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Flurbiprofen Axetil Provides Effective Analgesia Without Changing the Pregnancy Rate in Ultrasound-Guided Transvaginal Oocyte Retrieval: A Double-Blind Randomized Controlled Trial

Zhao, Hong MD*; Feng, Yi MD*; Jiang, Yan MD*; Lu, Qun MD

doi: 10.1213/ANE.0000000000002025
Obstetric Anesthesiology: Original Clinical Research Report

BACKGROUND: In this prospective double-blind randomized study, we evaluated the analgesic effect and potential effect on pregnancy rate of the nonsteroidal anti-inflammatory drug flurbiprofen axetil in patients undergoing ultrasound-guided transvaginal oocyte retrieval under propofol–remifentanil anesthesia.

METHODS: A total of 200 patients scheduled to undergo ultrasound-guided transvaginal oocyte retrieval were randomly allocated to receive 1.5 mg/kg of flurbiprofen axetil (FA group) or placebo (control group) 30 minutes before the procedure. Postoperative pain scores, embryo implantation rate, and pregnancy rate were recorded. Neuroendocrine biomarkers and prostaglandin E2 levels in follicular fluid were tested after oocyte retrieval.

RESULTS: Patients in the FA group awakened earlier after surgery than patients in the control group (3.3 ± 2.6 vs 5.3 ± 3.4 minutes, P < .05) and had lower pain scores than patients in the control group (2.0 [0.0, 2.8] vs 5.0 [3.0, 5.0], P< .001). The difference in pregnancy rates between the 2 groups (44%–44%) was 0% (conventional 2-sided 95% confidence interval, –13.8% to 13.8%). The lower limit of the 90% 1-sided confidence interval for this difference was −9.0%, which was within the predefined noninferiority margin of −15.0%. The concentration of prostaglandin E2 in follicular fluid was decreased in the FA group (24.51 ± 1.52 vs 25.15 ± 1.49 pg/mL, P = .039), although the difference does not appear to be clinically important.

CONCLUSIONS: Flurbiprofen axetil given before ultrasound-guided transvaginal oocyte retrieval for patients under propofol–remifentanil general anesthesia relieves pain without any detrimental effect on clinical pregnancy rate.

Published ahead of print April 19, 2017.

From the *Department of Anesthesiology and Reproductive Medical Center, Peking University People’s Hospital, Beijing, China.

Accepted for publication February 6, 2017.

Published ahead of print April 19, 2017.

Funding: Department research funding, 2016-01.

The authors declare no conflicts of interest.

Clinical trials registration number is ChiCTR-IPR-16008133 (, March 22, 2016; Yi Feng, MD).

Reprints will not be available from the authors.

Address correspondence to Yi Feng, MD, Department of Anesthesiology, Peking University People’s Hospital, 11 Xizhimen South St, Beijing, China 100044. Address e-mail to

It has been estimated that 48.5 million couples suffered from infertility worldwide in 2010,1 many of whom required in vitro fertilization (IVF) treatment to achieve pregnancy. Ultrasound-guided transvaginal oocyte retrieval from the ovary is an important step of IVF. Compared to oocyte retrieval laparoscopically, transvaginal oocyte retrieval is less invasive and can be completed under sedation or general anesthesia in an ambulatory facility, allowing for faster recovery. During the procedure, all suitable follicles need to be aspirated, so the procedure requires patient immobilization. Maternal anxiety is aggravated by the family planning policy of China; women suffering from infertility are often under great pressure to conceive.2 Therefore, appropriate anesthesia needs to provide anxiolysis, facilitate the conduct of the procedure, and ensure rapid recovery in an ambulatory setting. Clinically, propofol–remifentanil–based anesthesia is widely adopted in transvaginal oocyte retrieval from the ovary. Both propofol3,4 and remifentanil5 appear to be safe, circumventing any detrimental effect on reproductive outcome.

Although transvaginal oocyte retrieval is less invasive, it is still stressful and moderately painful,6 and postoperative pain has been underestimated.4 The potent analgesic, nonsteroidal anti-inflammatory drugs (NSAIDs) improve pain relief and clinical outcome via antiplatelet and anti-inflammatory actions.7

Prostaglandin E2 (PGE2) is involved in ovulation and implantation,8 so theoretically, NSAIDs administered for oocyte retrieval could decrease the pregnancy rate. Although several studies have investigated the use of NSAIDs after oocyte removal,9 and before embryo implantation,10 to our knowledge, no study has evaluated the use of a potent NSAID administered before oocyte retrieval.

Flurbiprofen axetil (FA) is an injectable and widely used NSAID that has a high affinity to inflammatory tissues because of its emulsified lipid microspheres.11 Preoperative intravenous administration of flurbiprofen reduces postoperative pain after tonsillectomy,12 spinal fusion surgery,13 arthroscopic rotator cuff repair surgery,14 and thyroidectomy.11

The aim of this study was to investigate the analgesic efficacy of FA in ultrasound-guided transvaginal oocyte retrieval and to explore its effect on the pregnancy rate. Here, we describe a double-blind randomized controlled trial on 200 patients undergoing transvaginal oocyte retrieval from the ovary using preprocedural FA for postoperative analgesia.

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This single-center, prospective, double-blind, randomized, placebo-controlled study was conducted at a university hospital in Beijing, China. The study protocol was approved by the institutional review board of the Peking University People’s Hospital (registration number for clinical trials is ChiCTR-IPR-16008133 [, March 22, 2016; Yi Feng, MD]). Patients scheduled for ultrasound-guided transvaginal oocyte retrieval under general anesthesia were recruited for possible enrollment in the study during the preanesthetic assessment. Written informed consent was obtained from all participants on admission to the study. Patients were excluded if they were allergic to any anesthetic, analgesic, or NSAID, had a history of asthma, peptic ulcer disease, or inflammatory bowel disease.

The stimulation protocols for IVF/intracytoplasmic sperm injection (ICSI) and embryo transfer have been described in detail previously.2 Briefly, patients undergo a long luteal downregulation protocol, a flareup agonist protocol, or an antagonist protocol according to physician evaluation of patients’ potential response to stimulation protocol. Patients suspected of having a normal response or hyper-response underwent a long luteal downregulation protocol, which began with gonadotropin-releasing hormone agonist (GnRHa) on menstrual day 21. Recombinant follicle-stimulating hormone (rFSH) supplemented with human menopausal gonadotropin (HMG) was given on the next menstrual cycle day 3 or 4 and continued for 4 days. Patients with a potentially low or poor response to gonadotropins underwent a flareup agonist or an antagonist protocol. For the flareup agonist stimulation, GnRHa was given on menstrual day 2, followed by rFSH and HMG. The flexible and multidose GnRH antagonist protocol was also initiated with rFSH and HMG on cycle day 2 and cotreatment with a GnRH antagonist when the leading follicle was 13 to 14 mm in diameter. Human chorionic gonadotrophin was administered when at least 2 follicles reached a maximum diameter of 18 mm. Transvaginal oocyte retrieval was performed under ultrasound guidance 36 hours after human chorionic gonadotrophin administration. After the procedure, the number of oocytes was assessed under a microscope, and fertilization was achieved by either IVF or ICSI. Fertilization results were then assessed 16–20 hours after insemination, and the luteal phase was supported with 60 mg of progesterone. On the third day after oocyte retrieval, 2 embryos were transferred to women <35 years of age, and 3 embryos were transferred to other women through transcervical procedure, during which no sedation or anesthesia was administered. Clinical pregnancy was confirmed by positive fetal cardiac activity measured using transvaginal ultrasound at a gestation of 6 weeks.

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Study Protocol

Patients were prospectively allocated to 2 groups, the flurbiprofen axetil group (FA group) or the placebo group (control group), according to a computer-generated random number list that was stored in sealed envelopes. On the morning of surgery, a nurse who was not involved in the actual conduct of the study opened the envelopes and prepared the FA or placebo. Usually, there were 8–14 patients scheduled each day, and 8–14 syringes were prepared and labeled with a sequence number. FA (50 mg/ampule) was obtained from Tyde Pharmaceutical (Beijing, China), and placebo was obtained with identical appearance provided. The study coordinator, attending anesthesiologist, data collection resident, and the patients were all unaware of treatment group assignment.

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Perioperative Management

In the preparation room on the day of surgery, intravenous infusion of lactated Ringer’s solution (5 mL/kg/h) was started, and 1.5 mg/kg of FA or placebo was given intravenously 30 minutes before the oocyte retrieval procedure. Upon arrival in the operating room, electrocardiogram, noninvasive blood pressure, and peripheral oxygen saturation (Spo2) were continuously monitored. All patients breathed spontaneously and received 5 L/min of oxygen via a facemask.

Anesthesia was induced with 2 mg/kg of propofol and 0.2 µg/kg of remifentanil by an attending anesthesiologist, and intravaginal sterilization was started after the patient had lost consciousness (ie, failing to respond to a verbal command to open eyes). Every 5 minutes, or when body movement occurred, an additional IV bolus of 30 mg of propofol and 3 µg of remifentanil was administered. During the oocyte collection procedure, the ovary was visualized with transvaginal ultrasound, and a single-lumen needle was inserted into the follicle. Rapid aspiration of follicular fluid was enabled by an electric pump attached to the other end of the needle, and this was repeated for all the follicles identified by ultrasound.

After surgery, patients recovered in the operating room and were called to open their eyes every minute after the end of the procedure. Emergence duration was defined as the time from the end of the procedure to the eye opening prompted by verbal commands. Fifteen minutes after the patients had regained consciousness, they walked to the postoperative recovery room under assistance from a nurse. Patients stayed in the recovery room for at least 1 hour and were discharged home when their Aldrete recovery score exceeded 9. The Aldrete recovery score, also known as the postanesthesia recovery score, was determined at 5 and 10 minutes after completion of the procedure. If required, 50 mg of tramadol was given intravenously, and patients in both groups were instructed to take 50 mg of tramadol when they felt pain after being discharged home.

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Study Outcomes and Measurements

After surgery, when patients had regained consciousness in the operating room (eye opening prompted by verbal commands), they were asked to rate their pain using verbal rating scales, with 0 indicating no pain, and 10 indicating the worst possible pain. Patients were asked to rate their pain again 1 hour after consciousness was regained in the recovery room. Intraoperative body movement upon surgical stimulation was recorded and graded as follows: grade 1, movement of upper limbs; grade 2, movement of lower limbs below knee joint and knee joint included; and grade 3, movement of the hip.15 Grade 3 movement would affect the performance of the procedure and could cause potential damage to tissues or organs in the vicinity.

After all oocytes were harvested from aspirated follicular fluid, pH value, level of interleukin 1 (IL-1), IL-6, tumor necrosis factor-α, and PGE2 in the follicular fluid were tested with a commercially available radioimmune kit (Sino-UK Bio, Beijing, China).

The primary outcome was the difference in pregnancy rate in the FA group compared with the control group. Secondary outcomes included consumption of analgesic rescue, the number and grading of body movements during the procedure, postoperative pain score, and biomarker (PGE2) concentration in follicular fluid.

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Statistical Analysis

Statistical analysis was performed using the SPSS statistical software package (SPSS Inc, Chicago, IL). Continuous variables are expressed as mean ± SD or medians with interquartile range and categorical variables as numbers and percentages. Between-group differences were evaluated using the independent t test or the Mann-Whitney U test for continuous variables and the χ2 test or Fisher exact test for categorical variables, as appropriate.

The clinical pregnancy rate was tested for noninferiority of the treatment group to the placebo group. A noninferiority margin was proposed based on a 1-sided 90% confidence interval (CI) for the difference in pregnancy rates (ie, Ratewith FA minus Ratewithout FA). The pregnancy rate with FA would be deemed “noninferior” if the lower limit of this CI was found to be within Δ (−15%), when α = .1 and β = .2.

Pain scores, not normally distributed, were compared between 2 groups with Mann-Whitney Utest. The 2-sided 95% CI for the difference between 2 medians was calculated with the Hodges-Lehmann estimator. Analgesia of FA would be considered superior to placebo if the lower limit of this interval exceeded 0, with α = .05 and β = .2. P < .05 was considered statistically significant.

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Sample Size

The study was initially powered as a noninferiority study for the pregnancy rate. Given the existing average pregnancy rate of 45% of IVF patients at the Peking University People’s Hospital, a proposed noninferiority margin of 15% (ie, the rate with FA would not fall below 30%), and a 1-sided α of .1 and β of .2, we calculated that 99 cycles would be needed in each group.

Oocyte retrieval under propofol–remifentanil anesthesia was associated with pain scores of 4 (SD 2.3) at the Peking University People’s Hospital. A sample size of 59 patients in each group would detect a 33% difference in pain scores between 2 groups, with an α of .05 and β of .2.

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A total of 200 consenting patients enrolled from March to April 2016 (100 in each treatment group) completed all the preoperative, intraoperative, and postoperative assessments (Figure 1). The 2 groups did not differ from a demographic perspective, diagnosis, or history of surgery (Table 1).

Table 1.

Table 1.

Figure 1.

Figure 1.

No difference was detected in clinical outcome, including the number of mature oocytes retrieved, patients receiving embryo transfer, the number of embryos transferred, or the patients reaching pregnancy between the 2 groups (Table 2). In both groups, 44 patients reached clinical pregnancy. The difference in the pregnancy rates (44%–44%) was 0% (2-sided 95% CI, –13.8% to 13.8%). The lower limit of the 1-sided 90% CI for this difference was −9.0%, which was within the predefined noninferiority margin of −0.15 (Δ).

Table 2.

Table 2.

The surgical duration, dose of propofol, and dose of remifentanil did not differ between groups (Table 3). The number of body movements was not different between groups, but grade 3 body movements (ie, movement of hip) only existed in the control group (0 of 100 vs 18 of 100, P< .001).

Table 3.

Table 3.

The emergence duration in the FA group was shorter than in the control group (3.3 ± 2.6 vs 5.3 ± 3.4, P < .05) (Table 3). Pain scores were significantly lower in the FA group both immediately after the surgery (2.0 [0.0, 2.8] vs 5.0 [3.0, 5.0], P< .001) and 1 hour later (0.0 [0.0, 2.0] vs 3.0 [2.0, 3.0], P< .001) (Figure 2). The 2-sided 95% CI for difference in pain score right after surgery is (2, 3), with the lower limit being 2, which is larger than the predefined superiority margin 0.

Figure 2.

Figure 2.

No patients consumed tramadol after being discharged home in either group. No bleeding or inadvertent hospital admission was observed in either group.

Table 4.

Table 4.

Follicular fluid was available to be tested in 53 patients in the FA group and in 47 patients in the control group. No difference was detected in pH value, IL-1, IL-6, or tumor necrosis factor-α between groups (Table 4). The concentration of PGE2 in follicular fluid was decreased in the FA group, although the magnitude of difference (2.5%) was small.

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In this prospective, double-blind, randomized, placebo-controlled trial, FA provided effective analgesia after ultrasound-guided transvaginal oocyte retrieval and did not change either the embryo implantation rate or the pregnancy rate.

Our study results are consistent with previous studies that also found no impact of periprocedural NSAIDs on the rate of clinical pregnancy. A recent randomized blinded trial involving 381 women showed that a diclofenac sodium suppository applied after oocyte retrieval provides satisfactory analgesia without detrimental effects on clinical outcome when compared with patients receiving no analgesic.9 A second study involving 200 women showed that the administration of oral piroxicam before embryo transfer had no effect on the rate of implantation or pregnancy in patients after IVF or ICSI.10 In the current study, embryo implantation was attempted 2 days after oocyte retrieval, after FA was eliminated from the body, given that the half-life of FA is 6 hours.13

Pain during oocyte retrieval is caused by puncture of the vaginal skin and the ovarian capsule, aspiration of the ovary, and manipulation of the ovary. Sudden patient movement in response to needle manipulation may increase the risk of injury to surrounding organs or tissues, which can lead to hospital admission. In this study, no patients experienced a severe complication or required hospitalization, but surgical manipulation still caused 18 people out of 100 in the control group to move their hips slightly. Preprocedure NSAID administration prevented this potentially harmful body movement.

NSAIDs are suggested to be given as part of a multimodal analgesic regimen in the ambulatory surgery setting.16 Pain level in the control group was mild to moderate, consistent with previous studies.6 No patients in either group consumed tramadol rescue, which could be attributed to patients’ successful pain relief in the FA group. Alternatively, women may have elected to avoid needed pain medication out of concern that additional medication could undermine their chances of successful assisted pregnancy.

Because NSAIDs act through inhibition of PGE2, a mediator involved with ovulation, fertilization, and implantation,8 the intrafollicular environment was tested after oocyte retrieval. The concentration of PGE2 in follicular fluid was decreased in the FA group (24.51 ± 1.52 vs 25.15 ± 1.49 pg/mL, P = .039), although the magnitude of difference (2.5%) was small and does not appear to be clinically important.

This study has several limitations. Surgical-field PGE2 level is an indicator of inflammatory response and postoperative pain related with surgical trauma.17 In our previous study, surgical-field PGE2 was elevated 2 hours after endoscopic nasal surgery, and circulating PGE2 remained unchanged.17 It is impossible to obtain follicular fluid before or after oocyte retrieval to test the time course changes of local PGE2 in this study. Due to the short duration of oocyte retrieval, usually finished within 5–10 minutes, and less invasiveness, it was considered unethical to withdraw blood to test circulating PGE2 concentration, which was expected to remain unchanged. Likewise, Bispectral index (BIS) could have provided a standardized measure of anesthesia depth, but the procedure did not last long enough to acquire accurate BIS recordings. Clinical pregnancy rate measured by heartbeat at gestational week 6 is an interim measure, and live-birth rate and healthy-term birth are the most desirable clinical outcome. However, because our patients come from all over China, after confirmation of pregnancy at 6 weeks, most of them would return to their hometowns. Systems for long-term follow-up are not established.

In conclusion, one single dose of FA given 30 minutes before ultrasound-guided transvaginal oocyte retrieval for patients under propofol–remifentanil general anesthesia relieves pain without impacting either the embryo implantation rate or the clinical pregnancy rate.

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The authors thank Jian Zhang from the Department of Applied Linguistics at Peking University Health Science Center, Beijing, China, who provided medical writing and editing.

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Name: Hong Zhao, MD.

Contribution: This author helped with study design, conduct of the study, statistical analysis, and manuscript preparation.

Name: Yi Feng, MD.

Contribution: This author helped with study design and manuscript preparation.

Name: Yan Jiang, MD.

Contribution: This author helped with conduct of the study.

Name: Qun Lu, MD.

Contribution: This author helped with conduct of the study.

This manuscript was handled by: Jill M. Mhyre, MD.

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