子宮血流變化對於子宮內膜胚胎著床能力影響之研究

Dynamic changes of uterine circulation during the peri-implantation period and its impact on endometrial receptivity

簡立維(Li-Wei Chien)

指導教授 ： 曾 啟 瑞 教授 ； 李 文 森 教授

臺北醫學大學/醫學院/醫學科學研究所/博士(2003年)

摘要

胚胎著床是目前影響不孕症治療，特別是人工生殖科技懷孕成功率的重要關鍵，本研究是假設子宮血流的變化，可以幫助我們了解著床前後子宮內膜的環境。 研究的方法是以經陰道超音波，在接受體外授精胚胎植入治療的病人，使用杜卜勒超音波觀察子宮內膜、子宮與卵巢動脈阻力，以及子宮內膜與內膜下血流分布的變化，研究對於胚胎著床成功率之影響。 為了解子宮與卵巢血流在早期胚胎著床時期的變化，以及對懷孕成功與否的影響，我們對三百一十七位病人，進行一前瞻與系列性的研究。 在胚胎植入前與植入後5至6天，分別測量左右兩邊子宮與卵巢動脈的血流。 結果發現懷孕病人胚胎植入前子宮動脈血流阻力係數RI和PI，比沒有懷孕的人來得低(P = 0.04 和P = 0.003)，但是植入後五至六天，兩組病人測得的血流阻力係數並無明顯差別。 卵巢動脈血流阻力則在胚胎植入前並無明顯差別，但是在植入後五至六天時，RI與PI值懷孕病人均比沒有懷孕的人來得低(P = 0.002 和P = 0.01)。 此項研究的結果顯示，子宮卵巢的血流在胚胎著床時期的變化，可反映出子宮內膜發育與黃體功能的情形；當病人有子宮血流在時間上有較晚達到理想情況時，會妨害胚胎的著床。 爲進一步了解子宮內膜血流情形對胚胎著床的影響，我們利用新的陰道彩色杜卜勒超音波技術，在植入胚胎前檢查六百二十三位病人。 依據子宮內膜與內膜下血流的分佈情形，將病人分為子宮內膜與內膜下均有血流分佈者，只有內膜下血流而無子宮內膜血流分佈者，以及子宮內膜與內膜下均無發現有血流者三組，結果發現懷孕的成功率分別為47.8% (64/134)、29.7% (102/343)和7.5% (11/146)。 子宮內膜與內膜下均發現有血流者懷孕率最高，而兩者均無血流者懷孕率最低。 子宮內膜與內膜下均無發現有血流時，病人的子宮內膜厚度較小，子宮動脈的阻力也較大。 此項結果顯示了子宮內膜附近的血流變化，確實會影響胚胎著床與懷孕的成功率，而檢查血流的分佈情形可以代表子宮的著床環境。 我們接著探討子宮內膜血流在排卵前後的變化，是否會影響子宮內膜對於胚胎著床時間帯的出現。 總共有一百三十八位病人在hCG注射前後，分別接受子宮內膜與內膜下血流分佈情形的檢查。 結果有六十六位病人(47.8%)，在給與hCG注射前和ET前，顯示有血流分佈情形的變化；其中五十一位病人有血流分佈減少，而九位(17.6%)後來受孕，另外十五位病人則有血流分佈增加，當中六位(40%)懷孕。 在給與hCG前出現的內膜下血流，在ET前可能會消失而影響到胚胎的著床，因此會造成在hCG注射前評估子宮內膜情形，預測懷孕成功率的影響。 子宮內膜血流在排卵前後動態性的變化，可能對於調控子宮內膜機能在接受胚胎著床的時間帶上，會有所關聯。 在此同時我們也發現在排卵前後，有些病人會出現子宮腔內積水的情形，因而影響胚胎著床。我們研究了七百四十六例接受IVF-ET治療的病人，發現子宮腔積水在治療過程中出現的機率約為4.7% (35/746)，這些病人值入胚胎後的懷孕成功率只有5.7% (2/35)，而沒有積水現象病人的懷孕成功率達27.1% (193/711)。 子宮腔積水在輸卵管因素病人出現的比例為8% (18/225) ，遠高於非輸卵管因素的不孕症病人的3.3% (17/521)。 而積水出現的時間絕大多數都是在注射hCG之後，這與已知hCG會促進VEGF的產生，進而改變子宮內膜微小血管的通透性可能有關，另外輸卵管阻塞等原因造成排出困難，是造成子宮腔內明顯積水的原因。 已知病人的年齡，刺激排卵藥物的使用與子宮肌層的收縮都會影響子宮的血流。 我們因此評估了七百零八位不同年齡層病人(範圍22至46歲)，將病人分成小於32歲(n = 250)，33到38 歲(n = 350) 間與大於39歲(n = 108)三組。 結果發現內膜下血流出現的比率分別為81.6% (204/250), 75.6% (264/350) 和 64.8% (70/108)，年紀最大的這組比年輕的病人，出現內膜下血流的比例有明顯較低。 另外我們也比較71位接受冷凍胚胎或捐卵的病人，在無刺激排卵藥物作用下，與她們本身或捐卵者在取卵週期(n = 60)時，子宮動脈與子宮內膜血流的分佈情形。 結果發現在沒有接受刺激排卵藥物的週期，雖然子宮動脈的阻力較大，子宮內膜厚度也較小，但是子宮內膜血流的分佈情形與她們在刺激排卵週期時並無不同。 子宮動脈的阻力係數無法用來預測自然或接受荷爾蒙補充週期時懷孕的成功率，但是在三組不同內膜與內膜下血流分布的病人間，懷孕的成功率卻是有明顯的差別。 我們也觀察子宮內膜收縮的變化，將病人分成沒有收縮 (n = 147)，低頻率- 1個波/3秒 (n = 175)，與高頻率- > 2個波/3秒 (n = 81) 收縮三組；出現內膜下血流的比例，在這三組病人分別為95.9% (141/147)， 76.6% (134/175) 和 49.4% (40/81)。 病人的年齡可能會影響子宮內膜血流的表現，刺激排卵藥物的使用則沒有影響。 子宮肌肉層的收縮會減少血流的供應，進而影響子宮內膜的血流情形。 內膜與內膜下的血管分布表現的偵測，可以反映出內膜局部的著床環境，而顯示子宮內膜接受胚胎的能力。 綜合以上的研究，我們發現子宮與子宮內膜的血流情形，會影響胚胎著床的環境。 然而調控血流變化的機轉卻是相當的複雜，女性的年齡、荷爾蒙濃度的變化、刺激排卵藥物與hCG的使用、子宮肌肉層的收縮等，對於子宮內膜生長與血流的變化都可能會造成影響。 我們的發現也證明了生殖過程不應該被視為固定的現象，而是隨著不同個體間的情況，不斷的變化與調整以適應其生理機能的結果。 因此連續追蹤與評估胚胎的著床環境，在不孕症治療的過程中，是非常重要的。 陰道超音波的檢查方式，確實可提供有關子宮內膜血流變化與胚胎著床功能之間的相關性，特別是對於子宮內膜著床能力有缺陷，而無法成功受孕的病人。 唯有不斷的發展新的非侵襲性檢查與治療方式，才能有效的應用在臨床上控制與促進胚胎的著床。 我們將計畫在沒有接受不孕治療時的病人做研究，先用經陰道杜卜勒超音波以及內膜腔內雷射超音波，檢查子宮內膜與內膜周圍血流的分佈情形，然後再採集子宮內膜，使用組織免疫染色與蛋白質定量等方法，研究子宮內膜微小血管的密度，與血管增生分子VEGF及其調節因子的表現情形，以進一步探討會影響子宮內膜血流變化的可能機轉。 我們需要更多深入的研究，才能了解不同個體間子宮內膜血流爲何會有差異，以及對胚胎著床的影響。

關鍵字

子宮血流 ； 子宮內膜 ； 胚胎著床

並列摘要

Endometrial receptivity is the key factor in determining the pregnancy outcome of ART treatment. In this study, we try to test the hypothesis that uterine perfusion can help determine the implantation window. Transvaginal ultrasonography coupled with color Doppler modality was used to assess the endometrial structure, utero-ovarian arterial resistance and vascular patterns within the endometrial-subendometrial interface in correlation with the pregnancy outcome in patients undergoing IVF-ET. Firstly, we investigated the utero-ovarian blood flow changes during the peri-implantation period and its significance in establishing the pregnancy. A prospective longitudinal study was conducted in a total of 317 women. Measurement of endometrial thickness and color flow imaging with pulsed waveform analysis of uterine and ovarian arteries were performed at the time before ET and 5 to 6 days after ET. Mean uterine arterial RI and PI values were significantly lower in the pregnant than the nonpregnant group before ET (P = 0.04 and P = 0.003, respectively), but no significant differences were found between the two groups 5 to 6 days after ET. In contrast, the mean ovarian arterial RI or PI values were similar between the two groups before ET, yet the pregnant group showed significantly lower RI and PI values than those of the nonpregnant group 5 to 6 days after ET (P = 0.002 and P = 0.01, respectively). The changes of uterine and ovarian blood flow resistance around the peri-implantation period may reflect the adequacy of endometrial development and corpus luteal function respectively. Women with a time lag in achieving adequate uterine perfusion during the temporal window of implantation may have impaired endometrial receptivity. To further elucidate the role of endometrial perfusion in affecting the embryo implantation, we performed transvaginal ultrasound examination in six hundred twenty-three patients selected prospectively on the day of ET. The blood flow detected by color Doppler sonography in the endometrial-subendometrial unit was evaluated to see if the blood flow distribution is correlated with the pregnancy outcome. The pregnancy and implantation rates of patients with the presence of both endometrial and subendometrial flow were 47.8% (64/134) and 24.2% (94/388); for patients with subendometrial flow only, 29.7% (102/343) and 15.8% (153/967); and for patients with no detectable endometrial-subendometrial flow, 7.5% (11/146) and 3.5% (13/376), respectively. The presence of both endometrial and subendometrial blood flow is indicative of good endometrial receptivity, while the absence of both represents a poor uterine environment. Non-detectable endometrial-subendometrial flow was associated with thinner endometrium and higher uterine arterial resistance compared to those with detectable flow. Changes of subendometrial vascularization during the peri-ovulatory period in women undergoing IVF cycles were examined to test the hypothesis that dynamic changes of uterine perfusion may affect the “opening” of implantation window. A total of 138 cycles of women were examined to compare the subendometrial vascularization pattern before and after hCG administration. There were 66 (47.8%) patients who showed different subendometrial vascularization between the day of hCG and the day of ET. Nine out of 51 (17.6%) patients with decreasing flow penetration became pregnant, while 6 out of 15 (40%) patients with increasing flow penetration conceived. The subendometrial blood flow detected on the day of hCG injection may disappear later, affecting its usefulness as a predictor of endometrial receptivity. Trend of decreasing penetration of subendometrial vascularization from the day of hCG administration to the day of ET may associate with impairment of implantation. Dynamic changes of the endometrial perfusion can be observed during the peri-ovulatory period, suggesting that it might have a correlation with the control of implantation window. Fluid accumulation within the endometrial cavity was detected in some cases when we studied the endometrial vascularization changes during the peri-ovulatory period. Thirty-five out of 746 (4.7%) IVF cycles were identified to have uterine fluid accumulation, and 15 (2.0%) persisted until the day of ET in our observation. Two of the 20 cycles of women with transient fluid accumulation were pregnant subsequently, but none of those with fluid retention on the day of ET conceived. Uterine fluid accumulation during IVF cycles was found in 8% (18/225) of women with documented tubal factor infertility compared with 3.3% (17/521) with non-tubal factor (P = 0.005). The excessive amount of fluid is related to the increased production and decreased drainage within the uterine cavity. Our data indicated that endometrial contents may affect the embryo implantation. Uterine perfusion can be influenced by the patient’s age, ovarian hormone levels and myometrial contractility. We tried to investigate whether these factors influence vascularization around the endometrium. A total of 708 patients aged 22-46 were recruited and grouped as < 32 years old (n = 250), 33-38 years old (n = 350), and > 39 years old (n = 108). Subendometrial flow can be detected in 81.6% (204/250), 75.6% (264/350) and 64.8% (70/108) respectively among the 3 different age groups of patients. Women with older age had a significantly lower incidence in presenting subedometrial flow compared with the younger groups (P < 0.05). Comparison of the uterine artery and endometrial-subendometrial Doppler measurements was then performed between cycles involving replacement of frozen-thawed embryos or embryos derived from donated oocytes (n =71) with cycles in which controlled ovarian hyperstimulation (COH) was given in the corresponding patient or donors (n = 60). Although there was significantly higher uterine arterial RI or PI, thinner endometrial thickness in patients received only exogenous estrogen to prime the uterus, endometrial-subendometrial vascularization was not different between cycles with and without COH. Uterine arterial Doppler indices were not predictive for pregnancy especially in patients underwent embryo replacement cycles without COH. In contrast, pregnancy outcome were significantly different among the 3 patterns of endometrial-subendometrial blood flow distribution in these patients. Endometrial movements were classified as no activity (n = 147), low (1 wave) activity (n = 175), and high (> 2 waves) activity (n = 81) during a time interval of 3 seconds. Subendometrial flow was detected in 95.9% (141/147), 76.6% (134/175) and 49.4% (40/81) of women respectively. Endometrial-subendometrial blood flow distributions can be affected by the age of women, but seem unrelated to the ovarian hyperstimulation. Increased uterine contractions might decrease blood perfusion to the myometrium and endometrium, subsequently minimize the vascularization pattern. By reflecting the blood perfusion to the endometrium where the embryo implants, endometrial-subendometrial vascularization patterns is thus a useful indicator of endometrial receptivity. To summarize, we found that dynamic changes of endomerial-subendomerial perfusion during the peri-implantation period reflect the uterine environment for embryo implantation. However, the mechanism in controlling the blood flow is complex. Age of the women, serum ovarian hormone levels, controlled ovarian hyperstimulation and hCG injections, myometrial contractility may affect both the endometrial growth and utero-ovarian blood flow. Our data confirmed the notion that the processes of reproduction are not static phenomenon, but rather they should be considered as dynamic and changing processes adaptable to the conditions of each individual's surroundings. The importance of serial evaluations in enhancing the effectiveness of the embryonic implantation milieu can not be overemphasized. Transvaginal ultrasound is helpful in assessing the uterine condition during ART treatments, especially in women with impaired endometrial receptivity. The development of new non-invasive techniques and new therapy modalities are crucial for better control and facilitation of embryo implantation.

並列關鍵字

uterine circulation ； endometrium ； embryo implantation

參考文獻

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