Hydrometrocolpos as is a rare condition in female newborns which leads to the accumulation of fluid above the obstruction. Its most common causes are imperforated hymen or vaginal abnormalities. A premature baby born at 33+2 weeks was found to have generalized body oedema. Foetal MRI revealed hydrometrocolpos with imperforated hymen and ureteral compression, which led to dilatation of the left renal pelvis. USG (ultrasonography) revealed that the patient also had free fluid in the abdominal cavity. A significantly enlarged vagina and uterus was seen extending to the bottom of the stomach. The patient was qualified for surgery, which involved incising the hymen and evacuating the watery-mucus contents of the vagina. Early diagnosis of hydrometrocolpos using ultrasound or MRI is crucial to detect other serious abnormalities.