obtaining a well defined land mark to use as a reference point. The reference points / methodology mentioned above is based on the previous work of Niedarau31.
In this study the mean liver dimensions for the MCL was 12.3cm (1.2SD) range 9.1-15.6cm) for males 12.3cm (1.2SD) (range 9.3 – 15.1cm) and for females 12.4 (1.2SD) (range 9.1 – 15.6cm) and there was no significant difference between males and females (P > 0.05). These values are higher than the values obtained by Niedarau et al (1983) in a study carried out in Germany with the values of 10.5cm (1.5SD) with a 95 percentile upper limit of 12.6cm.
Although they did not give average values of males and females separately, but they found no significance difference between males and females (P > 0.05)31,32. The higher mean value for this study may be due racial or environmental factors.
This may be true because Singh et al in their study in India with similar tropical environment like ours, had similar value with this study of the MCL measurement to be 12.6cm.46
In another more extensive study carried out by Wolfgang Kratzer et al in over 2000 subjects, again in Germany, found the MCL dimension to be 14.0 (1.6SD) while for females was 13.5(1.7SD)30. In their study they found significant difference between male and female MCL dimensions (P = 0.006).
Their mean value is higher than the mean for their study (12.3cm (1.2SD). It may be due to the varied methodology. This dimension varies with the level of inspiration which could also affect the measurement. Gosink et al in comparing ultrasound measurement with autopsy findings in this same patients after death
found that those with ultrasound measurement of 13.0cm, or less at MCL had normal liver size in 93% of the cases.47 The higher female values in this study may be due to the higher BMI in females than males in this study in which was significant (P = 0.007).
In this study most of the dimensions show some correlation with age in varying degree; and it showed that the liver dimensions increases with age up to 50 – 69 age group and then one can observe a decline in all the dimensions as from the age group of 60 – 79. Most of the previous authors have reported either increase in the dimensions or a decrease in the dimensions especially the MCL without paying critical attention to the different age groups24,30,31,42. The reduction in size in the elderly group have been attributed to reduction in hepatocytes42.
The mean mid axillary line (MAC) dimension in this study was found to be 15.2cm (0.9SD) (range 12.8 – 17.6). That for males 15.1cm (0.9SD) while for female, 15.3cm 0.9SD). The mean value is close to the value obtained by Gotzberger et al in another German study46 and the only other study that measured this dimension and AAL. The mean value in their study was 14.9cm (2.0SD). There was no correlation with sex or with age, weight or BMI.
In this study the female dimension is slightly more than that for the male but the difference is not statistically significant. P = 0.06. However this difference may be due to the higher BMI in female still. Like the midclavicular measurement (MCL) these minor differences have been said to be of no clinical significance30. This dimension may be closest to the actual cranio-candal length
of the liver than the MCL, and the influence of respiratory excursion of the diaphragm and lung fields is reduced.
The mean APD for this study was 13.8cm (1.5SD) (range 9.6 – 17.2cm).
This is much more than that obtained by Niedarau et al which was 8.1cm (1.9SD). The mean for male and female were 13.8cm (1.5SD) (range 9.6 – 17.2cm) and 13.8cm (1.5SD) (range 9.6 – 16.7cm) respectively.
The diagonal dimension was not measured in any of the previous studies and arguably this study may be the first to make this measurement. This in a way tells us of the transverse diameter of the liver and possible lateral enlargement of the liver. The mean DIA diameter of the liver in this study was 19.8cm (1.3SD) (range 16.4 – 23.3). For males the mean was 20.2cm (1.2SD) while for female it was 19.3cm (1.3SD). The difference was statistically significance.
The last dimension is the PSL. The mean in this study is 10.2cm (1.1SD) (range 6.7 – 12.9). The value is far more than that obtained by Niedarau et al who got 8.3cm (1.7SD) as their mean value31. Possible racial differences cannot be excluded. In their study, they did not compare the sexes. In this study the mean for males was 10.0cm (1.1SD) (range 6.7 – 12.8cm) and for female 10.4cm (1.0SD). The difference between male and female is significant but of weak correlation (P = 0.001, r = 0.187). This difference may be due to the higher BMI in females.
In this study, the weight and BMI corelated with all the dimensions (MCL, MAL, APD, DIA, PSL) (P < 0.001) (r = 0.264, 0.387, 0.316, 0.427, 0.343
respectively for weight and r = 0.218, 0.371, 0.316, 0.323 and 0.325 respectively for BMI). This was the same for the findings of Wolgang et al and Niedarau et al.
although Wolgang study was only on MCL, while the Niedarau et al study covered MCL, ASD and PSL30,31.
For the males the weight and BMI did not show significant correlation with MCL (P > 0.05) but show significant correlation with the other dimensions (MAL, APD, DIA) (P < 0.005). The BML did not show significant correlation with the MCL and PSL (P > 0.05). However, for the females both weight and BML show significant correlation with all the dimensions (P < 0.001). The other studies did not go into details of comparing the sexes. The mean height for this study was 1.7m ( 0.09SD) (range 1.48 – 1.93; for male 1.7m (0.08) and for female 1.6m (0.07SD). The height show weak significant correlation with the MCL and DIA (P < 0.05 r = 0.121; and P < 0.001 r = 0.245 respectively.
It is important to note that most of the previous works have measured only MCL or at best MCL, APD, PSL or MCL, MAL and AAL (anterior axillary line).
In one of the most quoted recent studies by Wolgang who measured only the MCL, it reported that, actually said that to judge liver dimensions by a single measurement, is inappropriate due to varied hepatic morphocyte30. In view of of this, the various dimensions which are simple, easy, and readily reproduceable due to the definite land marks used become handy in assessing hepatomegaly.
The 95% of upper confidence limit for the various dimensions in this study for MCL, MAL, APD, DIA, PSL, are 12.5cm (1.2 SD) 15.3cm (0.9sd), 13.9cm (1.5SD) 20.0cm (1.3SD) 10.3CM (1.1SD) respectively. In this environment,
the values may be used to distinguish and thus better assess individuals with markedly enlarged liver outside the normal range.
CONCLUSION
This study has been able to establish a normal range of liver dimensions in asymptomatic healthy adults in a Nigerian population. This data can be used for comparisons in cases of proven or doubtful hepatomegaly. The study also show a reverse in some of the dimensions of the widely accepted believe of bigger organs in male than female. Although, if corrected for weight and BMI the reversal may not hold and that the perceived reversal is mainly due to increased BMI in females. The study also show that most of the dimension increase with weight and BMI but not all show the same relationship with height. Therefore height is a poor predictor of liver size in this environment. An important observation from this study is the increase in the liver dimensions with age up to age 50 – 60years and a general reduction in all the dimensions from age 60 – 69years.
RECOMMENDATIONS
1. Ultrasound evaluation should serve a complementary role to clinical evaluation for more accurate determination of liver size.
2. More than one dimension should be assessed during ultrasound assessment. The MCL, MAL, APD and DIA are particularly recommended for assessment.
3. Since ultrasound does not make use of ionizing radiation and there is no known side effects at the routine diagnostic frequencies, measurement could be repeated several times and for follow up in monitoring treatment of an enlarged liver.
4. Due considerations should be given to patients age, weight and BMI and possible chest dimensions before conclusions are drawn.
5. Finally, it is hoped that this study will stimulate further studies in the environment in the ultrasound assessment of the dimensions of the liver.
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APPENDIX
QUESTIONNAIRE
Patient Bio data
Serial number ... Age ... Sex ...
Occupation ...
Religion (a) Christianity , Islam , African tradition others ...
Marital status ... Tribe ...
Height ... Weight ...
Social History
1. Are you married? Yes/No Widow , Widower Divorced Separated
2. Do you take alcohol Yes/No
(a) Daily…… (b) Occasionally….. …… (c) Regularly…………..
3. What type? (a) Local gin………, (b) English gin (c)Beer …….
(d) Mixed……….
4. How much per day ...
Past medical History
1. Have you been admitted in hospital before Yes/No
2. If Yes, for how long ...
3. What was the nature of the illness? ...
4. Have you had any liver problem before? Yes/No
5. If Yes what was it ...
6. Have your eyes been yellow before ...
7. If Yes, for how long ...
8. What was the problem? ...
9. Has your spouse(s) eyes been yellow before Yes/No ...
10. Do know what was wrong?...
Drugs History
1. Are you on any form of medication Yes/No
2. If Yes, what are they ...
3. How long have you been on this medication
4. What is this medication for ...
5. Have you been taking Native herbs before or currently on native herbs Yes/No
6. If Yes, for how long? <one month………, <3month ……….
1 year……. 3 years……….
MEASUREMENTS
First Measurement
Second Measurement
Third Measurement
Average
Mid clavicular Mid axillary
Anterio-posterior Diagonal
Parasternal
Variation of normal seen ...