SANTA FE, N.M. — Although the complication rate for hysteroscopic myomectomy is relatively low, physicians must guard against uterine perforation and hyponatremia during the procedure, Stephen M. Cohen, M.D., advised at a conference on gynecologic surgery sponsored by Omnia Education.
All but the smallest fibroids should be removed in an operating room, according to Dr. Cohen, chief of the division of gynecology and director of women's minimal access surgery at Albany (N.Y.) Medical College. In cases in which a large vascular fibroid is detected, Dr. Cohen also recommended allowing time to shrink it with a GnRH agonist before attempting removal.
He noted that patients should be forewarned that a second operative procedure might be necessary to remove the entire fibroid.
Uterine perforation—usually during cervical dilation—is the most common complication of operative hysteroscopic, occurring in 1%–10% of cases, according to Dr. Cohen. Patients with Asherman's syndrome and cervical stenosis are most at risk.
He advised physicians to prevent perforation by withdrawing the resectoscope as soon as advancing it becomes difficult.
“Back out, redilate, and make it go easy. Don't keep pushing ahead if you can't see where you're going,” he said.
The hyponatremia risk stems from the pumping of low-viscosity fluids containing sorbitol, mannitol, or glycine to distend the uterus during the procedure. Younger women are at greater risk for permanent brain damage and death from severe sodium depletion, according to Dr. Cohen.
He cited the theoretical effects of estrogen's possible interference with sodium balance, the decreased effect of vasopressin in the reduction of cerebral edema, and the smaller intracranial space in young women.
Dr. Cohen said intrauterine pressure ideally should be kept to a mean arterial pressure of 75 mm Hg. This may not be adequate in some patients, however, so he occasionally starts as high as 120 mm Hg and titrates down until he sees the uterus beginning to collapse.
Physicians need to have a system for keeping meticulous track of the intake and output of fluids, noted Dr. Cohen. Some patients absorb more fluid than do others, he said, and the amount can increase substantially during a long procedure.
If the imbalance reaches 1,000 mL, he recommended giving intravenous Lasix (furosemide). If the amount reaches 1,500 mL, the operation should be stopped immediately, he said.
“When they absorb 1,500 mL, that's done—case over. … It's better to go back a second time for a fibroid than to be reporting a death,” Dr. Cohen said, advising that extreme cases of fluid overload may need to be treated in the intensive care unit.
If the patient is under general anesthesia, Dr. Cohen advised watching for decreased oxygen saturation and dilated pupils as the first signs of hyponatremia. Should the plasma sodium level fall below 120 mEq/L, he recommended infusion of a 3% saline solution monitored in the ICU.
Under local anesthesia, symptoms of mild hyponatremia (130–135 mEq/L) include apprehension, disorientation, irritability, twitching, nausea, vomiting, and shortness of breath. As sodium levels drop, the list grows to include pulmonary edema, moist skin, polyuria, hypotension, bradycardia, cyanosis, mental changes, encephalopathy, chronic heart failure, lethargy, confusion, twitching, and convulsion.
With sodium less than 115 mEq/L, the patient faces brain stem herniation, respiratory arrest, coma, and death, he said.