Toxic megacolon complicating chemotherapy for acute myeloid leukaemia

Acute colonic pseudo-obstruction complicating chemotherapy in paediatric oncohaematological patients: clinical and imaging features

OBJECTIVE

Although acute colonic pseudo-obstruction (ACPO) complicating chemotherapy is still a controversial entity, it is one with which radiologists should be familiar. We describe the imaging features of ACPO in children following chemotherapy for treatment of a haematological malignancy.

METHODS

We retrospectively reviewed the imaging features of eight children (age 3-14 years) with chemotherapy-related ACPO, all of whom had undergone plain radiography and CT examinations. The diagnosis of ACPO was based on both clinical features and imaging findings.

RESULTS

Abnormalities noted on plain radiography included faecal gaseous distension of the transverse colon (4/8), faecal gaseous distension of the ascending colon (3/8), gaseous distended transverse colon (3/8) and gaseous small bowel loops (6/8). As seen on CT scans, findings of faecal fluid distended the ascending and transverse colon (5/8), faecal gas distended the transverse and ascending colon (3/8), and small bowel dilatation (5/8) and pneumatosis intestinalis (2/8) were noted. Seven of the eight patients had colonic dilatation from the caecum to the transverse colon with the transition zone near the splenic flexure.

CONCLUSION

In children presenting with abdominal pain and constipation following chemotherapy, imaging features of progressive colonic dilatation seen on radiography and dilatation from the caecum to the transverse colon with the transition zone near the splenic flexure, as noted on CT, are suggestive of ACPO. CT is more successful than plain radiography for evaluating this finding, particularly in colonic segments filled primarily with fluid, but CT should not be necessary for making the diagnosis as plain radiographs and clinical evaluation should be adequate.

Management of uncommon chemotherapy-induced emergencies

Chemotherapy can induce various clinical emergencies. Prompt recognition and management of these adverse events are important for avoiding further morbidity and mortality. Some events such as hypersensitivity and extravasation are quite common, whereas emergencies such as neutropenic typhlitis, pancreatitis, and acute haemolysis are very rare. Little information exists on the management of rare chemotherapy-induced emergencies that affect fewer than 1% of patients. We review these uncommon chemotherapy-induced life-threatening emergencies, their pathogenesis and management, and recommendations for rechallenge with the offending chemotherapy.

A new look at toxic megacolon: an update and review of incidence, etiology, pathogenesis, and management

Toxic megacolon (TM) is an infrequent but devastating complication of colitis. Numerous forms of colonic inflammation can give rise to TM but the majority occur in individuals with inflammatory bowel disease (IBD). Recently there has been a marked increase in the number of reports of TM associated with pseudomembranous colitis. Because of the associated high morbidity and mortality, early recognition and management of TM is of paramount importance. The mechanisms involved in development of TM are not clearly delineated, but chemical mediators such as nitric oxide and interleukins may play a pivotal role in the pathogenesis. New evidence suggests that TM and its associated morbidity may be predicted by the extent of small bowel and gastric distension in patients with colitis. CT scanning may also play an important role the management of TM, in that it may be the only noninvasive mode to detect subclinical perforations and abscesses. Management involves close medical attention, supportive care, and treatment of the underlying colitis. Possible exacerbating factors such as narcotic and anticholinergic medications must be withdrawn, and colonic decompression via tube drainage or positional techniques must be considered. Signs of progression or complications of the disease must be treated aggressively with surgical intervention, as delay is associated with even greater risk of mortality.