Evaluation of the inner thigh as site for mantoux test among children in Owerri South Eastern Nigeria

Abstract

Background: Mantoux test, a type IV hypersensitivity reaction, is commonly used to screen children for possible tuberculosis. It is applied on the volar surface of forearm. Sunlight ultraviolet rays (UV) have recently been shown to induce immunosuppression that alters the skin response to Mantoux test negatively.

Objective: The study aimed to evaluate the inner thigh as a possible site for Mantoux test in children attending Federal Medical Centre Owerri whom their primary attending Physicians requested a Mantoux test.

Methods: This was a cross sectional study conducted between June and October 2011. Concomitant intradermal injection of 0.1ml of purified protein derivative on the volar aspect of the forearm and the inner thigh was carried out. Induration was measured concurrently in 106 consecutive children, between the ages of 3months and 15 years. Using volar surface of forearm as gold standard, values of inner thigh induration at a set cut-off was determined. Students’t test, Pearson correlation coefficient and the Chi square were used to compute data.

Results: The mean diameter of induration on the inner thigh (12.51 ±3.44mm) was higher than mean diameter of induration on the volar surface of the arm (11.03±6.34mm). This is however not statistically significant. There were (29) children who had reactive induration on the inner thigh whilst 19 had similar induration on the volar surface of the forearm. In the presence of factor(s) that negatively affects the response of the skin to Mantoux test; the inner thigh induration yield was higher. There was a strong positive correlation between the two site measurements.

Conclusions: The inner thigh as a site for Mantoux test in children has shown potential for higher yield.

Keywords: Sunlight, Inner thigh, Mantoux test, TB, Children