Another look at pneumoperitoneum

Accuracy of radiographic diagnosis of pneumoperitoneum secondary to gastrointestinal perforation in dogs and cats

BACKGROUND

Radiography is commonly included in the diagnostic investigation of animals with suspected gastrointestinal perforation and resultant pneumoperitoneum. This study aimed to (1) identify the accuracy of radiographic diagnosis of pneumoperitoneum and (2) determine if observer experience affected accuracy.

METHODS

This was a retrospective case-controlled study evaluating abdominal radiographs of dogs and cats with surgical confirmation of gastrointestinal perforation or peritonitis without pneumoperitoneum. Radiographs were reviewed by a radiologist, an imaging resident, a general practitioner and a veterinary student.

RESULTS

Radiographs from 60 dogs and eight cats were evaluated; 34 animals had confirmed perforation. Accuracy was fair to excellent for all observers: student 61.8%, general practitioner 70.6%, resident 85.3% and radiologist 83.8%. There was no significant difference in sensitivity between observers (all 70.6%-85.3%); however, there was a significant difference in specificity between both the resident (91.2%) and radiologist (91.2%) compared to the student (52.9%) (p < 0.001) and the general practitioner (55.9%) (p = 0.002). Overall, there was slight to substantial agreement between observers (κ = 0.28-0.73), with the highest being between the radiologist and resident.

CONCLUSION

Abdominal radiography, when interpreted by veterinarians with differing experience, has variable accuracy for diagnosis of pneumoperitoneum for animals in this study. Further studies are needed to determine if these results are applicable for other populations of animals with pneumoperitoneum.

Gastrointestinal tract perforation: CT diagnosis of presence, site, and cause

Gastrointestinal tract perforation is an emergent condition that requires prompt surgery. Diagnosis largely depends on imaging examinations, and correct diagnosis of the presence, level, and cause of perforation is essential for appropriate management and surgical planning. Plain radiography remains the first imaging study and may be followed by intraluminal contrast examination; however, the high clinical efficacy of computed tomographic examination in this field has been well recognized. The advent of spiral and multidetector-row computed tomographic scanners has enabled examination of the entire abdomen in a single breath-hold by using thin-slice sections that allow precise assessment of pathology in the alimentary tract. Extraluminal air that is too small to be detected by conventional radiography can be demonstrated by computed tomography. Indirect findings of bowel perforation such as phlegmon, abscess, peritoneal fluid, or an extraluminal foreign body can also be demonstrated. Gastrointestinal mural pathology and associated adjacent inflammation are precisely assessed with thin-section images and multiplanar reformations that aid in the assessment of the site and cause of perforation.

Jacuzzi jet-induced pneumoperitoneum

Pneumoperitoneum outside the setting of recent surgical intervention usually indicates perforation of the gastrointestinal tract. Following radiologic evidence of pneumoperitoneum, surgical exploration of the abdomen may be indicated depending on the nature of the patient's presentation. We present the radiological findings of a healthy young woman who presented with acute onset of abdominal pain and was found to have extensive pneumoperitoneum. No visceral disruption was evident by multidetector CT or by single-contrast barium fluoroscopic evaluation of the upper gastrointestinal tract. Knowledge of benign causes of pneumoperitoneum by the radiologist may avert an unnecessary laparotomy.

Significance of intra-abdominal extraluminal air detected by CT scan in blunt abdominal trauma

The purpose of this study was to determine the frequency and significance of computed tomographic (CT) scan-detected pneumoperitoneum in blunt abdominal trauma. We retrospectively reviewed 118 consecutive CT scans of the abdomen in blunt abdominal trauma patients (mean Injury Severity Score 24), performed at our Regional Trauma Unit over a 12-month period. Seven (5.9%) patients had intra-abdominal extraluminal air. None of these seven patients had evidence of bowel perforation at laparotomy (two) or on clinical follow-up (five). All seven had chest tubes in place before the CT scan. None of the seven patients were on mechanical ventilation at the time of CT scan. In the setting of blunt abdominal trauma pneumoperitoneum does not necessarily indicate hollow viscus injury. It frequently is secondary to other etiologies, especially dissection of interstitial air from the chest, as suggested in this study. The decision for laparotomy should be based on a combination of the clinical findings, CT scan results, or other diagnostic tests such as peritoneal lavage.

Plain abdominal radiography in the detection of major disease in children: a prospective analysis

STUDY OBJECTIVE

To prospectively evaluate previously described high-yield clinical criteria for obtaining plain abdominal radiographs in the emergency evaluation of children.

DESIGN

Prospective, observational study.

SETTING

Emergency departments of a university medical center and an affiliated county hospital.

PARTICIPANTS

Three hundred fifty-four children 15 years old or younger who underwent plain abdominal radiography during a one-year period.

METHODS AND MEASUREMENTS

Physicians ordering plain abdominal radiographs completed data forms that included historical and physical examination information before viewing films. At a later date, records of all patients were reviewed for radiologist interpretation and final diagnosis. The data were analyzed to determine the sensitivity, specificity, and predictive values of previously described high-yield criteria (from a retrospective series) in detecting radiographs that were diagnostic or suggestive of "major" abdominal disease.

MAIN RESULTS

Sixty-one patients (17%) had major diseases potentially requiring procedural intervention (eg, appendicitis, ingested foreign bodies, and intussusception), whereas 296 patients (83%) had minor diseases not requiring procedural intervention (eg, gastroenteritis and nonabdominal diagnoses). The presence of any of the following features--prior abdominal surgery, foreign body ingestion, abnormal bowel sounds, abdominal distention, or peritoneal signs--was 93% sensitive and 40% specific in detecting diagnostic or suggestive radiographs in patients with major disease. Positive and negative predictive values were 11% and 99%, respectively. If only these criteria had been used to obtain radiographs, 38% of films would have been omitted (at an estimated savings of $20,000) with only two suggestive radiographs missed.

CONCLUSION

Our results suggest that restricting abdominal radiographs to patients with at least one of these five high-yield clinical features will detect most diagnostic and suggestive radiographs in children with major abdominal diseases.

Pneumoperitoneum without peritonitis

We present our experience with 5 patients, all of whom were noted to have radiological signs of pneumoperitoneum in the absence of clinical features of peritonitis. All 5 cases were eventually shown to be due to causes not requiring surgery. We review the numerous unusual causes of pneumoperitoneum which do not require urgent surgical intervention and emphasize their importance in cases where the absence of signs of peritonitis may cause diagnostic difficulty.

Benign persistent pneumoperitoneum in scleroderma

We present a 68-year-old patient who, over a two-year period, was observed to have persistent benign pneumoperitoneum. The free air was present in the abdominal cavity without gastrointestinal perforation or pneumatosis cystoides intestinalis. The persistent pneumoperitoneum was a benign process and was not associated with peritonitis or other ill effects. The source of the free air was not clear. Conceivably, microperforations occurring in colonic diverticula or in distended intestinal wall induced the persistent benign pneumoperitoneum.

Gastric-bypass-induced pneumothorax

Substernal gastric bypass has been recently revived to palliate unresectable esophageal carcinoma. We report an unusual postoperative complication of gastric bypass: recurrent pneumothorax responding to nasogastric tube decompression of a distended thoracic stomach.

Nonsurgical pneumoperitoneum

The radiographic evidence of free air in the abdomen is usually associated with gastrointestinal perforations which represent a surgical emergency. However, pneumoperitoneum may also develop in a variety of benign conditions and following diagnostic or therapeutic procedures. This article provides a comprehensive list of nonsurgical causes of pneumoperitoneum.

Jejunal diverticulosis and chronic pneumoperitoneum

A unique case of pneumoperitoneum, without peritonitis or perforation, associated with jejunal diverticulosis is presented. Pneumoperitoneum is documented over the course of many years, with recurrence after partial small bowel resection. Jejunal diverticulosis is one of the leading gastrointestinal causes of pneumoperitoneum without peritonitis or surgery. The distended diverticular mucosa may function as a semipermeable membrane allowing transmural gas equilibration.

Pneumoperitoneum following hernia repair

In a small series of 20 consecutive patients it proved impossible, using conventional radiography, to detect free intraperitoneal air following herniorrhaphy.