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. 2021 Feb 17;2021(1):hoab003.
doi: 10.1093/hropen/hoab003. eCollection 2021.

A short anogenital distance on MRI is a marker of endometriosis

A Crestani  1 , C Abdel Wahab  2 , A Arfi  1 , S Ploteau  3 , K Kolanska  1 , M Breban  1 , S Bendifallah  1   4   5 , C Ferrier  1 , E Darai  1   4   5   6
Affiliations

A short anogenital distance on MRI is a marker of endometriosis

A Crestani et al. Hum Reprod Open. .

Abstract

Study question: Could the anogenital distance (AGD) as assessed by MRI (MRI-AGD) be a diagnostic tool for endometriosis?

Summary answer: A short MRI-AGD is a strong diagnostic marker of endometriosis.

What is known already: A short clinically assessed AGD (C-AGD) is associated with the presence of endometriosis.

Study design size duration: This study is a re-analysis of previously published data from a case-control study.

Participants/materials setting methods: Women undergoing pelvic surgery from January 2018 to June 2019 and who had a preoperative pelvic MRI were included. C-AGD was measured at the beginning of the surgery by a different operator who was unaware of the endometriosis status. MRI-AGD was measured retrospectively by a senior radiologist who was blinded to the final diagnosis. Two measurements were made: from the posterior wall of the clitoris to the anterior edge of the anal canal (MRI-AGD-AC), and from the posterior wall of the vagina to the anterior edge of the anal canal (MRI-AGD-AF).

Main results and the role of chance: The study compared MRI-AGD of 67 women with endometriosis to 31 without endometriosis (controls). Average MRI-AGD-AF measurements were 13.3 mm (±3.9) and 21.2 mm (±5.4) in the endometriosis and non-endometriosis groups, respectively (P < 10-5). Average MRI-AGD-AC measurements were 40.4 mm (±7.3) and 51.1 mm (±8.6) for the endometriosis and non-endometriosis groups, respectively (P < 10-5). There was no difference of MRI-AGD in women with and without endometrioma (P = 0.21), or digestive involvement (P = 0.26). Moreover, MRI-AGD values were independent of the revised score of the American Society of Reproductive Medicine and the Enzian score. The diagnosis of endometriosis was negatively associated with both the MRI-AGD-AF (β = -7.79, 95% CI (-9.88; -5.71), P < 0.001) and MRI-AGD-AC (β = -9.51 mm, 95% CI (-12.7; 6.24), P < 0.001) in multivariable analysis. Age (β = +0.31 mm, 95% CI (0.09; 0.53), P = 0.006) and BMI (β = +0.44 mm, 95% CI (0.17; 0.72), P = 0.001) were positively associated with the MRI-AGD-AC measurements in multivariable analysis. MRI-AGD-AF had an AUC of 0.869 (95% CI (0.79; 0.95)) and outperformed C-AGD. Using an optimal cut-off of 20 mm for MRI-AGD-AF, a sensitivity of 97.01% and a specificity of 70.97% were noted.

Limitations reasons for caution: This was a retrospective analysis and no adolescents had been included.

Wider implications of the findings: This study is consistent with previous works associating a short C-AGD with endometriosis and the absence of correlation with the disease phenotype. MRI-AGD is more accurate than C-AGD in this setting and could be evaluated in the MRI examination of patients with suspected endometriosis.

Study funding/competing interests: N/A.

Trial registration number: The protocol was approved by the 'Groupe Nantais d'Ethique dans le Domaine de la Santé' and registered under reference 02651077.

Keywords: MRI; anogenital distance; endocrine disruptor; endometriosis; fertility; optimal cut-off.

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Figures

Figure 1.
Figure 1.
Measurements of anogenital distance. Anogenital distance (AGD) was measured clinically (C) using a ruler, or after MRI. C-AGD-AC: from the clitoral surface to the anus; C-AGD-AF: from the posterior fourchette to the anus; MRI-AGD-AC: from the posterior wall of the clitoris to the anterior edge of the anal canal; MRI-AGD-AF: from the posterior wall of the vagina to the anterior edge of the anal canal.
Figure 2.
Figure 2.
Flow chart of participants in the study of endometriosis diagnosis by measuring AGD on MRI. AGD, anogenital distance.
Figure 3.
Figure 3.
ROC curves of AGD measures. C-AGD-AF: green; C-AGD-AC: yellow; MRI-AGD-AF: blue; MRI-AGD-AC: red.
Figure 4.
Figure 4.
Definition of an optimal cut-off for MRI-AGD-AF.
See this image and copyright information in PMC

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