Presentation A 27-year-old male presented to the Emergency Department with acute severe left flank pain following ingestion of 5 pints of beer. Approximately 20 bouts of similar episodes over the past year, in the setting of alcohol ingestion. Despite attending GP, no diagnosis reached yet. Diagnosis "Pelvo-ureteric junction (PUJ) obstruction Syndrome". Bedside ultrasound in the Emergency Department during the acute pain crisis: massive hydronephrosis left kidney. Finding confirmed on CT scan. Subsequent 99m-Tec renogram showed markedly decreased renal function on the left. Treatment Interval Pyeloplasty two months later. Conclusion Delayed recognition is the norm for PUJ obstruction syndrome, as CT/MRI/US studies often do not display hydronephrosis if the patient is asymptomatic. We could not find any reports in the literature of diagnosing PUJ obstruction syndrome using bedside ultrasound in the Emergency Department. We advise acquiring rapid bedside ultrasound imaging in suspected cases of PUJ obstruction syndrome, enabling earlier diagnosis.