Reflectance spectrometry for real-time hemoglobin determination of placental vessels during endoscopic laser surgery for twin-to-twin transfusion syndrome.
OBJECTIVE
The objective of the study was to develop a noninvasive technique to determine hemoglobin (Hb) content through spectral analysis of diffusely reflected broadband visible illumination from individual blood vessels during endoscopic fetal surgery for twin-to-twin transfusion syndrome (TTTS).


METHODS
The reflection of an incoming xenon endoscopic light source was captured through a 630-mum-diameter optic fiber coupled to a fixed grating spectrometer (2-nm resolution). A 450- to 700-nm wavelength range was used for analysis. Three data-capturing methods were studied: (1) fixed-image spectrum capture with fiber aimed at (but not touching) center of a vessel, (2) no-touch scanning perpendicular to the vessel and dynamic spectral capture, and (3) dynamic spectral capture and analysis of the reflectance spectra during brief vessel touch.


RESULTS
Eight controls (elective laparoscopic and thoracoscopic operations in children aged 1-17 years) were enrolled. Four vessels were analyzed in each case. The brief-touch technique with intensity peak analysis yielded the most reproducible results between multiple vessels in the same patient. Spectrometry was also applied to 2 TTTS patients. The (anemic) donor and (polycythemic) recipient twin fetuses could be differentiated with good correlation between vessels (arteries and vein) of the same fetus.


CONCLUSIONS
It is possible to differentiate donor from recipient placental vessels by spectral analysis of the reflected light through the endoscope using a noninvasive and real-time method. This may improve the accuracy of endoscopic laser ablation of placental vessels in TTTS and may allow instant endoscopic Hb determination for laparoscopic procedures as well.
Curran
Sean
S
Division of Pediatric Surgery and Maternal-Fetal Medicine, Program in Fetal Medicine, Alpert Medical School of Brown University, Providence, RI 02905, USA.
McMurdy
John W
JW
Carr
Stephen R
SR
Muratore
Christopher S
CS
O'Brien
Barbara M
BM
Crawford
Gregory P
GP
Luks
Francois I
FI
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005330:Fetofetal Transfusion / Q000097:blood* / Q000601:surgery*; D005332:Fetoscopy / Q000379:methods*; D006452:Hemoglobinometry / Q000379:methods*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007223:Infant; D010535:Laparoscopy; D017075:Laser Coagulation / Q000379:methods*; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D013053:Spectrophotometry / Q000379:methods*; D013906:Thoracoscopy
D006454:Hemoglobins