CASE PRESENTATION
A 48-year-old woman presented with a one-year history of irregular heavy vaginal bleeding. She was hemodynamically stable at presentation and physical examination was unremarkable. Bimanual examination revealed the cervix to be thin and dilated to 8cm with a large mass protruding from the external os suspicious for an aborting myoma. Initial laboratory investigations are summarized in table 1. A total abdominal hysterectomy (TAH) and bilateral salpingo-oophorectomy (BSO) was planned and she was optimized with blood transfusions, IV fluids and tranexamic acid.
Her surgical course was complicated by left ureteral injury requiring left intravesical ureteral reimplant and left ureteral stent placement by urology. Serum osmolality increased from 287 mosm/kg on admission to 322 mosm/kg. Urine electrolytes were performed at this time which showed urine osmolarity of 93 mOsm/kg, urine sodium of 23 mmol/L, urine chloride 30 mmol/L, urine potassium of 9.0 mmol/L and urine creatinine of 23.5 mg/dl. Twenty-four urinary output on post-operative Day 1 was 7.1L and 11.9L on postoperative Day 2. She was extubated on postoperative Day 2. Renal ultrasonography (Day 4 post-operation) showed adequate placement of the left ureteral stent with left hydronephrosis.
Given the timeline of events, it was unclear if the polyuria was secondary to ureteral injury and post-obstructive diuresis versus diabetes insipidus. She was treated with intravenous desmopressin with a marked reduction in urine output to 4.2L in 24 hours and increased urine osmolarity (315m Osm/kg). MRI brain was performed which showed absence of the posterior pituitary bright spot consistent with posterior pituitary dysfunction suggestive of central diabetes insipidus (DI) (See Figure 1). Further investigation revealed normal ACTH, cortisol, TSH and IgG levels. She was encouraged to drink to meet the demand of her thirst level and was treated with desmopressin when her urine output was more than or equal to 300ml/hr for 3 consecutive hours and serum sodium was more than 145 mmol/L. She was discharged on Desmopressin 0.1 mg daily.