Short-Term Use of Umbilical Artery Catheters May Not Be Associated With Increased Risk for Thrombosis

Umbilical arterial catheters (UACs) have rare but serious complications related to thrombus formation. Two specific serum markers of thrombogenesis--prothrombin fragment (F1.2) and thrombin-antithrombin (TAT)--can be assayed and correlated with abdominal ultrasound visualization of UAC thrombosis. Levels of these markers of thrombogenesis have not been studied in infants with UACs. The objective of this study was to determine F1.2 and TAT levels longitudinally and compare the levels with platelet counts and ultrasound evidence of thrombi during the first week of life in infants with UACs. This study was conducted as a prospective, nonblinded, observational study performed between June 2001 and January 2002 at Christiana Care Hospital, a level III neonatal intensive care unit. Infants with a UAC in place in the first 24 hours of life were studied. All received equal amounts of heparin in the UAC. F1.2, TAT, platelet counts, and abdominal aorta ultrasounds were examined every other day starting within 24 hours of life. Studies were not done when the UAC was removed within the 5-day study period. Enzyme-linked immunosorbent assay for TAT and F1.2 was performed using a commercially available kit from Enzyngost. Data were analyzed with repeated measures analysis of variance evaluating TAT, F1.2, and platelet count over time. Thirty-three patients were investigated (mean +/- standard deviation; gestational age: 27.4 +/- 3.5 weeks; birth weight: 1139 +/- 729 g). A total of 66 measurements of TAT, F1.2, and platelet counts were obtained. Sixty-one abdominal ultrasounds were performed; only 1 study was positive for UAC thrombus. There was no significant difference between F1.2 and TAT over time during the study period. Platelet counts seemed to fall over the 5-day study period, although this decrease did not reach statistical significance. Indwelling UACs in sick infants may not carry an increased risk of thrombosis during the first 5 days of use.