Keywords
Colon - diverticulitis - fistula - malignancy - uterus
Introduction
Colouterine fistula is very rare condition with only around 25 reported cases of post-diverticulitis
colouterine fistula so far.[1],[2],[3],[4],[5],[6] Other causes include sigmoid malignancy, radiotherapy, and iatrogenic conditions
such as insertion of intrauterine devices, endometrial curettage with uterine, and
bowel perforation, or obstetrical injury.
The most common type of fistula associated with colon is colovesical fistula followed
by a colovaginal fistula arising from the sigmoid colon. Because uterus is a thick
muscular organ, it provides a protective barrier against invasion of benign or malignant
disease. Therefore, a colouterine fistula is an extremely rare. Here, we present two
cases of a colouterine fistula caused by diverticulitis and malignancy of sigmoid
colon.
Case Reports
Case 1
A 77-year-old female came to the hospital with complaints of lower abdominal pain
localized particularly in the left iliac fossa. On initial examination, she was febrile
(100.4°F). The abdomen was distended with ill-defined palpable mass in the left lower
abdomen. The pelvic examination showed a spontaneous malodorous discharge in the vagina
and cervical os. She had leukocytosis (14,500/mm3) and raised erythrocyte sedimentation rate (ESR) (40 mm/h).
She underwent contrast-enhanced computed tomography (CECT) scan which revealed a large
collection adjacent to the sigmoid colon. The collection was seen abutting the uterus
with air-fluid level within the uterine cavity [Figure 1]. Based on CT findings, possibility of sigmoid diverticular abscess and colouterine
fistula was considered. The patient underwent abscess drainage, hysterectomy, and
colostomy. About 2 cm defect was noted in the posterior uterine wall communicating
with the abscess and sigmoid colon. The patient improved clinically following surgery.
Figure 1 (A-D): Contrast-enhanced abdomen and pelvis CT scan (A and B) Axial images show air filled
collection adjacent to sigmoid colon. (C) Axial image shows air within the endometrial
cavity. (D) Sagittal reformat shows air filled collection extending between the air
filled endometrial cavity (straight white arrow) and the thickened sigmoid colon (curved
white arrow)
Case 2
A 73-year-old female patient came to the outpatient department with complaints of
lower abdominal pain, blood in stools, and whitish discharge through vagina for 10
days. On examination patient’s vitals were stable. The patient underwent a CECT scan
abdomen which revealed irregular wall thickening involving the rectosigmoid region
for a length of ~ 7 cm, with wall thickness of ~ 18 mm. There was loss of fat plane
between the uterus and the thickened rectosigmoid colon with air pockets within the
endometrial cavity [Figure 2]. Mesocolic fat and perirectal fat stranding was also seen with multiple adjacent
subcentimetric lymph nodes. Based on CT findings, possibility of rectosigmoid malignancy
and colouterine fistula was considered. The sigmoidoscopy and biopsy of the lesion
revealed infiltrating moderately differentiated adenocarcinoma of colon. The en bloc
resection of the uterus and sigmoid colon with colostomy was performed on the patient
and adjuvant chemotherapy started.
Figure 2 (A-D): Axial images of contrast-enhanced abdomen and pelvis CT scan (A) shows heterogeneously
enhancing circumferential irregular wall thickening involving the recto-sigmoid region.
(B-D): Straight white arrows show air pocket in the endometrial cavity. Curved arrow
in B shows thickened rectum abutting the posterior wall of lower uterus with no fat
plane in between
Discussion
Colouterine fistula was first reported by Lejemtel in 1909.[7] Three main etiologies were described at that time were uterine trauma, abscess rupture
into the bowel, and the uterus and uterine or sigmoid carcinoma. Later radiotherapy
was also identified as one of the etiological factors. Although, fistulas are usually
caused by injury or surgery, they may also form after an infection which led to severe
inflammation and decompresses by perforating into an adjacent viscus, or through the
skin. The fistulation occurs between the colon and the urinary bladder (colovesical
fistula) in 65% of the cases and between the colon and the vagina (colovaginal) in
25% of the cases. Colouterine fistula is a rare complication of diverticulitis of
the colon.[7]
Diverticular disease of the colon is common in developed nations and thought to result
from structural abnormalities of the colonic wall, disordered intestinal motility,
or deficiencies of dietary fibers. The signs and symptoms of diverticulitis include
fever, abdominal pain, and leukocytosis. As per the data recorded among all the nations,
there is high prevalence rate of left-sided diverticulosis.
Besides the usual signs and symptoms, in the course of the diverticulitis, several
unusual complications like pylephlebitis, perforation, intestinal perforation, abscess,
and fistula formation may be encountered.[8] While colovesical fistula is the most common type of fistula associated with diverticulitis
of the colon occurring in 2–22% of patients with known diverticulitis, colouterine
fistulas are a relatively uncommon entity arising in the setting of the disease.[9] The rarity of the condition is probably explained by the fact that the uterus is
a thick muscular organ, which poses obstacles for invasion for both benign and malignant
disease.
Colon cancer, the most common type of gastrointestinal cancer, is a multifactorial
disease process, with etiology encompassing genetic factors, environmental exposures
(including diet), and inflammatory conditions of the digestive tract. Among the cancers
of the colon, the most common type is adenocarcinoma. As colon cancer grows and spreads
beyond the colon mucosa, it is called invasive or infiltrating adenocarcinoma. Metastases
to the female genital tract from extragenital malignancies are very uncommon, and
the most common extragenital primary sites are breast and gastrointestinal system.[7],[8] The common metastatic sites of colorectal cancer include the liver, lung, lymph
nodes, and peritoneum, with uterus being a rare site. Mazur et al.[10] reported that the endometrium was the metastatic site for colon and rectum carcinoma
in only 3.6% of the 56 cases in their study.
Patients with the colouterine fistula usually present with malodorous fecal or purulent
vaginal discharge as the colonic lumen and the uterus are linked by a fistula tract.[2] The most common presenting symptom of uterine metastasis is vaginal bleeding whereas
in cases of diverticulitis causing fistula, patients may present with fever and recurrent
abdominal pain.
Many imaging modalities have been used for diagnosing colouterine fistula, but computed
tomography (CT) is being increasingly used nowadays for evaluation of acute abdomen
and diagnosing intraperitoneal and retroperitoneal lesions. In a colouterine fistula,
air bubbles in the uterine cavity and colonic wall joined together may be identified
on CT, but limitations are there as it may fail to demonstrate the fistulous tract.
However, CT and magnetic resonance imaging (MRI) may play an important role in preoperative
surgical planning.
Ultrasound is the preferred initial diagnostic modality for gynecologic disease and
captures the real-time images of organs and blood flow without radiation hazards.
Additionally, ultrasound is almost always the first modality used to analyze the endometrium
and to guide further diagnostic work-up in these patients, such as endometrial biopsy.
Takada et al.[11] reported diagnosis of colouterine fistula by sonohysterography with contrast medium
using it to track and diagnose the fistula tract.
Kassab et al.[12] reported that MRI could be a versatile, non-invasive, detailed, and accurate diagnostic
modality comparable to CT scan. In their report, MRI was used to identify fistulae,
and T1-weighted images portrayed the extension of the fistula relative to the adjacent
organ and showed inflammatory changes in fat planes. T2-weighted images and diffusion
weighted images can depict the collections and abscesses better.
Beattie et al. suggested that the use of multidetector CT (MDCT) allows excellent multiplanar reconstructions
and improves visualization of pathology with shorter acquisition time.[13] If a positron emission tomography/computed tomography (PET/CT) scan is performed,
an increased activity in the endometrium is often expected in cases of carcinoma,
but sometimes infection or inflammatory change associated with diverticulitis may
also raise standardized uptake values (SUV).[14]
Additionally, the ’Charcoal Challenge Test’ has also been described in diagnostic
aid. This test helps in diagnosing colouterine fistula through orally administered
activated charcoal which passes across the bowel lumen into the cervical os, but it
does not tell us the exact site of the fistula.[15] Diagnostic hysteroscopy is also considered a very good choice for investigating
patients with malodorous vaginal discharge, enabling direct visualization, and biopsy
of the pathological area.[1]
Most cases of colouterine fistula need surgical management. Various surgical approaches
have been reported. An en bloc resection,[2] according to the patient’s condition, is mandatory in cases of colouterine fistula
caused by malignancy. However, in benign conditions, the need for a hysterectomy has
not been established. Resection of the colon alone and drainage of the purulent uterine
lesion may be sufficient for definite treatment. In cases of colouterine fistula due
to diverticulitis, a two-stage procedure involving resection and end colostomy, followed
by reanastomosis later is most effective. Therefore, selection of an appropriate surgical
approach according to the patient’s condition is necessary.
Conclusion
Colouterine fistula is a rare complication of diverticulitis of colon and malignancy
of colon. It should be suspected when patient presents with malodorous discharge from
vagina. It can be diagnosed by air and fluid within the uterus on ultrasound or CT
scan. However, CT scan is essential for an accurate preoperative assessment. The surgical
treatment is indicated in almost all patients except in very high risk cases.
