Fluid Management at Hysteroscopy
During hysteroscopy, systemic absorption of uterine distension fluid occurs largely through disrupted endometrial and myometrial venous sinuses as a result of the pressure gradient between the uterine cavity and open sinuses or vessels. Higher intrauterine pressure, longer procedure duration, deep myometrial penetration, and large uteri are associated with increased fluid absorption. The lowest intrauterine pressure that provides adequate visualization should be used, and when possible that pressure should be below the mean arterial pressure.
Distension media are categorized by viscosity, tonicity, and electrolyte status. Normal saline is a low viscosity, isotonic solution, with electrolytes, and is best suited for use with bipolar electrocautery or mechanical instruments. It cannot be used with monopolar electrocautery due to current dispersion by activated ions in the media. Monopolar electrocautery requires use of electrolyte-free fluids including hypotonic (1.5% glycine and 3% sorbitol) and isotonic solutions (5% mannitol).
Excessive absorption of hypotonic electrolyte free fluids, such as 1.5% glycine and 3% sorbitol, can cause hypo-osmolality, hyponatremia, cerebral edema, hypotonic encephalopathy, permanent neurologic injury, heart failure, pulmonary edema, and death. While 5% mannitol is less likely to cause hypo-osmolality, it can lead to hyponatremia. Premenopausal women are more likely to have permanent brain damage or die from hyponatremic encephalopathy than post-menopausal women. Excessive absorption of normal saline is not associated with hyponatremia; however, it can cause volume overload, right-sided heart failure, pulmonary edema, and death.
Fluid deficit can be estimated by manual calculation or by use of an automated fluid management system. With manual calculation, the volume of fluid collected in the perineal bag is subtracted from the known quantity infused every 15 minutes during the procedure. There are limitations with manual calculation, so automated fluid management systems that use calibrated electronic weighing scales are preferred.
When using hypotonic solutions, the maximum allowed fluid deficit is 1000mL for healthy patients and 750mL for elderly patients or those with medical comorbidities. For normal saline, the maximum allowed fluid deficit is 2,500mL for healthy patients and 750mL for those with cardiovascular disease. The procedure should be terminated when approaching the allowable fluid deficit. In the event of a rapid increase in fluid deficit, the occurrence of a uterine perforation should be considered.
Fluid absorption can be reduced by pre-operative treatment with GnRH agonists and intraoperative injection of dilute vasopressin (0.05 U/mL). If excessive absorption of fluid occurs with a hypotonic fluid, serum electrolytes should be obtained and the patient should be evaluated for volume overload. Asymptomatic hyponatremia can be treated with fluid restriction and careful monitoring of urine output. Treatment of symptomatic hyponatremia requires infusion of 3% sodium chloride (0.5-2mL/kg/hr) and management by a multidisciplinary team including a specialist in intensive care. Fluid overload from normal saline can be managed by fluid restriction; IV furosemide (20-40mg) is indicated if there is clinical or radiological evidence of pulmonary edema.
American Association of Gynecologic Laparoscopists, Munro MG, Storz K, et al. AAGL Practice Report: Practice Guidelines for the Management of Hysteroscopic Distending Media. J Minim Invasive Gynecol. 2013 Mar-Apr;20(2):137-48. doi: 10.1016/j.jmig.2012.12.002.
Kho KA. Minimally Invasive Surgery Fundamentals. Williams Gynecology. 3rd ed. New York, NY: McGraw-Hill Education LLC. 2016.
Initial Approval: July 2018. Reaffirmed January 2020
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