Pelvimetry
Author:
Mikael Häggström [notes 1]
Planning
- Indication
A review in 2003 considered routine performance of pelvimetry to be a waste of time, a potential liability, and an unnecessary discomfort.[1] A woman's pelvis loosens up before birth by hormones, so an investigation before labor do not represent the physiologic capacity of the birth canal. Still, pelvimetry can be indicated when a woman has had failure to progress in a previous pregnancy.
- Choice of modality
Low-dose 3D CT can be used for estimating pelvimetry parameters.[2]
Measurement
| Parameter | Image (maximum intensity projection) |
Definition | Normal measures | |
|---|---|---|---|---|
| Pelvic inlet | Transverse diameter of the pelvic inlet | 
|
13 to 14.5 cm.[2] | |
| Obstetric conjugate |  Median plane |
The line between the narrowest bony points formed by the sacral promontory and the inner pubic arch | 10 to 12 cm.[2] | |
| Pelvic outlet | Interspinous distance | 
|
The line between the narrowest bone points connects the ischial spines | 9.5 to 11.5 cm.[3] |
| Sagittal pelvic outlet diameter | 
|
9.5 to 11.5 cm.[3] | ||
| Intertuberous diameter | File:Low-dose CT scan of intertuberous diameter.jpg | 10 to 12 cm.[3] | ||
Interpretation
This only needs to be done if requested by the clinician, otherwise it is only necessary to state the numerical values of the parameters.
| Normal | Borderline | Narrow | |
|---|---|---|---|
| Sum of inlet measures | >24 cm | 23- 24 cm | < 23 cm |
| Sum of outlet measures | >31,5 cm | 29,5 – 31,5 cm | <29,5 cm |
| Obstetric conjugate | >11,0 | 9,5 – 11,0 | <9,5 |
A sagittal outlet is < 8 cm or interspinous diameter is <7 cm is regarded as narrow, even if the sum of outlet measures is normal.[4]
Report
The length of each of the distances above, but make an interpretation of any narrowing only if requested.
If the images are taken during a pregnancy, note the position of the fetus.
Notes
- ↑ For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.
References
- ↑ "A retrospective review of performance and utility of routine clinical pelvimetry ". Family Medicine 36 (7): 505–7. 2004. PMID 15243832.
- ↑ 2.0 2.1 2.2 "Pelvimetry by Three-Dimensional Computed Tomography in Non-Pregnant Multiparous Women Who Delivered Vaginally ". Polish Journal of Radiology 81: 219–27. 2016. doi:. PMID 27231494.
- ↑ 3.0 3.1 3.2 "Magnetic resonance pelvimetry for trial of labour after a previous caesarean section ". Sultan Qaboos University Medical Journal 10 (2): 210–4. August 2010. PMID 21509231.
- ↑ 4.0 4.1 Kira Kersting (2017-01-04). Kronoberg County Council.
