Rupture of pyloric ulcer; Imaging findings and CT demonstration of contrast medium leakage

Clinical History

The patient presented with sudden and intense epigastric pain which started 4 hours after a meal. The pain soon spread to the whole abdomen. The patient had a history of gastric ulcer. Clinical examination showed board-like abdominal rigidity. WBC count was normal, but there was increased blood amylase and bilirubin.

Imaging Findings

Chest radiography showed a small air collection under the right hemi-diaphragm. (Fig.1) Supine and erect abdomen X-rays confirmed the presence of air under the diaphragm and gave evidence of the existence of free fluid. (Fig. 2) Ultrasonography confirmed the existence of fluid collections in the peritoneal cavity. (Fig. 3) Abdomen CT showed free air and fluid collections inside the peritoneal cavity. Extravasation of gastrografin from the pylorus could be seen in some particular images of the CT examination. (Fig. 4)

Discussion

The term pneumoperitoneum refers to the presence of air inside the peritoneal cavity. Its causes include rupture of a hollow viscus (peptic ulcer, diverticulitis etc), trauma, iatrogenic and spontaneous pneumoperitoneum. It must be differentiated from pseudopneumoperitoneum which is caused by Chilaiditi syndrome, gas-distended bowel loops, abscesses, diaphragm irregularities or subdiaphragmatic fat. [1]

Upright chest or abdominal x-rays for the diagnosis of perforated viscus should include the diaphragms. Small volumes of free air are horizontal and slit-like. For optimal images the patients must be positioned (erect or decubitus) for at least 5 minutes. [2]

When perforated, peptic ulcer causes pneumoperitoneum or pneumoretroperitoneum (due to retroperitoneal position of duodenum) and infiltration of surrounding fat and organs like pancreas. When located in the posterior gastric wall, the ruptured ulcer will be confined by adjacent soft tissues or will break into the lesser sac. [3, 4, 5]

Regarding the detection of pneumoperitoneum, plain abdominal X-ray has a sensitivity of 30-59%. CT is 96% to 100% sensitive in identifying free air and 80% to 90% accurate in localising the viscus perforation. In a study published in 2012, the most frequent causes of pneumoperitoneum were visceral perforation and postoperative air. Among patients with visceral perforation, only 45% had free air identified on imaging studies and the most frequent causes of rupture were peptic ulcer, diverticuli, trauma, malignancy and bowel ischaemia. The same study showed that in patients with perforated peptic ulcer the probability of identifying free air in imaging studies was 72% and that large air collections may equally be caused by gastroduodenal, small bowel or colonic perforation. [6] When evaluating patients with suspected rupture of gastrointestinal tract with CT, we should search for both direct signs like extraluminar air or gastrografin and indirect signs like abscesses, fluid collections or other findings. Extravasation of gastrografin due to perforation of an ulcer is not frequently seen. [5]

In another study published in 2011, perforation was gastric/pyloric in 72% and duodenal in 28% of patients. The diagnosis was made by plain abdominal X-ray in 75% and by abdominal computed tomography in 98% of cases. [7] Perforated peptic ulcer needs surgical treatment which can be done either with laparotomy or with laparoscopy. [6]

Our patient underwent surgery which revealed perforation of the anterior wall of pylorus with diffusion of fluids into the lesser sac and the peritoneal cavity. Histologic examination showed pyloric ulcer without signs of malignancy.

Differential Diagnosis List

Final Diagnosis

Rupture of pyloric ulcer

URL:	https://www.eurorad.org/case/11172
DOI:	10.1594/EURORAD/CASE.11172
ISSN:	1563-4086