Accuracy of abdominal ultrasound for the diagnosis of pneumoperitoneum in patients with acute abdominal pain: a pilot study

Abstract

BackgroundPneumoperitoneum is a rare cause of abdominal pain characterized by a high mortality. Ultrasonography (US) can detect free intraperitoneal air; however, its accuracy remains unclear. The aims of this pilot study were to define the diagnostic performance and the reliability of abdominal US for the diagnosis of pneumoperitoneum.MethodsThis was a prospective observational study. Four senior and two junior physicians were shown, in an unpaired randomized order, abdominal US videos from 11 patients with and 11 patients without pneumoperitoneum. Abdominal US videos were obtained from consecutive patients presenting to ED complaining abdominal pain with the diagnosis of pneumoperitoneum established by CT. Abdominal US was performed according to a standardized protocol that included the following scans: epigastrium, right and left hypochondrium, umbilical area and right hypochondrium with the patient lying on the left flank. We evaluated accuracy, intra- and inter-observer agreement of abdominal US when reviewed by senior physicians. Furthermore, we compared the accuracy of a “2 scan-fast exam” (epigastrium and right hypochondrium) vs the full US examination and the accuracy of physicians expert in US vs nonexpert ones. Finally, accuracy of US was compared with abdominal radiography in patients with available images.ResultsConsidering senior revision, accuracy of abdominal US was 88.6 % (95 % CI 79.4-92.4 %) with a sensitivity of 95.5 % (95 % CI 86.3–99.2 %) and a specificity of 81.8 % (95 % CI 72.6–85.5 %). Inter- and intra-observer agreement (k) were 0.64 and 0.95, respectively. Accuracy of a “2 scan-fast exam” (87.5 %, 95 % CI 77.9–92.4 %) was similar to global exam. Sensitivity of abdominal radiography (72.2 %, 95 % CI 54.8–85.7 %) was lower than that of abdominal US, while specificity (92.5 %, 95 % CI 79.5–98.3 %) was higher. Accuracy (68.2 %, 95 % CI 51.4–80.9 %) of junior reviewers evaluating US was lower than senior reviewers.ConclusionsSenior physicians can recognize US signs of pneumoperitoneum with a good accuracy and reliability; sensitivity of US could be superior to abdominal radiography and a 2 fast-scan exam seems as accurate as full abdominal examination. US could be a useful bedside screening test for pneumoperitoneum.Trial registry ClinicalTrials.gov; No.: NCT02004925; URL: http://www.clinicaltrials.govElectronic supplementary materialThe online version of this article (doi:10.1186/s13089-015-0032-6) contains supplementary material, which is available to authorized users.

Manual vs. pressure-controlled facemask ventilation for anaesthetic induction in paralysed children: a randomised controlled trial

“…23 It has been considered that air is hardly detected with US because the sound wave does not travel through the gas and leaves artefacts. Recently, these artefacts have gained diagnostic properties in detecting pneumoperitoneum, 28,29 as well as the detection of the air injected into the stomach through a nasogastric tube. 30 In a study by Moriwaki et al, 28 the sensitivity and specificity of US for detecting intraperitoneal free-air rose up to 85-100%.…”

Ultrasound findings in critical care patients: the “liver sign” and other abnormal abdominal air patterns

“…However, a recent study showed that senior physicians with experience in abdominal US can rapidly learn to identify patterns suggestive of pneumoperitoneum with almost 90 % accuracy [ 20 ]. The study also indicated that a focused abdominal US exam comprising two views (epigastric and right hypochondrium) was similar in sensitivity and specificity to the full abdominal exam.…”

The value of ultrasound in diagnosis of pneumoperitoneum in emergent or critical conditions: A meta-analysis

“…After removing irrelevant articles, 13 studies were read in full test. Finally, five studies were eligible for meta-analysis, [4][5][6][7][8] and the whole procedure of literature screening is shown in Figure 1.…”

“…Several studies with limited sample size reported the ability of ultrasonography in diagnosing of pneumoperitoneum. [4][5][6][7][8] But there was significant controversy among these studies. The aim of this meta-analysis was to explore the diagnostic value of ultrasound of pneumoperitoneum in emergent or critical conditions.…”