An 18 years old girl presented to the preoperative anesthesia clinic for surgery of a distal phalanx fracture. She had a history of delayed milestones and irregular periods with easy fatigability. Physical examination revealed that the patient was short-statured with a webbed neck (Fig. 1A). Family history was not significant except for short-statured parents. Her heart rate was 70 beats/min, blood pressure was 100/66 mmHg, respiratory rate was 14 breaths/min, and body temperature was 36.5ºC. Her preoperative investigations were normal except for an electrocardiogram, which showed low-voltage complexes (Fig. 1B), and chest radiographs, which showed a moneybag heart (Fig. 1C). Point-of-care ultrasound examination of the heart showed a swinging motion within the anechoic space (Fig. 2, video). In the four-chamber apical view, the anechoic space measured > 2 cm posterior and > 1 cm anterior to the heart, suggesting a large pericardial effusion (Fig. 2C). No collapse of the right atrium or ventricle was observed, which ruled out tamponade physiology and precluded the need for pericardiocentesis (video). A thyroid function test was also ordered, and its result showed severe hypothyroidism (Thyroid stimulating hormone > 496 µIU/ml, T3 < 0.05 ng/ml, and T4 < 2 µg/dl). Other differential diagnoses included tuberculosis, autoimmune diseases, renal failure, and tumors, which were excluded based on biomarker and antibody measurements. Other routine hematological investigations were normal. A cardiologist’s opinion was sought, who advised only correction of the hypothyroid status for the management of the effusion. The patient was started on thyroxin therapy at 100 µg, which was increased to 150 µg. One week later, the patient underwent an uneventful surgery under a wrist block. The thyroid function test and echocardiography were repeated after 4 weeks, which showed a return to the euthyroid status with minimal pericardial effusion. Karyotyping results showed a mosaic variant of Turner Syndrome, for which she was advised to undergo gynecological and endocrinological follow-up.