Purpose: Shiga-toxin producing Escherichia coli (STEC) infections can range from mild diarrhoea to severe gastrointestinal bleeding and life-threatening complications including haemolytic uremic syndrome (HUS). This report highlights the diagnostic and management challenges in a rare case of prolonged severe per rectal (PR) bleeding caused by STEC. Methodology: We present the case of a 42-year-old woman with recurrent PR bleeding and hemodynamic instability. Initial investigations included routine blood tests, stool PCR testing, upper and lower endoscopy, capsule endoscopy, nuclear scintigraphy, and CT angiography to identify the source of bleeding. Results: Initial oesophagogastroduodenoscopy (OGD) and colonoscopy failed to identify the bleeding source. Imaging revealed active gastrointestinal bleeding within the right colon, with a 99mTc-labelled red blood cell scan showing activity near the caecum and CT angiography indicating a faint arterial blush without a feeding vessel. The patient required multiple blood transfusions and fresh frozen plasma for stabilisation. Despite ongoing bleeding and hemodynamic instability, mesenteric angiography failed to locate a specific bleeding vessel. Hemicolectomy was considered; but given her stabilisation and lack of a clear surgical target, conservative management was chosen. Stool PCR later confirmed Shiga toxin 2-producing Escherichia coli, and her symptoms resolved without surgery. Conclusion: Severe PR bleeding due to STEC infection is rare but should be considered in the differential diagnosis of unexplained gastrointestinal bleeding. Early stool PCR testing aids diagnosis, and supportive care is the mainstay of treatment, with surgery reserved for refractory cases.