First, etiology

　　To date, it is not clear, and it is considered to have three possibilities:

　　1, Genetic factors This inference only applies to individual cases.

　　2, Secondary to lower urinary tract obstruction Due to lower urinary tract obstruction, secondary megacystis and abdominal distension can occur, leading to poor development of abdominal muscles and also hindering testicular descent. This inference cannot explain all cases, such as those with only poor development of abdominal muscles without other malformations.

　　3, Embryonic developmental disorders Since the muscle, skeleton, kidney, and ureter are all derived from the mesoderm, when the germ layer develops abnormally, it can lead to malformations in related systems. This inference is recognized by most scholars. In summary, the etiology of PBS needs further exploration.

　　Second, pathogenesis

　　1, The most common associated malformation in male patients with reproductive system malformations is cryptorchidism. Welch reported that among 42 male patients, 41 had cryptorchidism, including 37 with bilateral and 4 with unilateral, with an incidence rate of 97.9%. The testes often remain in front of the ureter, and some testes have no pedicle. If the testes are not timely surgically descended to the bottom of the scrotum, it will lead to developmental disorders of germ cells. There are also reports that cryptorchidism in PBS patients can become a seminoma.

　　2, Urological malformations have various forms and a high incidence rate. PBS patients often have renal hypoplasia, solitary kidney, polycystic kidney, renal cysts, or hydronephrosis. In a group of 43 patients reported by Welch, there were 81 renal malformations, with an incidence rate of 91%. Renal failure is the most common cause of death in PBS patients. Renal parenchymal hypoplasia, ureteral and distal urinary tract lesions all affect renal function.

　　3, The lesions of the ureters in PBS patients are often segmental dilatation, tortuosity, and poor peristalsis, and the lesions at the proximal end are often less severe than those at the distal end. Histological examination shows that the muscular bundles of the lower ureter are almost completely replaced by fibrous tissue, lacking cells, and some normal muscles are distributed in a jumping manner. Apart from the distal part, the normal ureteral wall has no ganglion cells, and the structure of the ureterovesical junction is often abnormal, but not necessarily with vesicoureteral reflux.

　　4, The bladder capacity of PBS patients is increased, with various shapes, mainly due to lower urinary tract obstruction and secondary to multiple bladder diverticula. There may be primary diverticula near the bladder ureteral junction, causing vesicoureteral reflux. The inner wall of the bladder is smooth, while the entire bladder wall is uneven in thickness. The diverticulum wall is very thin, with some having only mucosa and not containing other layers of bladder wall tissue. The bladder trigone becomes thin and abnormally extended. The bladder neck often expands, and some can extend to the membranous urethra. Umbilical urachal diverticula at the top of the bladder are common, and they are connected to the umbilicus. It is also not uncommon for the umbilical urachus to remain patent, forming an umbilical urachal fistula.

　　5. The urethra in PBS patients may be atretic or dilated. Reinberg (1993) reported that in 34 PBS cases, 6 cases had urethral atresia, 3 males and 3 females, with a relatively higher incidence rate in females. Kroovand (1982) observed 19 male PBS patients, of whom 13 had urethral dilation, with an incidence rate of over 60%. When the urethra in the descending part of the PBS patient is dilated, the penis may also be large. When the urethra in the prostate part is dilated, fibrous tissue extends and separates the lobules of the prostate. The narrowing of the urethra below the prostate may be caused by the surrounding abnormal tissue pulling.

　　6. Respiratory system malformations: Underdeveloped lungs are a common malformation in individuals with congenital underdevelopment of abdominal muscles and are the main cause of death within the first week of life in neonatal PBS patients. In addition, PBS patients have a low respiratory exchange volume. Kwig et al. (1996) reported their research results, observing that all 9 PBS patients aged 6 to 31 years had poor respiratory function and a low effective respiratory exchange volume. Seven of them had abnormal respiratory movements, with a significant decrease in respiratory exchange volume, especially during expiration. There are also individual cases reported with pulmonary sequestration and lung cysts.

　　7. Musculoskeletal system malformations: PBS patients are more likely to have congenital amputation, hip dysplasia, congenital clubfoot, scoliosis, chest deformities, and other malformations. There are also individual cases reported with bifid sternum.

　　8. Other associated malformations such as non-attached mesentery, malrotation of the intestines, anal atresia, megacolon, abdominal cleft, and umbilical hernia have been reported in several cases. A few cases are associated with various types of congenital heart disease, cleft palate, and other malformations.

　　1. Renal failure: Underdeveloped renal parenchyma, tortuous and dilated ureters, and malformations of the distal urinary tract, as well as urinary tract obstruction, all affect renal function to varying degrees, leading to renal failure, which is the most common cause of death in PBS patients.

　　2. Children with overall underdevelopment and respiratory system malformations have a low effective respiratory exchange volume, leading to chronic hypoxia. This not only affects heart function but also impacts the normal metabolism and growth of the body.

　　3. Abdominal hernias occur when abdominal organs protrude outside the abdomen through underdeveloped abdominal wall muscles, which can lead to abdominal hernias.

　　1. The degree and location of underdeveloped abdominal muscles vary, resulting in significant differences in clinical manifestations. Severe cases may present with the typical 'dried prune abdomen', characterized by the abdomen protruding forward and to the sides, the navel moving upwards, the skin becoming dry and thin with many wrinkles, and the peristalsis of the intestines visible through the abdominal wall. It is also easy to palpate or see the outline of a large bladder, dilated ureters, and polycystic or hydronephrotic kidneys.

　　2. In individuals with underdeveloped local abdominal wall muscles, the area may swell slightly or severely, with part of the abdominal viscera protruding into it, forming an abdominal hernia. The skin covering the area is thin and uneven, and through the thin abdominal wall, the shape of the contained viscera can also be seen.

　　3. Mild abdominal muscle underdevelopment, malformation is mild, the appearance of body posture is close to normal.

　　4. Children with concomitant patent urachus, continuous urinary leakage from the umbilicus, periumbilical skin often occurs irritant rash, accompanied by other congenital malformations of the system, should have their unique clinical manifestations.

　　The etiology of this disease is not yet clear, and it may be related to environmental factors, genetic factors, dietary factors, and emotional and nutritional factors during pregnancy. Therefore, it is impossible to prevent the disease directly by targeting the etiology. Early detection, early diagnosis, and early treatment are of great significance for indirect prevention of the disease. Regular prenatal examinations, for suspected early diseases, can be performed by karyotype examination to clarify, and it is necessary to decide whether to perform an induced abortion based on the severity of the child's lesions.

　　1. Amniotic fluid quantitative analysis:From 15 to 38 weeks of pregnancy, the uterine fluid is aspirated for quantitative analysis, with sodium content below 130 mmol/L and creatinine content above 115 μmol/L, which can prove that the fetal renal function is normal. In cases where the amniotic fluid is less, it sometimes indicates underdevelopment of the fetal lungs.

　　2. Children:Blood creatinine, blood urea nitrogen, creatinine clearance test, etc., are helpful to understand kidney function and the judgment of malformation degree.

　　3. Ultrasound:Ultrasound examination is performed between 20 to 30 weeks of gestation, which can detect obstructive lesions and malformations of the fetal urinary tract, and is also the first choice for diagnosis, which can detect the location of urinary tract malformations and cryptorchidism in children.

　　4. Renal pelvis造影(IVP) and micturition bladder造影:Carried out when necessary, it can clarify renal function, the degree and location of urinary tract malformation.

　　5. CT scan:It can understand the degree of malformation of the abdominal wall muscles, respiratory system, and urinary system.

　　1. What foods are good for the abdominal muscle deficiency syndrome

　　1. Strengthen nutrition, eat more dietary foods rich in protein and vitamins, such as lean meat and shrimp.

　　2. Eat easily digestible foods such as chicken and fish.

　　3. Eat a light diet, and eat more fresh fruits and vegetables to ensure adequate intake of vitamins.

　　2. What foods should be avoided for abdominal muscle deficiency syndrome

　　1. Avoid foods that can easily cause intestinal bloating, such as milk, soy milk, eggs, and other foods.

　　2. Avoid smoking, alcohol, greasy, fried, moldy, and salted foods.

　　3. Avoid high-fat foods such as fatty meats and other foods

　　1. Treatment

　　1. The symptomatic treatment for respiratory insufficiency: Respiratory insufficiency is a major cause of death within the first week after birth, caused by underdevelopment of the lungs and low muscle function of accessory respiratory movements. There is no radical treatment method, only symptomatic treatment: oxygen therapy, clearing secretions from the respiratory tract, and using a ventilator to assist breathing when necessary. Most cases can only delay death, while a few underdeveloped lungs can gradually develop and improve lung function.

　　2. Protecting renal function and releasing urinary tract obstruction as soon as possible, actively preventing and treating urinary tract infections, is the preferred therapy for protecting renal function. Different measures should be taken to relieve urinary tract obstruction according to the child's overall condition, the location and severity of urinary tract obstruction. In cases where the child's condition is poor and the obstruction is severe, emergency surgery should be performed to perform nephrostomy, ureterostomy, or cystostomy at the proximal side of the obstruction to divert urine to the outside. After the general condition improves, the obstruction can be根治ed by surgery. There are many methods of radical surgery, and they should be selected according to the condition of the lesion.

　　3. The treatment for mild abdominal muscle hypoplasia is still good, and those who are not restricted in labor do not need treatment. They can also wear elastic abdominal bands or underwear. For those with local abdominal muscle hypoplasia that has formed an abdominal wall hernia, local repair surgery should be performed.

　　4. Due to the rarity of PBS, reconstructive surgery for severe abdominal muscle hypoplasia has a small number of cases, and the experience is not rich. The main methods of surgery can be summarized into three categories.

　　II. Prognosis

　　1. The mortality rate of PBS patients is relatively high, and the causes of death in the neonatal period are mostly pulmonary hypoplasia or renal hypoplasia. During the growth process, the causes of death are mostly renal failure.

　　2. Druschel observed 60 neonatal patients, 36 died, with a mortality rate of 60%. Most of those who died in the first week after birth died due to pulmonary hypoplasia. Pillion followed up 14 PBS cases for 20 years, 4 died within a month after birth, 2 due to sepsis, and another 2 due to renal failure. Among the remaining 10 cases, 6 were over 10 years and 6 months old with normal renal function. Another 4 were aged 8 to 17 and suffered from chronic renal failure, including 3 in the late stage of renal failure. Between 1970 and 1987, Reinberg followed up 32 PBS children, 11 died due to renal failure in the neonatal period or early infancy, 9 were autopsied, 6 with diffuse severe renal hypoplasia, and the 10 longer survivors also had renal dysfunction. Renal histology was performed on 13 cases, with 9 specimens showing regional renal hypoplasia accounting for 25% of the entire renal parenchyma, mainly due to lower urinary tract obstruction and pyelonephritis, which damaged the renal tissue and affected renal function.