Normal findings
- • No dilated bowel loops
- • Gas in colon and rectum
- • Psoas shadows visible bilaterally
Common abnormal findings
Small bowel obstruction
- • Central dilated loops >3 cm
- • Valvulae conniventes across full width
- • Multiple air-fluid levels
Large bowel obstruction
- • Peripheral dilation >6 cm (caecum >9 cm)
- • Haustra not across full width
Sigmoid volvulus
- • "Coffee bean" sign pointing to RUQ
- • Loss of haustra
Pneumoperitoneum
- • Rigler sign — gas on both sides of bowel wall
- • Free gas under diaphragm on erect CXR
Interpretation tips
- • Erect + supine views improve sensitivity
- • Look for renal stones along ureteric line
Clinical correlation
- • Obstruction symptoms + dilated loops → CT abdomen for cause
- • Free gas → surgical emergency
Common mistakes
- • Missing toxic megacolon (transverse colon >6 cm with mucosal islands)
Educational support only — not a substitute for clinical judgment.
