Crown-Rump Length

Embryology - 16 Apr 2024 Expand to Translate
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Introduction

Crown-rump length measurement of a human embryo (Carnegie stage 13)

(CRL) A measurement used in embryology to more accurately stage the early embryo, also historically called the "greatest length" (GL). Measured from the curvature at the top (crown) to the curvature at the bottom (rump) of the "C-shaped" early embryo.

Used in clinical ultrasound as a measurement between the periods of 7 to 13 weeks as an accurate estimation of the GA gestational age.

Links: Embryonic Development | Carnegie Stage Comparison | Carnegie Institution - Contributions to Embryology | Human Embryo Collections

Ultrasound CRL

Note that clinical GA gestational age is about 2 weeks more than the fertilisation age.

Fertilization and Gestational Age - Crown-Rump Length (ultrasound)

Fertilization Age (days)	Gestational Age GA (week.day)	Crown-Rump Length (mm)
37	5.2	1
38	5.3	2
39	5.4	3
40	55	3
41	5.6	4
42 Week 4	6	4
43	6.1	5
44	6.2	6
45	6.3	7
46	6.4	8
47	6.5	9
48	6.6	10
49 Week 5	7	11
50	7.1	11
51	7.2	12
52	7.3	12
53	7.4	13
54	7.5	14
55	7.6	15
56 Week 6	8	17
57	8.1	18
58	8.2	19
59	8.3	20
60	8.4	21
61	8.5	22
62	8.6	22
63 Week 7	9	23
64	9.1	24
65	9.2	26
66	9.3	27
67	9.4	28
68	9.5	29
69	9.6	31
70 Week 8	10	34
71	10.1	36
72	10.2	37
73	10.3	38
74	10.4	39
75	10.5	39
76	10.6	40
77 Week 9	11	44
78	11.1	45
79	11.2	47
80	11.3	48
81	11.4	52
82	11.5	55
83	11.6	56
84 Week 10	12	57
85	12.1	58
86	12.2	60
87	12.3	61
88	12.4	63
89	12.5	64
90	12.6	65
91 Week 11	13	68
92	13.1	70
93	13.2	72
94	13.3	74
95	113.4	76
96	135	77
97	13.6	80
98 Week 12	14	81
99	14.1	84
100	14.2	85
101	14.3	86
102	14.4	87
Reference: Table data measured by ultrasound, adapted from Westerway (2015) PDF and^[1] Links: ultrasound \| Fetal Development

Gestational Age and Crown-Rump Length (measured by ultrasound)

Gestational Age GA (week.day)	Crown-Rump Length (CRL)
5.2	1
5.3	2
5.4	3
55	3
5.6	4
6	4
6.1	5
6.2	6
6.3	7
6.4	8
6.5	9
6.6	10
7	11
7.1	11
7.2	12
7.3	12
7.4	13
7.5	14
7.6	15
8	17
8.1	18
8.2	19
8.3	20
8.4	21
8.5	22
8.6	22
9	23
9.1	24
9.2	26
9.3	27
9.4	28
9.5	29
9.6	31
10	34
10.1	36
10.2	37
10.3	38
10.4	39
10.5	39
10.6	40
11	44
11.1	45
11.2	47
11.3	48
11.4	52
11.5	55
11.6	56
12	57
12.1	58
12.2	60
12.3	61
12.4	63
12.5	64
12.6	65
13	68
13.1	70
13.2	72
13.3	74
113.4	76
135	77
13.6	80
14	81
14.1	84
14.2	85
14.3	86
14.4	87
Reference Table adapted from Westerway (2015) PDF and <pubmed>11065037</pubmed>