Safety of Intravenous Glyceryl Trinitrate in Management of Retained Placenta*
Authors: Lowenwirt Isaac P. , Zauk Rose M. , Handwerker Sara M. 
Published: February 2008

EDITORIAL COMMENT: We accepted this paper for publication because it shows that gyceryl trinitrate is useful for the management of retained placenta and seems to safely overcome the need for general anaesthesia for uterine relaxation. The authors give careful details about the haemodynamic changes in the patients they report. We have asked the authors to tell us the manual removal rate in their institution so that the reader can get a picture of what proportion of manual removals require this technique. Presumably it is only necessary when there is complete retention of the unseparated placenta without it extruding into the cervical canal since it is in these cases that manual removal performed under epidural analgesia although possible is often difficult and sometimes painful for the patient. For perspective, at the Mercy Hospital for Women, Melbourne, the incidence of manual removal of the placenta is 4.2% which includes cases where the detached placenta, caught in the cervix by an oxytocin‐induced contraction was removed digitally. At this hospital in the triennium 1987–1989 there were 15,216 women delivered, and 524 of those delivered vaginally had a manual removal of the placenta. During this time there were 190 patients where the anaesthetist was called to the delivery room because of a retained placenta and general anaesthesia was used for the manual removal in 100 cases and epidural analgesia in 90. In addition to this there would be a similar number of patients who had a ‘top‐up’ of an epidural analgesic in order to perform a manual removal when the placenta was retained.

Author's Response to Editorial Comment: During the three and a half year study period at our hospital, 6,211 (74.7%) of 8,337 women delivered vaginally, with 70.8% having received epidural analgesia in labour. The total manual removal rate, which would include patients who did not require the presence of an anaesthetist, such as those with easily removable, only partially adherent placentas, has not been logged at our hospital. Our study has determined, however, that approximately 0.7% (41 of 6,211) of our patients delivering vaginally required the assistance of an anaesthetist specifically for removal of a completely adherent placenta. The 8 patients who did not receive glyceryl trinitrite, and were given general anaesthesia, represent 20% (8 of 41) of such patients, in contrast to 53% (100/190) of presumably similar patients who were managed with general anaesthesia at the Mercy Hospital for Women. Although in many cases the use of general anaesthesia may have been discretionary, these numbers again suggest a role for glyceryl trinitrate in the management of such patients

Summary: A retrospective chart review of all anaesthesia consultations for retained placenta at 28 weeks' gestational age or more was performed to determine the safety and efficacy of intravenous glyceryl trinitrate therapy in the management of retained placenta. Of the 33 patients who received glyceryl trinitrate, 1 received a total dose of 50 μg and the remainder received 100 to 200 μg. All placentas were extracted within 4 minutes of the first bolus. The systolic and diastolic blood pressures and the haematocrit fell by a mean of 8.1 ±5.3 mmHg, 6.0 ± 3.5 mmHg, and 2.6 ± 1.7%, respectively (mean difference ± SD, p<0.05 for each). The pulse rose by a mean of 7.7 ±4.5 bpm (p<0.001). Only 1 patient required ergometrine for continued atony. None of the patients required transfusions or operative therapy other than dilatation and curettage. The use of glyceryl trinitrate in doses of 200ug or less for retained placenta appears efficacious and safe, and may obviate the need for general anaesthesia for uterine relaxation.