In the pediatric population, the presence of hepatic portal venous gas (PVG) has been described in association with various disease processes such as necrotizing enterocolitis, gastroenteritis, following umbilical catheter, bowel obstruction, Hirschsprung’s disease, duodenal stenosis, SMA syndrome, and hypertrophic pyloric stenosis [1, 8].
There are four main theories that explain the pathophysiology of PVG: (1) bacterial—intramural gas-forming bacterial proliferation, (2) mechanical—increased intraluminal pressure during gastric or intestinal obstruction, (3) mucosal damage—air enters through disrupted mucosa, and (4) pulmonary disease—alveolar air dissects down through the mediastinum to the gastric wall [1]. In some cases, these factors appear to contribute in combination [2].
Intramural gas bubbles detected as pneumatosis intestinalis (PI) may be absorbed into the intestinal venous system, may travel into the portal vein, and can be localized as PVG by real-time ultrasound as flowing echogenic dots. Finally, PVG is trapped in the small branches of the portal vein inside the liver inducing dense granular echogenicities in hepatic parenchyma [3].
Reports of PVG as well as PI detected in the case of intestinal malrotation are rare, and the most reported cases showed intestinal necrosis that necessitated bowel resection and showed poor prognosis [1, 4,5,6,7].
In the present case, the micro-bubbles of gas were detected as highly echogenic particles flowing within the intrahepatic portal vein, and this become an opportunity for further evaluation and the intestinal malrotation was diagnosed. Operative findings showed a mild volvulus with neither congestion nor ischemic change of the twisted bowel. Raised intraluminal pressure or direct stimulation of the bowel wall induced by the volvulus might allow gas to infiltrate the bowel wall and mesentery portal venous flow. Therefore, PVG in this case appeared to be in a transient process that resolves within a short interval after spontaneous winding down or decompression of twisted bowels.
Recent literatures have stated that midgut volvulus in malrotation can be managed well in infants without deteriorating condition. The laparoscopic approach is feasible and effective for the case that even shows PVG, and should have the advantage of minimally invasive surgery with small incisional scar.