Rectus diastasis – colloquially called midline hernia – (Greek διάστασις diastasis “splitting, standing apart”; Latin diastasis recti) (English out of alignment; ICD-10 M62.0-: muscle diastasis) is the bilateral standing apart of the straight abdominal muscles (Mm. recti abdominis) in the area of the linea alba.
The abdominal muscles consist of paired skeletal muscles that enclose the abdominal and pelvic spaces and connect the thorax (chest) to the pelvis. The abdominal muscles are divided into three groups according to their location:
- Anterior abdominal wall muscles:
- Musculus rectus abdominis (straight abdominal muscle).
- Musculus pyramidalis (pyramidal muscle)
- Lateral abdominal wall muscles:
- Musculus obliquus externus abdominis (external oblique abdominal muscle).
- Musculus obliquus internus abdominis (internal oblique abdominal muscle).
- Musculus transversus abdominis (transverse abdominal muscle).
- Posterior abdominal wall muscles:
- Musculus quadratus lumborum (quadratic lumbar muscle).
- Musculus iliopsoas (large lumbar muscle).
The rectus sheath is the sheath formed by the aponeuroses (tendon plates) of the abdominal wall muscles Musculus transversus abdominis, Musculus obliquus internus abdominis and Musculus obliquus externus abdominis, which surrounds and guides the Musculus rectus abdominis.
The linea alba is a vertical suture of connective tissue in the middle of the abdomen, extending from the processus xiphoideus (lower part of the sternum) to the symphysis pubica (pubic symphysis).
The most common cause of rectus diastasis is pregnancy. Pregnant women physiologically have a rectus diastasis at the time of delivery. The gap between the straight abdominal muscles expands to make room for the growing baby.
To the extent that a rectus diastasis occurs in a male, it is usually limited to the area above the navel.
Rectus diastasis may also occasionally occur in newborns and infants, but it disappears as soon as the children start walking.
Sex ratio: Women are affected much more frequently than men.
Course and prognosis: As a rule, rectus diastasis regresses on its own after pregnancy. However, 60% of all women still have to struggle with the rectus diastasis 6 weeks after giving birth; 32% still have problems with the overstretching of the abdominal muscles 12 months after delivery.The rectus diastasis should not only be understood as a cosmetic problem, but often there is also a functional disorder. This can lead to back pain – especially in the lower back – as well as buttock and hip pain.If 6 months postpartum (after birth) the rectus diastasis has not regressed on its own, physiotherapeutic measures should be used to support regression. Only in very rare cases does surgery need to be performed.
