http://informahealthcare.com/jmf ISSN: 1476-7058 (print), 1476-4954 (electronic) J Matern Fetal Neonatal Med, 2015; 28(1): 16–22 ! 2015 Informa UK Ltd. DOI: 10.3109/14767058.2014.899575 ORIGINAL ARTICLE A new approach to an old hypothesis; phototherapy does not affect ductal patency via PGE 2 and PGI 2 Ozge Surmeli-Onay 1 , Murat Yurdakok 1 , Tevfik Karagoz 2 , Pinar Erkekoglu 3 , Ilker Ertugrul 2 , Sahin Takci 1 , Belma Kocer Giray 3 , Hayrettin Hakan Aykan 2 , Ayse Korkmaz 1 , and Sule Yigit 1 1 Division of Neonatology, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey, 2 Division of Pediatric Cardiology, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey, and 3 Department of Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey Abstract Objective: Numerous investigations have demonstrated that phototherapy (PT) directly or indirectly causes ductal patency by photorelaxation effect. In this observational study, we aimed to assess the effect of PT on the incidence of patent ductus arteriosus (PDA) together with prostaglandins (PGE2) and (PGI2) levels in preterm infants. Methods: Preterm infants whose gestational age534 weeks and who required PT in the first 3 d of life were enrolled in this prospective study. The clinical signs of PDA, the data of detailed echocardiographic study were recorded and plasma PGE 2 and PGI 2 levels were measured before and after PT. The outcome measures were the status of ductus arteriosus and alterations of PGE 2 and PGI 2 levels under the effect of PT. Results: A total of 44 preterm infants were enrolled in the study, of these 21 (47.7%) were in Group 1 (Non-PDA Group) and 23 (52.3%) were in Group 2 (PDA Group). After PT, ductal reopening occurred in three infants (14.3%) in Group 1, while ductus closed in four infants in Group 2 (17.3%). PT does not seem to effect ductal patency for both groups (p ¼ 0.250 and p ¼ 0.125, respectively). PGE 2 levels were not different before and after PT for both groups (p ¼ 0.087, p ¼ 0.408, respectively). However, PGI 2 levels were significantly decreased after PT in both groups (p ¼ 0.006, and p ¼ 0.003, respectively). Conclusion: There was no effect of PT on ductal patency. We can conclude that PGs were eliminated simultaneously with ductal closure and photorelaxation effect did not influence PG levels. Keywords Patent ductus arteriosus, preterm infant, phototherapy, prostaglandin History Received 5 September 2013 Revised 18 January 2014 Accepted 26 February 2014 Published online 12 December 2014 Introduction Phototherapy (PT) is widely used for the management of neonatal indirect hyperbiliribunemia. Although it is known as safe and effective treatment, short- and long-term side effects including interference with mother–infant bonding, imbalance of thermal environment and water loss, electrolyte disturb- ances, hypocalcemia, disorder of circadian rhythm, bronze baby syndrome, allergic diseases (asthma, allergic rhinitis, and conjunctivitis), melanocytic nevi, melanoma, skin cancer, retinal damage and patent ductus arteriosus (PDA) have been reported [1]. PT is commonly required in the first week of life when PDA may also be a clinical problem in preterm infants. In a preterm infant, a hemodynamically significant PDA, can lead to pulmonary overflow and systemic hypoperfusion which may result with cerebral hypoxia, acute renal failure and necrotizing enterocolitis [2]. Photorelaxation of smooth muscle of the rabbit aorta was first described in 1961 [3]. Subsequently, Clyman and Rudolph [4] demonstrated that exposure of isolated lamb ductal rings to light resulted in photorelaxation and preven- tion of ductal closure despite stimulation with O 2 . In the light of these in vitro studies, first in 1986, a positive relationship between PT and PDA was reported in preterm infants with respiratory distress syndrome (RDS). The authors reported that chest shielding resulted with significant reduction in the incidence of PDA [5]. Afterwards, Barefield et al. [6] showed similar results in extremely low birth weight infants. Infants who received PT had a significantly increased incidence of PDA compared to those not receiving PT (76% versus 53%). Another investigator reported ductal reopening during PT in preterm infants who had a closed ductus arteriosus before PT [7]. Although the exact mechanisms preventing ductal closure are uncertain, it was hypothesized that light could penetrate the thin chest wall of preterm infants and caused vasodilation. The light photon may give rise to photorelaxa- tion on aortic smooth muscle directly or indirectly, through the activation of the nitric oxide–cyclic GMP pathway and Ca 2+- dependent K + ion channels [8,9]. Address for correspondence: Ozge Surmeli-Onay, MD, Division of Neonatology, Department of Pediatrics, Faculty of Medicine, Hacettepe University, 06100, Ankara, Turkey. Tel: +90-312-3051390/91. Fax: +90- 312-3105509. E-mail: ozgeonay79@gmail.com