|Year : 2017 | Volume
| Issue : 1 | Page : 1-7
Sonographic measurement of uterine dimensions in healthy nulliparous adults in Northwestern Nigeria
Umar Muhammad Umar, K Isyaku, Yahuza Mansur Adamu, SA Abubakar, NA Kabo, I Nura, AT Naimatu
Department of Radiology, Bayero University/Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Web Publication||11-Apr-2017|
Umar Muhammad Umar
Department of Radiology, Bayero University/Aminu Kano Teaching Hospital, Kano
Background: Data on uterine dimensions in nulliparous women are vital for public health consideration as the presence of uterine pathology in nulliparous women effectively reflects the status of fertility and other gynecological conditions in general population. In the last two decades, sonography has become the most important imaging modality for the study of the uterine pathology. The estimation of uterine size has been widely reported by several authors from different parts of the world. Materials and Methods: Sonographic measurements of the uterine size in 400 nulliparous women with age ranging from 15 to 25 years were done during the secretory phase of the menstrual cycle, with the uterus measured in the anteroposterior (AP), longitudinal, and transverse planes. The uterine volume was calculated using the ellipsoid algorithm. Height and weight of the subjects were also measured. The data were analyzed with the aid of computer-based SPSS 20.0 software for Windows. Results: The mean AP diameter of the uterus was 3.3 cm with standard deviation of 0.3 while the mean longitudinal and transverse dimensions were found to be 6.4 cm ± 0.4 cm and 5.1 cm ± 0.2 cm, respectively. The mean uterine volume of the subjects was 57.4 cm 3 with standard deviation of ± 9.1. The uterine AP diameter showed poor correlation with age and weight but showed positive correlation with the height. Uterine length and width correlated positively with age and height but poorly correlated with weight of the subjects. Conclusion: Mean uterine dimensions in nulliparous women in Kano, Northwestern Nigeria, is virtually the same as that reported in Southwestern and north central parts of Nigeria, Iran, and Scandinavia but differ from those of other Europeans probably due to body habitus, racial, and genetic factors. This emphasizes the fact that normograms for each geographical area should be established.
Keywords: Dimensions, nulliparous, ultrasound, uterus
|How to cite this article:|
Umar UM, Isyaku K, Adamu YM, Abubakar S A, Kabo N A, Nura I, Naimatu A T. Sonographic measurement of uterine dimensions in healthy nulliparous adults in Northwestern Nigeria. Sahel Med J 2017;20:1-7
|How to cite this URL:|
Umar UM, Isyaku K, Adamu YM, Abubakar S A, Kabo N A, Nura I, Naimatu A T. Sonographic measurement of uterine dimensions in healthy nulliparous adults in Northwestern Nigeria. Sahel Med J [serial online] 2017 [cited 2017 Jun 29];20:1-7. Available from: http://www.smjonline.org/text.asp?2017/20/1/1/204328
| Introduction|| |
The uterus is a dynamic female reproductive organ that is responsible for several reproductive functions, including menstruation, implantation, gestation, labor, and delivery. It is responsive to the hormonal milieu within the body, which allows adaptation to different stages of a woman's reproductive life. The uterus adjusts to reflect changes in ovarian steroid production during the menstrual cycle and displays rapid growth and specialized contractile activity during pregnancy and childbirth. It can also remain in a relatively quiescent state during the prepubertal and postmenopausal years.
Diagnostic ultrasound (US) is a simple, quick, accurate, reliable, harmless, and noninvasive procedure. The main advantage of this diagnostic method is that it is not known to produce the dangers associated with the use of ionizing radiation. This makes it a safe investigation at all ages and most especially during pregnancy and childhood., Real-time US is especially useful for imaging mobile structures, such as the fetus or heart, and for quickly viewing an organ from different angles. Transabdominal and transvaginal ultrasonography have been used intermittently during the menstrual cycle (usually only during the follicular phase) to assess follicle development.
Furthermore, US is the most reliable noninvasive method that can give information on changes in the endometrium., It has also reduced the need for pelvic examination under anesthesia and other invasive procedures such as hysterosalpingography, laparoscopy, and gas gynecography.,
The uterine size as determined by gynecological examination, i.e., bimanual palpation, even under the most favorable circumstances is considered as an approximate estimate and a rough guide as to whether or not the uterus is larger than normal. Hence, an objective method of measurement that ensures that all the information needed is obtained and fully utilized and interpreted with maximum efficiency is desirable. This is obtained by US and magnetic resonance imaging (MRI). However, the relative nonavailability and high cost of the MRI in our environment leaves the US to be the widely used mode of imaging of the uterus.
The ability of US to adequately predict the uterine size has been widely investigated and studied by many workers.,, Variation in uterine size due to patient's age, parity, and hormonal status in the menstrual cycle has been reported previously.,,,, These changes can be investigated by US examination, which also reveals uterine pathology, if and when present.
The accuracy of ultrasonographic measurement of uterine size, when compared with direct measurement of histological specimens, has been investigated and found to have a very high accuracy with no significant difference in US dimension and that obtained with direct caliper measurement of histological specimens.,
The ultrasonic uterine size measurement has been well documented in Caucasians since the use of US in clinical practice started on 1958. A study on sonographic evaluation of the normal uterine size in nongravid females in Nigeria was carried out in Ibadan South-western Nigeria.
Also, a study on real-time sonographic assessment of common uterine sizes, shapes, and positions in Nigerians was done in Benue State, North-Central Nigeria. However, after thorough review of the literature, sonographic data correlating the uterine size in nulliparous females with the age, weight, and body height in Kano, Northwestern Nigeria, were not available. The purpose of this study, therefore, is to provide a baseline data of uterine size by the US, correlating it with the age, body weight, and height in Northwestern Nigeria, with which reference can be made as alteration in uterine size may suggest the presence of pathology.
| Materials and Methods|| |
Transabdominal Sonography was performed using the commercially available real-time US machine Mindray Digi Prince DP8800 (Shenzhen, China). This was achieved using a 3.5 MHz sector transducer, with acoustic gel as a coupling medium, thus avoiding inherent interference by air between the anterior abdominal wall skin and transducer.
The study was prospective and the period of study was 12 months from January to December 2010. Estimated number of patients was 384; however, the number was rounded up to 400 to allow for those subjects that defaulted.
Subjects were instructed to drink about 500–1000 ml of water to promote diuresis and to refrain from micturating until the examination was completed. A full bladder for the US examination of the nongravid uterus was achieved, thus acting as an acoustic window for its visualization. Scanning was done when the subject felt the urge to micturate, i.e., having a full bladder. At each US examination session, subjects were scanned in supine position in both longitudinal and transverse planes and uterine size determined by three measurements obtained directly from the frozen image for each of the following parameters using in-built caliper.
- The longitudinal dimension in sagittal section from the highest fundal point in the midline to the corresponding midline cervical point
- The anteroposterior (AP) diameter, in sagittal section at 90o to the longitudinal plane at the widest fundal dimension
- Greatest (widest) transverse diameter (width) in transverse section.
All dimensions were taken at least twice to allow for observer error and the mean obtained was recorded. The dimensions were taken at their widest portions and recorded in centimeter (cm) to the nearest decimal point.
Uterine volume based on the sonographic parameters was calculated using the formula for a prolate ellipsoid as shown below:
Volume = 0.5233 × D 1 × D 2 × D 3
D 1 = maximum length (longitudinal dimension)
D 2 = maximum AP dimension
D 3 = maximum width (transverse dimension).
The weight of the subject was obtained using a weighing scale and measurements were recorded in kilograms (kg) to the nearest decimal point.
The height of the respondents was measured using a linear scale and measurements recorded in meters (m) to the nearest decimal point.
The expected age group for the study was 15–25 years.
- Nulliparous women in the 15–25 years age group referred to the Radiology Department, Aminu Kano Teaching Hospital, for abdomino-pelvic and pelvic US scans with no clinical history of pelvic pathology
- Nulliparous female volunteers among staff of Aminu Kano Teaching Hospital, medical students, and school of nursing students in the 15–25 years age range who have no history of uterine pathology.
- Pregnant women or those who had been pregnant before
- Women below the age of 15 years and older than 25 years
- Women who are non-Nigerians
- Women with known uterine pathology and those who had uterine surgery
- Women who when they were scanned had some pathology or the other.
The study was prospective and data collection lasted for the duration of 12 months. Before the commencement of data collection, ethical clearance was sought and obtained from the research ethical committee of the Aminu Kano Teaching Hospital. Informed consent was obtained from the subjects or their parents/guardians before the procedure.
Data were analyzed using SPSS 20.0 student version statistical software for Windows 7 (IBM Corporation 2015, California State University). The mean dimensions of the uterus for nulliparous women aged between 15 and 25 years were calculated and tabulated generating the desired normogram for the study using tables, graphs, histograms, and Student's t-test.
The relationships with age, weight, height, and the different uterine dimensions in the subjects were examined using the regression and correlation coefficients. The analysis of variance was performed to test the significance of regression coefficients.
| Results|| |
A total of 400 nulliprous women aged 17–24 years were recruited in this study. The age distribution of the subjects recruited as represented by a histogram [Figure 1] showed that 20 years old subjects had the highest frequency of 105 and accounted for 26.3% of all respondents. This was followed by 19, 22, and 23 years with frequencies of 63, 49, and 49, respectively. The frequencies of 21, 24, and 18 years old subjects stood at 41, 40, and 38, respectively. The least frequent were the 17 years old respondents which stood at 15.
The mean, ranges, and standard deviations of the physical data of the subjects are analyzed and represented in [Table 1]. The mean age for the subjects was 20.6 years (±1.9) and range of 17.0–24.0 years.
|Table 1: The mean, range, and standard deviation of the physical data of the subjects|
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The mean height for the subjects was 1.6 m (±0.1) with range of 1.5–1.8 m. The mean weight of the subjects was 54.6 kg (±7.7) and range of 18.0–70.0 kg.
The mean, ranges, and standard deviations of the uterine measurements are represented in [Table 2]. The mean AP diameter of the uterus for the subjects was 3.3 cm with standard deviation of 0.3 and range of 2.8–4.9 cm. The mean longitudinal dimension of the uterus for the subjects was 6.4 cm with standard deviation of 0.4 and range of 5.0–8.5 cm. The mean transverse dimension of the uterus for the subjects was 5.1 cm with a standard deviation of 0.2 and range of 4.5–6.4 cm. The mean volume of the uterus for the subjects was 57.4 ml with standard deviation of 9.1 and range of 38.0–122.8 ml.
[Table 3] depicts the mean uterine dimensions of various age groups and showed that the highest values were seen in age group of 23 years with all the uterine parameters being higher than in other age groups while the least were in 18 and 19 age groups.
Regression analysis of the relationship of the physical parameters and uterine dimensions [Table 4] showed statistically significant association between the age of respondents with the length, width, and volume of the uterus (P < 0.005) while there was poor correlation of the age against the AP diameter with P = 0.142.
|Table 4: Correlation coefficients of the relationship of the physical data and uterine dimensions|
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The relationship of AP diameter, length, and width of the uterus with height showed statistically significant association P< 0.005.
Also, the relationship of the weight of respondents to uterine dimensions revealed statistically significant correlation with Pearson regression coefficient P< 0.005.
The scatter graphs of the relation of the age of respondents and uterine dimensions are depicted in [Figure 2],[Figure 3],[Figure 4],[Figure 5].
|Figure 2: A scatter diagram showing relationship between the age of the subjects and uterine anteroposterior diameter|
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|Figure 3: A scatter diagram showing relationship between the age of the subjects and uterine length|
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|Figure 4: A scatter diagram showing relationship between the age (years) of the subjects and uterine transverse diameter (cm)|
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|Figure 5: A scatter diagram showing relationship between the age (years) of the subjects and uterine volume (cm3)|
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The regression analysis showed that there was statistically significant association between the age of respondents and uterine dimensions. The Pearson correlation coefficient of the age and longitudinal dimension was 0.019 and that of the age and transverse diameter was 0.000 which are statistically significant. The relationship of the age and uterine volume showed positive association with P = 0.001. However, this was not true between the age of respondents and the AP diameter (P = 0.142).
The regression analysis of the relationship between the height of respondents and the uterine AP diameter showed statistically significant association (P = 0.000), likewise the relationship of the height of respondents and the uterine length, width, and volume all with correlation coefficient of P= 0.000.
| Discussion|| |
Knowledge of the ranges and mean values of the normal uterine size and its correlation with varying clinical conditions is essential in predicting uterine pathology and its knowledge enables the radiologist to make accurate diagnosis at each US session.
In this study, the mean for the AP diameter, length, width, and volume of the uterus has been obtained for the nulliparous women in the age range 17–24 years. It was found to be 3.3 cm ± 0.3 cm for AP diameter, 6.4 cm ± 0.4 cm for length, and 5.1 cm ± 0.2 cm for transverse diameter. The volume was 57.4 cm 3 ± 9.1 cm 3. Also, correlation between age, height, and weight of the subjects with uterine dimensions has been established.
These findings are similar to the findings by Ijeruh in Ibadan, South–western Nigeria. Although the age range of the subjects recruited in the study by Ijeruh was 10-70 years, findings of the corresponding age group of 3.6 cm ± 0.7 cm for the AP diameter, 6.3 cm ± 1.2 cm and 5.3 cm ± 0.7 cm for the longitudinal and transverse dimensions, respectively, are almost the same as those obtained in this study. Ijeruh found that there was significant statistical correlation between age, height, and weight of the subjects and AP diameter, length, and width of the uterus both showing Pearson correlation of <0.000. However, in this study, the correlation between age, height, and weight of the subjects with the uterine dimensions was statistically significant (P < 0.005) except for age against the AP diameter which was not statistically significant (P = 0.142). This could be due to the narrow age range of the subjects used in this study (17–24 years compared to 10–70 years).
The study by Ohagwu et al. established the uterine dimensions for nulliparous women 3.3 cm ± 0.5 cm, 5.7 cm ± 0.6 cm, and 4.1 cm ± 0.5 cm for AP, longitudinal, and transverse dimensions, respectively. This agrees with the findings of the index study. Their study showed relatively strong positive correlation between the uterine dimensions and age, height, and weight of the subjects. Ohagwu et al. did not evaluate the uterine volume in their study. However, assessment of uterine shape, version, and rotation was evaluated and showed predominance of pear-shaped uterus in nulliparous women with 99.2% and globular shape in only 0.8%. Anteversion and dextrorotation were predominant in nulliparous with 91.6 and 98.8%, respectively, as against 8.4 and 1.2% for the retroversion and levorotation, respectively.
The results of the present study were almost in consonance with the findings in Iran, which showed the mean dimensions for the nulliparous women in Babol, Northern Iran as 3.20 cm ± 0.1 cm, 7.28 cm ± 1.3 cm, and 4.28 cm ± 1.2 cm for AP diameter, longitudinal, and transverse dimensions, respectively. However, in the Iran study, the uterine volume was not determined and correlation was made between the uterine dimensions and age, parity, and body mass index of respondents.
Findings in Scandinavia  also agree with those obtained in the current study. Piiroinen  established the mean uterine dimensions for nulliparous women to be 2.9 cm ± 0.4 cm and 7.6 cm ± 0.7 cm for AP and longitudinal dimensions, respectively.
Uterine dimensions have been mentioned in studies by Michael  and Merz et al. and these correspond with the findings of the index study.
According to Michael, the normal adult uterus measures approximately 7.0–9.0 cm long, 4.5–6.0 cm wide, and 2.5–3.5 cm deep (AP dimension). The wider range of dimensions obtained in this study is due to the wider age range of respondents. This contrasts with the current study, in which narrow age range was used.
A study by Merz et al. showed uterine dimensions in nulliparous women to be 4.0 cm ± 0.6 cm, 7.3 cm ± 0.8 cm, and 3.2 cm ± 0.5 cm for AP, longitudinal, and transverse dimensions, respectively. This is similar to the findings obtained in the current study.
Olayemi et al. evaluated the effect of parity on uterine involution and analysis revealed positive (Pearson's) correlation between parity and uterine diameters and uterine volume.
The result of this study contrasts with that of Holt et al., which showed the uterine dimensions for nulliparous women to be 7.0 cm, 4.0 cm, and 4.0 cm for length, width, and AP dimensions, respectively.
It also contrasts with the study by Waldroup and Liu  of 8.0 cm, 3.0 cm, and 5.5 cm for longitudinal, AP, and transverse dimensions, respectively. In the study, all categories of women in the postpubertal age both nulliparous and multiparous were considered.
The result of this study does not agree with that of Sanders  which showed the dimensions of the uterus as 4.0 cm, 6.0–9.0 cm, and 4.0 cm for AP, longitudinal, and transverse dimensions for nulliparous women, respectively.
| Conclusion|| |
This study showed the mean uterine dimensions in nulliparous women in Kano, Nigeria and there was increase in uterine dimension with increase in age and height and weight of the subjects. The uterine AP diameter showed poor correlation with age but significant correlation with the height and correlated poorly with the weight. Uterine length and width correlated positively with age, height but poorly with the weight of the subjects. Statistically significant correlation was found between the uterine volume and physical parameters. Mean uterine dimensions in nulliprous women in Kano, Northwestern Nigeria, are virtually the same as that reported in Southwestern and north central parts of Nigeria, Iran, and Scandinavia but differ from those of other Europeans possibly due to body habitus racial and genetic factors. This emphasizes the fact that normograms for each geographical area should be established.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4]