Small bowel vs large.pptx

radiology

1. Small bowel vs. Large bowel The small bowel usually lies more centrally, with the large bowel framing it. The small bowel’s mucosal folds are known as valvulae conniventes and are visible across the full width of the bowel. The large bowel wall features pouches or sacculations that protrude into the lumen, known as haustra . In between the haustra are spaces known as plicae semilunaris . The haustra are thicker than the valvulae conniventes of the small bowel and typically do not appear to completely traverse the bowel. Faeces have a mottled appearance and are most often visible in the colon, due to trapped gas within solid faeces 1

2. Bowel diameter The   upper   limits  for the  normal   diameter  of different  bowel   segments  are as follows: Small bowel:  3cm Colon:  6 cm Caecum:  9 cm 2

3. A normal abdominal X-ray showing large bowel (white arrow) framing the small bowel (black arrow) Example of faeces and its typical mottled appearance The small bowel’s mucosal folds are called valvulae conniventes and cross the full width of the bowel  Haustra (white arrow) and plicae semilunaris (black arrow) 3

4. Small bowel obstruction Typical abdominal X-ray features of  small bowel obstruction  include  dilation of the small bowel  ( >3cm diameter ) and much more  prominent   valvulae   conniventes  creating a ‘ coiled-spring appearance ‘. When interpreting an abdominal X-ray you should always inspect the  inguinal   regions , particularly if considering a hernia as a cause of small bowel obstruction, as they are often fairly obvious (even on plain abdominal X-rays). 4

5. Small bowel obstruction (note the dilated loops of small bowel creating a “coiled-spring” appearance) 5

6. Large bowel obstruction Characterised by colonic distension proximal to the obstruction, with collapse distally. Considered dilated if it is over 6 cm in diameter, with the caecum having an upper limit of 9 cm. V ery few or no air-fluid levels are found in the large bowel because water is reabsorbed. rectum has little or no air.   6

7. Large bowel obstruction 7