Anesth Analg 2006;103:511-512
© 2006 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000227115.35626.09
LETTER TO THE EDITOR
Nitroglycerin for Uterine Inversion in the Absence of Placental Fragments
Richard W. Hong, MD,
Mary Lou V. H. Greenfield, MPH, MS, and
Linda S. Polley, MD
Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, hongr{at}umich.edu
To the Editor:
Nitroglycerin has been used as a uterine relaxant for managing several obstetric conditions, including uterine inversion (1–5). Articles published in this journal suggest that nitric oxide (NO) plays a key role in nitroglycerin’s effects on the uterus and that placental tissue must be present in the uterus to enable nitroglycerin-mediated uterine relaxation (4,6). An interesting debate continues as to whether nitroglycerin can act through an NO-independent mechanism to relax uterine tone (4,6–8). Evidence that nitroglycerin can relax the uterus without the presence of placental tissue would appear to support the existence of a NO-independent mechanism. We report a case of a uterus that inverted after cesarean delivery of the infant and placenta and relaxed after sublingual administration of nitroglycerin.
A 30-yr-old, gravida 3 para 2, ASA physical status II woman presented at 39 wk gestation for an elective repeat cesarean delivery. During placental delivery, the uterus inverted. We initially administered 2 sprays of nitroglycerin (400 µg/spray) sublingually. Within 2 min the obstetrician noticed a change in uterine tone. We administered a third sublingual spray, along with a 20 µg IV dose of nitroglycerin, immediately before uterine relaxation, which enabled the obstetrician to reposition the uterus.
This is the first report of sublingual nitroglycerin used to manage uterine inversion during cesarean delivery. Surgical exposure permitted us to completely visualize the endometrium and confirm the absence of placental fragments. No fragments were visible when the patient received nitroglycerin, and yet we observed uterine relaxation temporally associated with nitroglycerin administration.
This case raises doubt about whether placental fragments must be present to achieve uterine relaxation with nitroglycerin. Our observation is consistent with the existence of a NO-independent mechanism for uterine relaxation. Even though we cannot exclude the presence of microscopic residual placental tissues adherent to the endometrium, the clinical implication is that gross placental tissue is not necessary for nitroglycerin to be effective for producing uterine relaxation.
References
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- Hartnett MJP, Segal S. Presence of placental tissue is necessary for nitroglycerin to provide uterine relaxation. Anesth Analg 2000;91:1043–4.[Free Full Text]
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- Segal S, Csavoy AN, Datta S. Placental tissue enhances uterine relaxation by nitroglycerin. Anesth Analg 1998;86:304–9.[Abstract]
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