Fox Michelle C, Hayes Jennifer L
Contraception. 2007 Dec;76(6):486-95. doi: 10.1016/j.contraception.2007.09.004. Epub 2007 Nov 9.
Roughly 11% of induced abortions in the United States are performed after 14 weeks of gestation, most commonly by dilation and evacuation (D&E). For a D&E procedure, the cervix must be dilated sufficiently to allow passage of operative instruments and products of conception without injuring the uterus or cervical canal. Preoperative preparation of the cervix reduces the risk of cervical laceration and uterine perforation. The cervix may be prepared with osmotic dilators, prostaglandin analogues, or both. Osmotic dilators currently available in the United States include Dilapan-S, Lamicel, and laminaria. Laminaria tents are made from dehydrated seaweed and require 12-24 h to achieve greatest dilation. The synthetic products, Dilapan-S and Lamicel, achieve maximum effect within 6 h. Dilapan-S achieves greater dilation than the others and, thus, requires fewer dilators to be placed but may be more difficult to remove. For same day procedures, Dilapan-S and Lamicel are preferable to laminaria. A single set of one to several dilators is usually adequate for D&E before 20 weeks of gestation. Additional sets over 1-2 days may be needed in challenging cases. Misoprostol, a prostaglandin analogue, is sometimes used instead of osmotic dilators; however, the data to support such use are limited. Misoprostol is inferior to overnight dilation with laminaria for cervical priming prior to D&E. Misoprostol use as an adjunct to overnight osmotic dilation is only marginally beneficial for priming beyond 16 weeks and does not truly demonstrate any benefit before 19 weeks of gestation. Limited data demonstrate the safety of misoprostol prior to D&E in patients with a uterine scar. The Society of Family Planning recommends preoperative cervical preparation to decrease the risk of complications when performing a D&E prior to 20 weeks of gestation. The three currently available osmotic dilators (laminaria, Lamicel, and Dilapan-S) are safe and effective for this use. Since no single protocol has been found to be superior, clinical judgment is warranted when selecting a method of preoperative cervical preparation.
在美国，约11%的人工流产是在妊娠14周后进行的，最常见的方式是扩张刮宫术（D&E）。对于扩张刮宫术，宫颈必须充分扩张，以便手术器械和妊娠产物能够通过，同时又不会损伤子宫或宫颈管。术前宫颈准备可降低宫颈撕裂和子宫穿孔的风险。宫颈可使用渗透扩张器、前列腺素类似物或两者联合进行准备处理。美国目前可用的渗透扩张器包括Dilapan-S、Lamicel和海藻棒。海藻棒由脱水海藻制成，需要12 - 24小时才能达到最大扩张效果。合成产品Dilapan-S和Lamicel在6小时内即可达到最大效果。Dilapan-S比其他产品能实现更大程度的扩张，因此放置的扩张器数量较少，但可能更难取出。对于当日手术，Dilapan-S和Lamicel比海藻棒更可取。对于妊娠20周前的扩张刮宫术，通常一套一至几个扩张器就足够了。在具有挑战性的病例中，可能需要在1 - 2天内额外增加扩张器。米索前列醇，一种前列腺素类似物，有时会被用来替代渗透扩张器；然而，支持这种用法的数据有限。在扩张刮宫术前，米索前列醇用于宫颈准备不如海藻棒过夜扩张有效；在妊娠16周后，米索前列醇作为过夜渗透扩张的辅助用药，对于宫颈准备仅具有微弱的益处，且在妊娠19周前并未真正显示出任何益处。有限的数据表明，对于有子宫瘢痕的患者，在扩张刮宫术前使用米索前列醇是安全的。计划生育协会建议，在妊娠20周前进行扩张刮宫术时，术前进行宫颈准备以降低并发症风险。目前可用的三种渗透扩张器（海藻棒、Lamicel和Dilapan-S）用于此目的是安全有效的。由于尚未发现单一方案具有优越性，因此在选择术前宫颈准备方法时需要临床判断。
