Introduction
Diverticulum is a tissue sach that is isolated from the tissue and associated with it  through a vent. One of the diseases of the urinary system is the diverticulum of the bladder, which can be seen in single or multiple sizes [1]. These lesions may be congenital and in the early stages of childhood they develop symptoms that are commonly diagnosed during this period, or may be acquired, resulting from narrowing of the urinary tract from the bladder [2] (for example, prostate hypertrophy) [2, 3]. Bladder diverticulum is a bladder urethral hernia through the muscular wall of the bladder wall [4]. This causes a different size structure to create a thin, full-blown urinary wall adjacent to the bladder that is connected to the bladder by a narrow vent or neck.
In the diverticular wall, the smooth muscles are scattered, inactive and non-coherent, and are unable to drain urine from diverticulum when urinating, and there is always a large amount of urinary residual in the diverticulum that is detected in diagnostic imaging techniques.
Bladder diverticules are divided into two congenital and acquired types. Congenital diverticules are characterized by a prevalence of 1.7% in childhood and are more common in boys [5, 6]. They are usually single and large and are caused due to congenital weakness at the urethrovesical connective area [1, 7]. Whether there is a evidence of a genetic disorder in the congenital type with diverticulum prevalence or not is not clear. However, since this complication has been reported in twins, it is likely to have an autosomal dominant aspect [8].
Acquired diverticulum of the bladder is due to blockage in the urinary tract and usually occurs in men over 60 years of age [2]. The most common cause is bladder hypertrophy (in 1 to 6% of patients with prostatitis), but there are other causes such as stones and tumors, and so on. Acquired diverticules are numerous and smaller [3, 9].
Bladder diverticulum shows itself as a frequent urinary tract infection [4, 10, 11], a feeling of incomplete urinary emptying [6, 12], urinary reflux [1, 13], abdominal pain, fever, and pain in the lower abdomen, Someties following the track of the cause, hemorrhage and urinary tract disorders are discovered.
To diagnose this disease, ultrasound, CT scan and MRI are required [14], but the best diagnostic method is Voiding Cystouetrography (VCUG).
 
Patient and methods
A 33-year-old woman, nulligravida, referred to the women's clinic with a complaint of pain at the lower abdomen for 2 years. Menstruation was normal. No gastrointestinal disorders, and urinary problems such as dysuria and repeat urination, incontinence, frequent urinary tract infections, and so on were mentioned by the patient. The patient did not have a history of surgery, kidney disease, trauma, or certain medications.
There was also no positive point in his family history. In the physical examination, the symptoms were normal. Abdomen was soft at the touch, there was no tenderness and rebound of tenderness and no mass was obtained. A gynecologic examination was performed. The uterus and the adnexa were normal. After bladder discharge, vaginal ultrasonography was performed and a cyst with a size of 8 × 9 cm in the pelvis was observed without any association with the uterus and adnexa.
The abdominal and pelvic grafts were requested by injection and without injection. Again, a cyst with a size of 10 × 9 cm was observed behind the bladder, and all the organs of the abdomen and pelvis, including the kidneys and urethra, were healthy. Therefore, a diagnostic laparoscopy was performed, in which the sticky masses to the anterior abdominal wall without any connection to the uterus, uterine tubes of the ovaries and intestinesof the same size as mentioned was noted. For the patient, Foley's catheter was fixed for 15 days, after which the patient had no problem (Figure 1).
It seemed that the mass was in the path [15], but with a closer examination, it was noticed that there was association of it with the medial Umbilical ligament. Therefore, the decision was laproscopy.
During laparotomy, diverticulum 8 x 8 cm above the bladder was associated with a bladder cavity osteomy.
After careful examination and observation of the pathway of the urethra to the bladder and to ensure their health, diverticulum was carefully removed from the bladder with a high degree of care and then the bladder tissue was reparied in two layers.
In the end, to ensure correct repair, methylene blue was insered into the bladder through the forely catheter [16],  that no defect was observed in the repaired tissue and the sutured layer.
 
Discussion
The mentioned report is a rare case of bladder diverticulum and is a rare case in the differential diagnosis of pelvic masses.
The patient did not have any urinary symptoms. In laboratory studies, there was no speical urine disorder. Imaging studies also reported a healthy urine system.
Laparoscopy played the role of a precise diagnostic tool, and the complete knowledge of the intra-abdominal organs causes the surgeon to reliably identify the nature of the lesion and resolve the problem.
Only if bladder diverticulum is a small and without clinical symptoms or if the general condition of the patient does not let the surgery, the surgery can be avoided. However, if clinical symptoms occur and the general condition of the patient is also possible, diverticulectomy can be done. . During diverticulectomy, there is a risk of injury to the intestine, uterus, bladder, and especially fistula formation. Therefore, surgical procedures should be carefully done and preferably through laparotomy.

Conclusion
Diseases should not necessarily reveal themselves with the typographical symptoms mentioned in the texts, and the important point is that paraclinical methods are not always accurate and recognizable. Laparoscopy can be considered as a precise diagnostic method and fully reveal the organs of the abdomen and pelvis.

Acknowledgments
Dear colleagues in the operating room of the Sarem Specialized Hospital are appreicated.
Ethical permission
The case was not found by the authors.
Conflict of Interest
The case was not found by the authors.
Financial support
Financial support is provided by the Sarem Fertility and Infertiltiy Research Center.
Contribution of Authors
Abotaleb Saremi (first author), author of article/methodologist/principal researcher/author of discussion part (60%); Mahboubeh Rasekhi (second author); author/principal researcher/author of disussion part (40%).