Variable Age (years) Mean (SD) Median (range) Parity n (%) 1 2 3 4 5 Site n (%) A B C D E Blood loss before treatment (mL)∗ Mean (SD) Median (range) Time from delivery to administration of nitroglycerin or placebo tablets (minutes)∗ Mean (SD) Median (range) Nitroglycerin (n = 55) 31.7 (5.0) 32 (19; 42) 23 (41.8) 20 (36.4) 10 (18.2) 0 (0.0) 2 (3.6) 11 (20.0) 13 (23.6) 7 (12.7) 17 (30.9) 7 (12.7) n = 53 Placebo (n = 56) 31.7 (5.6) 32 (20; 44) 24 (42.9) 22 (39.3) 7 (12.5) 2 (3.6) 1 (1.8) 11 (19.6) 14 (25.0) 8 (14.3) 17 (30.4) 6 (10.7) n = 54 554 (464) 548 (457) 450 (50; 2400) 450 (0; 2000) Obstetrics and Gynecology International while in one case umbilical cord disruption occurred before administration of tablets. Furthermore, in nine women surgical removal of placenta was performed initially due to the preference of the obstetrician on duty despite the fact that the women had given their informed consent to participate. Thus, the total number of patients in the intention to treat group (ITT) was 111 (all randomized patients, including 4 patients who did not receive study medication and 2 patients who only received 0.5 mg nitroglycerin), and the number of patients in the per protocol group (PP) was 105 (randomized patients who all received study medication, i.e., 1 mg nitroglycerin or placebo tablets). There were no diﬀerences between the two groups regarding maternal age, parity, or site of study (Table 1). For the intention to treat group (ITT) detachment of placenta following sublingual administration of nitroglycerin occurred in 36.4% of the women compared to 23.2% in the placebo group (P = 0.13) (Table 2). The corresponding results for patients per protocol group (PP) were 37.3% and 20.4% (P = 0.056), respectively (Table 3). In the two hospitals with some experience of the method placenta was successfully removed in 9 of 19 (47.4%) women following treatment with nitroglycerin compared to 3 of 17 (15.0%) women in the placebo group. The diﬀerence between the treatment groups was 32.4% (95% CI −0.5; 58.8). A signiﬁcant diﬀerence in blood pressure as well as pulse rate between the nitroglycerin group and the placebo was registered at 5 and 15 minutes after administration of tablets (Figure 1). Maximum drop in blood pressure was measured 5 minutes after nitroglycerin had been given. However, in all women who received nitroglycerin hemodynamic changes were moderate and considered not to be of clinical importance. There was no diﬀerence between the groups regarding total blood loss or blood loss more than 1000 mL. No complications of clinical importance due to nitroglycerin were registered. Headache and palpitations were relatively common in both groups (Table 4). However, reported maternal side eﬀects were only of minimal or moderate intensity with a maximum of 6 on a VAS scale from 1 to 10. No statistical diﬀerence was registered between the two groups regarding frequency of side eﬀects or intensity of side eﬀects. 4. Discussion In the present study successful release of placenta occurred in 37.3% of the women with retained placenta following sequential administration of oxytocin and nitroglycerin. The corresponding ﬁgure in the two hospitals with some experience of the method was 47.4%. Although none of these ﬁgures reached statistical signiﬁcance compared to placebo, the higher success rate in the two hospitals with some experience could indicate that clinical experience is of importance in order to achieve placental detachment. Several descriptive and retrospective studies have exam- ined the use of nitroglycerin for the release of retained placenta [7, 10–14]. However, only one randomized study has previously evaluated the eﬃciency of sequential admin- P value 0.98 3 0.77 1.00 0.94 0.06 Table 1: Demographic and baseline characteristics (intention to treat group, ITT). 49.5 (8.9) 50 (27; 70) 46.3 (7.5) 46 (31; 62) Intention to treat group, ITT: all randomized patients, including 4 patients who did not receive study medication and 2 patients who only received 0.5 mg nitroglycerin. ∗Four patients who did not receive study medication are not included. istration of oxytocin intravenously and nitroglycerin tablets [6]. In that study, retained placenta was successfully released in all 12 women following administration of nitroglycerin compared to only 1 of 12 women in the placebo group [6]. In addition, in a chart review of 24 women with retained pla- centa, successful delivery of the placenta occurred in 21 of the women following sequential treatment with intravenously administered oxytocin and 1 mg of nitroglycerin tablets administered sublingually [7]. However, in both studies only obstetricians who were experienced in the method were involved in the attempts to remove the placenta. Thus, it seems likely that clinical experience is essential in order to accomplish a high success rate. Three main causes of retained placenta have been identiﬁed: (1) placenta adherens (81%); (2) trapped placenta (13%); partial placenta accreta (6%) [15]. Placenta adherens is due to inadequate myometrial contractions to separate the placenta [3]. Trapped placenta signiﬁes a detached placenta that is trapped behind a closed uterine cervix, while placenta accreta indicates that an area of the placenta is ﬁrmly