Spontaneous idiopathic pneumoperitoneum with acute abdomen

Abstract

Pneumoperitoneum often occurs following a visceral perforation and is usually seen with peritonitis, requiring urgent surgical intervention. Non-surgical spontaneous pneumoperitoneum (not associated with organ perforation) is a rare situation caused by intrathoracic, intra-abdominal, gynaecologic, iatrogenic, and other reasons, and may be treated conservatively. Spontaneous idiopathic pneumoperitoneum is seen much less often than visceral perforation or other reasons causing intraabdominal gas. We present a case of idiopathic spontaneous pneumoperitoneum. A 75-year-old female patient applied with acute abdominal pain, subfebrile fever and nausea. Abdominal findings were not definitive, there was no leucocytosis but free intraabdominal air on the abdominal X-ray. The patient was observed for one day without oral feeding, nasogastric tubing, prophylactic antibiotics and saline infusion. At the first day of follow up she had only generalized abdominal pain on deep palpation, without other acute abdominal signs. She had mild leucosytosis, neutrophilia, and pneumoperitoneum on direct abdominal X-ray. On abdominal computerized tomography there was no pathologic sign other than intraabdominal free air and minimal free fluid in Douglas pouch. There was only a cholecystectomy (10 years ago) in her history, no chronic illness or other situation such as drug abuse, smoking or alcohol consumption. An emergency laparotomy was performed. Although no abdominal pathology could be found and the etiology could not be determined, the patient was discharged on the 5th postoperative day. Good patient history, appropriate laboratory tests, and radiologic tests combined with physical examination should be combined to avoid unnecessary laparotomy on non-surgical pneumoperitoneum, and minimally invasive techniques should also be considered.

Keywords: Idiopathic pneumoperitoneum, spontaneous pneumoperitoneum, acute abdomen

Introduction

More than 90% of pneumoperitoneum occur as a result of gastrointestinal perforation (1). Gastric or duodenal perforations due to peptic ulcer are the most common causes of pneumoperitoenum. Pneumoperitoneum may also occur following abdominal trauma or diverticular perforation (1). The most common presentation is a patient with signs of peritonitis and free air on chest X-ray. Most cases require urgent exploration and intervention.

However, sometimes pneumoperitoneum is not associated with visceral perforation and is called spontaneous pneumoperitoneum (SP) or nonsurgical pneumoperitoneum. SP is associated with intrathoracic, intra-abdominal, gynecologic, iatrogenic or various other reasons (1). Generally, SP is not complicated by peritonitis, is benign and can be treated conservatively (1-4). Idiopathic SP is a very rare condition of unknown etiology, which can only be identified by exclusion of visceral perforation and other causes leading to presence of intra-abdominal free air (1, 5-7). SP diagnosis is usually made following a negative laparotomy. Presence of vague signs of peritonitis and pneumoperitoneum prior to laparotomy is especially challenging for the surgeon.

Case Presentation

A 75-year-old female patient presented with acute abdominal pain and nausea for the last 24 hours. Her past medical history was uneventful except cholecystectomy performed 10 years ago with no chronic disease, drug use, smoking, or alcohol use. The patient’s facial expression was depressed. Her blood pressure was 110/70 mm-Hg, heart rate: 90 beats/min, and body temperature: 37.6°C. There was no abdominal tenderness. The WBC count was 7000 leukocytes/mL, and neutrophil ratio was 72%. Subdiaphragmatic free air was detected on posteroanterior chest radiograph, without air insufflation by nasogastric tube (Figure 1a, b).

Figure 1. a, b. Sub-diaphragmatic free intraabdominal air

Figure 2. Free intra-abdominal air on upper sections of abdominal computed tomography

Figure 3. Generalized free intra-abdominal air on abdominal computed tomography

Figure 4. Free intraabdominal air on lower sections of abdominal computed tomography

Figure 5. Minimal free fluid in the pelvic sections of abdominal computed tomography

The patient was discharged on postoperative day 5. The patient underwent abdominal CT, upper and lower gastrointestinal endoscopy one month after the operation. There was no pathology.

Discussion

Spontaneous peritoneum is associated with intrathoracic, intra-abdominal, gynecologic, iatrogenic, and other reasons (1, 2). Trauma (including barotrauma), pneumothorax, and severe thoracic diseases such as broncho-peritoneal fistula can be complicated with SP (1). The co-existence of pneumopericardium and pneumomediastinum with SP has been reported, due to positive end-expiratory pressure (PEEP) in mechanical ventilation, (1). Pneumatosis cystoides intestinalis is the most common intra-abdominal cause of SP (1). Rare causes of SP include emphysematous cholecystitis, spontaneous bacterial peritonitis, ruptured liver abscess and perforated pyometra in women (1). It has been reported that air may reach the intraabdominal cavity through the endometrium or salpinx after rough sexual intercourse or use of hot tubs leading to pneumoperitoneum (1). Laparoscopic and endoscopic (colonoscopy) procedures may cause iatrogenic SP (1).

The underlying reason for and clinical symptoms of pneumoperitoneum dictates whether surgical treatment is required or not. While surgery is inevitable in the presence of signs and symptoms of acute abdomen, conservative treatment is indicated for mild symptoms without peritonitis (2). A detailed history and physical examination may be helpful in the differentiation of surgical and non-surgical pneumoperitoneum, therefore, avoiding unnecessary laparotomy (2). Radiological imaging prior to and after insufflation of air into the stomach through a nasogastric tube (pneumo-gastrography), can be used for the diagnosis or confirmation of upper gastrointestinal visceral perforation (8). Although plain chest and abdomen X-ray are common investigation tools in the diagnosis of even small amounts of intra-abdominal air, abdominal CT is more sensitive for identification of pneumoperitoneum and differential diagnosis of acute abdomen (9, 10).

It is suggested that in some cases of sub-clinical intestinal perforations, only air may leak without leakage of intestinal contents causing pneumoperitoneum (1). Other unknown reasons may also cause idiopathic pneumoperitoneum (1).

Only few patients are diagnosed with idiopathic pneumoperitoneum, nevertheless, most of them undergo surgical exploration. Van Gelder et al. (5) reported six pneumoperitoneum patients with acute abdominal symptoms and without any detectable cause on laparotomy. Chandler et al. (11) reported the rate of laparotomy in non-surgical pneumoperitoneum patients as 28%. Mularski et al. (12) identified 11 cases who underwent laparotomy out of 36 (31%) non-surgical pneumoperitoneum patients.

Conclusion

A thorough medical history, appropriate laboratory tests and radiological techniques and physical examination are valuable tools to identify patients with non-surgical pneumoperitoneum, and to avoid unnecessary laparotomy. Despite similar success rates of both laparoscopy and laparotomy in the diagnosis and treatment of pneumoperitoneum, minimally invasive surgery may be preferred due to its advantages.

Written informed consent was obtained from patients who participated in this case.

Externally peer-reviewed.

Concept - N.İ., O.N.G.; Data Collection and/or Processing - N.İ., B.K.; Analysis and/or Interpretation - N.İ., M.N.K.; Writer - N.İ., O.N.G.

No conflict of interest was declared by the authors.

The authors declared that this study has received no financial support.

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