Oral vs Intravenous Acetominophen for Postoperative Pain in Minimally Invasive Gynecologic Surgery

Hypothesis: Postoperative pain will be equivalent in patients receiving preemptive oral acetaminophen as compared to patients receiving preemptive intravenous acetaminophen following minimally invasive benign gynecologic surgery.

Importance/significance: Adequate control of postoperative pain is important for patient satisfaction, adequate healing, and optimizing length of stay. The idea of preemptive analgesia (giving an analgesic prior to first skin incision to prevent sensitization of nerve pathways from the trauma of surgery) has been shown in many studies to improve postoperative pain. Intravenous acetaminophen has been found to be an effective agent when given preemptively, and many surgeons have adopted this practice. Unfortunately, the IV formulation of acetaminophen, unlike the oral formulation, is expensive as it is a relatively new drug. There are other oral analgesics (i.e. Celebrex) that have been found to be efficacious for postoperative pain control when given preemptively. There are no studies in gynecologic surgery, however, comparing the effectiveness of PO acetaminophen with IV acetaminophen. Given that PO acetaminophen is significantly cheaper than the IV formulation, this could result in cost savings for hospital systems while maintaining adequate patient comfort and satisfaction.

Primary outcome:

• Difference in postoperative pain comparing preemptive use of PO versus IV acetaminophen
• Mean VAS scores will be compared between the intervention group (PO acetaminophen) and the control group (IV acetaminophen).

Secondary outcomes:

• Difference in postoperative analgesic use between groups - Narcotics, NSAIDs
• Difference in postoperative N/V between groups
• Patient rated measure - none, mild, moderate, severe
• Cost comparison between drugs

Methods:

Patients scheduled to undergo minimally invasive benign gynecologic surgery will be randomized to one of two groups:

Group 1: acetaminophen 1 gram PO 30min before surgery, then saline placebo IV after anesthesia induction but before skin incision

Group 2: receives placebo pill PO 30min before surgery, then acetaminophen 1 gram IV after anesthesia induction but before skin incision

Primary outcome: After surgery, postoperative pain measured at various time points by blinded investigator

2 hours postop, 4 hours postop, 24 hours postop

Secondary outcomes:

• Evaluate N/V - self-rated as none, mild, moderate, severe
• Document amount of analgesic use (narcotic, NSAIDs) during hospital course
• Compute cost comparison between medications

Demographics to collect:

Age, parity, BMI, procedure indication, pathology including uterine weight, procedure length

Inclusion criteria

• Patients 18 years of age or older scheduled to undergo robotic-assisted laparoscopic hysterectomy for benign conditions.

Exclusion criteria

• Known or suspected malignancy,
• Active liver/renal disease,
• Chronic alcohol use/alcoholism,
• Allergy to acetaminophen,
• Conversion to laparotomy,
• hx gastroparesis,
• Poorly controlled insulin dependent diabetes or gastric bypass surgery,
• Regular/recent (past 6 months) narcotic use,
• Inability to swallow pills.