BackgroundRape is one of the trauma incidents with the highest risk of subsequent post-traumatic stress disorder. Early interventions, such as prolonged exposure therapy (PE), have shown promise in preventing PTSD following a sexual assault. The primary objective of this internal pilot trial was to examine the feasibility of the EIR study protocol, which used modified prolonged exposure therapy (mPE) as a preventive intervention after rape.MethodsThis parallel two-arm clinical pilot study involved three sexual assault centers (SACs) in Trondheim, Oslo, and Vestfold, with data collected between June 2022 and March 2023. Women seeking assistance at one of these three SACs within 72 h after rape or attempted rape received acute medical treatment and forensic examinations. Women who wanted further psychosocial treatment were, if eligible and consenting, recruited to complete baseline assessments and a clinical interview before being randomized to one of two study arms. The intervention group prescribed up to five sessions of modified PE (mPE) in addition to treatment as usual (TAU), starting within the first 14 days after the rape incident, followed by weekly sessions. The other group received TAU.The present pilot evaluation is based on 22 participants, i.e., nine mPE + TAU and 13 TAU alone. Primary outcomes were predefined progression criteria regarding recruitment, retention, intervention implementation, a harm reporting system, and applying biological measurements and actigraphy.ResultsDuring the 6-month recruitment period, 235 women visited the three SACs. After eligibility screening and consent, 22 (9.4%) women were randomized. Three months later, 14 (63.6%) participants completed the final assessments. Intervention implementation was successful using trained SAC personnel to deliver mPE. The harm reporting system was used according to the study’s plan, and adverse and serious adverse events were detected during the trial. The biological measurements and actigraphy had substantial missing data but were still considered usable for statistical analyses.ConclusionIt may be feasible to conduct a full-scale RCT of early intervention after rape by comparing mPE + TAU to TAU alone. Minor design refinements were made to the protocol to enhance the main study outcome.Trial registrationClinicalTrials.gov Identifier: NCT05489133. Registered on 15 July 2022, retrospectively.