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Accuracy of five formulae to determine the insertion length of umbilical venous catheters
  1. Wei Ling Lean1,
  2. Jennifer A Dawson1,2,3,
  3. Peter G Davis1,2,3,
  4. Christiane Theda1,2,3,4,
  5. Marta Thio1,2,3,4
  1. 1 Newborn Research Centre, The Royal Women’s Hospital, Parkville, Victoria, Australia
  2. 2 Murdoch Children’s Research Institute, Parkville, Victoria, Australia
  3. 3 Department of Obstetrics and Gynaecology, The University of Melbourne, Melbourne, Victoria, Australia
  4. 4 PIPER – Neonatal Retrieval Services Victoria, The Royal Children’s Hospital, Melbourne, Victoria, Australia
  1. Correspondence to Dr Wei Ling Lean, Newborn Research Centre, The Royal Women’s Hospital, Parkville VIC 3052, Australia; leanweiling{at}


Introduction Umbilical venous catheter (UVC) placement is a common neonatal procedure. It is important to position the UVC tip accurately at the first attempt to prevent complications and minimise handling. Catheters positioned too low need to be removed, but catheters positioned too high may be withdrawn in a sterile fashion to a safe position. We aimed to determine the precision and accuracy of five published formulae developed to guide UVC placement.

Methods This was a prospective observational study. Following UVC insertion, anteroposterior and lateral X-rays were performed to identify catheter tip position. Parameters required to apply the five formulae were recorded. Insertion lengths were then calculated and compared with the gold standard (UVC tip at the level of the diaphragm on the lateral X-ray). They were also used to classify predicted UVC tip position as either correct (UVC tip at or up to 1 cm above the diaphragm), too high or too low.

Results Of 118 eligible infants, 70 had the UVC tip in a position where measurements could be used. Their median (IQR) gestational age and weight were 28.5 (26–36) weeks and 1035 (745–2788) g, respectively. The predicted success rate for each formula ranged from 44.9% to 55.7%. A formula based on birth weight had the highest rate of either correct or high position (95.8%).

Conclusions Inserting a UVC into a safe position on first attempt is difficult and low tip placement is common. Around half of UVCs need to be manipulated to achieve the desired position.

  • formula
  • insertion length
  • neonatal intensive care unit
  • infant
  • umbilical venous catheter

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  • Contributors WLL conceived and designed the study. She contributed to the literature search, acquisition of data, analysis and interpretation of data, and writing of the first draft of the manuscript. JAD contributed to the analysis and interpretation of data, and revision of the manuscript drafts. PGD and CT contributed to the conception and design of the study, interpretation of data and revision of the manuscript draft. MT supervised all aspects of the study. She contributed to the acquisition of data, analysis and interpretation of data, and revision of the manuscript drafts.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Ethics approval This study was endorsed by The Royal Women’s Hospital Research and Ethics Committee as meeting the National Health and Medical Research Council requirements for quality assurance.

  • Provenance and peer review Not commissioned; externally peer reviewed.