A 70-year-old white British women with previous unremarkable medical history presented to the emergency department (ED) with diarrhoea and vomiting for 1 week. Lives independent in a flat, walks without aids, her two daughters visit her regularly. Non-smoker and occasional alcohol consumption, (one glass of wine on the weekend). On admission to ED, observations showed blood pressure 93/45 mmHg, pulse 75, initial lactate 5 mmol/L, temperature 37.6  C. The patient was initially assessed and described daily episodes of nausea and vomiting with watery diarrhoea for the past 2 weeks that had become more frequent in the last 48 hours; she did not describe any other related symptoms and specifically no abdominal pain or urinary symptoms. The physical exam was unremarkable; she was started on intravenous fluids. Bloods on admission revealed WBC of 16,800 per microliter, sodium 132 mmol/L, potassium 2.6 mmol/L, urea level 13.9 mmol/L, creatinine 347 mmol/L, GFR calculated 11 (baseline 60), serum C reactive protein level 332 mg/L. The initial diagnosis was sepsis secondary to gastroenteritis (the department had seen several cases due to a norovirus outbreak that had closed one of the hospital wards) and prerenal acute kidney injury.  2 litres of fluid were administered and a urinary catheter inserted. The patient was initially referred to the medical unit. After a reassessment in ED, despite 2 litres of fluid there was no urine output in the catheter bag, blood pressure was 75/45 mmHg, lactate 2.5 mmol/L, the patient remained communicative without any other related symptoms. Multi-organ POCUS was performed in order to guide fluid management and rule out other sources of infection. The echocardiogram showed a normal contractile left ventricle with no obvious source of endocarditis, normal right ventricle and normal inferior vena cava (IVC).  A passive leg-raising test was performed after measuring the initial Velocity Time Integral (VTI) with a second set of VTI measurements 2 minutes after the change in position showing an increment of 9%. Lung ultrasound showed scattered bibasal B lines, but no obvious consolidation. Abdominal ultrasound did not reveal dilated bowel and the aorta was normal. Hepato-biliary ultrasound showed a normal, non-distended gallbladder and normal common bile duct.  However, renal and genitourinary ultrasound revealed a right kidney with moderate hydronephrosis (Figure 1) with an empty bladder (urinary catheter in place). Intravenous antibiotics were started and an abdomen and pelvis computed tomography (CT) was requested. The CT scan demonstrated a right proximal ureteric obstructive stone and moderate right-sided hydronephrosis (Figure 2). 
Despite being hypotensive, the patient remained with a heart rate between 65 and 75 during her admission in the resuscitation room. On further questioning, the patient mentioned that she was able to pass urine early in the morning but has not pass more urine since them. The urologist on-call was contacted and an emergency nephrostomy was immediately performed with pus aspirated. The patient was admitted to the intensive care unit and required vasopressor treatment over the next 24 hours. During admission, the bloods improved to WCC 13.2, CRP 74 and diarrhoea had settled. She remained apyrexial and was discharged home with a plan for an elective flexible ureterorenoscopy.