Rombauts L, McMaster R, Motteram C, Fernando S
Monash IVF, Epworth Hospital, 89 Bridge Rd, Richmond, Victoria 3121, Australia Hudson Institute of Medical Research, 246 Clayton Rd, Clayton, Victoria 3168, Australia Department of Obstetrics and Gynaecology, Monash University, 246 Clayton Rd, Clayton, Victoria 3168, Australia
Department of Obstetrics and Gynaecology, Monash University, 246 Clayton Rd, Clayton, Victoria 3168, Australia.
Hum Reprod. 2015 Dec;30(12):2846-52. doi: 10.1093/humrep/dev249. Epub 2015 Oct 1.
Is endometrial combined thickness (ECT) measured prior to embryo transfer (ET) associated with ectopic pregnancy (EP)?
Following IVF, the risk of EP is 4-fold increased in women with an ECT of <9 mm compared with women with an ECT of >12 mm.
Known risk factors for EP include tubal damage, maternal cigarette smoking and endometriosis. EP is also more common following IVF but the underlying causes for this remain unclear.
STUDY DESIGN, SIZE, DURATION: Retrospective cohort study restricted to all IVF cycles leading to a pregnancy (βhCG > 50 IU/l) between January 2006 and December 2014. A total of 6465 patients achieved a pregnancy in 8120 cycles. Cycles using preimplantation genetic screening or donor oocytes were excluded.
PARTICIPANTS/MATERIALS, SETTING, METHODS: This cohort consists of 6465 patients achieving a pregnancy in 6920 stimulated cycles with fresh embryo transfers (STIM ET) and 1200 hormone replacement therapy frozen embryo transfers (HRT-FET) cycles at a private IVF unit (Monash IVF, Melbourne, Australia). ECT was the primary independent variable of interest; the primary outcome was a diagnosis of EP. The dataset was analysed using binary logistic general estimating equations (SPSS v22.0) to calculate odds ratio (OR) for EP adjusted for known confounders (aOR). There was no loss to follow-up in the dataset.
The study groups did not differ significantly prior to IVF treatment. After adjusting for confounders, ECT remained statistically significant as an independent risk factor for EP. Compared with women with an ECT of <9 mm, women with an ECT of 9-12 mm had an aOR of 0.44 (95% CI 0.29-0.69, P < 0.01) and women with an ECT > 12 mm had an aOR of 0.27 (95% CI 0.10-0.77, P = 0.01). These differences remained statistically significant after performing a sensitivity analysis excluding HRT-FET, smokers and patients with tubal infertility.
LIMITATIONS, REASONS FOR CAUTION: The study design is retrospective, and it is possible that not all confounders have been accounted for. Measurement of ECT was performed by highly trained sonographers, but some inconsistency between individuals may be present.
Our group has previously demonstrated an increased risk of placenta praevia with increased ECT. These new findings suggest that the directionality of the uterine peristalsis waves matters more than their frequency or amplitude. Combining the data from both studies we now hypothesize that increased ECT is a marker for increased fundus-to-cervix uterine peristalsis, explaining both the increased placenta praevia risk and the lower EP risk. Further prospective studies are required to confirm these observations.
胚胎移植（ET）前测量的子宫内膜联合厚度（ECT）与异位妊娠（EP）有关吗？
体外受精（IVF）后，ECT＜9mm的女性发生EP的风险比ECT＞12mm的女性高4倍。
已知的EP风险因素包括输卵管损伤、孕妇吸烟和子宫内膜异位症。IVF后EP也更常见，但其潜在原因尚不清楚。
研究设计、规模、持续时间：回顾性队列研究，纳入2006年1月至2014年12月期间所有导致妊娠（βhCG＞50IU/L）的IVF周期。共有6465例患者在8120个周期中成功妊娠。排除使用植入前基因筛查或供体卵母细胞的周期。
参与者/材料、设置、方法：该队列包括6465例在澳大利亚墨尔本莫纳什IVF私人IVF机构进行新鲜胚胎移植（STIM ET）的6920个刺激周期和1200个激素替代疗法冷冻胚胎移植（HRT-FET）周期中成功妊娠的患者。ECT是主要的独立感兴趣变量；主要结局是EP诊断。使用二元逻辑广义估计方程（SPSS v22.0）分析数据集，以计算调整已知混杂因素后的EP比值比（OR）（aOR）。数据集中无失访情况。
研究组在IVF治疗前无显著差异。调整混杂因素后，ECT作为EP的独立危险因素仍具有统计学意义。与ECT＜9mm的女性相比，ECT为9-12mm的女性aOR为0.44（95%CI 0.29-0.69，P＜0.01），ECT＞12mm的女性aOR为0.27（95%CI 0.10-0.77，P = 0.01）。在排除HRT-FET、吸烟者和输卵管性不孕患者进行敏感性分析后，这些差异仍具有统计学意义。
局限性、谨慎原因：研究设计为回顾性，可能未考虑到所有混杂因素。ECT测量由训练有素的超声检查人员进行，但个体之间可能存在一些不一致。
我们的研究小组先前已证明，ECT增加会增加前置胎盘的风险。这些新发现表明，子宫蠕动波的方向性比其频率或幅度更重要。综合两项研究的数据，我们现在假设ECT增加是子宫从底部到宫颈蠕动增加的标志，这既解释了前置胎盘风险增加，也解释了EP风险降低。需要进一步的前瞻性研究来证实这些观察结果。
