Atypical variable deceleration in the first stage of labor is a characteristic fetal heart-rate pattern for velamentous cord insertion and hypercoiled cord.

AIM

To evaluate whether various umbilical cord abnormalities, including velamentous, marginal cord insertion (VCI, MCI), hypercoiled cord (HCC) and nuchal cord (NC), affect the appearance of atypical variable deceleration (VD) during labor.

METHODS

A cohort study was conducted which included cases with cord abnormalities (314 cases) and without them (487 controls), both of which were delivered in our hospital between June 2005 and December 2006. The relationship between cord abnormalities and the intrapartum fetal heart-rate (FHR) pattern were retrospectively investigated focusing on VD. Analysis of FHR patterns was performed for 30 uterine contractions at the end of the first stage and throughout the whole of the second stage of labor. FHR patterns were analyzed for the presence of VD, atypical and pure VD. The frequencies of each FHR patterns per uterine contraction were assessed. The type of atypical VD was diagnosed in sequence as loss of variability during VD, overshoot, slow return of the FHR to the baseline, VD with no acceleration, and biphasic deceleration. Pure VD was typical VD without signs of atypia.

RESULTS

Frequencies of total VDs were significantly high in cases with VCI, HCC or NC in the first stage. Atypical VDs frequently occurred in cases with VCI, HCC and NC, and pure VDs did in cases with NC. In the second stage, frequencies of total and all types of VDs were not different.

CONCLUSION

Mainly atypical VD in the first stage was a characteristic FHR pattern for VCI and HCC, and the appearance of such a pattern in cases with antepartum information on these abnormalities could suggest unfavorable fetal status.