Background: Depo Provera (medroxyprogesterone acetate) 150 mg intramuscular injection every 12 weeks is one of the most common, effective, affordable and popular methods of contraception. Depo Provera shows excellent results in comparison to oral contraceptive agents as well as the contraceptive patch.

Objective: The aim of the study was to determine the effects of the chronic use of medroxyprogesterone acetate 150 mg injections on the endometrium and myometrium of the uterus as measured by means of ultrasound.

Methods: An analytical case-control investigation was performed. Two groups were included and participants were actively selected and recruited by the researcher. Patients in both groups were similar with regard to socio-economic background, age and clinical profile. Each patient in the study group was paired with a patient in the control group. During patients' visits, measurements were performed by means of a Medison Sonoace 5500 digital ultrasound apparatus. A structured interview was conducted with each participant in order to obtain relevant patient information.

Results: Fifty participants were recruited and selected for both the study group and the control group. All the participants were women from the Thaba Nchu and Botshabelo municipal areas in the Free State Province, served by the researcher's private general practice in Botshabelo. Participants in the study group (20–46 years; median age 31 years) were treated with Depo Provera, while the control participants (19–48 years; median age 30.5 years) were not on any chronic medication or hormonal contraception, did not have intrauterine devices and were not pregnant or breastfeeding during the 12 months preceding the study. The medians of all the parameters (uterus length and width; endometrial thickness) were determined in the patients selected from the researcher's practice. The presence of uterine myomata was documented and compared between the two groups. Statistically significant differences with regard to all the measurements of the uterus and presence of myomata were observed between the study and the control group.

Conclusions: It was concluded that intramuscular administration of 150 mg medroxyprogesterone acetate was responsible for these differences.