Measurement error of mean sac diameter and crown-rump length among pregnant women at Mulago hospital, Uganda
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Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
BMC Pregnancy and Childbirth
Abstract
Ultrasonography is essential in the prenatal diagnosis and care for the pregnant mothers. However,
the measurements obtained often contain a small percentage of unavoidable error that may have serious clinical
implications if substantial. We therefore evaluated the level of intra and inter-observer error in measuring mean sac
diameter (MSD) and crown-rump length (CRL) in women between 6 and 10 weeks’ gestation at Mulago hospital.
Methods: This was a cross-sectional study conducted from January to March 2016. We enrolled 56 women with an
intrauterine single viable embryo. The women were scanned using a transvaginal (TVS) technique by two observers
who were blinded of each other’s measurements. Each observer measured the CRL twice and the MSD once for each
woman. Intra-class correlation coefficients (ICCs), 95% limits of agreement (LOA) and technical error of measurement
(TEM) were used for analysis.
Results: Intra-observer ICCs for CRL measurements were 0.995 and 0.993 while inter-observer ICCs were 0.988 for CRL
and 0.955 for MSD measurements. Intra-observer 95% LOA for CRL were ± 2.04 mm and ± 1.66 mm. Inter-observer LOA
were ± 2.35 mm for CRL and ± 4.87 mm for MSD. The intra-observer relative TEM for CRL were 4.62% and 3.70% whereas
inter-observer relative TEM were 5.88% and 5.93% for CRL and MSD respectively.
Conclusions: Intra- and inter-observer error of CRL and MSD measurements among pregnant women at Mulago
hospital were acceptable. This implies that at Mulago hospital, the error in pregnancy dating is within acceptable
margins of ±3 days in first trimester, and the CRL and MSD cut offs of ≥7 mm and≥ 25 mm respectively are fit for diagnosis
of miscarriage on TVS. These findings should be extrapolated to the whole country with caution. Sonographers can achieve
acceptable and comparable diagnostic accuracy levels of MSD and CLR measurements with proper training and adherence
to practice guidelines.
Description
Keywords
Mean sac diameter, Crown-rump length, Measurement error
Citation
Ali, S., Byanyima, R. K., Ononge, S., Ictho, J., Nyamwiza, J., Loro, E. L. E., ... & Karamagi, C. (2018). Measurement error of mean sac diameter and crown-rump length among pregnant women at Mulago hospital, Uganda. BMC Pregnancy and Childbirth, 18(1), 1-6. https://doi.org/10.1186/s12884-018-1769-2