Preterm Labor
Patient Presentation:
A.W. was a 27 y.o. G2P1 at 32 weeks with a history of preterm labor who presented to Labor and Delivery triage with contractions every 5-10 minutes causing back and abdominal pain. Upon admission to the triage unit, her cervix was 1 cm/70% effaced/soft and her bag of waters remained intact. She was given an IV and was bolused with 1L of lactated Ringer’s solution. After observing her on the monitors, it was apparent she was having contractions every 3-12 minutes and the fetal heart tracing was reassuring. She was given a tocolytic called terbutaline, aiming to suppress her uterine contractions. This medication was given subcutaneously with a dose of 0.25mg 20 minutes apart x 3 doses. In addition, A.W. received her first dose of betamethasone 12mg IM. This medication is a corticosteroid that aids in fetal lung development. Women in PTL will receive two betamethasone injections, either 12 or 24 hours apart. After an hour passed and A.W. received 3 doses of terbutaline, her cervix was checked. A.W. had progressed to 3 centimeters and was transferred to a Labor and Delivery room. Reviewing her obstetrical history and noting her current cervical change (despite the tocolytics) team was led to believe that A.W.’s labor would progress even further.
While the goal of managing a PTL labor patient is to delay delivery as long as possible, the immediate goal is to postpone delivery until both doses of betamethasone have been administered and had time to take effect. Therefore, she was started on Magnesium Sulfate, a stronger tocolytic that is infused intravenously. The recommended loading dose of 6 grams was given first and then the dose was set at 2 grams/hour. Magnesium sulfate is mainly used as an anticonvulsant for the prevention of seizures in pre-eclampsia. However, it has been used as a tocolytic agent because it seems to have an effect on the calcium in the body. The reduction of calcium influx into the cell at depolarization may cease contractions. There is a strict protocol for magnesium patients due to the effects as a CNS depressant. A.W.’s serum magnesium level was drawn 6 hours after the bolus finished, and repeated every 6 hours. Her deep tendon reflexes were tested every 3 hours and her vital signs, particularly her respiratory rate, were evaluated every 30 minutes. She was NPO and had a foley catheter to allow us to measure her intake and output. Lastly, she was continuously monitored for contractions and for a reassuring fetal heart tracing. She, just like other magnesium patients, felt tired, nauseated, and hot. Her contractions spaced out to about every 10 minutes and she was able to rest through them. Her second dose of betamethasone was given at the appropriate time and her magnesium continued for a total of 24 hours.
Outcome:
Shortly after that, A.W. was moved to the High Risk Pregnancy unit where she was prescribed oral Procardia® and was put on bedrest with bathroom privileges. Procardia® works in a similar way that magnesium sulfate works—blocking the passage of calcium into certain tissues, therefore relaxing the uterine muscles. A.W. remained on the Procardia® for 3 days before she delivered a 4 lb, 3 oz baby girl.
Case created by Andrea Weiss, 2010.