INTRODUCTION
Duodenocaval fistula (DCF) is a rare and life-threatening condition that presents significant diagnostic challenges. Its high mortality rate is largely due to difficulties in achieving a timely diagnosis before effective treatment can be implemented. Only a limited number of cases, 39 to be exact, have been documented in English medical literature [1–9], underscoring its rarity. With a reported mortality rate of 41% (16 out of 39 cases), prompt and accurate diagnosis is paramount. This article details a specific case of DCF where the patient underwent multiple diagnostic procedures, including endoscopy, computed tomography (CT), magnetic resonance imaging (MRI), and cavography. We aim to explore the radiological manifestations of DCF through this case study and a comprehensive review of existing literature, highlighting the critical role of Radiological Diagnosis.
CASE PRESENTATION
A 78-year-old male patient was admitted to the hospital with a primary complaint of right-sided abdominal pain that had persisted for a month. Accompanying symptoms included fever, rigors, and chills, which had manifested for a day prior to admission. His past medical history was notable for a right nephrectomy performed five years prior due to renal cell carcinoma, and a mass in the right adrenal gland treated with gamma knife radiotherapy ten months prior. Upon initial physical examination, his vital signs were concerning: temperature of 39.5°C, heart rate of 120 beats/min, blood pressure of 110/70 mmHg, respiratory rate of 25 breaths/min, and a peripheral oxygen saturation (SaO2) of 97%. Initial laboratory investigations revealed a significantly elevated leukocyte count of 22 × 109/L, low hemoglobin at 80 g/L, and a decreased platelet count of 33 × 109/L. Other blood chemistry, clotting parameters, and liver function tests were within normal limits. Blood cultures identified Enterococcus faecium and Enterobacter cloacae bacteremia, as well as Candidia albicans fungemia. The patient was started on intravenous broad-spectrum antibiotics and antifungal therapy (meropenem and caspofungin), which led to some initial clinical improvement.
However, throughout his 76-day hospital stay, the patient experienced recurrent episodes of fever, elevated leukocyte counts, sepsis, and persistent fungemia. Approximately one month post-admission, he developed watery stools that tested positive for occult blood. To investigate the underlying pathology, a series of diagnostic examinations were performed, including upper gastrointestinal (GI) endoscopy, abdominal ultrasound, CT scans, MRI, and inferior vena cavography. Upper GI endoscopy, performed on day 3 of hospitalization, revealed a large ulcer in the second portion of the duodenum, without evidence of active bleeding at that time. Abdominal ultrasound was largely unremarkable, except for the known mass in the right adrenal gland. Crucially, a series of abdominal CT scans were conducted on days 2, 19, 59, 67, and 73 of his hospital stay (Figure 1). On the CT scan performed on day 67, low-density air bubbles were unexpectedly observed in the inferior vena cava (IVC), at the level of the first lumbar vertebra, adjacent to the duodenum. Retrospective review of the earlier CT scans revealed a small, low-density dot in the IVC as early as day 2 of hospitalization, which became more apparent on day 19 and progressively enlarged in subsequent scans. A repeat abdominal CT scan on day 73, utilizing water-soluble enteric contrast, demonstrated low-density air bubbles within the IVC, surrounded by high-density contrast medium or thrombus. This finding strongly suggested the presence of a duodenocaval fistula (DCF). T2-weighted MRI, performed on day 74 (Figure 1), further confirmed the suspicion of DCF, clearly showing high-signal enteric contrast medium or thrombus and signal-void air bubbles within the IVC. In contrast, inferior vena cavography, performed on day 75 of hospitalization, failed to demonstrate any evidence of IVC thrombus (Figure 1). Surgical consultation was arranged; however, before surgery could be performed, the patient experienced a significant episode of hematemesis. Massive hemorrhage ensued, and despite aggressive resuscitation efforts, the patient unfortunately died. A postmortem examination definitively confirmed the presence of a fistula between the second portion of the duodenum and the IVC.
Figure 1.
Radiological progression of Duodenocaval Fistula (DCF) visualized through various imaging modalities. Over the course of the 2-month hospitalization, a subtle, low-density air bubble emerged within the inferior vena cava (IVC) and progressively increased in size, as evidenced by serial computed tomography (CT) scans. The leakage of enteric contrast medium into the IVC is also depicted. Magnetic resonance imaging (MRI) provided clear visualization of the high-signal enteric contrast medium or thrombus alongside the signal-void air bubbles. Notably, cavography did not detect the thrombus within the IVC. A: CT scan on hospital day 2, revealing an initial low-density dot in the IVC (arrow), along with a mass in the right adrenal gland. B: CT scan on hospital day 19, showing the low-density dot becoming more distinct. C, D: CT scans on hospital days 59 and 67, illustrating the gradual enlargement of the low-density dot, now identifiable as an air bubble. E: CT scan on hospital day 73, utilizing water-soluble enteric contrast, clearly demonstrating the air bubble encased by contrast medium within the IVC. F: T2-weighted MRI on hospital day 74, showcasing the high-signal enteric contrast medium or thrombus and signal-void air bubble within the IVC. G: Inferior vena cavogram on hospital day 75, failing to reveal any evident thrombus in the IVC.
DISCUSSION: The Importance of Radiological Imaging in DCF Diagnosis
Duodenocaval fistula (DCF) is an exceedingly rare condition, typically arising as a complication of various underlying factors. These include migrating IVC filters, peptic ulcer disease, retroperitoneal tumor resection often in conjunction with radiation therapy, or the transmural migration of ingested foreign bodies. The diagnosis of DCF is notoriously challenging due to the nonspecific nature of its clinical presentation. Consequently, it is often diagnosed only during laparotomy or at autopsy. The most common presenting symptoms of DCF are sepsis and gastrointestinal (GI) hemorrhage. Sepsis in DCF is usually polymicrobial, caused by the translocation of Gram-positive and Gram-negative enteric bacteria into the systemic circulation. Fungemia can also occur, as was observed in the presented case [1–9].
Upper GI endoscopy frequently reveals a duodenal ulcer, which may exhibit signs of bleeding. However, endoscopy often underestimates the depth of ulcer penetration and the presence of a fistula [1]. Radiological diagnosis, particularly with CT and MRI, plays a crucial role in the noninvasive evaluation of the IVC and adjacent structures. CT is effective in detecting thrombus and air bubbles within the IVC, identifying infectious fluid collections or abscesses around the IVC and duodenum, and visualizing incarcerated foreign bodies or migrated caval filters [1–4]. Studies indicate that CT can correctly identify DCF in approximately 50% of cases [2]. In this particular case, the serial CT scans were instrumental in observing the evolution of the DCF, from a subtle low-density dot on day 2 to a progressively enlarging air bubble over the 2-month period. The presence of air bubbles in the IVC in DCF can be attributed to bacterial gas production or the direct passage of air from the duodenum into the IVC due to peristalsis. Repeated CT examinations are often necessary, especially when initial findings are subtle, to observe the progression of air bubbles and confirm the diagnosis. For the detection of thrombus in the IVC, contrast-enhanced CT is essential.
While MRI was not prominently featured in earlier DCF diagnostic studies, its utility is increasingly recognized. MRI, utilizing conventional or flow-sensitive sequences, excels at delineating thrombus within the IVC, even without the use of intravenous contrast media [10,11]. Thrombus, intestinal contents, and enteric contrast exhibit distinct signal characteristics against the signal void of normal blood flow in the IVC, allowing for clear differentiation. In the presented case, MRI was particularly valuable, clearly demonstrating the high-signal enteric contrast medium or thrombus and signal-void air bubbles within the IVC, further solidifying the radiological diagnosis of DCF.
Cavography, while sometimes used, has shown limited diagnostic yield in DCF. It has occasionally revealed thrombus or filling defects in the IVC but has been diagnostic of DCF in only two out of six reported cases [1,4,12]. In our case, cavography failed to demonstrate enteric contrast medium or thrombus in the IVC. A plausible explanation is that the thrombus, potentially unstable in nature, was dislodged and flushed away by the high-pressure injection of intravenous contrast medium during the cavography procedure. It is also worth noting the reported risk of fatal pulmonary embolization of intestinal contents through a DCF [13]. In our case, the patient’s demise due to hematemesis occurred within 24 hours after cavography, raising concerns about potential complications associated with this invasive procedure in the context of DCF. Therefore, caution is advised when considering invasive cavography for detecting unstable thrombus in suspected DCF cases.
CONCLUSION
In conclusion, this case underscores the critical role of radiological diagnosis in identifying duodenocaval fistula. We advocate for noninvasive imaging modalities, specifically CT and MRI, as the first-line investigative tools for suspected DCF. When clinical suspicion for DCF is present, meticulous review of IVC and surrounding structures on CT and MRI images is paramount for accurate and timely diagnosis, ultimately improving patient outcomes in this challenging condition.
Footnotes
Peer reviewer: Martin D Zielinski, MD, Department of Trauma, Critical Care and General Surgery, Mayo Clinic, 1216 2nd St Sw, Rochester, MN 55902, United States
S- Editor Wang YR L- Editor Kerr C E- Editor Lin YP
