Chauhan Suneet P, Shields Dawn, Parker Donna, Sanderson Maureen, Scardo James A, Magann Everett F
Division of Maternal-Fetal Medicine, Spartanburg Regional Medical Center, Spartanburg, South Carolina 29303, USA.
J Reprod Med. 2004 Apr;49(4):279-84.
To use recommendations made by the Evidence-Based Medicine Working Group to determine the accuracy of sonographically estimated fetal weight to diagnose fetal growth restriction (FGR) (estimated or actual birth weight < 10% for gestational age [GA]) or discordancy in dichorionic and monochiorionic twin gestations.
The inclusion criteria for this retrospective analysis were nonanomalous twins, reliable GA and sonographic estimate of fetal weight within 21 days of live births of both fetuses beyond 26 weeks. For likelihood ratio (LR) and odds ratio (OR), 95% confidence intervals (CIs) were calculated.
Over 52 months, 126 twin gestations met the inclusion criteria; 29% were monochorionic and 71% dichorionic. The incidence of FGR in 1 of monochorionic twin fetuses (46%) was twice as high as in dichorionic (26%; OR 2.01; 95% CI 1.00, 4.03), but the rates of discordance > or = 20% were similar (21% vs. 18%, respectively; OR 1.26; 95% CI 0.64, 2.47). The LR (95% CI) of detecting discordant growth > or = 20% was 6.1 (2.5, 15.1) for dichorionic twins and 6.0 (1.8, 20.0) for monochorionic. The LR of identifying FGR in twin A and B in dichorionic twins was 6.3 (2.0, 19.7) and 8.7 (2.9, 26.9), respectively; the corresponding LR for monochorionic twins was 14.5 (1.9, 112.3) and 18.7 (2.6, 135.1). To determine the number of twins required for a tight confidence interval around an LR of 10, post hoc sample size calculations indicated: (1) regardless of chorionicity, attaining LR > 10 is not feasible; (2) in dichorionic twins, detection of FGR with twin A or B is not possible; and (3) about 500 monochorionic pregnancies are necessary to ensure that estimated fetal weight can accurately identify FGR.
Using guidelines proposed by the Evidence-Based Medicine Working Group, at present it may not befeasible to identify aberrant growth in twins.
运用循证医学工作组提出的建议，确定超声估计胎儿体重用于诊断胎儿生长受限（FGR）（估计或实际出生体重低于孕周[GA]的10%）或双绒毛膜和单绒毛膜双胎妊娠中胎儿体重不一致情况的准确性。
本回顾性分析的纳入标准为非畸形双胎、孕周可靠且在孕26周后两个胎儿活产的21天内有可靠的胎儿体重超声估计值。计算似然比（LR）和比值比（OR）的95%置信区间（CI）。
在52个月期间，126例双胎妊娠符合纳入标准；其中29%为单绒毛膜双胎，71%为双绒毛膜双胎。单绒毛膜双胎中一个胎儿发生FGR的发生率（46%）是双绒毛膜双胎（26%）的两倍（OR 2.01；95% CI 1.00，4.03），但体重不一致≥20%的发生率相似（分别为21%和18%；OR 1.26；95% CI 0.64，2.47）。检测双绒毛膜双胎中体重不一致≥20%的LR（95% CI）为6.1（2.5，15.1），单绒毛膜双胎为6.0（1.8，20.0）。双绒毛膜双胎中识别胎儿A和胎儿B发生FGR的LR分别为6.3（2.0，19.7）和8.7（2.9，26.9）；单绒毛膜双胎相应的LR为14.5（1.9，112.3）和18.7（2.6，135.1）。为确定围绕LR为10的紧密置信区间所需的双胎数量，事后样本量计算表明：（1）无论绒毛膜性如何，使LR>10都不可行；（2）在双绒毛膜双胎中，无法通过胎儿A或胎儿B检测FGR；（3）约需500例单绒毛膜妊娠才能确保估计胎儿体重能准确识别FGR。
按照循证医学工作组提出的指南，目前识别双胎中的异常生长可能不可行。
