Background:

The presence of subdiaphragmatic air observed on a chest x-ray after a laparoscopic procedure is a common finding and can lead to clinical confusion. Measuring the volume of gas present may be a useful tool to determine if this could be associated to a surgical complication.

Objective:

Describe the frequency of presentation of residual pneumoperitoneum in patients undergoing laparoscopy and emphasize the importance of measuring its volume with a simple method.

Method:

This is a retrospective study where 42 chest x-rays of patients operated by laparoscopy were reviewed. Cases with residual pneumoperitoneum were registered and subdiaphragmatic gas volume measured for each of them. Mean and standard deviation for the volume were calculated. Correlations between the variables of height, length and volume of the gas bubbles seen on each x-ray were established.

Results:

The incidence of residual pneumoperitoneum was 0.55. Median for volume was 4 cm3 (mean of 9.5 cm3 with standard deviation of 14.8 cm3 and range between 0.09 a 62 cm3). Height and length of the arc both had positive correlations with volume of r = 0.74, p = 0.000 and r = 0.77, p = 0.000, respectively. Height and length had a correlation of r = 0.44, p = 0.03.

Conclusions:

More than 50% of the studied patients presented residual pneumoperitoneum. Correlation between the variables of height, length and volume were positive. According to the data in this study, the presence of > 40 cm3 of gas may be considered as abnormal.