References
- Edmonds HW. The spiral twist of the normal umbilical cord in twins and in singletons. Am J Obstet Gynecol 1954;67:102–120.
- Cunningham, et al. Williams obstetrics. 20th ed. Stamford, Connecticut: Appleton and Lange; 1997.
- Benirschke K, Kaufmann P. Pathology of the human placenta. New York: Springer; 1995.
- Blackburn W, Cooley NR The umbilical cord. In: Stevenson RE, Hall JG, Goodman RM, editors. Human malformations and related anomalies, volume II, chapter 37. New York: Oxford University Press; 1993.
- Sherer DM, Anyaegbunarn A. Prenatal ultrasonographic morphologic assessment of the umbilical cord: A review. Part I. Obstet Gynecol Surv 1997;52(8):506–514.
- Sadler TW. Langmans medical embryology, 10th ed. Balti-more: Williams and Wilkins Co. 1988.
- Fujikura T. Fused umbilical arteries near placental cord insertion. Am J Obstet Gynecol 2003;188(3):765–767.
- Fox H, Khong TY. Lack of innervation of the human umbilical cord. An immunohistochemical and histochemical study. Placenta 1990;11:59–62.
- Malpas P, Symonds EM. Observations on the structure of the human umbilical cord. Surg Gynecol Obstet 1966;123:746–750.
- Chaurasia BD, Agarwal BM. Helical structure of the human umbilical cord. Acta Anat (Basel) 1979;103:226–230.
- Roach MR. The umbilical vessels. Perinatal medicine, 13th ed. Hagerstown, Maryland: Harper and Row. 1976. p 134–142.
- Sepulveda W. Time for a more detailed prenatal examination of the umbilical cord? Ultrasound Obstet Gynecol 1999;13:157–160.
- Di Naro E, Ghezzi F, Raio L, Franchi M, D'Addario V. Umbilical cord morphology and pregnancy outcome. Eur J Obstet Gynecol Reprod Biol 2001;96:150–157.
- L,acro RV, Jones KL,, Benirschke K, The umbilical cord twist: direction, and relevance. Am J Obstet Gynecol 1987;157: 833–838.
- Strong TH, Finberg HJ, Mattox JH. Antepartum diagnosis of noncoiled umbilical cords. Am J Obstet Gynecol 1994; 170(6): 1729–1733.
- Strong TH, Jarles DL, Vega JS, Feldman DB. The umbilical coiling index. Am J Obstet Gynecol 1994;170:29–32.
- Van Dijk CC, Franx A, de Laat MWM, Bruinse HW, Visser GHA, Nikkels PGJ. The umbilical coiling index in normal pregnancy. J Matern Fetal Neonatal Med 2002;11:280–283.
- Strong TH, Elliot JP, Radin TG. Non-coiled umbilical blood vessels: a new marker for the fetus at risk. Obstet Gynecol 1993;81:409–411.
- Rana J, Ebert GA, Kappy KA. Adverse perinatal outcome in patients with an abnormal umbilical coiling index. Obstet Gynecol 1995;85:573–577.
- Atalla RK, Abrams K, Bell SC, Taylor DJ. Newborn acid-base status and umbilical cord morphology. Obstet Gynecol 1998;92:865–868.
- Ezimokhai M, Rizk DEE, Thomas L. Maternal risk factors for abnormal vascular coiling of the umbilical cord. Am J Perinat 2000;17:441–445.
- Machin GA, Ackerman J, Gilbert-Barness E. Abnormal umbilical cord coiling is associated with adverse perinatal outcome. Pediatr Devl Pathol 2000;3:462–471.
- Degani S, Lewinsky RM, Berger H, Spiegel D. Sonographic estimation of umbilical coiling index and correlation with Doppler flow characteristics. Obstet Gynecol 1995;86:990–993.
- Finberg HJ. Avoiding ambiguity in the sonographic determi-nation of the direction of umbilical cord twists. J Ultrasound Med 1992;11:185–187.
- Qin Y, Lau TK, Rogers MS. Second-trimester ultrasono-graphic assessment of the umbilical coiling index. Ultrasound Obstet Gynecol 2002;20:458–463.
- Reynolds SRM. The umbilical cord. Scientific Am 1952;187:70–74.
- Reynolds SRM. Mechanisms of placentofetal blood flow. Obstet Gynecol 1978;51:245–249.
- Nakai Y, Imanaka M, Nishio J, Ogita S. Umbilical venous pulsation and regional circulatory disturbance. Ultrasound in Med and Biol 1997;23 (8) :1165–1169.
- Georgiou HM, Rice GE, Walker SP, Wein P, Gude NM, Permezel M. The effect of vascular coiling on venous perfusion during experimental umbilical cord encirclement. Am J Obstet Gynecol 2001;184(4):673–678.
- Strong TH Jr, Manriquez Gilpin MP, Gilpin BJ. Umbilical vascular coiling and nuchal entanglement. J Mat Fet Med 1996;5(6):359–361.
- Cullen TS. Embryology, Anatomy and Diseases of the Umbilicus, together with Disease of the Urachus. Illustrations by Max Brödel. Philadelphia, and London: WB Saunders Co; 1916.