An unusual case of gastric distention in a preterm infant

A preterm male infant born at 29 weeks’ gestation presents with bilious output from his orogastric (OG) tube on day of life 2. Physical examination reveals a patent anus, normoactive bowel sounds and no masses but abdominal distension. Gastric decompression is performed, but the abdominal distention and bilious output persist.

Abdominal radiograph (AXR) demonstrates gastric distention with presence of distal bowel gas (Figure 1). Due to the risk of hypothermia in the preterm infant, a bedside upper gastrointestinal (UGI) contrast study is performed. In this technique, 2 mL of isotonic water-soluble contrast is administered via the OG tube with AXR taken 1 and 3 minutes after administration to visualize the gastroduodenal junction (Figure 2).

Bedside UGI shows no malrotation with a markedly dilated stomach and focal narrowing of the pre-pyloric gastric antrum, consistent with congenital antral stenosis suggestive of a congenital antral web. Abdominal ultrasonography (AUS) (Figure 3) additionally demonstrates pre-pyloric distal antral narrowing.

Exploratory laparotomy confirms diagnosis, with antral thickening and a ring consistent with antral web found and resected with antroplasty performed.

Background

Congenital antral web is a rare cause of gastric distention and occurs in about 1 in 100,000 births [1, 2]. It is found approximately 1 to 2 cm proximal to the pylorus resulting in gastric outlet obstruction and is thought to be due to incomplete canalization of the foregut with localized endodermal proliferation of the gastrum [2-4].

Clinical Perspective

Infants may present with nonspecific symptoms such as feeding difficulties, nonbilious emesis, abdominal distension or failure to thrive [2, 5]. Symptoms in older children typically include nausea, early satiety or epigastric pain [5]. Hematemesis or gastric perforation are more serious clinical manifestations that may present in severe cases [1]. In an insidious presentation, other more common entities, such as pyloric stenosis or peptic ulcer disease, are often confused with congenital antral web, particularly in older children [5]. Failure of timely diagnosis may result in complications and undesired delay in treatment [1].

Imaging Perspective

Imaging considerations include an AXR, AUS, UGI series or endoscopy. Findings of gastric distension with paucity of distal bowel gas on AXR should raise suspicion for possible antral web [4]. AUS is often nonrevealing and only diagnoses a minority of cases, usually when dilated bowel loops suggestive of bowel obstruction are visualized [1, 4, 6].

Diagnosis is more frequently made on UGI, which detects between 60-90% of cases [1, 4, 6]. In preterm infants at higher risk of hypothermia or equipment dislodgement during off-unit procedures, it is pertinent to consider bedside UGI series, especially when evaluation for malrotation or volvulus is indicated [7]. Suspicious findings on UGI include a radiolucent linear septum proximal to the pylorus or a “double duodenal bulb” sign reflecting filling of the antrum distal to the web [1, 6, 8]. Diagnosis may additionally be confirmed by endoscopy, more commonly performed in the older pediatric patient [1, 6, 8].

Outcome

Following diagnosis, this infant was administered post-pyloric feedings for further growth prior to surgical management. While mild cases may be treated conservatively with medical management, most symptomatic individuals require surgical or endoscopic intervention [1, 4, 5]. Postoperative outcomes are generally favourable and demonstrate symptom resolution [1, 8].

Take Home Message / Teaching Points

Imaging considerations for unexplained persistent gastric distention should include UGI with or without endoscopy, which can demonstrate findings suspicious for gastric outlet obstruction.

Modified bedside imaging techniques may be useful in the preterm infant who is critically ill or at risk of hypothermia.

Written informed patient consent for publication has been obtained.