BACKGROUND: Pneumoperitoneum, a surgical catastrophe, requiring surgical exploration in the majority is described as the presence of free air in the peritoneal cavity. While a majority of cases of pneumoperitoneum represent a surgical abdomen, a small entity of non-surgical pneumoperitoneum often referred to as spontaneous pneumoperitoneum is the culprit in 10% of cases (Insert Reference 1). A diagnosis of non-surgical spontaneous pneumoperitoneum is appropriate when surgical repair is not the indicated treatment for the known cause of pneumoperitoneum, or when an exploratory laparotomy is done and no perforation is found.1,2 We present a case of Nonsurgical pneumoperitoneum in the setting of gram-negative septicemia.
CASE REPORT: An 87-year-old Caucasian male with a past medical history of benign prostatic hyperplasia and irritable bowel syndrome presented to the hospital with urinary incontinence, diarrhea, abdominal pain, hypotension and altered mental status. A diagnosis of septic shock secondary to urinary tract infection was made on arrival based on symptomology and initial investigation. The patient had a history of lower abdominal pain for last two weeks. He visited his primary care physician and underwent a CT scan of abdomen and pelvis which showed hypertrophy of the prostate and bilateral hydronephrosis. The patient reported deterioration of symptoms leading to hospitalization. On arrival to hospital, the patient was hemodynamically stable but quickly decompensated, and vitals showed a blood pressure of 88/55 mmHg, heart rate of 143 beats per minute, respiratory rate of 20 breaths per minute, and temperature of 96.3? F. Initial pertinent laboratory findings included acute kidney injury with serum creatinine of 12 mg/dL (from baseline of 1.2 mg/dl) and BUN 161 mg/dL. A high anion gap metabolic acidosis secondary to lactic acidosis was seen in labs. Urinalysis was positive for urinary tract infection and blood and urine cultures were drawn. Physical exam at arrival was significant for ……….((Please include initial pertinent exam findings)…….. The remainder of laboratory findings are shown in table 1.1 below (Include a table of important labs). The patient received appropriate empiric intravenous antibiotics and resuscitation in the emergency department along with placement of a urinary catheter to relieve urinary obstruction. Blood and urine culture was positive for E. coli and initial antibiotics were deescalated to ceftriaxone, to which the organism was sensitive.
On day 5 of his admission, the patient experienced increased abdominal pain, constipation, and subjective fevers. Vitals showed a blood pressure of 111/70 mmHg, a pulse of 87 beats per minute, respiratory rate of 20 respirations per minute. Abdominal exam was significant for hypoactive bowel sounds, mild distension, guarding, tympanic to percussion, and diffuse tenderness to palpation. An upright chest x-ray was ordered revealing free intraperitoneal air. A chest x-ray was taken three days prior (Figure 2), which revealed no acute findings. Abdominal x-ray showed a nonobstructive bowel gas pattern and no signs of dilated loops of bowel or air-fluid levels. The surgical team was emergently consulted for evaluation of pneumoperitoneum, and an urgent exploratory laparoscopy was recommended. The patient went for emergent surgery where exploratory laparoscopy and laparotomy was performed. Surgical exploration of the abdominal cavity revealed no perforation. Post-operative x-ray, completed on post-operation day one demonstrated resolution of the pneumoperitoneum (Figure 3).
A Combination of abdominal pain and air under the diaphragm, even in absence of other clinical signs will usually suffice for most to undergo an explorative laparotomy in search of the causative lesion. Among the surgical and non-surgical classifications, there are thoracic, abdominal, gynecological, and idiopathic causes.2 Reported cases of pneumoperitoneum with an unknown cause are termed idiopathic spontaneous pneumoperitoneum (ISP), and are extremely rare.3,4 Common etiologies of surgical pneumoperitoneum include appendicitis (34%), diverticulitis (12%), and perforated peptic ulcer (10%).5 Rare causes (totaling only 10%) include sepsis, pneumatosis cystoides intestinalis, pneumomediastinum (caused by esophageal or pulmonary pathology), oro-genital sexual intercourse, aerophagia, or recent history of mechanical ventilation, cardiopulmonary resuscitation, and peritoneal dialysis.2,6–9
Kumar A, et al. (2012) and colleagues described visceral perforation causing 42% of cases of pneumoperitoneum, closely followed by 37% representing post-operative residual air.5 In modern day era where Computerized Tomography (CT) scanners are widely available in Emergency Department and provide invaluable etiologic data, conventional radiography using x-ray still holds diagnostic significance in the diagnosis of pneumoperitoneum. Studies showed that the upright chest radiograph holds a sensitivity of 71-98% in diagnosing pneumopeitoneum.10–12 The sensitivity for free air detection was greatest with use of left decubitus abdominal radiograph (98%) and upright chest radiograph (85.1%).12 However, the ability for free air to be detected on imaging is dependent on the cause and location of the perforation.5 Multiple studies have suggested extraluminal (free) gas in the sub-phrenic space as one of the most common radiological findings,2,13 first described by Popper in 1915. Another radiographic sign indicative of pneumoperitoneum, established in 1941, Rigler’s sign, is when the outer and inner wall of the intestinal tract can be visualized on supine abdominal x-ray.12,14,15 A study by Chiu et al. reported anterior superior oval sign as the most common finding in supine abdominal and chest radiography, and sub-phrenic radiolucency as the third most common on supine chest radiograph.12 Other radiographic signs are detailed by Kumar et al. and Chiu et al and colleagues.5,12
Surgical pneumoperitoneum typically presents with signs of peritonitis, such as abdominal rigidity, abdominal tenderness, fever, leukocytosis, and/or elevated inflammatory markers.15 Management options include intravenous fluids, nutritional support, administration of broad-spectrum antibiotics, hyperbaric oxygen (for necrotizing enterocolitis) and surgical exploration.16,17
Exploratory laparotomy is typically performed in patients with radiographic pneumoperitoneum, abdominal pain, and signs of peritonitis.2 Conservative approach is taken in certain select patient population, however usually futile in surgical pneumoperitoneum, leading to clinical decoration in many. In cases of pneumoperitoneum where the etiology is believed to be nonsurgical in nature, conservative treatment has been proposed to prevent unnecessary laparotomy.1,3,4,13 Conservative treatment includes but not limited to parenteral nutrition, intravenous fluid resuscitation, intravenous antibiotics, and serial abdominal examinations and imaging to document resolution.17
There are many proposed etiologies to explain the presence of pneumoperitoneum on radiographic imaging. Most commonly, pneumoperitoneum is classified by caused by a surgical etiology, or rarely a non-surgical etiology (10%).1,2 Iatrogenic causes were immediately dismissed for our patient as there was no recent history of positive airway pressure use, cardiopulmonary resuscitation, mechanical ventilation, peritoneal dialysis, or invasive procedures (endoscopy, colonoscopy, laparoscopy, laparotomy).
Certain case reports have been reported gram-negative bacteremia as a causative agent of pneumoperitoneum (Include case report). It is believed that etiology is related to micro perforation related to inflammatory mediators. We believe our patient developed nonsurgical pneumoperitoneum secondary to sepsis caused by gram-negative gas forming bacteria (E.coli in this patient), and there is no objective evidence of any other etiology.
Chandler et al. report that 28% of patients with nonsurgical spontaneous pneumoperitoneum were subjected to surgical exploration. They report three recurring themes amongst these patients: a decision to perform exploratory surgery completely based on radiological evidence, radiolucency consistent with pneumoperitoneum was not located at the apex of the diaphragm, and the presentation of marginal peritoneal symptoms.20
Recognition of the potential for nonsurgical spontaneous pneumoperitoneum is important in preventing unnecessary surgical procedures that expose patients to infection, complications, and extended recovery periods. More insights