IV Acetaminophen vs IV Morphine for Pain Control in Pregnant Women

Purpose: To determine if IV acetaminophen can 1) decrease pain in pregnancy women, 2)reduce the amount of opioid use in pregnant women who encounter pain, 3) reduce maternal and fetal adverse effects compared to opioids.

Design: This is a comparative effective trial that is a randomized, controlled trial of IV acetaminophen vs. IV morphine in pregnant women.

Procedures: Women meeting inclusion/exclusion criteria will be randomized to IV acetaminophen or IV morphine. The IV acetaminophen group will get up to four standard doses of IV acetaminophen during their stay at the hospital. The second group will get up to six standard doses of morphine. Subjects will complete a pain scale after medication administration and will be asked about any side effects.

Rationale for this clinical trial The goal of analgesia in pregnancy is to reduce pain while minimizing both maternal and fetal adverse effects. Current opioids used in pregnancy provide minimal pain relief and are associated with adverse effects. IV acetaminophen has been shown to significantly improve pain control following cesarean section and in the first stage of labor. Moreover, IV acetaminophen reduces the need and consumption of opioids following surgery. If IV acetaminophen can be as effective in controlling pain associated with maternal medical conditions and uterine contractions with labor, then the use of parenteral opioids in pregnant women and its exposure to the fetus could be reduced. This could provide new opportunities in the medical management of pain in pregnancy. Thus we propose a comparative effectiveness trial of IV acetaminophen compared to IV morphine.

Hypothesis:

We hypothesize that IV acetaminophen is as effective as IV morphine in reducing pain in pregnant women. In doing so, IV acetaminophen can reduce the amount of narcotics needed in women with pain.

Objectives:

To determine if IV acetaminophen can:

1. Decrease pain in pregnant women
2. Reduce the amount of opioid use in pregnant women who encounter pain
3. Reduce maternal and fetal adverse effects compared to opioids

Study Design:

For this comparative effective trial, we propose a randomized, controlled trial of IV acetaminophen vs. IV morphine in pregnant women. Prior studies have confirmed that IV acetaminophen is effective in controlling pain compared to placebo.\[14,20\] Thus, administering just a placebo for pain control is not justified at this time.

We will include 3 different groups of pregnant populations who encounter pain for different reasons.

Group 1: Pregnant women with uterine contractions, but not in labor Group 2: Pregnant women with uterine contractions in the first stage of labor Group 3: Pregnant women with a medical condition associated with pain.

Eligibility Criteria:
Inclusion criteria:

Group 1. We will include pregnant women greater than 24 weeks of pregnancy who present with uterine contractions, but are not in labor and who are warranting treatment with intravenous medication for pain control as part of their routine treatment. This will be defined as the presence of uterine contractions documented on the tocodynamometer. However, the cervix remains less than 2 cm dilated and has not changed after 1 hour after re-examining her cervix.\[23\]

Group 2. We will include pregnant women greater than 34 weeks of pregnancy who present with uterine contractions and are in the first stage of labor and who are warranting treatment with intravenous medication for pain control as part of their routine treatment. This will be defined as the presence of uterine contractions documented on the tocodynamometer and cervical dilation greater than 2 cm, but less than 6 cm. \[23\]

Group 3. We will include pregnant women greater than 16 weeks of pregnancy who present with pain due to a maternal medical condition including sickle cell crisis, pyelonephritis, pancreatitis, cholecystitis, nephrolithiasis or headache and who are warranting treatment with intravenous medication for pain control as part of their routine treatment.

Exclusion criteria:

We will exclude women less than 18 years of age, less than 16 weeks gestation, with weight less than 50 kg, and contraindications to acetaminophen including reported elevated liver function tests, hepatic injury, hepatic disorder, active liver disease, alcoholism, chronic malnutrition, known coagulopathy, hemorrhage, creatinine \> 1.0, or known allergy or hypersensitivity to acetaminophen. We will also exclude women who have received any opioids within the last 24 hours.