Ultrasound for the determination of appropriate needle length for intragluteal injection of long-acting rilpivirine-cabotegravir.

OBJECTIVES

Long-acting (LA) intramuscular injections of cabotegravir (CAB) and rilpivirine (RPV) are an effective maintenance therapy for people living with HIV who are virologically suppressed. However, virological failures (VFs) have been reported, often associated with elevated body mass index (BMI), potentially due to inadequate intramuscular drug delivery. Current recommendations mainly rely on BMI to guide needle length selection and do not routinely incorporate imaging techniques. Furthermore, they do not recommend the use of ultrasound as an investigative tool in cases of LA treatment failure.

METHODS

We retrospectively reviewed anonymized records of two patients experiencing virological rebound under LA CAB/RPV. Clinical, virological and resistance data were extracted from their medical records.

RESULTS

The first case involves an obese patient. Ultrasound revealed subcutaneous adipose tissue thickness >3 cm and intra-adipose injection granulomas, suggesting non-intramuscular injections. After adapting needle length, virological suppression was restored. The second case involves a patient with a normal BMI in whom ultrasound revealed a gluteal subcutaneous adipose tissue thickness of 45 mm and bilateral subcutaneous granulomas.

CONCLUSION

Ultrasound is a simple and accessible tool to help optimize drug injection in case of obesity or gynoid fat distribution and investigate injection technique-related issues in cases of VF.