Comparative study of plain abdominal films and small bowel enema in clinically unclear cases of small bowel obstruction.

A study was undertaken to compare the usefulness of plain abdominal X-rays (PABR) and small bowel enema (SBE) in evaluating cases of clinically unclear small bowel obstruction. The PABR of the patients taken just before the small bowel enema were compared to the films of the SBE. Fifty-two out of 76 were eventually operated on. The results show the gross limitations of PABR in excluding the presence of small bowel obstruction. The sensitivity and negative predictive value of SBE in identifying or excluding obstruction were 100% each, while the corresponding values of PABR were 42 and 40%. However, the margin of specificity and positive predictive values were narrow; 94 and 97 percent in SBE and 86 and 88 in PABR. SBE was also superior in identifying the cause and location of obstruction. In conclusion, due to the specificity of PABR it will remain the first line of investigations in suspected intestinal obstruction. However, its limitation in excluding the presence of obstruction cannot be overemphasized. The SBE confirms or excludes obstruction promptly and should be applied as the most accurate evaluation.