Korean J Obstet Gynecol.  2004 Jan;47(1):83-90.

Patterns of Hyrtl's Anastomosis and their Effects on Obstetric Outcomes

  • 1Department of Obstetrics and Gynecology, Holy Family Hospital, College of Medicine, The Catholic University of Korea, Korea.


This study was conducted to investigate the presence and pattern of Hyrtl anastomosis, and to examine the effect that each type has on obstetrical outcome.
This study was carried out from January of 2001 to May of 2003 on 904 randomly selected patients who had given birth by Cesarean section or vaginal delivery at Catholic University Holy Family Hospital. Immediately proceeding delivery, barium sulfate was infused into the umbilical artery. This was followed by umbilical artery dissection to grossly confirm Hyrtl anastomosis. In order to evaluate the effect that each type of anastomosis has on obstetrical outcome, we retrospectively examined chart for birth weight, Apgar score, results of cord blood gas analysis, obstetrical complications, etc.
Out of the 904 cases studied, 99.7% possessed Hyrt's anastomosis with frequency according to type as follows: 50.8% oblique, 48.0% transverse, 1.8% of anastomosis between one umbilical artery and the branch of the other, 1.6% of fusion of branches of each umbilical artery, 0.6% of anastomosis represented by two separate vessels between umbilical arteries, 0.1% of anastomosis between branches of each umbilical artery, 0.1% lacking anastomosis, and 0.2% of a single umbilical artery. In terms of obstetrical outcome, there was no significant difference for term and preterm infants in the frequency of type of Hyrtl's anastomosis according to birth weight, maternal age, Apgar score, obstetrical complications, etc.
In an attempt to verify the presence and type of Hyrtl anastomosis, 8 types of Hyrtl's anastomosis were found, of which the oblique and transverse variety were the most common. There was no significant difference in the types of Hyrtl's anastomosis in relation to obstetrical outcome. Frequency was also similar with oblique and transverse types being the most common. Further studies detailing anatomical features of and blood flow/volume through the anastomosis are required in order to better understand the effects of Hyrtl's anastomosis on obstetrical outcome.


Umbilical artery; Hyrtl's anastomosis; Obstetrical outcome
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