Abdominal Pain and the Peritoneal Fat Margins
Radiology Cases in Pediatric Emergency Medicine
Volume 3, Case 19
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
This is a 4-year old female with a history of
abdominal pain for 3 days. She was seen by her
private physician in the morning and then referred to the
emergency department for further evaluation because
of tenderness in the right lower quadrant.
Exam: VS T37.0 (oral), P122, R24, BP 108/73,
oxygen saturation 99% in room air. Alert, cooperative,
uncomfortable, but no acute distress. Oral mucosa
sticky. Neck supple. Heart regular without murmurs.
Lungs clear. Abdomen flat. Guarding on the right. She
points to the epigastrium as the site of her pain.
However, most of the tenderness is elicited in the right
lower quadrant. Bowel sounds are hypoactive. Color
and perfusion are good.
An abdominal series is ordered.
View abdominal series: Flat (supine) view.
Abdominal series: Upright view.
The following laboratory results are obtained:
CBC WBC 17.5, 51% segs, 23% bands, 21% lymphs,
4% monos, Hgb 12.8, Hct 37, platelets 405,000.
ESR 43
UA SG 1.033, 3+ ketones, no WBC's, 0-2 RBC's per
hpf
Her abdominal series shows diffuse gaseous
distention of the colon and small bowel compatible with
an ileus or an early obstruction. The distribution of gas
is good. No free air is visible under the diaphragm. No
appendicolith is visible.
Compare the radiographic appearance of the left
lower quadrant with the right lower quadrant. Can you
appreciate any differences? Look at the peritoneal fat
stripe on the left and on the right. The bowel should
generally lie very close to this fat stripe. This is true
on the patient's left (right on image), but note that this is
not the case on the patient's right (left on image). In the
right lower quadrant, the bowel is about 1 cm from the
peritoneal fat stripe. In the left lower quadrant, the
bowel is about 1-2 mm from the fat stripe. This can be
best visualized in the magnified focused view of the
lower abdomen.
View close-up of lower abdomen.
Look at the peritoneal fat stripes on both sides just
above the iliac crests (white arrows). Note that on the
patient's left, there is a very narrow space between the
fat stripe and the bowel. However, on the patient's
right, the bowel is farther away from the fat stripe
suggesting that there is fluid, a mass, or thickened
tissue pushing the bowel aside.
The black arrow points to a small gas pocket that
does not appear to be within bowel. These findings
together are highly suggestive of a ruptured appendix.
The patient is taken to surgery where a ruptured
appendix is found. There is exudate extending from the
right paracolic gutter to the liver and diaphragm. She
recovers and is discharged in good condition on the
sixth post-operative day.
The radiographic findings in appendicitis are
infrequent and diverse. Radiographic findings highly
suggestive of an acute appendicitis include an
appendicolith, free air, RLQ sentinal loops (dilated
bowel loop(s) in the RLQ in an otherwise nearly gasless
abdomen), and absence or indistinctness of the right
psoas margin. Free air may not always be present
under the diaphragm since it may be loculated. Less
specific findings include diminished intestinal gas, a
scoliosis to the left (concavity to the right, due to
splinting), or a bowel obstruction.
References
Swischuk LE. Emergency Radiology of the Acutely
Ill or Injured Child, second edition. Baltimore, Williams
and Wilkins, 1986, pp 191-209.
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