Postsurgical pneumoperitoneum - comparison of abdominal ultrasound findings with plain radiography.

OBJECTIVE To compare abdominal ultrasonography findings with plain radiography in the detection of postsurgical pneumoperitoneum. STUDY DESIGN Cross-sectional, observational. PLACE AND DURATION OF STUDY Radiology Department, PNS Shifa Hospital, Karachi, from October, 2005 to April, 2006. METHODOLOGY Thirty patients of either gender who underwent laparotomies were included in the study. Patients were examined with plain radiography and abdominal ultrasound to detect postsurgical pneumoperitoneum within 24 hours of surgery. Upright chest radiography and left lateral decubitus views of abdomen were used to detect free air. McNemar test was applied to compute relationship between sonographic and radiographic findings. RESULTS Among 30 patients, 22 (73.3%) were females and 8 (26.7%) were males (M: F = 1: 2.75). Average age was 38.07 +/- 12.41 years. Out of 30 patients of postsurgical pneumoperitoneum, 27 (90%) were detected on ultrasonography while 3 (10%) were not detected. On plain X-rays, 4 patients were observed in group-I (no free air) and 26 in group-II (1-10 mm thickness). Significant (p<0.001) relationship was observed between the two findings. CONCLUSION Since both modalities can diagnose pneumoperitoneum reliably, ultrasonography can be a useful alternative imaging modality for the detection of pneumoperitoneum.