Metastatic involvement of the male genitourinary tract by lung cancer is exceedingly rare. We report a 56-year-old man with metastatic lung adenocarcinoma (initial stage T3N2M1b) under pembrolizumab, who presented with severe pelvic pain. Pelvic magnetic resonance imaging and computed tomography demonstrated a large mass with an imaging epicentre favouring the left seminal vesicle, involving the prostate and fistulising to the distal rectum, without pelvic ascites or peritoneal disease. A total PSA of 0.81 ng/mL and a previous negative prostate biopsy made a primary prostatic malignancy less likely. Biopsy of the rectal component revealed a poorly differentiated carcinoma with an immunophenotype (CK7+, TTF-1+, p40-, CDX2-, NKX3.1-, PAX8-) consistent with metastatic adenocarcinoma of pulmonary origin. The patient underwent palliative pelvic radiotherapy, with improvement of pelvic pain; he subsequently developed pneumaturia and faecaluria and died eight months later from disease progression. Seminal vesicle metastasis from lung carcinoma has been reported previously; to our knowledge, however, this is the first report presenting with rectal fistulisation. This case highlights a diagnostically challenging presentation and the need to consider metastatic disease when evaluating atypical seminal vesicle masses in oncological patients.

Rectoprostatic fistula (RPF) is an exceedingly rare but severe complication of transrectal ultrasound (TRUS)-guided prostate biopsy. It typically represents the terminal stage of a post-biopsy prostatic abscess that perforates the Denonvilliers' fascia. We present a case of RPF successfully managed through a conservative "urinary-first" strategy. A 70-year-old male with type 2 diabetes mellitus and a glycated hemoglobin level of 8% presented eight weeks following a TRUS-guided biopsy with pathognomonic symptoms of fecaluria, pneumaturia, and urine passage per rectum. The patient had a history of recurrent Enterococcus faecalis urinary tract infections post-procedure. Digital rectal examination and multi-modal imaging (voiding cystourethrography, cystoscopy, and MRI) confirmed a Rivera class II rectourethral communication. Initial management with a transurethral Foley catheter was complicated by recurrent obstructions. A transition to a "dual-drainage" strategy, utilizing both a urethral catheter and a suprapubic tube (SPT), was implemented to ensure superior anatomical rest. After four weeks of diversion, follow-up cystoscopy and sigmoidoscopy confirmed complete spontaneous closure of the fistula. In high-risk patients, particularly those with diabetes, persistent post-biopsy symptoms should prompt immediate investigation for a prostatic abscess to prevent fistulization. This case highlights that a conservative approach using dual urinary drainage (SPT and Foley) can effectively facilitate secondary intention healing, potentially sparing patients from the morbidity of major reconstructive surgery.

Colovesical fistula (CVF) is an uncommon but clinically significant complication of diverticular disease and colorectal surgery, particularly in the postoperative setting. We report the case of a 49-year-old man who developed pneumaturia and fecaluria following elective sigmoid resection for diverticulitis. Sequential imaging with contrast-enhanced computed tomography (CT) and a water-soluble contrast enema documented the progression from pelvic abscess formation to a well-defined colovesical fistula, with associated extensive soft tissue involvement. Serial CT examinations were crucial for identifying the fistulous tract, evaluating disease evolution, and guiding conservative management. This case highlights the key role of longitudinal multimodal imaging in the diagnosis and management of complex postoperative CVF.

Acute epididymo-orchitis (AEO) is an uncommon complication of colovesical fistula (CVF). We present the first documented case of a patient requiring emergency orchidectomy for recurrent AEO, complicated by intratesticular necrosis and a scrotal wall abscess, secondary to an undiagnosed diverticular CVF. Definitive management involved a laparoscopic high anterior resection, employing trans anal natural orifice specimen extraction, to cure the fistula. This case underscores the importance of maintaining a high index of suspicion for rare anatomical abnormalities such as CVF in patients presenting with recurrent bacterial AEO, across specialties for both the urologist and colorectal surgeon. Early and thorough investigation is crucial to avoid the severe complications of untreated diverticular disease-particularly in individuals with significant intra-abdominal adiposity, where classic signs of peritoneal inflammation may be absent. Delayed diagnosis can lead to serious outcomes, including testicular loss and life-threatening sepsis.

A fistula is an irregular connection between two epithelialized surfaces. It can be classified or named based on which organs it connects. A connection between the colon and the bladder is termed a “colovesicular fistula.” To understand this disease process and the operative planning, clinicians must understand the intricate anatomy of the pelvis and the organs it contains. Anatomy Sigmoid Colon Sigmoid colon begins as the descending colon crosses the pelvic brim. The sigmoid colon is relatively mobile compared to the more fixed descending colon. Sigmoid colon varies in length ranging from 15 to 50 cm (average of 38 cm). The rectosigmoid junction (defined by [1] located at the level of the sacral promontory or [2] where the taeniae converge) marks the transition from the sigmoid colon to the rectum. The rectum is bordered anteriorly by Denonvilliers’ fascia, which separates the rectum from the prostate/seminal vesicles in men, and separates the rectum from the vagina in women. Histologically the colon has four layers, from deep to superficial: 1. Mucosa (columnar epithelium). 2. Submucosa (contains most of the collagen within the bowel wall and is the strength layer). 3. Muscularis Propria (contains inner circular and outer longitudinal layers) - the outer longitudinal layer is separated into the three taenia coli on the colon. 4. Serosa  Blood Supply The blood supply to the rectum and sigmoid colon is primarily from the inferior mesenteric artery (IMA). IMA gives off the left colic to the ascending colon, sigmoidal branches to the sigmoid colon and the superior rectal artery to the proximal rectum. The terminal branches of these arteries form an anastomotic arcade with the adjacent branches. Urinary Bladder The urinary bladder is situated in the retropubic space (Retzius) and is considered extra-peritoneal. In a male patient, the posterior bladder wall lies adjacent to the anterior sigmoid colon and rectum. In the female patient, the superior bladder abuts the lower uterus, and the bladder base sits adjacent to the anterior portion of the vaginal wall. The uterus separates the colon from the bladder making fistula between them much less common in females. Ureters The ureters leave the renal pelvis and course anterior to the psoas muscle. They diverge medially at the pelvic brim crossing anterior to the iliac vessels near their bifurcation. They course along the pelvic sidewall and pass under the uterine artery in women and finally enter the bladder at the lateral aspect of the base.

An enterovesical fistula (EVF) is an abnormal connection between the intestinal tract and urinary bladder, typically developing with symptoms of pneumaturia and fecaluria. We herein present the case of an 81-year-old man with 10-day watery diarrhea. After ineffective empiric antidiarrheal treatment, computed tomography and cystography revealed EVF and gas in the bladder lumen and within its wall. His diarrhea improved after urethral catheter placement. EVF can occasionally cause diarrhea in a delicate pressure balance between the bladder and intestine. Clinicians should be aware of this unusual condition and include "urinary diarrhea" in the differential diagnosis of diarrhea.