The child was a female, 12 years old. She was admitted to the hospital with “recurrent urinary leakage for 8 years”. She had fractional urination with a volume of about 30m-50ml each time. signs: average nutrition, moderate development. The abdomen was flat, soft, without pressure pain, no obvious masses were palpated, and the liver and spleen were not palpable. There was no pressure pain in the bilateral kidney area, ureteral point and bladder area, the limbs moved freely, the muscle strength and muscle tone of the limbs were normal, and the gait was normal. There was no abnormal elevation or depression in the sacrococcygeal region. CTU: left renal hypoplasia with cortical thinning of about 2-5 mm; bladder morphology was abnormal with long pear shape, rough wall and small papillary protrusions; neurogenic bladder was considered; IVU: delayed visualization of left renal pelvis and calyces, dilated left ureter throughout and slightly dilated right lower segment. The bladder was “Christmas tree” like, consistent with neurogenic bladder changes. MRU: Hypoplastic left kidney, neurogenic bladder; occult spina bifida in the fifth lumbar vertebra and the first sacral vertebra, with the end of the spinal cord at the T1 level.ECT: Poorly visualized left kidney, basically non-functional. Urodynamic examination: decreased bladder capacity, increased residual urine volume, maximum bladder capacity of 80 ml, decreased bladder compliance of 3.25 ml/cmH2O, end-filling Pves:69 cmH2O. cystoscopy: no narrowing of the bladder neck opening, bladder floor was less smooth, all bladder walls except the bladder floor were intertwined in a muscle trabecular pattern, and the bladder apex was convex upwards, consistent with neurogenic bladder manifestations. Admission diagnosis: small volume hypertonic bladder, left vesicoureteral reflux, and left-sided reflux nephropathy. After adequate preoperative preparation, left ureteral bladder reimplantation + sigmoid cyst enlargement + cystostomy was performed. At the time of discharge 1 month after surgery, the child had no further urinary leakage. Intermittent catheterization showed a bladder volume of about 200-240 ml; in February postoperatively, it showed a bladder volume of about 300-400 ml and a residual bladder volume of about 30 ml; in March postoperatively, cystoscopy and removal of the left ureteral stent tube were performed, and the mucosa at the top of the bladder was as normal (at the intestinal substitution bladder), with no trabeculae formation or diverticulae; in May postoperatively, there was no more incontinence during the day or night, and intermittent catheterization had been stopped without No medication was applied, no urinary tract infection, bladder volume was maintained at 350-400 ml, and normal study and life resumed. Discussion: Small volume hypertonic bladder is a type of non-neurogenic voiding dysfunction, which can be clinically manifested as urinary frequency, urgency, incontinence, enuresis, increased nocturia or difficulty in urination, but without neurological disease, long-term recurrent urinary tract infection can lead to instability of the detrusor muscle and low compliance bladder; imaging manifests as small bladder volume, bladder wall thickening, trabeculae or diverticulum formation; urodynamic manifests as bladder volume The urodynamic manifestations are decreased bladder capacity, increased bladder pressure during the filling phase, and often strong contractions of the detrusor muscle at the end of filling. The principle of treatment is to eliminate infection and susceptibility factors. However, in this child, with a long history of disease and a long-term state of bladder hypertension that has led to left-sided reflux nephropathy and a severe decrease in left renal function, conservative treatment alone is hardly effective; in fact, the child had also undergone home-cleaning intermittent catheterization for several years, but his condition was not ideally controlled. The main purpose of bladder enlargement is to increase bladder capacity and compliance and to reduce intravesical pressure in order to obtain good urinary storage and voiding function and to avoid functional impairment of the upper urinary tract.Buson et al. first reported a single-layer intestinal plasma muscle layer bladder enlargement with preservation of bladder mucosa.This method combines bladder self-expansion with intestinal plasma muscle layer enlargement, which avoids both the disadvantages of bladder self-expansion prone to bladder lining contracture and It is also less prone to complications such as metabolic disorders and acid-base imbalance resulting from full-layer gastrointestinal cystoplasty due to preservation of the gastrointestinal mucosa, as well as contracture and fibrosis of the plasma muscle layer due to urinary irritation of the plasma muscle layer after simple enlargement of the intestinal plasma muscle layer. The application of the plasma muscle layer to cover the bladder mucosa can increase the bladder emptying capacity and obtain a larger bladder volume than simple resection of the detrusor muscle, and the commonly used bowel segments are the sigmoid colon, ileocecal and small intestine. In this case, we used sigmoid bladder enlargement with good results. In conclusion, if the history of small-volume hypertonic bladder is long and conservative treatment is not effective, bowel bladder enlargement can be considered.