Table 2 Presenting symptoms, imaging and clinical considerations in relation to site and causes of small bowel and appendiceal perforation

Small bowel

Non-specific, abrupt sudden-onset pain, vomiting, anorexia, nausea, sepsis, peritonitis

IP gas (minimal/absent), oral contrast leakage, mural defect, wall thickening, poor/inhomogeneous mural enhancement, mesenteric fluid, fat stranding, extraluminal faecal material

Trauma

Pneumoperitoneum not diagnostic in penetrating trauma, wound track extending to intestinal segment.

History of trauma

IIschemia

Decreased/absent bowel enhancement, pneumatosis intestinalis, gas/thrombi within mesenteric/portal vessels

Mechanical obstruction, large vessel occlusion, venous outflow obstruction, vasculitis, sepsis, congestive heart failure, acute MI, hypovolemic shock

Inflammatory

Phlegmon/abscess formation

Typhoid fever, HIV, tuberculosis, hookworms

IBD

Phlegmon/abscess formation, lengthy bowel wall thickenning, sinus tracts, fistulas

Crohn's disease

Tumour

Circumferential wall thickening aneurysmal luminal dilatation multifocal bowel involvement lymphadenopathy hepatosplenomegaly heterogeneous mass

Commonly lymphoma adenocarcinoma malignant GISTs metastases

Diverticulae

Inflamed diverticulum

Meckel's diverticulum

Foreign body

Foreign body,

may be located distal to perforation site

Common in ileocaecal area Avoid oral contrast

Iatrogenic

persistent/progressively increasing free gas and/or ascites, oral contrast leakage

Laparoscopic surgery, anastomotic leakage, endoscopic procedures. Pneumoperitoneum normal < 2 weeks post laparoscopy

Appendix

Long standing abdominal pain, fever, muscle guarding

Periappendiceal/IP gas, appendiceal wall defect, phlegmon/abscess, fat stranding, free fluid

Inflammation

Extraluminal appendicolith

Tumour

Luminal diameter > 1.3 cm,

mural calcifications, pseudomyxoma peritonei, mass, enhancing wall nodularity