Is there a role for routine duodenal biopsy in diagnosing giardiasis in a European population?

Giardia lamblia is the most common enteric protozoan world-wide. The prevalence varies internationally. Patients with giardiasis typically have diarrhoea but may have atypical symptoms when referred for endoscopy. The purpose of this study was to investigate whether a policy of routine duodenal biopsies increased the yield of diagnosing Giardia and whether treatment improved the patient's presenting symptoms.

Our hospital endoscopy database was examined retrospectively, from January 2003 to January 2004, to identify patients who had undergone gastroscopy and targeted duodenal biopsies. Thereafter, routine duodenal biopsies were carried out prospectively on unselected adult patients referred for gastroscopy from January 2004 to April 2006. Patients diagnosed with Giardia were assessed for symptoms and response to treatment.

In the retrospective group, of the 5979 gastroscopies performed, 1464 duodenal biopsies were carried out; 5 patients had giardiasis, a prevalence of 0.08%, CI 0.01-0.16%. In the prospective group, 2000 gastroscopies with duodenal biopsies were performed; 9 patients had giardiasis, a prevalence of 0.45%, CI 0.16-0.74%. The difference in prevalence was 0.37%, CI 0.06-0.67%, which was statistically significant with a Yates' chi(2)(CC) of 9.49, p<0.005. On comparing response to treatment, the Fisher exact test revealed a proportional difference that was not statistically significant.

In a UK population, the prevalence of Giardia was low. Although a policy of routine duodenal biopsy resulted in more cases of Giardia being identified, this increase in detection did not correspond with an improvement in patients' symptoms. This suggests that Giardia may be a coincidental finding. This study does not support the approach of routine duodenal biopsy in diagnosing giardiasis.