Application of Near-Infrared Spectroscopy for the Evaluation of Placental Oxygenation

Jun Kakogawa1, Naohiro Kanayama2, *
1 Department of Obstetrics and Gynecology, National Center for Global Health and Medicine, Tokyo, Japan
2 Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Japan

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© 2012 Kakogawa et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: * Address correspondence to this author at the Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Japan.Tel: +81-453-435-2309; Fax: +81-453-435-2308; E-mail:


Aims: As the utero-placental circulation have major impact on the fetus, and the placental function can be critical for determining fetal conditions, the placental oxygenation status was investigated. Methods: Near-infrared spectroscopy (NIRS) is a non-invasive technique used for the evaluation of regional tissue oxygenation in a number of organs. The trans-abdominal NIRS was developed as a non-invasive technique for monitoring placental oxygenation, which was evaluated by the ratio of oxygenated hemoglobin to total hemoglobin (%) (tissue oxygenation index ,TOI) values. The near-infrared light was confirmed to reach the placenta using the NIRS probe with an inter- optode distance of 4.5 cm and the NIRO apparatus (Hamamatsu Photonics, Hamamatsu, Japan). Results: Placental TOI values in pregnant women with pregnancy-induced hypertension and intrauterine fetal growth restriction were significantly higher than those of pregnant women without complications, although there were no differences of TOI values between the women with threatened preterm delivery and those without complications. Conclusion: Non-invasive monitoring of placental tissue oxygenation assessed by NIRS for the study of utero-placental function may have a high potential for clinical application, particularly in prenatal management.

Keywords: Near-infrared spectroscopy, placenta, oxygenation, tissue oxygenation index (TOI), IUGR.