BS is said to be giant when it weighs 100 gm or more and is more than 4 cm in the greatest diameter [3, 5, 6, 10, 11]. The biggest BS weighed 6294 gm and was reported by Arthure in 1953 and found in a bladder diverticulum [4, 6, 10, 12, 13]. The calculus reported by Randall in 1921 weighed 1914 gm and by Powers and Matfferd in 1952 weighed 1410 gm [13]. Charles Azuwike Odoemene reported on three cases of giant BS from Nigeria the largest one weight 1736 gm [8]. Giant BS is a rare condition in developed countries, and fewer than 100 cases were reported worldwide up to date, of them only 30 cases were reported in English literature up to 2018 [9,14,15,16]. Azuwike Odoemene reported three cases in nine years [8].

We see giant BS more frequently as we reported 4 cases in one year. This may be attributed to difficulties to access health facilities in greater Darfur where people need to travel for long distances to reach the optimum health services. Civil wars and conflicts also led people to suffer for reaching optimum health services.

Giant BS formed in non-healthy urinary bladder secondary to bladder outlet obstruction, neurogenic bladder or foreign body, and recurrent UTI [7, 17], in this series one case had obstructing enlarged prostate, one had tough fibrotic bladder neck, the rest two had recurrent UTI of them one is psychotic. BS is suspected in any patient with recurrent UTI not responding to treatment. There was recurrent UTI following urine stasis in all four cases. Urine culture and stone analysis were not done, so the nature of the stones was not specified.  In literature, it is postulated that urease-positive organisms are predisposed to magnesium, phosphate, ammonium, and carbonate apatite while E. coli was associated with the formation of calcium oxalate and urate stones [6,8]. Most BS are Struvite (triple phosphate) [4,9,15]. Most patients with giant BS present with storage LUTS including dysuria, increased frequency of micturition, hematuria, suprapubic pain, and/or voiding LUTS as urine retention that may eventually lead to hydronephrosis and renal failure [8]. Only in case one in this series there is bilateral hydronephrosis, hydroureter, and impaired renal function. The delayed presentation may be attributed to post-war internal displacement, poverty, ignorance, and lack of facilities with optimum imaging modalities, this was admitted by other authors in developing countries [8]. Contrast-enhanced CT scan is the modality of choice for diagnosis of urolithiasis including uric acid stones, albeit it is not done for any of our patients in this series [4, 9, and 15]. All patients (100 %) in this series had USS abdomen, it is easy, cost-effective, and available with acceptable accuracy in diagnosing giant BS. One case had plain X-ray KUB. Doumi BA in a comparable geopolitics' area used plain X-ray pelvis or USS to diagnose urinary bladder stones [7]. Cystoscopy was done on one patient to assess the prostate and to visualize the bladder wall for other pathology as bladder tumors may coincide with BS [12]. In this series, cystoscopy was useful in the assessment of the prostate, but it was difficult to visualize the entire bladder wall because the stone filled almost the whole cavity. All cases in this series underwent open VL. Three of them were under spinal anesthesia and one was done under general anesthesia because of his psychiatric illness. Open VL is the modality of choice for the treatment of giant BS, it is easy to perform, no need for a drain or catheter unless the procedure is accompanied by other procedures like prostatectomy done simultaneously. [4, 9, 12, 15, 18]. Endoscopic procedures though it has advantages in evaluating and correcting urethra and bladder neck obstruction, it is not suitable for such large stones. [9, 15]. Tan J, Singh reported on the spontaneous passage of two giant bladder stones in females [14].