Air in the Abdomen

Question 1

Extraluminal air

Answer 1

(gas in the abdomen outside of the bowel)

Question 2

4 most common locations:

Answer 2

intraperitoneal (pneumoperitoneum = free air); retroperitoneal; air in the bowel wall (pneumotosis), biliary system (pneumobilia)

Question 3

3 signs of pneumoperitoneum:

Answer 3

1) air beneath the diaphragm 2) visiualization of both sides of the bowel wall (riggler’s sign), visualization of the falciform ligament

Question 4

most common causes of free air:

Answer 4

1) perforated peptic ulcer 2) trauma 3) perforated diverticulitis

Question 5

rare causes of free air

Answer 5

1) perforated appendicitis 2) perforated carcinoma of the colon

Question 6

key signs of extraperitoneal (retroperitoneal air):

Answer 6

1) streaky linear / mottled blotchy appearance of extra-peritoneal structures

Question 7

causes of extraperitoneal air

Answer 7

1) bowel perf 2/2 inflammatory / ulcerative disease, trauma, FB ingestion,

Question 8

key signs of pneumotosis (air in the bowel wall)

Answer 8

1) linear radiolucency 2) paralleling air to the bowel lumen 3) a mottled / blotchy appearance = air + poop

Question 9

causes of pneumotosis

Answer 9

1) primary form (you just have it) 2) secondary form: caused by something else [1: bowel necrosis – necrotizing enterocolitis in infants; ischemic bowel disease in adults; 2: obstructing lesions – tumor / hirschsprung’s disease]

Question 10

signs of air in the biliary system

Answer 10

1) tube-like branching lucency in the RUQ (over liver) 2) gas in the lumen of the gallbladder

Question 11

causes of pneumobilia

Answer 11

oddi incompetence, prior sphincterotomy, gallstone ilieus

Question 12

3 findings of gallstone ileus

Answer 12

1) air in the biliary system 2) SBO 3) visualization of the gallstone itself