CHRISMED Journal of Health and Research

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 6  |  Issue : 3  |  Page : 172--175

Sonographic assessment of normal fetal cerebral lateral ventricular diameter at different gestational ages among fetuses in Southern Nigeria


Benjamin Effiong Udoh1, Anthony Chukwuka Ugwu2, Alhaji Modu Ali3, Hyacinth Uche Chiegwu2, Joseph Chukwuma Eze2, Ulu Okoro Ulu4,  
1 Department of Radiography and Radiological Sciences, Faculty of Allied Medical Sciences, University of Calabar, Calabar, Cross River State, Nigeria
2 Department of Radiography and Radiological Sciences, Faculty of Health Sciences and Technology, Nnamdi Azikiwe University, Nnewi Campus, Nigeria
3 Department of Radiology, Federal Neuro-Hospital, Maiduguri, Borno State, Nigeria
4 Department of Radiology, Jos University Teaching Hospital, Jos, Plateau State, Nigeria

Correspondence Address:
Alhaji Modu Ali
Department of Radiology, Federal Neuro-Hospital, P. M. B 1322, Maiduguri, Borno State
Nigeria

Abstract

Aim: The study was to determine the normal fetal lateral ventricular diameter using ultrasound at different gestational ages (GAs). Materials and Methods: This is a prospective cross-sectional descriptive study of the fetal cerebral lateral ventricular diameter of 685 singleton fetuses. Measurement of the fetal lateral ventricular diameter was obtained from fetuses of pregnant mothers that met the inclusion criteria during the routine ultrasound scan in Calabar metropolis. A sufficient ultrasound gel was applied on the abdomen of the subject and scanning was done at different planes until a good ovoid shape of the fetal skull was achieved. Axial images at the level of the lateral ventricles were obtained. The widest part of the posterior lateral ventricle far from the transducer was measured more than once and the average value computed for each subject. Results: About 85.4% of the patients were multiparous while 14.6 were primipara. The ages of the pregnant mothers ranged from 20 to 35 years with a mean age of 28 ± 3 years. The male fetuses were 311 while the female was 374. The lateral ventricular diameter did not show any significant correlation with fetal characteristics such as gender, estimated fetal weight, and fetal head circumference throughout gestation. However, the fetal ventricular diameter had a weak but not statistically significant correlation with GA of the fetus (r, P = 0.13, 0.06). Conclusion: Our studies show that 10 mm is the acceptable upper limits of normal for fetal lateral ventricular diameter (FLVD) of fetuses in Southern Nigeria. Ventricular diameter out of this normal range in this region could be considered abnormal and may demand further investigations.



How to cite this article:
Udoh BE, Ugwu AC, Ali AM, Chiegwu HU, Eze JC, Ulu UO. Sonographic assessment of normal fetal cerebral lateral ventricular diameter at different gestational ages among fetuses in Southern Nigeria.CHRISMED J Health Res 2019;6:172-175


How to cite this URL:
Udoh BE, Ugwu AC, Ali AM, Chiegwu HU, Eze JC, Ulu UO. Sonographic assessment of normal fetal cerebral lateral ventricular diameter at different gestational ages among fetuses in Southern Nigeria. CHRISMED J Health Res [serial online] 2019 [cited 2019 Nov 17 ];6:172-175
Available from: http://www.cjhr.org/text.asp?2019/6/3/172/264384


Full Text



 Introduction



Ventricles develop within the brain at the 5th week of embryonic life [1] and are seen on either side of the brain. An increase in the fetal skull dimension had been suggested to be due to the alterations of the ventricular system diameters, that is, the distance of each ventricle from one wall to another.[2] Increase in size of the anterior horn of the lateral ventricle; initially takes place in its anteroposterior portion in most cases of ventricular dilatation. Therefore, at this stage of ventricular dilatation, the ventricular hemisphere Ratio may still be normal and not very efficient for early diagnosis of ventricular dilatation.[3]

Fetal cerebral ventriculomegaly has been shown to be the known causes of the fetal ventricular system dilatation.[4] This also leads to the alteration in the fetal ventricular diameters. The diagnosis of fetal ventriculomegaly/hydrocephalus is important for several reasons: the abnormal dilatation may impact adversely on the normal development of the fetal brain; the dilatation may be part of or result of other neural axis abnormalities or the dilatation may be part or signal the presence of other syndromic or nonneural axis abnormalities.[5]

Fetal ventriculomegaly is one of the most common findings on second-trimester obstetrical ultrasound examination, and the widely used definition of fetal ventriculomegaly is a transtrigone measurement of ≥10 m at any stage of pregnancy.[6] Ventriculomegaly can be caused by a variety of disorders which results in neurological, motor, and/or cognitive disorders impairment.[6] Many cases are associated with other abnormal findings, but in some fetuses, ventriculomegaly is the only abnormality.[7]

Fetal ventriculomegaly can also result from a number of underlying pathological mechanisms which include obstruction of cerebrospinal fluid (CSF) tract, overproduction of CSF, absorption disorder, and inadequate brain development or destruction of brain tissues.[8]

Ventriculomegaly is usually determined by the diameter of the lateral ventricles and increase in the fetal skull dimension had been suggested to be due to the alterations of the ventricular system diameters,[2],[6] but the variation of fetal cerebral lateral ventricular diameter at different gestational ages (GAs) of singleton fetuses in Southern Nigeria has not been investigated to the best of our knowledge. The aim of this study was to determine the normal fetal lateral ventricular diameter using ultrasound at different GAs among Southern Nigerian fetuses.

 Materials and Methods



This was a prospective cross-sectional study of singleton fetuses of Southern Nigerian descent. A convenient sampling method was used to examine 685 singleton fetuses between 20 and 40 weeks of GA from February 2016 to March 2017. Ethical approval for the study was obtained from the Human Research and Ethics Committee of the hospital.

Brief explanations of the aim, objectives, and scanning process of the study were given to the subjects (pregnant mothers). After verbal explanations of the research to the participants, a pretested questionnaire was administered to all the participants to obtain their biomedical data, presence of possible complications of index pregnancy, past obstetric and medical histories, and other necessary information. Candidate with possible complications of index pregnancy or diabetes mellitus, alcoholic mothers, participants with multiple pregnancies or poor obstetric history were excluded from the study. Only participants who gave their written informed consent were included in the study.

The pregnant mothers were well received at the reception and were taken into the ultrasound room for ultrasound examinations and measurements. Participants were told to lie supine on the ultrasound couch. The sufficient ultrasound gel was applied to the abdomen. Scanning was done at different planes until a good ovoid shape of the fetal skull was achieved. The axial image at the level of the lateral ventricle was obtained. At this plane, the ultrasound beam was directed perpendicular to the long axis of the lateral ventricle at a level just above the transthalamic plane which is usually used for fetal biometric measurements. The widest part of the posterior lateral ventricle farthest from the transducer was measured. More than one measurement was taken in each case and the average value computed to represent the average diameter for that subject. Measurement of the ventricular diameter was taken at the level of the atria, Cursors were placed from the anterior wall to the posterior wall of the lateral ventricle [Figure 1] and the diameter reads off electronically. Other parameters of the fetus, such as biparietal diameter, femur length, head circumference (HC), and abdominal circumference were also measured sonographically. The GA (GA), estimated fetal weight and fetal gender (visualized sonographically) were also documented. Mother's biodata were also documented.{Figure 1}

Each candidate had a period of brief interview. This brief period of interview enabled us to identify and excluded candidates that may have been examined previously for the same purpose. The sonographic measurements were carried out using Edan digital ultrasonic diagnostic imaging system, model DUS3, serial number, 317201-M12C04260001 (manufactured by Edan Instrument Inc., China). Sonographic measurements were carried out by a single well-experienced sonographer.

The lateral ventricular diameter was grouped according to GA, sex, and head circumference. Descriptive statistics were used to find the mean, standard deviation, and range of the variables. The Kolmogorov–Smirnov test was used to ascertain the normality of the distribution. Pearson correlation coefficient was used to determine the correlation of the variables with each other and with bio-data. P < 0.05 was taken as the level of statistical significance. The data were analyzed using statistical package for social science (SPSS, version 22) Inc., Chicago Illinois.

 Results



About 85.4% of the participants were multiparous while 14.6 were primipara. The age of the pregnant mothers ranged from 20 to 35 years [Table 1] with a mean age of 28 ± 3 years. The male fetuses were 311 while the female was 374. The mean lateral ventricular diameter in male was 6.60 ± 2.53 mm and 6.63 ± 2.50 mm in the female [Table 2]. There was no statistically significant difference in lateral ventricular diameter between male and female fetuses. The ventricular diameter was normally distributed. The mean of the lateral ventricular diameter of the entire study (male and female) was 6.62 ± 2.51 mm [Table 3]. It ranged from 4.12 to 9.54 mm. The lateral ventricular diameter did not show any significant correlation with fetal characteristics such as gender, estimated fetal weight, and fetal HC throughout gestation [Table 4]. However, fetal ventricular diameter had a weak but not statistically significant correlation with GA of the fetus (r, P = 0.13, 0.06).{Table 1}{Table 2}{Table 3}{Table 4}

 Discussion



The mean fetal lateral ventricular diameter in this study was 6.62 ± 1.21 mm. It ranged from 4.12 to 9.54 mm [Table 2] and [Table 4]. Our result is similar to those of Alagappan et al.[9] (500 participants studied), Achiron et al.[10] (5400 participants studied) and Heiserman et al.[9],[11] (52 participants studied), who stated the mean LVD of their participants to be 6.6 ± 1.4 mm, 6.6 ± 1.2 mm, and 6.5 ± 1.3 mm, respectively. Bassey et al.,[12] in their own study of FLVD of fetuses in Ibadan, Nigeria reported 6.5 ± 1.3 mm as the mean FLVD. The findings of their study (which was also carried out among Nigerian fetuses) are similar to the findings of our study. Bassey et al.[12] also agrees with the present study that 10 mm is the upper limit of normal for FLVD of fetuses in Nigeria. Another study by Farrell et al.[13] of 739 fetuses in Durham USA recorded 5.4 ± 1.2 mm as the mean FLVD. This value is lower than the value obtained in our study. On the other hand, Cardoza et al.[14] in their study reported 7.6 ± 0.6 mm while McLennan et al.[15] and VanHaltren et al.[16] recorded 7.7 ± 0.7 mm as the mean FLVD for the population they studied. This value is higher than the value reported in our study. Although 10 mm is widely accepted by many researchers and confirmed by our study as the upper limit of normal FLVD, Pretorius et al.[17] and Hilbert et al.[18] rather suggest 11 mm and 12 mm (respectively) to be the upper normal limit. Yet some other studies gave lower and upper limits of 4 mm and 8 mm as normal fetal ventricular diameter.[19]

The result of this study also reveals that there is no correlation between lateral ventricular diameter with GA. The findings of Farrell et al.[13] and Patel et al.[20] are similar to the findings of this study. The lateral ventricular atrium diameter had been said to remain <10 mm in diameter throughout gestation.[21] This is a plausible finding because if the lateral ventricles dramatically increase in diameter throughout gestation, the diagnosis of hydrocephalus might be difficult,[5] hydrocephalus is usually diagnosed in utero by the measurement of the fetal lateral ventricular diameter.

Enlargement of the ventricles may occur for some reasons, such as loss of brain volume (perhaps due to infection or infarction), or impaired outflow or absorption of CSF.[1] Ventriculomegaly affects 1–2 in 1000 birth [22] and the prognosis of this abnormality is well documented in the literature, but mild ventriculomegaly has been a matter of discourse among researchers.

Alteration in the lateral ventricular diameter above the upper limit of 10 mm is agreed by many researchers to be diagnostic of ventriculomegaly. Ventriculomegaly is usually described as being mild, moderate, or severe based on the measured size of the lateral ventricles, but many fetuses with isolated mild ventriculomegaly, i.e., ventricular enlargement >10 mm, turned out to have no abnormalities on neonatal assessment.[23]

Our studies show that the lateral ventricular diameter does not increase significantly with head circumference. Head circumference, which linearly increases with GA, had no correlation with fetal lateral ventricular diameter even though the lateral ventricles occupy large areas of the fetal cerebral hemispheres. This again, indicates that the diameter of the lateral ventricle does not necessarily depend on the circumference of the head.

 Conclusion



The present study shows that the normal ventricular diameter of fetuses in Calabar Metropolis ranges from 4.12 to 9.54 mm. The mean of these values was 6.62 ± 1.21 mm. Ventricular diameter out of this normal range in this region could be considered clinically abnormal and may demand further investigations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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