Spontaneous or nonsurgical pneumoperitoneum: A retrospective study with a review of literature

Pneumoperitoneum, or gas in the peritoneal cavity, is a surgical emergency in adults and children. In about >90% of cases, perforated intra-abdominal viscous,e.g. peptic ulcer, Meckel's diverticulum, toxic megacolon, necrotizing enterocolitis, Crohn's disease, and/or perforation of the bowel due to trauma or tumours, are responsible for pneumoperitoneum³. The entity of 'benign', 'spontaneous', 'nonsurgical', 'asymptomatic', or 'idiopathic' pneumoperitoneum is reported in the literature, which, when identified, needs conservative management only.

Surprisingly, not all hollow viscous perforations result in pneumoperitoneum, and about 69% of the cases of gut perforationare present with air under the diaphragm on X-Ray⁴. This can happen due to spontaneous perforation sealing with invisible minimal gas leakage. Similarly, all pneumoperitoneum is not due to perforated viscus. The decision to go for laparotomy cannot be made solely on the presence of pneumoperitoneum without signs of peritonitis.Such cases in the literature are explained as nonsurgical pneumoperitoneum or spontaneous pneumoperitoneum^2,5,6.

Most nonsurgical (spontaneous) pneumoperitoneum cases may occur as a procedural complication or a complication of medical intervention. The most common abdominal aetiology of NSP can be retained postoperative air (prevalence 25% to 60%). NSP frequently occurs after peritoneal dialysis catheter placement (10% to 34%) and gastrointestinal endoscopic procedures (0.3% to 25%, varying by procedure)⁷.

Thepathophysiology of spontaneous pneumoperitoneum is unclear. Whenintra-thoracic pressure increases, air maydissect its way downwards along the oesophagus and aorta into the retroperitoneal tissue [12/8]. The air can alsodissect through the diaphragm defectsin the posterolateral region secondary to arrest in the closure of the pleuroperitonealcanal and diaphragmatic defects at the sternocostal andlumbo-coastal region[13/9]. Another suggested theory is that there are micro-perforations (2 to 4 mm)in the anterior wall of the stomach, which can cause pneumoperitoneum. [14/10]

The causes of spontaneous pneumoperitoneum can be divided into:

• Intrathoracic,
• Abdominal,
• Gynaecological and
• Idiopathic:-

Thoracic

Pneumothorax, pleuroperitoneal fistula, pneumomediastinum due to thoracic trauma, barotraumas, cardiopulmonary resuscitation and pneumonia.

Abdominal

Abdominal causes include pneumatosiscystoidesintestinalis. In this disease, gas-filled submucosal or sub-serosalcysts are mostly found in the terminal ileum and are the most important cause.

Upper gastrointestinal endoscopy, emphysematous cholecystitis and post-surgical pneumoperitoneum are other possible causes.

Gynecological

Forceful coitus, vaginal douching, pelvic inflammatory disease & postpartum knee-chest exercise are possible gynaecological causes [9,11/11].

Idiopathic

In the current era of increasing critical care, ventilator management and COVID cases, idiopathic pneumoperitoneum is no longer a diagnosis of exclusion. It should be kept in mind while evaluating critically ill patients in ICU with sepsis and ventilator support. If feasible, moving ahead with exploratory laparotomy must be planned after cross-sectional imaging with oral and IV contrast.

Reviewing the literature revealed that watchful waiting is important with favourable outcomes. It also helps decrease hospital stays and avoid unnecessary surgeries with related morbidity and mortality. Conservative treatment was successful in Idiopathic cases without signs of peritonitis. [8/13]

Review of literature for spontaneous pneumoperitoneum: Management

This condition is demanding as most cases are misdiagnosed as perforated viscus resulting in immediate laparotomy. The literature review advocates for conservative management if peritoneal signs of visceral perforation are absent. Whereas if peritoneal signs of perforation are present, then laparotomy is necessary. Avoid negative exploratory laparotomy in patients with spontaneous pneumoperitoneum and thus save the patients from unnecessary morbidity [10/22].

Diagnostic laparoscopy is a good diagnostic and therapeutic tool in a hemodynamically stable patient with pneumoperitoneum without obvious features of viscera perforation. It will prevent unnecessary exploratory laparotomy with morbidity in already sick patients, especially in the COVID era, when many patients need prolonged ICU stay and mechanical ventilation (both risk factors for spontaneous pneumoperitoneum).[21] However, the use of diagnostic laparoscopy in such cases is quite limited in the literature.