The study was conducted in the department of Obstetrics and Gynaecology of the Saudi German Hospital, Madinah- Kingdom of Saudi Arabia, as a randomized clinical trial during the period from April 2019 to July 2020. The study protocol was approved by the local ethics committee. Before participating in the study, a written informed consent was obtained from all patients. The study included 148 patients with Clomiphene Citrate resistant PCOS who fulfilled the following inclusion criteria: age 18 to 35 years, Body mass index (BMI) between 18.5 and 34.9 kg/m2, presenting with primary or secondary infertility. PCOS was diagnosed according to the Rotterdam ESHRE/ASRM Consensus workshop , with at least 2 of the following 3 criteria:
A- Oligo- and/or anovulation; manifested by oligomenorrhea or amenorrhea. Oligomenorrhea was defined as cycle interval of more than 35 days but less than six months. Amenorrhea was defined as absence of menstruation for six months or more.
B- Hyperandrogenism; biochemical and/or clinical in the form of acne or hirsutism defined as a score of 8 or higher using the modified Ferriman–Gallwey scoring system  when abnormal hair distribution was assessed in nine body areas and given a score of 0 to 4.
C - Polycystic ovarian morphology detected by transvaginal ultrasound with the presence of 12 or more follicles measuring 2–9 mm in diameter in one or both ovaries, and/or increased ovarian volume >10 mL.
With exclusion of other etiologies that may also lead to oligoovulation and/or androgen excess such as androgen-secreting tumors, congenital adrenal hyperplasia, hyperprolactinemia or Cushing’s syndrome.
Patients with anovulation who had clinical or laboratory evidence for hyperandrogenaemia were primarily assessed for the cause before establishing the diagnosis of PCOS and indeed before exposure to clomiphene citrate as a first line for ovulation induction. In this study, we enrolled only PCOS patients with clomiphene citrate resistance. Patients with hyperandrogenaemia due to other causes such as, androgen secreting tumours diagnosed when the level of testosterone is higher than 2 ng/mL, and congenital adrenal hyperplasia diagnosed by high level of 17-OH progesterone, were excluded.
Clomiphene Citrate resistance was defined as failure of ovulation after administration of Clomiphene Citrate in a dose of 150 mg for 5 days per cycle, for two or three cycles . All Patients had patent both fallopian tubes and normal uterine cavity as evidenced by hysterosalpingography (HSG) and their partners had normal semen parameters as defined by the modified WHO 2010 criteria .
Exclusion criteria were: Morbidly obese patients with BMI ≥35 Kg/2m, abnormal husband semen analysis, abnormal HSG or laparoscopic evidence of pelvic adhesions. Patients receiving statin drugs for cholesterol, beta-blockers for high blood pressure, or tricyclic antidepressants, were also excluded as these drugs can lower the levels of ubiquinol in the body.
All patients were initially assessed at the booking visit, with detailed history taking, including personal, medical, surgical, obstetric and menstrual history. The body mass index (BMI) was calculated. Basal hormonal profile; serum follicle stimulating hormone (FSH) and luteinizing hormone (LH), were measured using Enzyme Linked Immunosorbent Assay (ELISA).
Ovarian stimulation and folliculometry
Patients were divided randomly into two groups (A and B), who underwent controlled ovarian stimulation and timed intercourse, using random table computer software (Open Epi version 3.21).
Basal transvaginal ultrasonography (TVS) was done on day 2 of the cycle before commencing ovarian stimulation. For patients presenting with amenorrhea or oligomenorrhea, dydrogesterone 10 mg (Duphaston®; Abbott Biologicals B.V.) was prescribed (3 times daily for 10 days) to achieve withdrawal bleeding before starting induction of ovulation.
In group A, controlled ovarian stimulation (COS) was done by Clomiphene Citrate (Fertab® 50 mg tablets, Zynova. SITCO Pharma.) as 150 mg (3 tablets) daily for 5 days (from 2nd day till 6th day of the cycle) together with Ubiquinol (active form of Coenzyme Q10) starting from 2nd day till the day of human Chorionic Gonadotropin (hCG) triggering in a dose of 100 mg capsules orally once daily, immediately after meal (Nutraquinol®; Jamjoom Pharma Nutraceuticals). In group B, Human Menopausal Gonadotropins (hMG) (Merional® 75 I.U. vials, IBSA.) IM was given from 2nd day of the cycle in a dose ranging from 75 to 225 IU according to the patient’s response. Patients were instructed not to take any non-study drugs during the whole study period. All patients did not receive any drug for induction of ovulation 3 months prior to participation in the study.
Patients were counselled regarding the possible side effects of Clomiphene Citrate such as: reversible enlargement of the ovaries, multiple pregnancy, ovarian hyperstimulation syndrome, blurred vision, light sensitivity, headache, hot flushes, mild abdominal pain and vaginal bleeding  as well as the possible side effects of Human Menopausal Gonadotropins such as: pain at the site of injection, abdominal discomfort and pelvic pain, breast discomfort, ovarian hyperstimulation syndrome, multiple pregnancy, weight gain, headache, mood changes, nausea, abnormal uterine bleeding, dizziness, ovarian cysts, adnexal torsion or ruptured ovarian cyst and ectopic pregnancy .
Serial transvaginal ultrasonography was done for assessment of follicular growth (number and diameter of follicles) and endometrial thickness (measured on sagittal view of the uterus by including the whole endometrium at the point of its maximum thickness), starting on cycle day 8, using vaginal 4.5 MHz endocavity transducer (Esaote Mylab 50 Xvision Ultrasound, Italy), and was continued with an interval of 1-3 days till the size of the leading follicle reaches 18 mm or more in mean follicular diameter. Then ovulation triggering was done by an intramuscular single dose of human Chorionic Gonadotropin (Epifasi® 5000 IU vials, EIPICO, Egypt.) 2 vials (10,000 IU). Thereafter, patients were advised for a timed intercourse (TI) 36 hours after ovulation triggering.
All measurements were obtained by a blinded single operator. All data were digitally stored and were not analyzed till the end of the study.
Thereafter, patients were asked to come for follow up, 7 days after hCG triggering, where a blood sample (2 mL) was withdrawn for measurement of serum progesterone (ng/ml). Collected samples were centrifuged and then stored at 2–8 °C until enzyme immunoassay was done. If the Patient presented with a missed period for a week, a serum sample was sent for β-hCG using immunoassay.
Patients with positive serum pregnancy test, defined as β-hCG concentration >10 mU/ml, were examined by abdominal ultrasonography 6 weeks after the first day of their last menstrual period with 3.5 MHz sector transducer (Esaote Mylab 50 Xvision Ultrasound, Italy) to detect an intrauterine gestational sac (Clinical pregnancy) . Patients who failed to get pregnant were requested for follow up for 2 more consecutive cycles with the same protocol.
The primary outcomes measured were; number of cases achieving follicular growth to the size of mature follicle ≥ 18 mm (1–3 follicles) during the three cycles of stimulation, number of stimulated cycles (till pregnancy occurs or completing the 3 cycles of the study, whichever is earlier), the endometrial thickness on the day of triggering, and the luteal function as assessed by mid-luteal serum progesterone measurements.
The secondary outcomes were; number of cases with positive serum pregnancy test and the clinical pregnancy rate among the two groups during the three cycles of treatment.
2.3. Sample size calculation: was done using a computer software G Power® version 3.1.5 (Franz Faul, Universität Kiel, Germany).