gestation: A. 2D ultrasound shows the dilated uterus didelphys with effusion in the lower abdominal. B. 2D ultrasound shows colonic dilatation. C. In 3D Crystal Vue imaging grayscale mode, after increasing transparency, it displays the dilated colon located behind the uterus didelphys. D. In 3D inversion mode, it shows the double uterus located behind the distended bladder. E–F: After induction, anal atresia, left descending colon dilatation, and uterus didelphys effusion were confirmed.

Fig. 11

ROC curve of dilated colon diameter in predicting adverse pregnancy outcome in fetuses with colonic dilatation.

Fig. 12

ROC curve of three-factor model in predicting neonatal operation in patients with fetal bowel dilatation.