Background:

Thickening of bowel wall at Ultrasound (US) is an aspecific sign in infectious-inflammatory bowel diseases. We evaluated US of colon as a tool for diagnosis and follow-up of antibiotic associated colitis (AAC).

Patients and methods:

We retrospectively studied clinical and imaging records of 32 patients (18 males; age: 27–80 years) with the diagnosis of AAC. All diagnosis were based on patients'history of massive antibiotic intake preceding clinical signs (diarrhoea, abdominal pain, fever). Causes of antibiotic intake were: porto-systemic encephalopathy in 13 cirrhotis patients, recent surgery in eight patients, respiratory tract infections in nine, liver abscess in two.

Cultures of blood and faeces were performed in all patients. In 10 cases, stools were tested for toxin of Chlostridium difficile by enzyme-linked immunosorbent assay (ELISA). All patients underwent colonic US within 24 h from admission at our institution and every 3 days during the following 15 days. Thirteen patients also underwent colonoscopy. All patients were treated with Metronidazole (125 mg × 4/day) and Vancomycin (500 mg × 4/day) for 10 days.

Results:

ELISA test for Chlostridium difficile toxins was positive in 4/10 (40%) patients. All blood cultures were sterile. In 4/13 patients (31%) colonoscopy showed mucosal pseudomembranes, pathognomonic pattern for the diagnosis of Pseudomembranous colitis while in nine patients it showed an aspecific pattern of acute colitis. US showed normal (<=4 mm) colonic wall thickness in seven patients and colonic wall thickening (ranging from 8 to 33 mm) in 25/32 patients (78%). Nineteen of 32 (59%) patients had colonic wall thickness <15 mm while in 13/25 (41%) patients it was >15 mm.

Follow-up:

Remission of symptoms occurred in all patients within 2–11 days (mean: 3.6 days). Persistence of symptoms was significantly longer in patients with colonic wall thickness >15 mm (mean: 5.1 days) than in patients with <15 mm (mean 2.5 days) at US. Four cirrhotic patients relapsed 7–14 days after completion of therapy. Three of them (75%) still showed persistence of colonic wall thickening after the 10 days of metronidazole-vancomycin therapy. Normalisation of colonic wall thickness (<=4 mm) at US occurred in 29 patients within 3–9 days. None of these patients relapsed after completion of treatment.

Conclusions:

Although aspecific, thickening of colonic wall at US seems to be a very sensitive tool for diagnosis and follow-up of AAC.