The Norplant® implant system was a progestin-based contraception medication formulated for five years of continuous use. The implant system consisted of six soft silastic implants, each containing 36 mg of levonorgestrel. The implants were 34 mm long and 2.4 mm in diameter. They were placed in a fan-shaped arrangement into the subcutaneous tissue on the medical aspect of a woman’s nondomit upper arm. It was removed from the US market in July 2002. A second generation, Norplant II® (also known as Jadelle®), consists of two small (43 mm X 2.5 mm) silicone rods, each containing 75 mg of levonorgestrel, instead of the original six capsules.

　　Norplant®是孕激素埋植劑，持續(xù)有效時間為五年。Norplant含有六個軟硅膠植入器，每個植入器內(nèi)含有36mg左炔諾孕酮。植入器長34mm，直徑2.4mm，以扇形排列植入放進女性非慣用手臂內(nèi)側皮下。2002年7月后美國市場上不再使用這種類型的埋植劑。其次 代Norplant II®(也稱為Jadelle®)改進了原來配置，把六個軟硅膠植入器改為兩個小的硅膠棒(43mm X 2.5mm)，每個硅膠棒含有75mg左炔諾孕酮。

　　The current contraceptive implant system available in the United States consists of a single rod (4 cm in length and 2 mm in diameter) of ethylene vinyl acetate copolymer core containing 68 mg of etonogestrel. The device allows for controlled release of etonogestrel over a period of three years. Etonogestrel is the active metabolite of desogestrel. It does not contain latex, is not biodegradable, and originally was not radiopaque. It was originally marketed as Implanon®. The insertion device was redesigned and the implant device made radiopaque and renamed Nexplanon®. Implanon was phased out in December 2012; since that day only Nexplanon has been available. The contraceptive implant is the most effective method of reversible contraception, with a typical-use pregcy rate of 0.05% (1).

　　目前美國可用的皮下埋植劑由一根乙烯醋酸乙烯酯共聚物芯棒(長4cm，直徑2mm)組成，內(nèi)含68mg依托孕烯，會在三年內(nèi)有控制性地釋放依托孕烯。依托孕烯是去氧孕烯的活性代謝物。這種皮下埋植劑上市的名字是Impanon®，不含乳膠，不可生物降解，較初設計是不透輻射的。后來植入器經(jīng)過重新設計改為可透輻射的，產(chǎn)品更名為Nexplanon®。Impanon于2012年12月退出市場，目前只有Nexplanon在售。皮下埋植避孕器是較有效的可逆避孕方法，理論使用妊娠率為0.05%(1)。

　　The most common side effects are changes in menstrual bleeding pattern including amenorrhea, oligomenorrhea, or prolonged bleeding. The bleeding pattern with contraceptive implant use is unpredictable and is cited as the most common reason for device discontinuation. However, a significant noncontraceptive benefit is a decrease in smenorrhea. Other reported adverse effects include gastrointestinal difficulties, headaches, acne, breast pain, vaginitis, and weight gain. According to the package insert, weight gain was reported in only 2.3% of patients who chose to discontinue the implant.

　　使用皮下埋植避孕藥較常見的副作用是月經(jīng)紊亂，包括閉經(jīng)，月經(jīng)稀發(fā)或出血時間延長。使用期間月經(jīng)出血情況無法預測，這是患者停止繼續(xù)使用埋植劑的較常見原因。不過，使有埋植劑除了避孕的作用外還有一個很明顯的好處，能減少痛經(jīng)的發(fā)生率。其他報告的不好反應包括胃腸道不適，頭痛，痤瘡，乳房疼痛，陰道炎和體重增加。根據(jù)包裝說明書，只有2.3%選擇停止使用埋植劑的患者有體重增加的情況。

　　The contraceptive implant is safe to insert anytime in nonbreastfeeding women after childbirth. In breastfeeding women, it is optimal to wait four weeks after childbirth because of theoretic concerns regarding milk production and infant growth and development. A randomized trial compared postpartum insertion of the etonogestrel contraceptive impant at one to three days with standard insertion at four to eight weeks postpartum. No differences were found in breastfeeding outcomes between the groups, including lactogenesis and the risk of lactation failure. An additional nonrandomized comparative stu compared milk composition in 80 women using nonhormonal IUD contraception with the etonogestrel implant. Breast milk composition (measured by total protein, fat, and lactose content) did not differ between the groups, nor did the quantity of breast milk. A three-year follow-up also showed no difference in neonatal bo length, biparietal head circumference, and bo weight. Given the excellent data regarding efficacy and safety for the contraceptive implant, expanded usage could substantially decrease the unintended pregcy rate.

　　埋植避孕劑可以在女性分娩后非母乳喂養(yǎng)期植入。對于正在母乳喂養(yǎng)的女性，理論上出于對泌乳和嬰兒生長發(fā)育的考慮，較好在分娩四周后再植入。根據(jù)一項對產(chǎn)后1至3天植入依托孕烯避孕劑和產(chǎn)后4-8周植入避孕劑的標準做法的隨機試驗，兩組之間的母乳喂養(yǎng)結果沒有差異，包括泌乳量和泌乳失敗危險 。另一項非隨機研究對比了80名使用非激素類宮內(nèi)節(jié)育器和依托孕烯植入器后的母乳成分，發(fā)現(xiàn)兩組之間沒有差異(比較總蛋白質(zhì)，脂肪和乳糖含量)，母乳量也沒有差異。三年隨訪結果也說明新生兒的體長，頭部雙頂徑和體重沒有差異。鑒于埋植避孕劑有效性高，靠譜性佳，擴大使用范圍可以大大降低意外妊娠率。

　　References

　　參考文獻

　　1. Basinski CM, A review of clinical data for currently approved hysteroscopic sterilization procedures. Rev Obstet Gynecol 2010;3:101-10. (Level III)

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