With the intent of helping in the memorization of information, we present an arrangement of data on hormone levels, gestational sac, yolk sac, and embryo in early pregnancy. When pertinent, we compare abdominal with endovaginal scanning parameters.
1. Nyberg DA, Mack LA, Laing FC, Jeffrey RB: Early pregnancy complications: Endovaginal sonographic findings correlated with human chorionic gonadotropin levels. Radiology1988;167:619-622.
2.
2. Nyberg DA, Filly RA, Laing FC, Mack LA, Zarutskie PW: Ectopic pregnancy. Diagnosis by sonography correlated with quantitative hCG levels. J Ultrasound Med1987;6:145-150.
3.
3. Bree RL, Edwards M, Böhm-Vélez M, Beyler S, Roberts J, Mendelson EB: Transvaginal sonography in the evaluation of normal early pregnancy: Correlation with hCG level. AJR Am J Roentgenol1989;153;75-79.
4.
4. Batzer R: Guidelines for choosing a pregnancy test. Contemp Obstet Gynecol1986;30:37-51.
5.
5. Nyberg DA, Laing FC, Filly RA: Threatened abortion: Sonographic distinction of normal and abnormal gestation sacs. Radiology1986;158:397-400.
6.
6. Pennell RG, Needleman L, Pajak T, et al. Prospective comparison of vaginal and abdominal sonography in normal early pregnancy. J Ultrasound Med1991;10:63-77.
7.
7. Hellman LM, Kobayashi M, Fillisti L, Lavenhar M, Cromb E. Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol1969;103:789-800.
