https://orcid.org/0000-0001-8778-4415
Abstract
Arteriovenous malformations (AVMs) are rare, especially in the pelvis. Colovesical fistulas (CVFs) occur when fistulas form between the intestine and bladder. The treatment for CVFs is generally intestinal resection and fistula resection between the colon and the bladder. However, in patients with pelvic AVMs, colectomies may increase the bleeding risk or exacerbate the AVMs due to vascular resection or blood flow changes. A 67-year-old man was diagnosed with an asymptomatic pelvic AVM during preoperative testing for a CVF associated with sigmoid diverticulitis. Laparoscopic sigmoid resection was performed for the CVF, and he recovered without complications. In bowel resections associated with CVFs complicated by asymptomatic pelvic AVMs, safe laparoscopic bowel resection is possible by preoperatively identifying the AVM’s inflow and outflow vessels and evaluating their relationship to the resected bowel. Herein, we report a case where a laparoscopic sigmoidectomy was performed for a sigmoid CVF associated with an asymptomatic pelvic AVM.
Introduction
Arteriovenous malformations (AVMs) are abnormal capillary-based connections between arteries and veins, with a nidus [1]. AVMs occur most frequently in the head and neck, followed by the extremities, trunk, and viscera [1]. Pelvic AVMs are rare (<2%) and are especially rare in men [2].
Enterovesical fistulas (EVFs) are abnormal communications between the intestine and the bladder [3]. They most commonly occur in people in their 60s and 70s, and are more common in men (male-to-female ratio, 3:1) [3]. Colovesical fistula (CVF) treatment generally entails intestinal diverticulitis and fistula resection between the bladder and colon. Recently, the usefulness and safety of laparoscopic surgery in patients with CVFs were reported, replacing conventional open surgery [3, 4].
We report the case of a patient with two rare conditions, a pelvic AVM and a vesicosigmoid fistula, who was successfully treated with laparoscopic sigmoidectomy.
Case report
The patient was a 67-year-old male with well-controlled type 2 diabetes mellitus and hypertension. He had pneumaturia and cloudy urine for 2–3 months and visited the urology department with sudden urinary retention. Cystoscopic examination revealed no feces in the bladder, but air and a fistular opening were observed. Contrast-enhanced computed tomography (CT) revealed multiple diverticula between the sigmoid and descending colon, air in the bladder, and findings suggestive of inflammatory adhesions between the bladder and the sigmoid colon (Fig. 1a). A pelvic floor AVM was detected (Fig. 1b). Pelvic AVM evaluation using 3D-CT angiography (3D-CTA) revealed the right internal iliac artery and both internal iliac veins as the inflow and outflow vessels, respectively; however, no communication between the inferior mesenteric artery (IMA) and inferior mesenteric vein (IMV) was observed (Fig. 1b and c). Barium enema radiography revealed numerous diverticula between the descending and sigmoid colon without contrast extravasation from the colon to the bladder (Fig. 2). Preoperatively, we consulted a cardiovascular surgeon and determined that surgical or interventional radiological AVM treatment was unnecessary, as there were no AVM symptoms (such as bloody stools or hematuria) or heart failure symptoms. A laparoscopic sigmoidectomy and temporary ileostomy were performed for the vesicosigmoid fistula (Fig. 3). During intraoperative laparoscopic observation, the pelvic AVM was not visible in the surgical field and did not affect the procedure. The fistula between the bladder and sigmoid colon was visible laparoscopically and resected. A bladder leak test was negative; therefore, no additional bladder repair was performed. The patient was discharged 13 days postoperatively. Two months after the initial surgery, the patient underwent colostomy closure. Approximately 1 year has passed since the surgery, and no sigmoid colon diverticulitis recurrence, pelvic AVM worsening on imaging studies, or clinical symptom worsening have been observed.
CT images. (a) The bladder is attached to the sigmoid colon, and a small amount of gas is observed within the bladder (arrowhead). (b) An AVM is observed in the right pelvic floor (arrow). (c and d) 3D-CTA shows that the AVM is fed by the right internal iliac artery and drained by both internal iliac veins, with no communication with the inferior mesenteric artery or vein.
Barium enema radiography. Scattered diverticula are observed from the sigmoid colon to the descending colon, but no colovesical fistula is visible.
Surgical findings. (a) Numerous fibrous adhesions are visible between the abdominal wall and sigmoid colon, as well as severe adhesions. The arteriovenous malformation was not identified intraperitoneally. (b) A fistula was identified between the bladder and rectum, which was transected (bladder wall side: arrowhead, colon side: arrow). (c) The leak test was negative, and the bladder was not sutured.
Discussion
AVMs are high-flow congenital vascular malformations characterized by abnormal blood supply shunting from high-flow nutrient arteries to low-resistance veins through an abnormal vessel cluster called the nidus [1, 5]. AVMs can occur almost anywhere in the body, but are most common intracranially, followed by extracranial head, neck, and extremity lesions [5]. Pelvic AVMs are rare, accounting for <2%–3% of cases [6]. The clinical symptoms of AVMs in the head, neck, and other superficial tissues include pink-red skin staining, fever, and palpable tremors or bruits [5, 7]. AVMs worsen over time, placing patients at risk of pain, ulcer formation, bleeding, and congestive heart failure. In pelvic AVMs, increased blood flow through the venous pathways causes dilated veins in the bladder, vaginal, and rectal walls, resulting in hematuria, excessive vaginal bleeding, and gastrointestinal bleeding [8]. However, one-fifth of cases are asymptomatic [8].
There is no standard AVM treatment. Embolization, sclerotherapy, and surgical resection are the primary reported treatment options [1]. Cho et al. [9] evaluated the shunt type and clinical and hemodynamic characteristics based on angiography, and classified AVMs into four subtypes (type 1: ≤3 inflow arteries and one outflow vein; type 2: multiple inflow arteries and one outflow vein; type 3: multiple inflow arteries and outflow veins), and provided predictive information regarding clinical outcomes. Accordingly, this case was a type 3 AVM, which is difficult to treat and has high treatment failure and recurrence rates. However, because there were no clinical AVM symptoms, consultation with a cardiovascular surgeon led to the decision to observe the patient, and as the lesion did not expand, no AVM-specific treatment was performed.
EVFs are abnormal connections between the intestine and the bladder. The CVF incidence is estimated at 0.5/10 000 cases (male-to-female ratio, 3:1) [4]. The most common symptoms are lower urinary tract symptoms, including pneumaturia (50%–70%), fecaluria (≤51%), and dysuria (45%) [4]. CT is the gold standard diagnostic modality [4]. Surgical resection is generally the treatment of choice. Basic surgery includes intestinal resection, encompassing the fistula and fistula tract [4]. Traditionally, open surgery was the norm; however, in recent years, laparoscopic and robotic surgeries have been reported.
Here, an asymptomatic pelvic AVM was incidentally discovered during a preoperative CVF evaluation. Intestinal resection adjacent to an AVM can cause nidus enlargement, bleeding, and worsening heart failure owing to impaired blood flow following intestinal resection. Furukawa et al. [10] performed ligation of the inferior mesenteric artery’s root in a pelvic AVM (inflow, IMA; outflow, IMV and Retzius shunt) complicated by rectal cancer, and performed a complete mesenteric bowel resection including the AVM. Inaguma et al. [11] treated a patient with a pelvic AVM associated with sigmoid colon cancer (inflow artery, left internal iliac artery; outflow vein, right great saphenous vein). To prevent intraoperative bleeding, they performed preoperative AVM embolization via interventional radiology. In intestinal resections for pelvic AVMs, evaluating vascular communications and the anatomical relationships between blood vessels and adjacent organs is important to avoid unexpected bleeding and injury. Blood flow assessment using 3D-CTA is thought to prevent unexpected bleeding during laparoscopic and open surgery. In our case, the course of the blood vessels was preoperatively confirmed through 3D-CTA, enabling sigmoid colectomy without altering AVM blood flow.
We report our use of laparoscopic sigmoidectomy to treat a vesicosigmoid fistula complicated by a pelvic AVM. Safe intestinal resection was possible after confirming vascular inflow and outflow using 3D-CTA preoperatively.
Conflicts of interest
The authors have no competing interests to declare.
Funding
None declared.
Consent for publication
Informed consent was obtained from the patient for the publication of this report.
