Complicated sigmoid diverticulitis causing colouterine fistula and recurring tubo-ovarian abscesses: a case report

A 54-year-old woman presented to the emergency department (ED) of a general teaching hospital in the Netherlands with left iliac fossa (LIF) pain, fever, and altered bowel habits for 3 weeks. She reported no vaginal discharge or urinary symptoms. Her medical history included left-sided ectopic pregnancy, colonoscopy-confirmed diverticulitis three years earlier, and an intrauterine device (IUD). She used no medication, was allergic to ibuprofen and naproxen (causing gastrointestinal complaints), and had quit smoking 2 years earlier (40 pack-years). She reported no alcohol or drug use and no family history of colorectal carcinoma or inflammatory bowel disease. CT imaging showed uncomplicated sigmoid diverticulitis and, according to national guidelines, no antibiotics were started. Table 1 summarizes clinical presentations, diagnostics, surgery and outcomes. Table 1 Timeline of presentation, diagnostics, surgery and outcomes. Time points and presentation Diagnostics Surgery Outcome 3 years before Colonoscopy: uncomplicated diverticulitis - No antibiotics per guidelines. Initial presentation: LIF pain, fever CT: uncomplicated diverticulitis - No antibiotics per guidelines. 1 week later: persistent pain and fever CT/TVUS: multiloculated left-sided pelvic mass → diagnosed as TOA. - IV antibiotics started. IUD removed. Clinical improvement and discharged. 8 weeks after discharge Follow-up colonoscopy: active sigmoid diverticulitis - - 3 days postcolonoscopy: persistent pain CT: persistent LIF abscess. No radiologic drainage possible. Diagnostic laparoscopy Abscess drainage and lavage. Clinical improvement and discharged. 10 months later: pain, tachycardia and fever CT: multiloculated RIF mass. Unsuccessful radiologic drainage. - IV antibiotics; improved clinically. Elective surgery planned; outpatient appointment scheduled in 2 months to discuss surgery; discharged. 2 days before the outpatient review: pain and fever CT: enlarging abscesses and free fluid. No radiologic drainage possible. Diagnostic laparoscopy (converted to open) Multiple abscesses drained (RIF, interloop, subphrenic); three drains placed. Ten days postop: acute increase in pain CT: residual abscess and free fluid. Unsuccessful radiologic drainage. Relaparotomy Colouterine fistula identified. Hartmann’s procedure, salpingo-oophorectomy, appendectomy, and ileal resection performed; colostomy created. Postoperative course - - Gradual recovery with weight gain and well-functioning colostomy. CT, computed tomography; EMD, emergency department; ICU, intensive care unit; IUD, intrauterine device; IV, intravenous; LIF, left iliac fossa; RIF, right iliac fossa; TOA, tubo-ovarian abscess; TVUS, transvaginal ultrasound. Timeline of presentation, diagnostics, surgery and outcomes. CT, computed tomography; EMD, emergency department; ICU, intensive care unit; IUD, intrauterine device; IV, intravenous; LIF, left iliac fossa; RIF, right iliac fossa; TOA, tubo-ovarian abscess; TVUS, transvaginal ultrasound. One week later, she was referred by her general practitioner (GP) to the ED with persistent abdominal pain and fever. On examination, she exhibited LIF tenderness without signs of generalized peritonitis, tachycardia, and a temperature of 38.7 °C. Laboratory tests showed elevated leukocytes (17.2 × 10 9 /l) and C-reactive protein (CRP 89 mg/l). CT and transvaginal ultrasound revealed a multiloculated mass in the LIF measuring 48.5 mm, and sigmoid diverticula without active diverticulitis or fistula formation (Fig. 1 ). Figure 1. Axial CT-abdomen showing a mass suggestive of a TOA (outlined in yellow) and the uterus (outlined in blue). Axial CT-abdomen showing a mass suggestive of a TOA (outlined in yellow) and the uterus (outlined in blue). A TOA was considered as most likely radiologic diagnosis, with paracolic abscess secondary to diverticulitis as differential diagnosis. The patient was admitted to the gynecology ward, started on intravenous (IV) antibiotics, and her IUD was removed. Cervical cultures were negative for sexually transmitted infections (STIs). After 3 days, she improved clinically, was switched to oral antibiotics, and was discharged home. A follow-up colonoscopy 8 weeks later, to rule out diverticulitis as a cause of the intra-abdominal abscess, showed active sigmoid diverticulitis. Three days later, the patient was presented to the ED by the GP with weakness, weight loss, and persistent LIF pain. Laboratory tests demonstrated elevated infection parameters (IPs). CT imaging demonstrated a persistent LIF abscess. Diverticulitis was now considered as most likely cause due to the colonoscopy (Hinchey stage Ib/II). She was re-admitted and started on IV antibiotics. Symptoms persisted, no radiologic drainage could be performed due to the abscess’s location, and the abscess was >3 cm. Due to these three facts, diagnostic laparoscopy with abscess drainage was performed per national guidelines. The abdominal cavity was flushed, and a drain was placed in the largest abscess cavity in the LIF. The sigmoid colon was adherent to the dorsal uterus. Her symptoms and IPs improved postoperatively. At 1-, 3-, and 8-month follow-up, her condition was gradually improving, but symptoms did not fully subside. Ten months later, she presented to the ED with abdominal pain, tachycardia, fever, and elevated IPs. CT revealed a multiloculated right iliac fossa (RIF) mass measuring 79.2 mm, suspicious for a right-sided TOA, anterior to a large pelvic fluid collection (Fig. 2 ). The patient was treated with IV antibiotics, and an attempt to drain the abscess produced no fluid or pus upon aspiration. Nonetheless, her condition improved. A gynecologist and a gastrointestinal surgeon discussed the case and agreed elective laparoscopic sigmoid resection with adnexa extirpation should be performed after recovery from the infection. An outpatient appointment was scheduled 2 months postdischarge. Figure 2. Sagittal CT-abdomen showing the mass suggestive of TOA (outlined in yellow) and fluid collection (outlined in blue). Sagittal CT-abdomen showing the mass suggestive of TOA (outlined in yellow) and fluid collection (outlined in blue). Two days before the appointment, she re-presented to the ED with abdominal pain and fever. Laboratory tests showed elevated leukocytes (15.5 × 10 9 /l) and CRP (203 mg/l). CT demonstrated free intra-abdominal fluid, suggesting Hinchey stage III [ 9 ] , and enlarged abscesses unsuitable for radiologic drainage. Diagnostic laparoscopy with abscess drainage was indicated due to Hinchey stage III [ 10 ] . The procedure was converted to laparotomy because of insufficient visualization. Multiple abscesses in the RIF, interloop, and subphrenic spaces bilaterally were drained, and three drains were placed. Bacterial cultures showed no growth. Postoperative CT scan demonstrated a 5.4 cm residual abscess. IV antibiotics were continued. Ten days after surgery, the patient developed acute abdominal pain. IPs had risen, and CT showed an enlarged abscess and increased free fluid. Radiologic drainage did not result in aspiration of fluid or pus. After shared decision-making, a Hartmann’s procedure was scheduled, indicated due to Hinchey stage III/IV, and lack of clinical improvement despite IV antibiotics and surgical abscess drainage [ 10 ] . Intraoperatively, the right adnexa appeared enlarged and purulent, so a right-sided salpingo-oophorectomy was performed. No abnormalities were observed in the descending colon or proximal sigmoid. The rectosigmoid was adherent to the dorsal uterus, which was dissected, revealing a sigmoid-uterine fistula, just above the cervix. Hartmann’s procedure was performed. During blunt dissection of extensive adhesions, damage to the appendix and ileum occurred, requiring appendectomy and limited ileal resection with side-to-side anastomosis. The uterus was left in situ . A sigmoid colostomy was created. She was transferred to intensive care postoperatively. Bacterial cultures taken during surgery grew Enterococcus faecalis . Histopathology confirmed a right-sided TOA and a colouterine fistula, closely associated with a sigmoid diverticulum without signs of active diverticulitis. She was discharged on postoperative day 10 and seen 3 and 8 weeks postoperatively, with a well-functioning colostomy, improved condition, and 4 kg weight gain.

Diverticulitis is caused by inflammation of diverticula, with a prevalence of 1.8/1000 patients in the Netherlands [ 1 ] . Complicated diverticulitis (e.g., perforation, local infiltration, abscess formation, and fistulas) occurs in approximately 12% of all diverticulitis cases [ 2 ] . Fistula rates vary from 4 to 20% for patients with complicated diverticulitis in the current literature [ 3 – 5 ] . Fistulas are most commonly colovesical (65%) or colovaginal fistula (25%) [ 5 ] . Woods et al observed colouterine fistulas in 3% of diverticular fistulas [ 6 ] . HIGHLIGHTS A case of complicated diverticulitis with a TOA and colouterine fistula is presented. Diverticulitis may be the cause of a TOA even without typical CT signs. A multidisciplinary approach is recommended in such complex presentations. A benign colouterine fistula can be treated without hysterectomy. HIGHLIGHTS A case of complicated diverticulitis with a TOA and colouterine fistula is presented. Diverticulitis may be the cause of a TOA even without typical CT signs. A multidisciplinary approach is recommended in such complex presentations. A benign colouterine fistula can be treated without hysterectomy. The development of a tubo-ovarian abscess (TOA) and a colouterine fistula in complicated diverticulitis cases is rare; only one case has been reported [ 7 ] . Our case involved a prolonged course with recurrent TOAs without CT signs of a colouterine fistula or diverticulitis. Surgical management was performed without hysterectomy. These findings highlight diagnostic difficulty and suggest treatment without hysterectomy is possible in benign cases. This case report is written in accordance with the SCARE checklist [ 8 ] .

Colouterine fistulas are rare. Complicated diverticulitis typically causes colovesical or colovaginal fistulas [ 11 ] , as the thick uterine wall offers protection [ 12 ] . Reported risk factors include uterine rupture, radiotherapy, colorectal malignancy, uterine foreign bodies, and previous ectopic pregnancy [ 13 ] . Our patient had both an IUD and a history of an ectopic pregnancy. Typical symptoms such as vaginal pus or gas discharge were absent [ 14 ] . Contrast-enhanced CT is standard for complicated diverticulitis [ 10 ] . A TOA can be caused by pelvic inflammatory disease (PID) or spread from infected adjacent organs. In this case, no active diverticulitis was observed on CT. CT imaging has low sensitivity for colouterine fistulas [ 15 ] . Intrauterine air-fluid levels may suggest their presence but were not observed here. The absence of typical symptoms and radiologic findings underscores the difficulty of diagnosing colouterine fistulas and of differentiating between complicated diverticulitis and PID as a cause of TOAs. Multidisciplinary consultation with a colorectal surgeon, a gynecologist and a radiologist was crucial for accurate diagnosis and treatment strategy. The preferred classification system for diverticulitis is the modified Hinchey classification [ 9 ] . In the Netherlands, Hinchey Ib-II cases (localized or distant abscesses) are managed with IV antibiotics and percutaneous drainage (for abscesses >3 cm). If no improvement is observed, laparoscopic lavage can be considered. Patients with purulent or fecal peritonitis, Hinchey III-IV, require laparoscopic lavage, sigmoid resection with primary anastomosis, or Hartmann’s procedure [ 10 ] . Dutch guidelines recommend treating a TOA with antibiotic therapy and considering IUD removal if present. Drainage is advised for abscesses ≥6 cm or if no improvement occurs after 48 hours of IV antibiotics. Laparoscopic drainage and flushing are preferred over extirpation of infected tissues in the acute phase [ 16 ] . The definitive treatment for colouterine fistulas is surgery. Percutaneous drainage or endoscopic clipping of the fistula is recommended solely for patients unfit for general anesthesia. Different resection methods have been described, including Hartmann’s resection combined with hysterectomy and en bloc resection of the sigmoid colon and uterus. [ 17 – 19 ] In benign conditions, such as diverticulitis, the need for hysterectomy has not been proven. An earlier case report on a colouterine fistula suggests sigmoid resection and abscess drainage could be sufficient [ 20 ] . This case suggests that a TOA and colouterine fistula caused by complicated diverticulitis can be managed with Hartmann’s procedure and adnexal extirpation without hysterectomy.

A limitation of this case is the prolonged course, despite guideline-adherent management, which underscores the challenges of diagnosing and treating this disease. The absence of clinical symptoms of colouterine fistula (e.g., vaginal discharge) and of radiologic signs of diverticulitis or a colouterine fistula (e.g., intra-uterine gas) complicated differentiation between PID and diverticulitis as a cause of the recurrent TOA. In such cases, a colouterine fistula should be considered, due to low sensitivity of CT for fistulas. A multidisciplinary approach helped to identify the most likely diagnosis. Furthermore, a patient perspective on this course is lacking. Nonetheless, this case report is a rare presentation of recurring TOAs caused by complicated diverticulitis with a colouterine fistula, a combination reported only once previously [ 7 ] . This is relevant to gynecologists and gastrointestinal surgeons, as both a TOA and complicated diverticulitis were present. Lastly, this case exemplifies that definitive surgical management of complicated diverticulitis with a TOA and benign fistula can be successful with Hartmann’s procedure without hysterectomy.