Original Contribution
Reappraisal of radiographic signs of pneumoperitoneum at emergency department

https://doi.org/10.1016/j.ajem.2008.03.004Get rights and content

Abstract

Purpose

This study aimed to evaluate the sensitivities of the reported free air signs on supine chest and abdominal radiographs of hollow organ perforation. We also verified the value of supine radiographic images as compared with erect chest and decubitus abdominal radiographs in detection of pneumoperitoneum.

Methods

Two hundred fifty cases with surgically proven hollow organ perforation were included. Five hundred twenty-seven radiographs were retrospectively reviewed on the picture archiving and communication system. Medical charts were reviewed for operative findings of upper gastrointestinal tract, small bowel, or colon perforations. The variable free air signs on both supine abdominal radiographs (KUB) and supine chest radiographs (CXR) were evaluated and determined by consensus without knowledge of initial radiographic reports or final diagnosis. Erect CXR and left decubitus abdominal radiographs were evaluated for subphrenic free air or air over nondependent part of the right abdomen.

Result

Upper gastrointestinal tract perforation was proven in 91.2%; small bowel perforation, in 6.8%; and colon perforation, in 2.0%. The positive rate of free air was 80.4% on supine KUB, 78.7% on supine CXR, 85.1% on erect CXR, and 98.0% on left decubitus abdominal radiograph. Anterior superior oval sign was the most common radiographic sign on supine KUB (44.0%) and supine CXR (34.0%). Other free air signs ranged from 0% to 30.4%.

Conclusions

Most free air signs on supine radiographs are located over the right upper abdomen. Familiarity with free air signs on supine radiographs is very important to emergency physicians and radiologists for detection of hollow organ perforation.

Introduction

Hollow organ perforation is always life threatening and usually needs the urgent surgical intervention. Detection of the intraperitoneal free gas is valuable in the diagnosis of hollow organ perforation. It is really a challenge to both emergency physicians and radiologists to detect free air on supine radiographs. Because computed tomography is the most sensitive examination to visualize the extraluminal air and plain supine radiographs cannot always detect the presence and extent of an abnormal lucency, the value of the plain supine radiographs to diagnose intraperitoneal free air is usually ignored by the emergency physicians in modern times [1], [2], [3], [4]. However, the plain radiography is still the fastest and most efficient and cheapest imaging examination for detecting intraperitoneal free air at emergency department (ED). On plain radiographs, very small amounts of extraluminal free air still can be visualized [2], [5], [6], [7]. This study aimed to evaluate the sensitivities of the reported free air signs on supine chest and abdominal radiographs of the patients with hollow organ perforation. We also verified the value of supine radiographic images as compared with erect chest radiographs and decubitus abdominal radiographs in detection of pneumoperitoneum.

Section snippets

Methods

Two hundred seventy-one cases with any sex, any age, and surgically proven hollow organ perforation from December 2000 to August 2007 were included in this study by electronic search of the medical registry database of our institute. After excluding the cases without available images and those with poor image quality or intervals between radiographs and operation longer than 3 days, 250 cases were used for our study. Five hundred twenty-seven radiographs of these cases were retrospectively

Results

Among the 250 patients of our study, 66 (26.4%) were females, and 184 (73.6%) were males. The mean age was 67.1 years (range, 1-98 years). There were 228 patients (91.2%) with UGI perforation, 17 patients (6.8%) with small bowel perforation, and 5 patients (2.0%) with colon perforation. The etiologies of the hollow organ perforation were summarized in Table 1. Peptic ulcer disease was the most common cause of hollow organ perforation. There was no statistically significant association between

Discussion

Gastrointestinal tract perforation can be caused by a variety of reasons, including peptic ulcer disease, traumatic event, foreign body, appendicitis, diverticular disease, inflammatory bowel disease, abscess, neoplasm, and iatrogenic factors [2], [24]. In the literature, gastrointestinal tract perforation has been reported to cause pneumoperitoneum from 40% to 80% of patients, and peptic ulcer diseases are the reasons of pneumoperitoneum in about 90% [2], [6]. In our study, we found that the

Limitation

The proportions of small bowel and colon perforation are less in our study than those in previous literatures. It might be due to the small case number of our study. Besides, this is a retrospective study with small population. There might be inherent bias in interpreting these cases for free air and statistical analysis. The consensual determination of the presence or absence of free air sign may be influenced by knowledge of the purpose of this study, especially for minimal intraperitoneal

Conclusions

Radiologic studies play an important role in the diagnosis of pneumoperitoneum. The demonstration of intraperitoneal free air on the radiographic images is often the initial clue to diagnose hollow organ perforation in an ED. Familiarity with the free air signs is important to emergency physicians and radiologists. Most free air signs on supine radiographs are located over the right upper abdomen, with anterior superior oval sign as the most common sign. Supine CXR is as sensitive as supine KUB

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