Pneumoperitoneum is defined as the presence of extraluminal air within the peritoneal cavity [3] and associated with perforation of the gastrointestinal tract in the vast majority of cases, mainly as the ultimate result of ischemia, erosion, infection, and mechanical or thermal injuries.[14] The presence of this finding is often concerning for severe intestinal compromise. [15] Despite the significant incidence of cases of pneumoperitoneum that require surgical intervention, there are some other causes considered as nonsurgical and can be grouped as thoracic (e.g., chronic obstructive pulmonary disease, mechanical ventilation, cardiopulmonary resuscitation, other pulmonary disorders), abdominal (e.g. pneumatosis cystoides intestinalis, peritoneal dialysis), [16] gynecologic (e.g., vaginal instrumentation, coitus/sexual intercourse), and miscellaneous (e.g., amyloidosis, cocaine use), among others. [2] This broad variety of etiologies can lead to the diagnosis of benign pneumoperitoneum, also called non-surgical, asymptomatic, or even idiopathic. [1]
In relation to urology practice, only one case report of benign pneumoperitoneum was described, which was in relation to an emphysematous pyelonephritis, whose clinical course needed surgical exploration that revealed an extra-peritoneal abscess in the left perinephric area, treated with drainage and antibiotics and with a subsequent successful recovery. [13]
In our case, the primary complaint of the patient was a renal colic associated with a ureteral stone, and the finding of a pneumoperitoneum was incidental. The initial assessment and diagnostic studies focused on the clinical suspicion of kidney or ureteral stones. Nonetheless, the radiological finding in non-contrast CT changed the therapeutic approach for this case. It is important to highlight that general surgery consultation should be obtained when a pneumoperitoneum is found, [2] especially in cases with no significant past medical history, like this one, since even if a surgical intervention, such as an exploratory laparotomy, is performed, no visceral compromise or other findings could be noticed.[17] Furthermore, it is relevant to emphasize that the surgical procedure performed for the treatment of urolithiasis could not be directly related to the spontaneous regression of the pneumoperitoneum, and the precise cause remains unclear, although the imaging studies required to rule out other causes were performed correctly.
In regard to urology practice, the non-contrast CT is largely used because of its higher sensitivity and specificity for assessment of ureteral stones, providing critical information about the size, density, and location of stones, [18] as well as the identification of extraurinary causes of renal colic. [19] Because of this, it is important to document the possibility of an incidental finding of a pneumoperitoneum and its benign nature, whose appropriate assessment is essential to avoid unnecessary surgical intervention, which may result in significant morbidity or even mortality, [20] particularly in urological conditions susceptive of initial medical management.
Finally, it is noteworthy that there is the possibility of subclinical microperforations, related to the leakage of gas but not bowel contents through the viscera, [3] and an extensive revision of the medical history and physical examination must be performed, as there is relative agreement about the signs and symptoms that should prompt surgical intervention. [21]