H and M lines on MRI proctography
Mixed stress and urge urinary incontinence. Vaginal discomfort. Difficult defecation.
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These images show the measurements taken on an MRI proctogram study, and are based on this case.
The measurements are taken at maximal straining and are as follows:
Bladder neck: 37 mm below line (mild cystocele)
Uterine cervix: 12 mm below line (mild uterine descent)
Anorectal junction: 63 mm below line (moderate anorectal junction descent)
H line: 75 mm (mild hiatal enlargement)
M line: 60 mm (moderate pelvic floor descent)
Anterior rectocele: 36 mm in depth (moderate sized anterior rectocele)
The pubococcygeal line is drawn on a mid sagittal image taken from the evacuatory phase of an MRI proctogram study, from the inferior margin of the pubic symphysis, to the final coccygeal segment, and corresponds anatomically to the plane of the levator muscle. The H line is drawn from the inferior margin of the pubic symphysis to the posterior aspect of the anorectal junction, and represents the diameter of the levator hiatus, and a normal value is < 6 cm. The M line is drawn perpendicularly from the posterior end of the H line to the PCL, and represents the descent of the hiatus, and a normal value is < 2 cm. An increase in the length of the H and M lines over the normal limits indicates pelvic floor laxity.
- Laura García del Salto, Jaime de Miguel Criado, Luis Felipe Aguilera del Hoyo, Leticia Gutiérrez Velasco, Patricia Fraga Rivas, Marcos Manzano Paradela, María Isabel Díez Pérez de las Vacas, Ana Gloria Marco Sanz, Eduardo Fraile Moreno. MR Imaging–based Assessment of the Female Pelvic Floor. (2014) RadioGraphics. 34 (5): 1417-39. doi:10.1148/rg.345140137 - Pubmed