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Laparoscopic UAO: Minimal Risks, Considerable Benefits


 

There was a time when almost all women with symptomatic leiomyomas were amenable to hysterectomy or myomectomy when medical therapy failed to relieve their pelvic pressure and pain, menorrhagia, and, in many cases, anemia.

Today, that has changed.

An increasing number of women don't want myomectomies or hysterectomies, regardless of whether they are performed abdominally or laparoscopically or—in the case of hysterectomies—vaginally. They go to the Internet and easily click on the names of 1,000 radiologists who promise a nonsurgical alternative that will “melt away” their fibroids.

Uterine artery embolization (UAE) involves making an incision in the groin and then threading a catheter through the femoral artery to the uterine artery to deliver thousands of polyvinyl particles into the uterus, as well as into the arteries, veins, and peripheral vessels that supply it. The intention is to cause transient uterine ischemia.

Originally used as a presurgical procedure to reduce blood loss during myomectomy or hysterectomy, UAE was also found to be effective in treating life-threatening bleeding that resulted from myomas. Success in controlling bleeding and improving symptoms led to its use as an alternative to primary surgery for leiomyomas in the late 1990s.

A recent surge in popularity was sparked by Food and Drug Administration approval of Embosphere microparticles for UAE and an aggressive marketing campaign by radiologists performing the procedure.

An Alternative to UAE

Laparoscopic uterine artery occlusion (UAO) offers a minimally invasive surgical option that also causes transient uterine ischemia and subsequent relief of leiomyoma symptoms, utilizing the same principles as UAE but permitting the gynecologic surgeon to inspect the uterine cavity, address other gynecologic issues, and rule out uterine cancer. Understanding either procedure requires a basic understanding of the principle behind bilateral UAO.

The uterine arteries provide most of the uterine blood supply. When this blood flow is blocked—either by polyvinyl microparticles, as in UAE, or by vascular clips during laparoscopic UAO—blood will then clot within the myometrium.

The myometrium becomes hypoxic and its metabolism undergoes a shift from oxidative pathways to anaerobic glycolysis.

Within hours to days, clots are lysed within the myometrium, and collateral arteries begin to reperfuse the uterus.

Myomas, in contrast, cannot lyse clotted blood and reperfuse. They eventually become infarcted and die.

In a proof-of-hypothesis study conducted by my colleagues and me several years ago, we found that the percentage and rate of decline and the return to baseline of pH (a proxy for hypoxia and lactic acidosis) after bilateral UAO were quite variable.

The myometrium has a complex, redundant blood supply that varies from patient to patient (J. Am. Assoc. Gynecol. Laparosc. 2003;10:553–66).

In the vast majority of women, these secondary, tertiary, and quaternary vascular pathways are insufficient to maintain aerobic metabolism.

In 1%–2% of women, however, one uterine artery is hypoplastic, and a large communicating artery connects the ovarian artery to the uterus. Without occlusion of this artery in these patients, the blood supply to the uterus would be maintained despite bilateral UAO.

In our study reviewing eight cases, the uterine pH change from baseline ranged from 0.4 to 1.7 units over a time period that ranged from 5 minutes to 210 minutes after bilateral UAO.

The time for pH to return to baseline ranged from 20 minutes to 660 minutes (J. Am. Assoc. Gynecol. Laparosc. 2002; 9:191–8).

Other investigators have shown via MRI that clots form more quickly in myomas (as indicated by uptake of contrast media) than in the myometrium, and myoma tissue remains unperfused at 1 year, even as myometrium demonstrates normal perfusion at 1, 2, 3, 4, and 6 months, and 1 year.

In our first study of laparoscopic UAO for symptomatic leiomyomas, we enrolled eight women whom we had counseled extensively about various alternatives, including gonadotropin-releasing hormones, hysterectomy, myomectomy, and embolization.

Operative Technique

The operative procedure is quite straightforward.

Patients are placed in dorsolithotomy position under general anesthesia. A Foley catheter is placed into the bladder. An examination is performed, followed by hysteroscopy, and—if warranted by findings—endometrial biopsies are performed. A uterine cannula is inserted for uterine manipulation.

Depending on uterine size, a 10-mm port is inserted using open technique in the umbilicus or the left upper abdominal quadrant.

For safety reasons, accessing the peritoneum above the psoas muscle prevents direct trauma to retroperitoneal vessels. Entering retroperitoneum lateral to the posterior broad ligament avoids uterine expansion.

Pneumoperitoneum is established under videolaparoscopic guidance. Two additional ports—one is a 5-mm port; the other is a 5-mm or 12-mm port—are then inserted under visualization bilaterally above the inferior epigastric vessels.

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