Increased release of retained placenta following sequential administration of oxytocin and nitroglycerin: Study
Retained placenta complicates up to 2.0-3.3% of all vaginal deliveries. The most common cause of retained placenta has been shown to be a failure of retroplacental myometrial contractions. Without immediate treatment, women are at high risk of hemorrhage. The delivery of oxytocin to the retroplacental myometrium via the umbilical vein or intravenously is often applied to induce myometrial contractions and placental detachment. The WHO guidelines for management of postpartum hemorrhage and retained placenta recommend injection of saline-diluted oxytocin into the umbilical vein.
Alternatively, when oxytocin fails, it has been shown that the sequential administration of oxytocin and sublingual nitroglycerin is efficient for the management of retained placenta. Nitroglycerin relaxes smooth muscle cells by releasing nitric oxide and is regularly used to induce prompt uterine relaxation in cases of obstetric emergency.
A very high success rate for management of retained placenta was reported following sequential administration of oxytocin and nitroglycerin when performed by obstetricians who were experienced in this method. However, in an everyday clinical setting, many obstetricians with little or no experience in this method often failed in their attempts to remove the placenta.
The primary aim of the present study was therefore to determine whether oxytocin in combination with nitroglycerin is effective in the management of retained placenta when performed by inexperienced obstetricians. Secondary aims were to examine hemodynamic effects, blood loss, and side effects following sublingual administration of nitroglycerin and to identify factors that could have a negative effect on placental detachment.
One hundred and five women with retained placenta were randomly selected to receive either 1 mg nitroglycerin or placebo tablets sublingually if intravenous oxytocin had failed to expel the placenta. At two of the hospitals, some of the midwives were familiar with the use of nitroglycerin.
The other midwives and all participating obstetricians had no clinical experience of the method. In the treatment group, detachment of the placenta following nitroglycerin occurred in 37.3% of the women compared with 20.4% in the placebo group (P=0.056). In the two hospitals with some experience of the method, the placenta was removed in 9 of 19 women (47.4%) in the nitroglycerin group compared with 3 of 17 women (15.0%) in the placebo group. No adverse effects of clinical importance were registered.
This study showed an increased release of retained placenta following sequential administration of oxytocin and nitroglycerin compared with oxytocin and placebo. However, the difference in success rate did not reach statistical significance. A tendency that clinical experience of the method could be important for removal of the placenta was registered. Nitroglycerin did not cause any adverse effects of clinical importance.
Source: Hindawi Publishing Corporation Obstetrics and Gynecology International Volume 2012, Article ID 321207, 6 pages doi:10.1155/2012/321207
