Prevalence and sonographic patterns of uterine fibroids in Northern Nigeria

Yusuf Lawal; Ishaku Bala Yaro; Ayyuba Rabiu; Richard Emmanuel

doi:10.4103/nnjcr.nnjcr_4_18

ORIGINAL ARTICLE

Year : 2019 | Volume : 8 | Issue : 13 | Page : 24-29

Prevalence and sonographic patterns of uterine fibroids in Northern Nigeria

Yusuf Lawal¹, Ishaku Bala Yaro², Ayyuba Rabiu³, Richard Emmanuel²
¹ Department of Radiology, Bayero University Kano/Aminu Kano Teaching Hospital, Kano, Kano State, Nigeria
² Department of Medical Radiography, Faculty of Allied Health Sciences, College of Health Sciences, Bayero University Kano, Kano, Kano State, Nigeria
³ Department of Obstetrics and Gynaecology, Bayero University Kano/Aminu Kano Teaching Hospital, Kano, Kano State, Nigeria

Date of Web Publication

19-Feb-2019

Correspondence Address:
Ayyuba Rabiu
Department of Obstetrics and Gynaecology, Bayero University Kano/Aminu Kano Teaching Hospital, P.M.B. 3011, Kano, Kano State
Nigeria

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/nnjcr.nnjcr_4_18

Abstract

Background: Uterine fibroids are benign tumors which commonly affect women of reproductive age. Ultrasound scan is regarded as the commonly available method of diagnosing and growth monitoring of uterine fibroids. Objectives: To determine the prevalence of uterine fibroids, their sonographic pattern, and their association with body mass index (BMI) among patients undergoing pelvic ultrasound scan. Methodology: It was a descriptive cross-sectional study that was conducted among patients in Aminu Kano Teaching Hospital. Ethical approval was obtained from the hospital's Ethics Committee. Information such as sociodemographic characteristics was recorded in the questionnaire after obtaining informed consent. Mindray Digital Ultrasound Imaging System (Model DC6; Shenzhen Mindray Biomed Electronics, Shenzhen, China) was used for the study. The data obtained were analyzed using SPSS software version 20 (SPSS Inc., IL, Chicago, USA). A test of association was computed on the categorical variables using Fisher's exact test. P < 0.05 was considered statistically significant. Results: The prevalence of uterine fibroids was 12.1%. Age group of 36–40 years had the highest number of patients with fibroids (25 [29.8%]). Multiple fibroids of more than two nodules were the findings in almost half of the participants (41 [48.8%]). There was no statistically significant association between the number of fibroid nodules and parity P (Fishers') = 0.474 or BMI P (Fishers') = 0.181. Age group was statistically associated with the number of fibroid nodules P (Fishers') = 0.030. Conclusion: The prevalence of uterine fibroids in this study was high. Mixed echo pattern of fibroid nodules was the predominant finding in this study.

Keywords: Fibroids, Northern Nigeria, prevalence, sonographic patterns

How to cite this article:
Lawal Y, Yaro IB, Rabiu A, Emmanuel R. Prevalence and sonographic patterns of uterine fibroids in Northern Nigeria. N Niger J Clin Res 2019;8:24-9

How to cite this URL:
Lawal Y, Yaro IB, Rabiu A, Emmanuel R. Prevalence and sonographic patterns of uterine fibroids in Northern Nigeria. N Niger J Clin Res [serial online] 2019 [cited 2023 Jun 10];8:24-9. Available from: https://www.mdcan-uath.org/text.asp?2019/8/13/24/252586

Introduction

Uterine fibroids are benign, monoclonal tumors of the smooth muscle cells found in the human uterus.^[1],[2] It is the most common benign gynecological tumor of the uterus, with an estimated incidence of 20%–40% in women during their reproductive years.^[3],[4] The incidence of fibroids increases with age; by the age of 50 years, up to 65% of women have uterine fibroids.^[5],[6],[7] Race has been shown to be an important epidemiological risk factor for uterine fibroids. It is more common, larger, and symptomatic among Black women than White women.^{[5],[7],[8],[9],[10]}

Uterine fibroids have varying degrees of presentation ranging from being asymptomatic to having different clinical features such as abdominopelvic mass, abdominal pain, menorrhagia, dysmenorrhea, recurrent pregnancy loss, and pressure symptoms.^[11]

In developed nations, where other options of imaging modalities such as magnetic resonance imaging (MRI), ultrasonography, and saline infusion sonography are available, fibroids can easily be diagnosed with better precision. In this regard, MRI is the preferred imaging modality for characterizing uterine fibroids and identifying their exact anatomical location; however, initial identification is usually by ultrasonography.^[12] In some rare occasions, fibroids may also be found incidentally on plain radiographs or computed tomography (CT) scans done for other indications.^[12]

In developing countries, ultrasound scan is the commonly available method of diagnosing and monitoring the growth of uterine fibroids. There is no consensus on whether transabdominal or transvaginal ultrasound scan is the preferred method of diagnosing uterine fibroids. Transvaginal ultrasound scans are more sensitive for the diagnosis of small fibroids and in skilled hands, a fibroid as small as 5 cm can be detected on transvaginal ultrasound scan. However, when the uterus is retroverted or bulky, the uterine fundus may lie outside of the field of view and in this scenario, transabdominal ultrasound scan is the better option. Transabdominal views are often of limited value in obese patients.^[13] Uncomplicated fibroids are usually hypoechoic but can be isoechoic or even hyperechoic compared to normal myometrium when viewed with ultrasound scan.^[14] Calcification can be seen as an echogenic focus with shadowing or amorphous echogenic foci within its substance; at times, cystic areas of necrosis or degeneration can be seen with ultrasound scans.^[14]

Fibroids are often grouped into four different types depending on the location within the uterus, namely submucosal (beneath the mucosa, or uterine lining), intramural (entirely within the wall of the uterus), subserosal (beneath the serosa which distorts the contour of the outer surface of the uterus), and pedunculated (attaches to the uterus by a stalk).^[15]

This study was aimed at determining the prevalence of uterine fibroids among patients undergoing pelvic ultrasound scan at the Aminu Kano Teaching Hospital, in Northern Nigeria.

Specific objectives

To determine the prevalence of uterine fibroids among patients undergoing pelvic ultrasound scan
To determine the sonographic patterns of uterine fibroids
To find out the association between uterine fibroids and body mass index (BMI).

Methodology

It was a descriptive cross-sectional study that was conducted among patients undergoing pelvic ultrasound scan at the radiology department of Aminu Kano Teaching Hospital from April 1 to October 31, 2017. Ethical approval to conduct the study was obtained from the hospital's Ethics Committee. Strict ethical standard and procedures were adhered to in line with Helsinki declaration; anonymity of the participants was ensured as well as making it clear to the participants that participation would be voluntary. A questionnaire was designed. Information such as sociodemographic characteristics of the patients and features of fibroid nodules were recorded on the questionnaire after obtaining informed consent. A simple random sampling method was used to recruit the patients until the required sample size was attained. All consenting women presenting for pelvic ultrasound between the ages of 18 and 50 years were included in the study. Women who declined consent, women below the age of 18 years, and women above the age of 50 years were excluded from the study. Mindray Digital Ultrasound Imaging System (Model DC6; Shenzhen Mindray Biomed Electronics, Shenzhen, China) was used using 3.5 MHz curvilinear transducer to scan the patients for generation of data. All the scans were done by the radiologist (principal investigator). For the purpose of obtaining qualitative results, all patients were placed in supine position on the examination couch. Coupling gel was applied to the suprapubic region following patients' preparation, and systematic scanning commenced by moving the transducer (identical curvilinear probe) over this region. All the images were obtained in longitudinal and transverse planes (anteroposterior and widest transverse dimensions). The data obtained were analyzed using the Statistical Package for the Social Sciences (SPSS) version 20 (SPSS Inc., IL, Chicago, USA) and were presented using frequencies and percentages. A test of association was computed on the categorical variables using Fisher's exact test. P < 0.05 was considered statistically significant.

Results

The study was conducted from June 1 to October 31, 2017. Six hundred and ninety-four female patients undergoing pelvic ultrasound scan were recruited. The mean age (±standard deviation) was 36.6 ± 1.44 years. The age range was from 18 to 50 years. Eighty-four female patients were diagnosed with uterine fibroids. The prevalence of uterine fibroids was 12.1%. A total of 56 (66.7%) cases were previously diagnosed, 55 by ultrasound, and 1 by clinical examination. Three patients (3.57%) had undergone myomectomy prior to the examination. Four patients with uterine fibroids were incidentally found to be pregnant (4.8%).

Patients in the age group of 36–40 years had the highest number of fibroids (25 [29.8%]) followed by the age group of 26–30 years with 18 (21.4%) patients. Age group with the least number of fibroids was 46–50 years with 7 (8.3%) patients [Table 1].

Table 1: Sociodemographic characteristics of the respondents

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Majority of the patients (59 [70.2%]) were Hausas (the predominant ethnic group in the study environment), whereas Yorubas and Igbos had 7 (8.3%) patients each. Home managers were the predominant occupation among the patients with 36 (42.9%), followed by civil servants who were 24 (28.6%). Up to a half of the patients, 42 (50.0%), had tertiary education, whereas 23 (27.4%) had only Qur'anic education. More than half of the respondents (43 [51.2%]) were nulliparas, whereas 27 (32.1%) delivered more than two children [Table 1].

Multiple fibroids with more than two nodules were the most common ultrasound findings in almost half of the participants. A few of the patients (8 [9.5%]) were found to have calcified fibroid nodules [Table 2]. Twenty-seven (32.1%) patients had normal BMI 18.5–24.9 kg/m², whereas 26 (31.0%), 24 (28.6%), and 7 (8.3%) were overweight, obese, and underweight, respectively [Table 2]. Majority of the patients with intramural fibroids, (17 [68.0%]), were within the age group of 36–40 years. In addition, the highest proportion of mixed types of fibroids (8 [32.0%]) was within the same age group of 36–40 years.

Table 2: Fibroid's features and other variables

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With regard to the location of fibroids, more than one-third were located at the corpus (body) and were within the age group of 36–40 years. Furthermore, the highest proportion of those with multiple locations (13 [52.0%]) were within the same age group of 36–40 years. Larger fibroids of at least 3–4.9 cm (10 [40.0%]) and ≥5 cm (11 [44.0%]) were mostly within the age group of 36–40 years [Table 2].

[Figure 1] depicts the echo pattern of the fibroid nodules. Ultrasound findings were more of mixed echo patterns.

Figure 1: Echo pattern of the uterine fibroid

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[Table 3] shows the association between fibroid nodules and different variables. There was no statistically significant association between the number of fibroid nodules and parity P (Fishers') = 0.474 or BMI P (Fishers') = 0.181. Age group was statistically associated with the number of fibroid nodules P (Fishers') = 0.030.

Table 3: Cross tabulation between parity, age group, body mass index, and number of fibroid nodules

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Discussion

In this study, a prevalence of uterine fibroids estimated among asymptomatic women using ultrasound scan was found to be 12.1%. This value is more than the figure of 6.83% reported in South-western Nigeria by Ukwenya et al.,^[14] but less than 13.6% reported by Obuna et al.^[15] in South Eastern Nigeria. Difference in the sociodemographic characteristics of the various study populations might be responsible for the finding. We incidentally found 4.8% of the study population with the co-existence of pregnancy with uterine fibroids. Our figure is less than the reported 25.0% of co-existing pregnancy with fibroids by Ukwenya et al.^[14] Obstetric scan for pregnant women is commonly done by the obstetricians in the obstetric department, while most gynecological scans are referred to the radiology department of the hospital. This could explain the low rate of pregnancy co-existing with uterine fibroids in this study.

There was a rise in the prevalence of uterine fibroids from the age groups of 30–35 years (15.0%) to 36–40 years (29.8%) in this study. Okogbo et al.^[16] in South-western Nigeria reported a similar rise in the prevalence of uterine fibroids from below the age of 20 years (0.0%) to a maximum of high prevalence of uterine fibroids of 40.3% in the age group of 30–39 years which decreased to 32.9% in the age range of 40–49 years. High prevalence of uterine fibroids in the age group of 36–40 years was also reported by other workers.^[17],[18] This is believed to be due to the fact that symptoms become manifest at this age group, prompting the need to seek medical intervention.^[19]

In terms of ultrasound findings, mixed echo pattern of fibroid nodules was the predominant finding (58.3%) in this study. This agrees with a previous study conducted by Sarkodie et al.^[17] in Ghanaian population which reported mixed echo pattern (55.5%) as the most common finding on ultrasound. Race might have played a role because both studies were carried out among Black populations.

Large fibroid nodule (≥5 cm) was common among the participants (48.8%), and this agrees with a previous study conducted in Kano where 40.4% of the presentation of fibroids were of large diameter.^[19] The relatively huge size of the fibroid is probably due to late presentation and asymptomatic nature of uterine fibroid. This same age group of 36–40 years also had the highest number of fibroid nodules. This could not be unconnected to the high prevalence of fibroids among the age group.

Three (3.57%) patients had undergone myomectomy (surgical removal of fibroids) prior to the examination either due to fibroid regeneration or incomplete removal. This indicates that fibroids regenerate after surgical removal. It has been reported that fibroids have a 15% recurrence rate and 10% of women undergoing a myomectomy will eventually require hysterectomy within 5–10 years.^[20] It was also reported that risk of recurrence is associated with age, preoperative number of fibroids, uterine size, associated disease, and childbirth after myomectomy.^[21]

Calcified fibroid nodules were observed in up to 9.5% of the patients, suggesting that some of the fibroids had undergone degenerative changes. Fibroids undergoing degenerative changes are not uncommon and have been reported by other workers.^[22],[23] The study showed no statistically significant association between the number of fibroid nodules and parity, but age group was statistically associated with the number of fibroid nodules. This is contrary to the findings of several researchers who documented an inverse association between the risk of fibroids and parity.^{[24],[25],[26],[27]} Smaller sample size and single-centered study nature could be responsible for that. BMI had no association with increasing number of fibroid nodule. This is contrary to the finding of Ofori et al.^[28] in Ghana where fibroids have significant association with obesity. Our study being a single-centered study could be the reason for this lack of association.

Conclusion

The prevalence of uterine fibroids in this study was high and predominant among the age group of 36–40 years. Mixed echo pattern of fibroid nodules on sonography was the predominant finding in this study.

Recommendation

We recommend yearly ultrasound scan for screening of fibroids commencing from earlier ages in order to achieve the goal of early diagnosis.

Limitation

The cross-sectional nature of the study and the findings from the study might not be a representative of the general women population because it is single-centered study.

Transvaginal ultrasound could have picked smaller nodules if done.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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