Pain scores during oocyte retrieval for IVF/ICSI: A retrospective cohort study comparing three different analgesia protocols

OBJECTIVE: Oocyte retrieval is a painful, but essential element of IVF/ICSI. Evidence for the best method of analgesia is lacking. In the Netherlands, the three most common analgesia protocols entail administration of oral analgesics, intravenous opioids, and intramuscular opioids. The aim of this study was to compare these methods. METHODS: A retrospective cohort study was conducted at three clinics. Clinic one provided oral analgesics (1000 mg paracetamol and 500 mg naproxen). The main component of analgesia at clinic two was opioids intravenously (50-100 µg fentanyl), and at clinic three, this was opioids intramuscularly (0.01 mg/kg alfentanil). Intraprocedural pain was registered on an 11-point scale. Univariate analyses were performed to identify factors significantly associated with pain scores. A mixed linear model was used to uncover mean pain scores per clinic. RESULTS: In total, 2,127 oocyte retrievals were included. Pain scores were lower in older women; scores decreased 0.06 points per year (95%-confidence interval (CI): 0.04-0.08). Per extra follicle, scores were 0.05 points higher (95%-CI: 0.03-0.06). Endometriosis resulted in 0.45-point higher scores (95%-CI: 0.01-0.88). Primary subfertility resulted in a 0.36-point increase in scores (95%-CI: 0.15-0.56). Nulliparous women had a 0.41-point higher score than multiparous women (95%-CI: 0.19-0.63). These effects were mostly similar in all clinics. Mean pain scores were 5.6 at clinic number 1 (95%-CI: 5.3-5.8), 5.1 at clinic number 2 (95%-CI: 4.9-5.3), and 3.9 at clinic number 3 (95%-CI: 3.8-4.1). CONCLUSION: The lowest pain scores were achieved in the clinic that used intramuscular administration of alfentanil, followed by intravenous fentanyl and, finally, non-sedative oral analgesics. Significant correlations between patient characteristics and pain scores were identified.