摘要Rationale:Acute pain is a medical emergency that requires prompt abdominal evaluation and management.Dengue,a mosquito-borne arboviral infection,can lead to complications such as acute abdominal pain.Patient concerns:A 72-year-old hypertensive female presented with high-grade intermittent fever with chills and rigors for four days.She was diagnosed with dengue fever(NS1Ag-reactive)the day before admission.A contrast-enhanced computed tomography of the abdomen showed a hematoma along the rectus sheath which was managed conservatively as per surgical opinion.Diagnosis:Dengue hemorrhagic fever with rectus sheath hematoma.Interventions:Blood transfusion and fluid therapy.Outcomes:Ten days after discharge,the patient reproted no pain in the right iliac fossa and the size of the hematoma was significantly reduced.Lessons:Although it is rarely seen as a cause of acute abdomen,complaints of adnominal pain should never be ignored in critical or convalescent phase of dengue fever.Radiological investigations should be promptly conducted as hematoma is often difficult to be diagnosed clinically.Delay in diagnosis of rectus sheath hematoma can be fatal.