Table 2 Differential diagnosis of intra-abdominal gas-filled cysts

GCD

>60

AXR, CT

>4 cm in size, air filled cyst

Usually arises from the sigmoid colon

Anti-mesenteric border [2]

Associated diverticular disease

60% palpable abdominal mass [4]-[6]

Pneumatosis cystoides

30-50 [11]

CT

Usually asymptomatic

Symptoms: abdominal distension, discomfort, mucoid stools

15% primary/idiopathic

85% secondary: IBD, diverticulosis, pulmonary disease

Numerous small pockets within bowel wall

Affects small and large bowel [11]

Meckels diverticulum

<30

Tech⁹⁹, CT

2% population, 95% asymptomatic

<2 cm in length

PR bleeding most common presenting symptom in children

Other symptoms: abdominal obstruction, inflammation, intussusception, ulceration and perforation

Contain all layers of bowel wall

Anti-mesenteric border, within 100 cm of ileocaecal valve

Volvulus (caecal/sigmoid)

>70

AXR, Sigmoidoscopy

Associated bowel obstruction

Redundant sigmoid colon, past history of chronic constipation

Haustra visible on distended loop on AXR [12]

Duplication cysts

<2

CT, USS, AXR

Anywhere along GI tract, most common in ileum

Can be single/multiple

50% have associated anomalies

Wide range of symptoms pending location

Mesenteric side, elongated in shape

90% Non-communicating with gut lumen

All bowel layers [12]

Emphysematous cystitis

>40

AXR, CT, USS

Due to bacterial fermentation of urinary glucose

Gas production in bladder lumen and wall

Assoc with diabetes, neurogenic bladder, bladder outlet obstruction, recurrent urinary tract infections

Symptoms include dysuria, frequency, pneumaturia

Distended tympanic mass arising from pelvis

Most commonly due to Escherichia coli

Emphysematous cholecystitis [12]

>40

AXR, CT

RUQ pain, vomiting, pyrexia +/- RUQ mass

Increased risk with diabetes and gallstones

Infection usually due to Clostridium perfringes

More risk of gangrene and perforation than with acute cholecystitis

Intra-abdominal abscess

-

CT

Source of intra-abdominal sepsis

Swinging pyrexia

Palpable mass