Umbilical cord abnormalities and stillbirth
Ibrahim Hammad, MD (1,2), Jessica Page, MD (1,2), Nathan Blue, MD, (1,2); Karen Gibbins, MD, MSCI (3), Robert Silver, MD (1,2)
(1) University of Utah Health, Salt Lake City, UT, USA; (2) Intermountain Healthcare, Salt Lake City, UT, USA; (3) Oregon Health and Science University, Portland, OR, USA
Umbilical cord abnormalities are commonly cited as a cause of stillbirth (SB) but details regarding these SBs are rare. Our objective was to characterize SB associated with umbilical cord abnormality using rigorous criteria based on pathologic findings and to examine associated risk factors.
The Stillbirth Collaborative Research Network conducted a prospective, population based, case-control study of SB and live births from 2006-2008. This analysis includes the 512 SB who had complete fetal and placental evaluations and underwent cause of death analysis using the INCODE (Obstet Gynecol 2010; 16:254) classification system. Umbilical cord abnormality was defined as cord entrapment (defined as nuchal, body, shoulder cord accompanied by evidence of cord occlusion and/or fetal hypoxia by pathologic exam), knots/torsions/strictures with thrombi or other obstruction and evidence of fetal hypoxia by pathologic exam, cord prolapse and vasa previa. We compared demographic and prenatal factors between women with SB attributable to umbilical cord abnormality with those due to other causes as well as control live born.
Of 512 stillbirths with complete analysis by INCODE, 53 (10.4%) were attributed to umbilical cord abnormality. 27 (5.2%) had cord entrapment, 23 (4.4%) knots/torsions/stricture, and 5 (0.9%) had cord prolapse. No cases of vasa previa were present. Characteristics were similar between groups except cotinine at delivery, which was more common in the Non-umbilical cord abnormality SBs (Table). SB due to umbilical cord abnormality were most common prior to 24 weeks (26.4%) and during the late preterm period (24.5%). Intrapartum stillbirth was less common in umbilical cord abnormality SBs.
Umbilical cord abnormality is an important cause of SB, accounting for over 10% of cases, even using robust pathologic criteria. It is difficult to identify cases at risk using clinical criteria. Further investigation should focus on prediction and prevention of SB associated with umbilical cord abnormality.
All participants gave written informed consent as part of the original study and the study was approved by the institutional review boards of each clinical site and the data coordinating and analysis center.