Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix

Figures & data

Figure 1.  (a) Transabdominal and (b) transvaginal ultrasound cervical length measurement.

Table I.  Descriptive statistics of the cervical length measurement (mm) performed by transabdominal and transvaginal ultrasound.

Descriptive statistics	Transabdominal	Transvaginal
Mean	34.6	34.8
SD	7.55	6.99
Percentiles:
5	23	21.6
10	26.5	25.9
25	30.5	31.6
50	34.8	36.1
75	38.8	39.1
90	43.3	42.7
95	46.3	44

SD, standard deviation.

Table II.  Differences in cervical length by ultrasound method in the complete study group and stratified by short cervix as determined transvaginally.

Ultrasound method	All studied population mm, mean (SD)	Cervical length mean (SD)
		<25 mm	>25 mm
Transabdominal	34.57 (7.1)	26.6 (9.2)	35.2 (6.4)
Transvaginal	34.81 (6.9)	20.1 (3.8)	36.4 (5.2)
Significance	p = 0.61	p < 0.001	p < 0.01

SD, standard deviation.

Figure 2.  Agreement of cervical measurements < 25 mm (a), or ≥ 25 mm (b) by transvaginal ultrasound with those obtained by transabdominal ultrasound.

Figure 3.  Intra-agreement plots of the cervical length measurement performed by transvaginal (a) or transabdominal (b) ultrasound.