40
Abdominal and gastrointestinal complications are common in patients post- HSCT,
with some being found in specific subsets of patients. A variety of abdominal compli-
cations can have overlapping clinical presentations. Appropriate imaging makes it
much easier to differentiate between them, especially when combined with the clini-
cal picture. Radiation enteritis generally presents as small bowel wall thickening with
inflammatory changes in the fat of the adjacent mesentery and retroperitoneum on
CT. Colitis, due to either infectious causes or GVHD, may have similar clinical pre-
sentations, but may have certain identifying features on CT that could help distin-
guish a more distal disease from neutropenic entercolitis (typhilitis), which is typically
found in the cecum, and is rarely seen in adults, but more common in the pediatric
population (Fig. 3.4) [ 4 ]. It may manifest as cecal wall thickening with signs of
inflammation in the surrounding fat and free intraabdominal fluid. If the colitis
advances to perforation then free intra-abdominal air would be seen.
Pseudomembranous colitis shows significant colonic wall thickening (11–15 mm)
that is uncommon in other types of colitis, mucosal enhancement in the affected areas,
and low-attenuation of the haustral folds. One sign particularly indicative of pseudo-
membranous colitis is the “accordion sign” which is due to the infiltration of contrast
material between the thickened colonic mucosa and the pseudomembranes (Fig. 3.5)
[ 4 ]. Pneumatosis intestinalis is a complication of HSCT that can be secondary to
many factors and may be a benign or serious finding depending on the patient’s pre-
sentation [ 1 ]. It can be described as having “bubbly” and “linear” intramural lucen-
cies i.e., the detection of gas in the intestinal walls. Pneumatosis intestinalis, if found
with concurrent neutropenic colitis, signals risks for impending bowel perforation.
Acute GVHD has a very good prognosis when treated quickly. The small bowel
and colon are among the earliest and most common tissues affected. Abdominal
manifestations on CT imaging typically demonstrate diffuse small bowel and
colonic wall enhancement with adjacent inflammatory changes, which when wide-
spread, can lead to infiltration of mesenteric fat that will show up as mesenteric
stranding. Bowel wall thickening is not very sensitive or specific for GVHD, and
Fig. 3.3 Bronchiolitis obliterans post stem cell transplant. Inspiration (a) and expiration (b) axial
CT images at the level of the upper lobes demonstrate areas of air-trapping
M. Atiq et al.