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Ginekologia i Poloznictwo
ISSN 1896-3315 e-ISSN 1898-0759

Research Article - (2022) Volume 17, Issue 2

Perifollicular vascularity as a potential variable affecting outcome in stimulated intrauterine insemination letrozole treated cycles: A study using transvaginal power Doppler

Mohamed I Taema*, Nada Alayed*, Salwa Neyazi, Ibrahim Ali and Amr Sobhy
*Correspondence: Mohamed I Taema, Department of Obstetrics and Gynecology, Faculty of Medicine, Ain Shams University Hospital, Abbassia, Cairo, Egypt, Email: Nada Alayed, Department of Obstetrics and Gynecology, College of Medicine, King saud university, Saudi Arabia,

Received: 21-Feb-2022, Manuscript No. gpmp-22-55037; Editor assigned: 24-Feb-2022, Pre QC No. P-55037; Reviewed: 04-Mar-2022, QC No. Q-55037; Revised: 29-Apr-2022, Manuscript No. R-55037; Published: 29-Jun-2022

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Aim: The aim of this work was to study the effect of letrozole on perifollicular vascularity and outcome in cases of intrauterine insemination (IUI).

Design: A prospective cohort study on 60 women with infertility attending the outpatient clinic in 2 hospitals in Saudi Arabia and undergoing intrauterine insemination preceded by ovulation induction with letrozole. Our study was conducted from January 2021 to December 2021.

Methods: Patients involved in this study were subjected to ovulation induction with letrozole 5 mg beginning from day 3 of the cycle for 5, folliculometry began on day 10-12 to monitor follicular size and endometrium morphology till the trigger timing by hCG. IUI was performed after hCG administration by 36 hours. On the day of the trigger, the peri-follicular vascularity, endometrial thickness, endometrial pattern, and the number of mature follicles were measured using a 2D transvaginal doppler. Pregnancy is confirmed by a blood test.

Results: The study showed that according to the modified grading system, the distribution of all follicles studied (all >17 mm in diameter) was grade1 (n=3), grade 2 (n=11), grade 3 (n=32), grade 4 (n=14), 14 patient got pregnant while 46 cases did not get pregnant (non-pregnant group). The mean baseline level of serum FSH concentration also tended to be high in the low-grade vascularity cycle, but this result was insignificant. There was giving a pregnancy rate of 16.7%, the follicles of high-grade vascularity were associated with a high pregnancy rate (grade 4=57%), (grade 3=18.8%), then cycles with low-grade vascularity with no pregnancy occur in grade 1 and 2 vascularity group (grade 1, 2=0%) this result is significant. Six pregnant patients had an endometrial thickness of 8-10 mm, 8 patients had an endometrial thickness of 10-12 mm, and zero patients had an endometrial thickness <8 mm, In our study the pregnancy rate was 42.9% with a distinct five-line endometrial pattern, 22.9% with hazy five-line Endometrial pattern, and 0% with no endometrial layering.

Conclusion: Perifollicular vascular perfusion appears to be an important factor in determining the outcome in stimulated IUI cycles, and may have clinical implications in assisted reproduction techniques.


Fertility; Ovulation; Perifollicular vascularity; Letrozole


Infertility is a major problem affecting about 14% of couples. There are many factors affecting couple fertility, roughly half of fertility problems with a diagnosed cause are due to male factors, and about half due to female factors. However, about one in five cases of infertility has no clear diagnosed cause. Unexplained infertility is still somewhat nebulous diagnosis of exclusion. Immunologic factors have been proposed to be involved in as many as 20% of otherwise unexplained cases of infertility [1].

Intrauterine insemination (IUI) with or without ovarian stimulation are an empirical treatment line that has been used in management of infertility, there is increasing role of expectant management, effectiveness of less invasive procedures and growing concern about the complications and costs associated among patients as well as service providers [2].

Intrauterine insemination (IUI) has long been established as an alternative to other forms of assisted reproductive techniques (ART). The use of letrozole in IUI has been shown to improve significantly the pregnancy rate. However, the risk of both ovarian hyperstimulation syndrome and multiple pregnancies is significantly increased, despite this; IUI has cost savings and is less invasive compared with other forms of ART in particular for non-tubal infertility [3].

Letrozole is a third generation non-steroidal reversible aromatase inhibitor. It can suppress oestradiol level up to 95% to 99% after administration according to pharmacodynamics and pharmacokinetics studies, When aromatization of androgens to estrogens is inhibited, a reduction of circulating estrogens causes modifications in the hypothalamic–pituitary–ovary axis, including release of the hypothalamic–pituitary axis from estrogenic negative feedback and FSH secretion is increased, with the resultant stimulating effect on the growth of ovarian follicles, thus use of letrozole in IUI has been shown to improve significantly the pregnancy rate [3].

The reported pregnancy rates per COH/IUI cycle in different parts of the world usually varied between 7% and 22%, there is also a lack of consensus regarding the optimum numbers of COH/IUI that patients should attempt before proceeding to IUI [4].

One of the earliest studies by Azim A and Oktay K [5] using letrozole as a fertility drug looked at 12 women with inadequate response to clomiphene citrate. Ovulation on letrozole occurred in 9 of 12 cycles and 3 patients conceived, a later study by the same investigators compared the effects of letrozole to those of clomiphene citrate, and this time 19 women were studied. Ten women received clomiphene citrate and nine women received letrozole. This study was unable to demonstrate any difference in the number of women who ovulated, the number of eggs that developed in each woman, or the thickness of the uterine lining during treatment, letrozole is associated with a thicker uterine lining and a lower miscarriage rate.

Gore MA, et al. [6] described that increased perifollicular blood flow can be measured in the perifollicular period using color and pulsed Doppler, automated estimation of blood volume around the ovarian follicles, the blood volume does not differ between follicles containing an oocyte and those with no oocyte in the aspirate, or a non-fertilizable oocyte, he hypothesize that those follicles containing oocytes able to produce pregnancy have a more uniform perifollicular vascular network.

The extension of vascularity was graded using a modified grading system. The grading system consisted of assessing the percentage of follicular circumference in which flow was identified from a single cross-sectional slice. The grading system was as follows: F1, with vascularity ≤ 25% of follicular circumference; F2, with vascularity between 26% and 50% of follicular circumference and, F3 between 51% and 75% of follicular circumference; and F4 with vascularity >75% of follicular circumference. The periovulatory follicles were categorized as high (grades 3–4) or low grade (grades 1–2) [7,8].

Aim of Work

The aim of this work was to study the effect of letrozole on perifollicular vascularity and outcome in cases of intrauterine insemination.


The Study was cross section clinical trial for patient undergoing IUI treatment cycles were recruited in this study carried out at infertility Unit in University Hospital with unexplained infertility attending the fertility unit of University hospital and undergoing ovulation induction with letrozole and intrauterine insemination, the study was conducted from October 2020 to June 2021, included 44 cases.

Inclusion criteria

All women underwent IUI treatment including:

• Infertile women aged 20-35 years.

• Infertility more than 1 year (after 12 month of regular intercourse).

• Body mass index between 20-30 kg/m2

• Normal prolactin level, follicular stimulating hormone on day 3 <12 iu/ml, thyroid stimulating hormone.

• Tubal patency ensured by hystrosalpingy graph or by laparoscope.

• Total sperm count of husband ≥ 10 million.

Exclusion criteria

• Total sperm count of husband <10 million

• Ovarian cyst, closed tube.

• Organic pelvic adhesions or severe endometriosis stage III-IV by laparoscope.

• Previous IUI treatment last 3 months.

• Liver disease or kidney disease.

Administrative design:

Explanation of study and the type of maneuver for each participant after which a written consent for approval was taken, Ethical consideration will be done.


Initial evaluation

Steps of performance and techniques used:

1. History taking

2. General, abdominal and pelvic examination.

3. Investigations: FSH, prolactin TSH, complete blood count, hystrosalpingo graphy, and hystrosalpingo graphy, semen analysis.


• Patient stimulated on day 3 to day 7 with letrozole 5 mg.

• Folliculometry: Follicular growth was measured by serial using transvaginal ultrasound scan with power and color Doppler facilities. Perifollicular vascularity was assessed on day of HCG administration by TVS power Doppler u/s D2, the power Doppler box was positioned on each ovarian follicle and the cross-section image of follicle with the maximum colour indication in the follicular circumference is frozen and vascularity is graded (according to F1- F4 grading system) [9].

1. Grade 1: <25% of circumference

2. Grade 2: 26-50%

3. Grade 3: 51-75%

4. Grade 4: >75%, grade 1 and 2 considered as low grade vascularity grade 3 and 4 were high grade, if more than one grade mean is considered [7].

• HCG 5000 IU was injected intramuscular and then IUI was carried out after 30-36 hours after HCG injection, HCG injection when less than 3 mature follicles is seen, HCG injection is canceled in present of >3 follicles with diameter ≥ 17 mm.

Day of IUI:

• Semen specimen was collected in site, and will be prepared within 1 hour semen dilute 1:2 with Ham’s medium and centrifuge at 250 × g for 10 min and then the pellets will be suspended and dilute in 1:1 with medium and centrifuge for 10 min and re-suspended and placed in incubator at temperature 37°C in 5% CO2 in air for 30 min, and transferred to insemination catheter and inseminated intrauterine [9].

• Progesterone support is given for 14 days after IUI is done.

• Pregnancy test is done after 14 days, it is +ve when serum B-HCG >10ml u/ml.

Outcome measures

Outcome of each case is determined according to:

1) Primary outcome: Response ovarian stimulation, number of follicles and size, perifollicular vascularity grases, endometrial pattern and thickness

2) Secondary outcome: a) Pregnancy b) Not-pregnant.

Statistical analysis

Data were analyzed with SPSS version 18.0. The normality of data was first tested with Shapiro-Wilk test.


Initially 56 case were included, but 12 cases was excluded, 10 cases non responder, 2 case HCG administration was canceled because of risk of hyper stimulation syndrome, a total of 44 women undergoing consecutive COS-IUI cycles were analyzed in our study.

Parameters included in this study age, type of infertility, duration, indication of IUI treatment, number and diameter of follicles, FSH prolactin BMI and LH level, vascularity grade, endometrium pattern and thickness.

The results of the study showed that according distribution modified grading system grade 1, n=2, grade 2, n=8, grade 3, n=24 grade 4, n=6 the distribution of all follicles studied (all >17 mm in diameter) in day of HCG administration. There was difference in the age between the mean age was higher within non-pregnant group compared with pregnant group, also duration of infertility was higher in group of follicle ≥ 17 mm in non-pregnant compared with pregnant one (Tab. 1.) Infertility due to ovulatory disorder found to be 59%, and 22% due to male factor, and unexplained infertility found to be 18% (Tab. 2.).

Parameter Total Pregnant Non- pregnant P-value
Number of patient 44 10 34 -
Age in years (Mean ± SD) 29.57 ± 4.47 29.07 ± 4.25 30.08 ± 4.69 0.443
BMI(Kg//m2) (Mean ± SD) 25.92 ± 3.9 25.59 ± 3.4 26.29 ± 4.5 0.396
Duration of infertility(years) (Mean ± SD) 5.02 ± 2.52 4.87 ± 2.07 5.18 ± 2.98 0.439
Type of infertility Primary 24 4 20 0.557
Secondary 20 6 14

Tab. 1. Demographic data of studied population.

Indication of IUI Total % Pregnant (10) Non-pregnant (34)
Ovulatory disorder 26 (59%) 8 (30%) 18 (70%)
Male factor 10 (22%) 4 (40%) 6 (60%)
Unexplained 8 (18%) 0 (0%) 8 (100%)

Tab.2. Comparison between preg- nant and non-pregnant patients ac- cording to indication of IUI.

The mean base line serum FSH, prolactin, LH, concentration also tended to be high in non-pregnant group, but this difference was not significant (Tab. 3.).

Parameter Total (44) Pregnant Non-pregnant P-value
Day 3 FSH (IU/mI) (Mean ± SD) 6.57 ± 0.77 6.22 ± 0.96 6.92 ± 0.59 0.943
LH (mIU/ml) (Mean ± SD) 7.6 ± 0.3 7.6 ± 2.0 7.6 ± 4.1 0.996
PROLACTIN(mIU/ml) (Mean ± SD) 12.2 ± 7.5 10.4 ± 5.8 14.0 ± 8.2 0.193
Ovarian volume (cm3) (Mean ± SD) 6.35 ± 2.1 6.1 ± 1.6 6.6 ± 2.6 0.739
Basal endometrium mm (Mean
± SD)
5.46 ± 0.6 5.31 ± 0.9 5.25 ± 0.7 0.173

Tab. 3. Basal investigation of stud- ied population.

The median number of pre-ovulatory follicles (>17 mm in diameter) on the day of HCG among the pregnant patients was 2 (± 1.6) and in non-pregnant cases was 1.79 (± 1.2). In cycles with a single pre-ovulatory follicle (>17 mm in diameter) the pregnancy rate (0%) was significantly lower than in cycles with more follicles (28% and 42% respectively with two or three dominant follicles), mean diameter in relation of diameter are not significant (the pregnant group) (Tab. 4.).

Parameters Pregnant Non- pregnant P value
Follicles on day of HCG No. of follices more than 17 mm One follicle 0 (0%) 16 (100%) 0.737
Two follicles 4 (28%) 10 (72%)
Three follicles 6 (42%) 8 (58%)
Mean diameter of follicles in mm (Mean ± SD) 20.1 ± 1.5 19.7 ± 1.2 0.53

Tab. 4. Comparison between preg- nant and non-pregnant patients ac- cording to no of follicles and mean diameter.

The follicles of high grade vascularity were associated with high pregnancy rate (grade 4=60%), (grade 3=16.6%), than cycles with low grade vascularity with no pregnancy occur in grade 1 and 2 vascularity group (grade 1, 2=0%) this result is significant (Tab. 5.).

Parameter Grade Pregnant Non- pregnant P value
Perifollicular vascularity Grade 1 0 (0%) 2 (100%) < 0.001
Grade 2 0% 8 (100%)
Grade 3 4 (17%) 20 (83%)
Grade 4 6 (60%) 4 (40%)

Tab. 5. Grading of follicles according to perifollicular vascularity.

Grade 1 found to be 4%, grade 2 was 18%, grade found to be 55%, and grade 4 was 23% (Tab. 6.). 10 pregnant patients, 4 patients had endometrial thickness 8-10 mm, 6 patients had endometrial thickness 10-12 mm, zero patient had endometrial of 8 mm, we found significant relation between endometrial thickness and pregnancy rates, highest (38%) with endometrial thickness ranging from 10 to 12 mm (p <0.05), however not all pts with thicker endometrium had positive outcome, In case endometrial thickness was 6-8 mm, it showed a significantly no pregnancy rates (Tab. 7.). Statistically higher pregnancy rate (40%) was reported in women with distinct five line appearance (p <0.05). Patients with no endometrial layering had poor pregnancy rate (0%) and 23% pregnancy was seen with hazy five line appearance (Tab. 8. and Tab. 9.).

Perifollicular vascularity Number Percent %
G1 2 -4%
G2 8 -18%
G3 24 -55%
G4 10 -23%

Tab. 6. Percent of grading system of follicles induced ovulation by letrozole.

Endometrial Thickness Pregnant(10) Non- pregnant(34) P-value
10-12 mm 6 (38%) 10 (62%) < 0.05
8-10 mm 4 (22%) 14 (78%)
Less than 8 mm 0 (0%) 10 (100%)

Tab. 7. Comparison between pregnancy and non-pregnancy according to endometrial thickness.

Parameter Pregnant Non-pregnant P-value
Endometrial layering No layering 0 (0%) 8 (100%) < 0.05
Hazy five line 6 (23%) 20 (77%)
Distinct five line 4 (40%) 6 (60%)
Endometrial thickness in mm on day of HCG (Mean ± SD) 10.13 ± 1.47 8.94 ± 1.60 < 0.001

Tab. 8. Comparison between pregnant and non-pregnant according to endometrial layering.

Endometrial Pattern No Layering Hazy Five Layer Distinct Five Line P value
Grade I 2 (100%) 0 (0%) 0 (0%) <0.05
Grade II 2 (25%) 2 (25%) 4 (50%) <0.05
Grade III 4 (25%) 14 (58%) 6 (17%) <0.01
Grade IV 0 (0%) 4 (40%) 6 (60%) <0.01

Tab. 9. Relation between perifollicular vascularity and endometrial pattern and fecundability rate.


Many studies have been conducted to evaluate the role of various ultrasound parameters in predicting pregnancy during ART, but little information exists in the literature with regard to their role in predicting subsequent pregnancy outcomes [10].

Our study was attempted to assess the effect of letrozole on perifollicular vascularity in IUI with regard to successful outcome (pregnant/non-pregnant) using colour Doppler transvaginal ultrasound so that the outcome of subsequent COS-IUI cycles could be more accurately predicted than before.

In our study pregnancy occurred in 10 patients (22%) of total 44 infertility with letrozole induced IUI cycles.

However, the success rate in some studies was lower than ours, about 12% [11], as regards the diagnosis of infertility, the highest pregnancy rate (33%) was achieved in women with ovulatory disorders, our study we found ovulatory disorder 45% with pregnancy rate 10%, male factor found to be 27% with pregnancy rate of 33%, and unexplained with 27% pregnancy rate 33% [11].

In present study we found that 55% of patients had primary infertility, and 45% patients had secondary infertility, other number of primary and secondary infertility was seen in Shamila S and Sasikala SL [12] (82.48%), (17.52%), Samal S, et al. [13] (62%), (38%).

Women with endometriosis have not been able to conceive. The second highest pregnancy rate was among patients with unexplained infertility (23%). According to Farimani and Amiri MF [14], women with ovulatory problems had the greatest pregnancy rate (23.1%), while those with endometriosis have the lowest (7.7%).

Despite the fact that most studies showed greater pregnancy rates in patients with unexplained infertility and ovulatory problems and considerably lower pregnancy rates in patients with endometriosis, IUI should not be used in patients with severe endometriosis [15].

In present study it was found that, 0 (0%) patients conceived when there was presence of one pre ovulatory follicle of >16 mm, 4 patients conceived with 2 follicles (28%), 6 (42%) patients conceived when follicles was 3.

In our research, we discovered that PR was 0% in induction with letrezol in IUI cycles with single pre- ovulatory follicles, which was significantly lower than PR in cycles with more follicles.

Perifollicular vascularity was linked to a higher pregnancy rate, with no pregnancy achieved when perifollicular vascularity was grade 1 or grade 2. With grade 3 perifollicular vascularity, the pregnancy rate was 19%, but with grade 4 perifollicular vascularity, the pregnancy rate was 68% (p 0.001).

The pregnancy rate was low in cycles with low-grade perifollicular vascularity, and it was greater in cycles with grade 3 and grade 4 perifollicular vascularity, according to Bhal PS, et al. [7]. Follicular vascularity did not appear to predict the likelihood of conception in women undergoing moderate COS and IUI cycles, according to Ragni G, et al. [3]. The pregnancy rate was 14.1, 10.0, and 11.8 percent, respectively, in the low-, medium-, and high-grade vascularity groups.

A variety of research has looked at endometrial thickness and pattern as a predictor of outcome, with mixed findings. While some research organizations discovered a link between endometrial thickness and pregnancy rate, others did not. Endometrial thickness was measured in our study. No pregnancy was reported when endometrial thickness was less than 8 mm, 10 patient get pregnant 6 when endometrial thickness more than 10 mm (37%), 4 endometrial between 10-8 mm (22%).

Friedler S, et al. [4] discovered in their study of literature survey (concerning endometrial thickness, which included 25 reports comprising 2665 assisted reproduction treatment cycles) that the difference in mean endometrial thickness of conception and non-conception cycles was statistically significant in 1203 cycles, but not in 331 cycles. They discovered that an endometrial thickness of 6 mm had a high NPV for recurrent pregnancy.

The multilayer endometrial pattern was significantly greater in the current letrozole cycle compared to the previous failed CC cycle. These results agree with the study of Jang EJ and Jee BC [16], multilayer endometrial pattern has a low positive predictive value (PPV) for pregnancy (33.1%), while the nonexistence of a multilayered pattern does not exclude conception but renders it improbable (NPV, 85.7%).

In our study the pregnancy rate was 40% with distinct five line endometrial pattern, 23% with hazy five line endometrial pattern, and 0% with no endometrial layering.

Pregnancy rate was higher in distinct five line endometrial appearance. Friedler S, et al. [4] in their study found that the difference in the endometrial patterns of conception and non-conception cycles was statistically significant in 2892 cycles; however in 844 cycles no such significance was noted [4].


Perifollicular vascular perfusion appears to be an important factor in determining the outcome in stimulated IUI cycles, and may have clinical implications in assisted reproduction techniques. As there were no pregnancies in women with low-grade vascularity, the identification of these cycles would be valuable early in cycles (before HCG/ IUI).

Perifollicular vascularity results could allow cancellation of treatment after careful counseling and cancellation of the cycles could be cost-effective both financially and emotionally. However more longitudinal data would be needed before this form of prospective management of treatment cycles could be applied clinically.

Author's Contribution

(A) Study Design · (B) Data Collection . (C) Statistical Analysis · (D) Data Interpretation · (E) Manuscript Preparation · (F) Literature Search · (G) Funds Collection


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Author Info

Mohamed I Taema*, Nada Alayed*, Salwa Neyazi, Ibrahim Ali and Amr Sobhy
Department of Obstetrics and Gynecology, Faculty of Medicine, Ain Shams University Hospital, Abbassia, Cairo, Egypt
Department of Obstetrics and Gynecology, College of Medicine, King saud university, Saudi Arabia
Department of Obstetrics and Gynecology, College of Medicine, King saud university, Saudi Arabia

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