LAUSR

We present a case of sudden onset abdominal pain and computed tomography findings of extensive pneumoretroperitoneum; followed by discussion of the relevant surgical anatomy, diagnostic workup and subsequent management. Gas in the retroperitoneal space or ‘pneumoretroperitoneum’ is a rare phenomenon. While it can give a dramatic radiological appearance, most cases can be successfully managed conservatively. Aetiologies reported in literature include colonoscopic perforation, retroperitoneal infection by gas-forming organisms, and instrumentation such as Endoscopic Retrograde Cholangiopancreatography (ERCP), trans-psoas lumbar spinal surgery, transanal and retroperitoneoscopic procedures. A 56-year-old female, without significant past medical history, presented to our emergency department with a 24-h history of left iliac fossa pain and multiple episodes of diarrhoea. She denied fever, dysuria, vomiting. She recently underwent routine gastroscopy and colonoscopy 2 months prior, both of which were normal. Abdominal examination was unremarkable apart from mild left iliac fossa tenderness without peritonism. In particular, there were no features of necrotizing fasciitis on her back or perineum. Proctoscopy revealed neither mucosal ulceration nor signs of trauma. She had elevated inflammatory markers with a leucocytosis of 17 × 10/L and C Reactive Protein level of 156 mg/L. The computed tomography of the abdomen and pelvis showed extensive retroperitoneal gas extending into the mediastinum (Fig. 1). There was also diverticulosis of the sigmoid colon. The patient was commenced on empirical intravenous antibiotics. An upper intestinal endoscopy was performed where apart from a small sliding hiatus hernia, the study was normal. This was followed by a colonoscopy that revealed a small area of noncircumferential inflammation in rectosigmoid junction with fibrin plugging of a diverticulum (Fig. 2), thus a diagnosis of perforated sigmoid diverticular disease was made. The patient’s clinical condition and inflammatory markers continued to improve over the course of 4 days, and she was subsequently discharged home. This case highlights the importance of a detailed history and clinical examination which must be undertaken to ascertain the source of pneumoretroperitoneum. This includes a systematic evaluation of all potential sources of injury, inflammation, infection in retroperitoneal structures – which includes extraperitoneal part of colon, rectum, vagina, pancreas, duodenum, renal tract, spine and connective tissue. It must also be noted that gas can move freely from the retroperitoneum via the oesophageal/aortic hiatus into mediastinum and upwards to deep fascia of neck. It is not uncommon to see pneumoretroperitoneum, pneumoperitoneum, pneumomediastinum, pneumothorax, subcutaneous emphysema in the same patient.