Cacciatore B, Stenman UH, Ylostalo P. Comparison of abdominal and vaginal sonography in suspected ectopic pregnancy. Obstet Gynecol 1989;73:770–774.
140.
Condous G. The accuracy of transvaginal ultrasonography for the diagnosis of ectopic pregnancy prior to surgery. Hum Reprod 2005;20:1404–1409.
141.
Fleischer AC, Pennell RG, McKee MS, et al. Ectopic pregnancy: features at transvaginal sonography. Radiology 1990;174:375– 378.
142.
Timor-Tritsch IE, Yeh MN, Peisner DB, et al. The use of transvaginal ultrasonography in the diagnosis of ectopic pregnancy. Am J Obstet Gynecol 1989;161:157–161.
143.
Bree RL, Marn CS. Transvaginal sonography in the first trimester: embryology, anatomy, and hCG correlation. Semin Ultrasound CT MR 1990;11:12–21.
144.
Bottomley C. The optimal timing of an ultrasound scan to assess the location and viability of an early pregnancy. Hum Reprod 2009;24:1811–1817.
145.
Cacciatore B, Ylostalo P, Stenman UH, et al. Suspected ectopic pregnancy: ultrasound findings and hCG levels assessed by an immunoﬂuorometric assay. BJOG 1988;95:497–502.
146.
Abramovici H, Auslender R, Lewin A, et al. Gestationalpseudogestational sac: a new ultrasonic criterion for differential diagnosis. Am J Obstet Gynecol 1983;145:377–379.
147.
Nyberg DA, Filly RA, Laing FC, et al. Ectopic pregnancy, diagnosis by sonography correlated with quantitative hCG levels. J Ultrasound Med 1987;6:145–150.
148.
Bradley WG, Fiske CE, Filly RA. The double sac sign of early intrauterine pregnancy: use in exclusion of ectopic pregnancy. Radiology 1982;143:223–226.
149.
Nyberg DA, Mack LA, Harvey D, et al. Value of the yolk sac in evaluating early pregnancies. J Ultrasound Med 1988;7:129–135.
150.
Jain KA, Hamper UM, Sanders RC. Comparison of transvaginal and transabdominal sonography in the detection of early pregnancy and its complications. AJR Am J Roentgenol 1988;151:1139– 1143.
151.
Bree RL, Edwards M, Bohm VM, et al. Transvaginal sonography in the evaluation of normal early pregnancy: correlation with hCG level. AJR Am J Roentgenol 1989;53:75–79.
152.
Nyberg DA, Hughes MP, Mack LA, et al. Extrauterine findings of ectopic pregnancy at transvaginal US: importance of echogenic ﬂuid. Radiology 1991;178:823–826.
153.
Rottem S, Thaler I, Levron J, et al. Criteria for transvaginal sonographic diagnosis of ectopic pregnancy. J Clin Ultrasound 1990;18:274–279.
154.