Diastasis of the rectus abdominis muscles

The rectus abdominis is two vertical muscles located between the costal arch and pubic bone. The right and left rectus muscles are interconnected by the so-called white line - a thin and strong tendon membrane of white color (which is why it is called the “white line”). White color gives it a large amount of strong fibrillar (fibrous) protein of collagen and the absence of muscle fibers. The white line has the largest width in the upper part, and gradually narrows downward, where in some people it may even be absent below the navel, while the right and left rectus muscles can be in close contact with each other. According to G. Beer, the normal width of the white line at the level of the xiphoid process is up to 15 mm, at the level of 3 cm above the navel to 22 mm, and at the level of 2 cm below the navel to 16 mm ^[2] .

In the navel area, the white line has a rounded hole with a diameter of up to 10 mm normal. Large vessels pass through this ring in the embryonic period, which obliterate after childbirth. The umbilical ring is closed by a rather thin umbilical fascia (connective tissue membrane) ^[3] . If the umbilical ring is stretched more than 10 mm, there is a risk of developing an umbilical hernia.

Diastasis is understood as the weakening and thinning of the white line, when it ceases to hold the rectus abdominis muscles in the correct position, and they begin to diverge to the sides (see figure).

Diastasis of the rectus muscles occurs in three categories of patients:

1. Diastasis in women associated with pregnancy
2. Diastasis in newborns is a consequence of insufficient development of the anterior abdominal wall and is more common in premature babies.
3. Diastasis in adults (including men) that is not associated with pregnancy is rare and may be due to general dystrophic tissue changes. For example, diastasis is relatively common (> 3%) in men with HIV ^[4] .

Most often in clinical practice, diastasis associated with pregnancy occurs. Such diastasis in the third trimester of pregnancy is present in most women, it is transient (temporary), and in most cases passes independently during the first year after childbirth. Nevertheless, approximately 30% of them postpartum diastasis of the rectus muscles remains permanently ^[5] .

Thus, in this problem, postpartum diastasis in women is definitely dominant and of the greatest practical importance.

The development of diastasis of the rectus muscles as pregnancy progresses is a natural and almost physiological phenomenon. According to the literature, in the third trimester of pregnancy, diastasis of the rectus muscles occurs from 66% to 100% of cases ^{[6] [7]} . An increase in the volume of the pregnant uterus leads to an increase in intra-abdominal pressure and stretching of the anterior abdominal wall. In addition, the development of diastasis contributes to a decrease in the strength of collagen in connective tissue as a result of physiological changes in the body of a pregnant woman. The fact is that during pregnancy in the woman’s body, the production of the hormone relaxin increases sharply ^[8] . The biological function of this hormone is to inhibit the synthesis of collagen and stimulate its breakdown. As you know, collagen is the basis of the strength of connective tissue. Accordingly, a decrease in the amount of collagen in the tissues is necessary to prepare for childbirth in order to ensure maximum extension of the birth canal. But the effect of relaxin is not limited to collagen of the tissues of the birth canal, it has a general effect on the body ^[9] , including the tissue of the anterior abdominal wall.

A direct correlation was shown between diastasis and the presence of such features as a woman’s age, obesity, cesarean section, multiple pregnancy, fetal macrosomia (large fetal size), flabby muscles, polyhydramnios (excess production of amniotic fluid), and the number of previous pregnancies ^{[10 ]} .

It was shown that the edges of the rectus muscles begin to diverge to the sides, starting from the 14th week of pregnancy, and this process continues until the time of birth ^[11] . The decrease in diastasis begins immediately after childbirth, and continues at a rapid pace up to 2 months, after which this recovery process is very much slowed down ^[12] . If diastasis exists for a year or more, natural self-healing cannot be expected.

Currently, two classifications of diastasis of the rectus abdominis muscles are best known: the classification of R.P. Askerkhanov and classification F. Nahas.

Classification R.P. Askerkhanova ^[13] refers to 1962 and is based on measuring the width of diastasis:

1. First degree: diastasis width from 2.2 to 5 cm
2. Second degree: diastasis width from 5.1 to 8 cm
3. Third degree: diastasis width more than 8.1 cm

F. Nahas developed a general classification of muscle aponeurotic weakness and protrusions of the anterior abdominal wall. He classifies isolated postpartum diastasis of the rectus muscles as type A.

Nahas Classification ^{[14] [15]} :

Despite the absence of a decisive role for measurements in the diagnosis and choice of treatment for diastasis, many studies are devoted to the study of this issue. In most cases, the maximum divergence of the edges of the muscles does not exceed 5 cm ^[16] . However, sometimes diastasis can reach extreme degrees of severity ^{[K 2] [K 3]} .

When measuring the divergence of the rectus abdominis muscles, they are initially guided by data on the normal parameters of the white line. So, according to Rath ^[17] , the normal width of the white line is as follows:

Under the age of 45 years:

• At the navel level, the distance between the rectus muscles should not be more than 27 mm
• Not more than 10 mm above the navel
• No more than 9 mm under the navel

Over the age of 45 years:

• At the navel level, not more than 27 mm
• No more than 15 mm above the navel
• No more than 14 mm under the navel

Another well-known study, which studied the normal width of the white line, belongs to researchers from Switzerland: Gertrude Beer et al. According to their data ^[2] , normally the width of the white line at the level of the xiphoid process is up to 15 mm, at the level of 3 cm above the navel to 22 mm, and at the level of 2 cm below the navel to 16 mm.

There are various approaches to the diagnosis of diastasis. In most cases, the diagnosis can be made clinically, without resorting to additional instrumental methods. In this case, inspection, palpation and simple measurements are enough. Sometimes, especially for scientific purposes, additional instrumental and hardware methods are used, for example, ultrasound (ultrasound) or CT (computed tomography).

Inspection in a standing position makes it possible to see diastasis in bright cases when a woman does not have subcutaneous fat, and her muscles are well developed. In this case, diastasis is determined visually in the form of a vertical defect between the rectus muscles. In the case when the patient strains the abdominal press, a keel-like longitudinal protrusion is observed in the diastasis zone. This protrusion is especially good if it is noticeable if the patient in the supine position is asked to raise her head and legs ^{[K 4]} .

You can palpate the internal edges of the muscles, determine the vertical defect between them, and if necessary, even measure the width of the defect with a ruler.

Ultrasound examination may be required in some cases, for example, if there is an overweight patient, when examination and palpation do not give an unambiguous clear picture. Ultrasound clearly sees the layers of the anterior abdominal wall and allows you to accurately measure the width of the diastasis at different levels.

CT is used extremely rarely in the diagnosis of diastasis, mainly in scientific research.

The course of diastasis is favorable and does not give serious complications that can be life-threatening. However, quite often there are functional disorders that are the result of diastasis.

The fact is that the abdominal muscles provide dynamic stability and control of the spine. In this regard, they work as a single functional system. In the case when the rectus abdominis muscles are not connected correctly using the white line aponeurosis, they cannot contract effectively. The muscles of the limbs in their work are based, inter alia, on the intra-abdominal pressure created by the abdominal press. In the presence of diastasis, the muscles work uncoordinated. At the same time, to perform daily physical exertion, the body is forced to redistribute the load to other departments, for example, to the back. In this regard, problems such as ^[18] may arise:

• Incorrect body position
• Lumbar Pelvic Pain
• Physical discomfort due to back pain
• Corset instability

In addition, the appearance of constipation can be noted from additional functional disorders.

It should be borne in mind that diastasis of the rectus abdominis muscle is not a hernia ^{[19] [20]} . The main difference between diastasis and hernia is that with simple diastasis there are no defects (holes) in the white line. The white line can be stretched, thinned, but there are no holes in it. At the same time, with a hernia there is always a defect (hole) in the white line. Through this hole, abdominal organs can exit under the skin.

In the case when diastasis of the rectus muscles is combined with a hernia, then there is a hernial defect in the stretched, weakened white line (see figure). Most often, umbilical hernia is associated with diastasis ^{[K 5]} . The presence of a hernia is an additional indication for surgery, since there is no chance of self-healing with a hernia. Surgery for diastasis simultaneously removes concomitant umbilical and other hernias ^[21] .

• Avoid lifting weights. If you must lift something heavy, bend your knees and straighten your back.
• Avoid any movements and exercises that may lead to further muscle divergence. Discuss this issue with your doctor.
• Support your stomach every time you have to strain your abdominal muscles, for example, when coughing, sneezing, laughing, do not let the diastasis protrude.
• Wearing a brace or corset to support the abdominal wall is recommended during the year after birth.
• During pregnancy itself, diastasis should not be treated.
• If you feel that quite a lot of time has passed, but your diastasis has not begun to improve, consult a specialist.

Despite the extensive medical literature on diastasis, there is no consensus on this issue.

In a number of studies (not randomized), a conclusion is made about the effectiveness of exercise to reduce the distance between the rectus muscles. ^{[23] [24] [25] [26] [27] [28]} .

Other authors came to the conclusion that physical therapy for diastasis does not give satisfactory results. Thus, in a study by Emanuelson P. et al ^[29] , it turned out that 87% of patients were dissatisfied with the exercise therapy program for the treatment of diastasis, and after the completion of this program they decided to resort to surgical treatment. Moreover, qualitative studies (that is, randomized controlled trials performed according to strict biomedical standards) concluded that there was no effect of exercise on rectal diastasis ^[30] .

Even among supporters of physiotherapy exercises, there is no common point of view on the problem; they could not develop a generally accepted protocol for the use of physiotherapy exercises for diastasis. It is not clear which exercises can be considered effective. The most commonly used exercises aimed at training the abdominal press (aimed at the rectus and transverse muscles), working out the correct technique of movement and lifting weights. Much attention is paid to training precisely the transverse muscles (Pilates, functional training, Tupler technique and using bandages and ribbons), Noble training (using manual retention of the rectus muscles in the correct position against the background of physical activity). A number of authors recommend avoiding exercises directly aimed at the rectus muscles, and avoiding any accidental load on these muscles, such as lifting the legs while lying down, lifting weights, and a strong cough ^{[23] [24]} .

Thus, the most balanced should be considered the point of view expressed by DR Benjamin et al. Based on the study of extensive literature data, they came to the conclusion that physical education may help with diastasis, but may not help ^[31] .

In addition, there are two popular commercial exercise therapy programs for diastasis:

• The Tupler Technique ^{[K 6]} , developed by nurse and trainer Julie Tupler ^[32] , includes 4 components: sitting and lying exercises, exercises to strengthen the transverse muscles, training to get up. The author of the method considers the 4th component to be extremely important - the use of special tapes to help avoid muscle divergence during exercise.
• The MuTu System ^{[K 7]} , developed by the Wendy Powel trainer, consists of 12-week low-intensity exercises. The author of the technique does not concentrate on the abdominal muscles, she believes that diastasis is a result of a general weakening of the muscular corset and improper posture. Accordingly, her exercises are aimed at creating the correct posture and strengthening the muscular corset of the body. She believes that as these two goals are achieved, diastasis disappears on its own.

In the event that after delivery 1 year or more has passed, diastasis will not disappear. In this case, the operation is the only way to solve the problem. In the presence of concomitant diastasis of the umbilical hernia ^{[K 8]} , surgery is again the only possibility.

An operation can be performed if:

• at least a year has passed since childbirth,
• the woman does not plan new pregnancies,
• abdominal muscles are generally in good condition

All operations with diastasis are divided into 2 large groups:

• Cutting operations
• Endoscopic surgery, without incision, through punctures

Sectional Surgery

Surgery through an incision is currently done only in the presence of sagging and excess skin, when it is planned to remove such excess. Surgery through an incision in cases where removal of excess skin is not required is morally obsolete, since it is not optimal from a cosmetic point of view (especially for vertical incisions along the midline - see photo).

In those cases when there is sagging and excess skin, the removal of "excess" skin is combined with the elimination of diastasis. This combined operation is called "abdominoplasty . " The skin incision during this operation can be done depending on the specific situation, most often a horizontal incision is made above the womb along the “bikini line”. At the same time, the elimination of diastasis is always done the same way - in the vertical direction, by stitching the edges of the rectus muscles. In cases where the patient has a concomitant hernia, the hernia is simultaneously eliminated.

Endoscopic surgery

These operations are done without performing a cut (through punctures) or through a cut of minimum length. All actions are monitored on the monitor screen, where the image is transmitted from a medical video camera. Naturally, surgery without an incision is much more beneficial from a cosmetic point of view (see figure). In addition, an important factor is a significant reduction in the frequency of complications compared with open operations through an incision ^[33] .

Endoscopic surgery is possible both by simple stitching of the edges of the rectus muscles ^{[K 10]} , and by additional installation of the hernial mesh in potentially weak spots ^{[K 11]} .

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