Investigating the Effect of Extracellular Calcium on Oxytocin-induced Human Myometrial Contractility In-vitro

• Status: Completed
• Trial end date: 2015-03-01
• Target enrollment: 0
• Participant gender: Female

Summary

Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality worldwide and is caused most commonly by poor uterine muscle tone after delivery. The first line agent used in the prevention and treatment of PPH is oxytocin, which acts by binding with the oxytocin receptor (OTR) found on myometrial cells to cause uterine contraction. It does this by increasing levels of calcium within the myometrial cell, which promotes contraction. Women who require augmentation of labor with intravenous oxytocin because of inadequate labor progression have been shown to be at increased risk of PPH. In-vitro human myometrial models have shown that following prolonged exposure to oxytocin there is desensitization of the myometrium resulting in a significant reduction in contractility upon delivery of further oxytocin.

Optimal levels of calcium are very important for contraction of the uterine muscle. Too little calcium results in a reduced contraction. Too much calcium may result in either stronger contractions, or even possibly relaxation of the muscle and therefore a reduced contraction. The investigators currently do not know the effects of calcium on the desensitized uterine muscle.

The investigators hypothesize that myometrial contractility following desensitization of the myometrium would be reduced in myometrial samples exposed to low calcium, when compared to normal calcium or high calcium exposure. These results will help in establishing whether myometrial contraction can be augmented by increasing calcium levels within the body, or by optimizing normal physiological calcium levels, in the setting of a augmented prolonged labor, which is at higher risk of poor uterine contraction and PPH.

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: Samuel Lunenfeld Research Institute, Mount Sinai Hospital
• Treatments: Calcium; Calcium, Dietary; Oxytocin

Criteria

Inclusion Criteria:

• Patients who give written consent to participate in this study

• Patients with gestational age 37-41 weeks

• Non-laboring patients, not exposed to exogenous oxytocin

• Patients requiring primary CD or first repeat CD

Exclusion Criteria:

• Patients who refuse to give written informed consent

• Patients who require general anesthesia

• Patients who had previous uterine surgery or more than one previous CD

• Patients with any condition predisposing to uterine atony and postpartum hemorrhage, such as abnormal placentation, multiple gestation, preeclampsia, macrosomia, polyhydramnios, uterine fibroids, bleeding diathesis, chorioamnionitis, or a previous history of postpartum bleeding

• Emergency CD in labor

• Patients on medications that could affect myometrial contractility, such as nifedipine, labetolol or magnesium sulphate.