Introduction

Gallbladder rupture is a surgical emergency and is a known complication of several posthepatic diseases such as cholecystitis. The diagnosis of gallbladder rupture is commonly concluded by the detection of high levels of bilirubin in abdominal effusion.^1–3 However, anicteric gallbladder rupture is characterized by the absence of icterus and high bilirubin concentration in serum and abdominal effusion, making the diagnosis more challenging.⁴ Similarly, abdominal ultrasound, which is another important tool for the diagnosis of abdominal pathology, is not always conclusive in detecting gallbladder rupture.⁵ Anicteric gallbladder rupture is uncommon and has more frequently been reported in dogs with gallbladder mucocele.¹ The present case describes an anicteric gallbladder rupture and cholecystitis in a dog with a reported elevation of bile acids in the abdominal fluid. The authors suggest the performance of further studies to conclude the diagnostic use of abdominal bile acid evaluation in cases of suspected gallbladder rupture.

Case Report

A 5 yr old, male, neutered Labrador retriever was referred for investigation of a 5 day history of acute onset anorexia, lethargy, and vomiting. The dog was routinely vaccinated and dewormed and fed with a commercial adult maintenance diet.

On the initial presentation, the patient was depressed and the mucous membranes were slightly icteric, but the rest of the physical examination was unremarkable.

Hematology and biochemistry were performed. Hematology revealed mild leucocytosis of 17.69 × 10⁹ cells/L (reference range 6–15 × 10⁹ cells/L) with neutrophilia of 15.74 × 10⁹ cells/L (reference range 3–11.5 × 10⁹ cells/L). Biochemistry showed hypoalbuminemia of 20 g/L (reference range 25–40 g/L), increased bilirubin of 30 μmol/L (reference range 0–16 μmol/L), moderate increase of alanine transaminase (ALT) 551 IU/L (reference range 13–88 IU/L) and severely increased alkaline phosphatase (ALP) 1264 IU/L (reference range 14–105 IU/L) and C-reactive protein of 111 mg/L (reference range ≤10 mg/L). On blood smear examination, mild toxic changes were observed in the neutrophils. Leptospirosis enzyme-linked immunoassay test^a was negative. Coagulation times (prothrombin time and activated partial thromboplastin time) were within the reference intervals at 7 s (7–12s) and 15 s (15–25s), respectively. Fasting ammonia was within normal limits with a value of 61 μmol/L (reference range 0–70 μmol/L). Abdominal ultrasound revealed the presence of a diffusely hypoechogenic liver with multifocal, illmarginated cavitary areas within the hepatic parenchyma adjacent to the gallbladder. Marked subjective enlargement of the gallbladder was observed, and severe wall thickening due to a nodular appearance was noted. There was also partially mineralized bile content that was generating acoustic shadow. Wall thickening varied from 2 to 7.5 mm, with the normal values being 2–3 mm in dogs.⁶ These changes were associated with mesenteric reactivity in the region of the liver (Figures 1A, B). The common bile duct and the rest of the biliary tree were unremarkable. A small amount of abdominal fluid was detected in the middle abdomen. Fine-needle aspiration of the liver parenchyma, hepatic cavitary lesion, abdominocentesis, and cholecystocentesis were performed. Liver cytology revealed the presence of increased numbers of neutrophils and monocytes, which is compatible with a pyogranulomatous inflammation. In the fine-needle aspirations from the hepatic cavitary lesion, there were numerous markedly degenerated neutrophils, but no infectious agents were detected. The abdominal fluid was classified as an aseptic exudate (90.73 × 10⁹ cells/L and 30g/dL of total protein) with high numbers of nondegenerated neutrophils interspersed with macrophages. Bilirubin concentration in serum and abdominal effusion were 30 μmol/L and 20μmol/L, respectively; therefore, they were not considered suggestive of bile peritonitis (bilirubin in effusion was not higher than the one of serum). Cytology of the bile revealed severe bacterbilia with the presence of extracellular rod-shaped bacteria. Anaerobic culture was negative and aerobic bacterial culture identified as Escherichia coli with a sensitivity profile, which included good sensitivity to marbofloxacin, enrofloxacin, pradofloxacin, gentamicin, nitrofurantoin, trimethoprim sulfadiazine, doxycycline, tetracycline, and amikacin but showed resistance to ampicillin, amoxicillin, amoxicillin and clavulanate, cephalexin, cefovecin, and cephalotin.

View Figure

• Download as Powerpoint
• Download Figure

In the light of the imaging and cytological findings, a bacterial cholecystitis was diagnosed, and concurrent cholangitis and hepatic abscess were suspected based on the imaging findings and clinical pathology results.

Surgical versus medical treatment were considered and discussed with the owner, but medical treatment was finally elected. The choice of medical treatment was based on the diagnosis of cholecystitis (with or without cholangiohepatitis) and no evidence or strong suspicion of biliary tract disruption, gallbladder rupture, or septic peritonitis. Also, the patient was stable to assess the response to medical treatment before considering more invasive treatment modality. The patient was started on IV fluid therapy^b (4 mL/kg/hr), marbofloxacin^c (2 mg/kg per os [PO] q 24 hr), omeprazole^d (1 mg/kg PO q 12 hr), maropitant^e (1 mg/kg PO q 24 hr), and continuous infusion of metoclopramide^f (1 mg/kg/day IV). A nasoesophageal tube was placed under sedation with butorphanol^g (0.2 mg/kg IV).

A second abdominal ultrasound was performed 1 day after admission with unremarkable changes. Another sample of the abdominal effusion was taken and was still consistent with an aseptic exudate (79.58 × 10⁹ cells/L and 29 g/dL of total protein) with the presence of a high number of nondegenerated neutrophils and a moderate number of macrophages. Because bacteria were not detected and the abdominal fluid bilirubin level (20 μmol/L) was not twice the bilirubin level in the serum, septic or bile peritonitis was not diagnosed.

Seventy-two hours after medical treatment, the patient was brighter, eating, and the clinical signs remitted. Physical general exam was unremarkable, and the patient was not considered icteric at that stage. Furthermore, liver enzymes and serum bilirubin values improved: ALT 262 IU/L (reference range 13–88 IU/L), ALP 827 IU/L (14–105 IU/L) and bilirubin 12 μmol/L (0–16 μmol/L), respectively. Another abdominal ultrasound was performed and revealed the presence of a larger amount of free fluid cranial to the bladder and in the hepatorenal and perisplenic spaces. The ultrasonographic appearance of the effusion differed from the initial examination, which at that time were strongly echogenic with hyperechoic particles in suspension and an increased echogenicity of the peritoneal fat extending in the entire abdomen. The gallbladder wall still appeared irregularly thickened (2–7.5 mm) but subjectively more flaccid. The gallbladder size was subjectively reduced from the previous examination; however, the gallbladder wall rupture could not be confirmed ultrasonographically (Figures 2A, B). A defined heterogeneous area within the left hepatic lobe parenchyma was seen, most likely representing the previously reported cavitary lesion. Analysis of the peritoneal effusion was performed and was compatible with a septic exudate (195.12 × 10⁹ cells/L and 32 g/dL of total protein). Cytology of the abdominal fluid revealed the presence of a high number of nondegenerated neutrophils with intracellular rods compatible with septic peritonitis. Because cholecystitis had been previously diagnosed, gallbladder rupture was considered a possible cause of the septic peritonitis along with a rupture of the hepatic abscess. However, culture of the abdominal effusion was not performed. Bilirubin and bile acids on serum and abdominal effusion were measured and revealed serum bilirubin and bile acids of 12 μmol/L and 12 μmol/L, whereas the bilirubin and bile acids of the effusion were 11 μmol/L and 223 μmol/L. The bilirubin value of the abdominal fluid in relation to the serum value was not suggestive of bile peritonitis because the fluid value was not twice the value of the serum.¹ Because of the diagnosis of septic peritonitis, surgical management was recommended.

View Figure

• Download as Powerpoint
• Download Figure

Gallbladder rupture was confirmed during exploratory laparotomy, and cholecystectomy was performed. The gallbladder wall was described macroscopically as thickened and necrotic, and a laceration in the fundus of the gallbladder was reported by a board specialist in small animal surgery. A large amount of opaque abdominal fluid and solidified material, suspected to be bile, was described. Liver and entire gallbladder tissues were submitted for histopathological exam, and gallbladder wall tissue for bacterial culture was submitted. Lavages of the abdominal cavity with sterile saline were also performed. An abdominal Jackson Pratt drain and an esophagostomy tube were placed.

Histopathology of the gallbladder confirmed the diagnosis of neutrophilic septic cholecystitis because gallbladder lumen revealed the presence of degenerate neutrophils with coccobacilli. At the site of the rupture, the wall of the gallbladder appeared thickened due to fibrosis and severe neutrophilic inflammation, but no signs of necrosis were detected. Neutrophilic cholangiohepatitis with periportal fibrosis as well as severe atrophy and fibrinous neutrophilic perihepatitis were described. Bacterial culture of the gallbladder wall was positive for Enteroccocus faecalis and was sensitive to cephalexin and cefovecin, doxycycline, marbofloxacin, enrofloxacin, and amoxicillin-clavulanate but had a resistant sensitivity pattern to trimethoprim-sulfadiazine. The bacterial culture of the liver tissue was not performed, and a bile sample was not obtained for bacterial culture.

Analgesia was provided with methadone^h (0.3 mg/kg intramuscularly q 4 hr). Ranitidineⁱ (3 mg/kg PO q 24 hr), and sucralfate ^j (1 g/dog PO q 8 hr) were also added to the previous treatment. Forty-eight hours after surgery, the patient was bright and comfortable at abdominal palpation. Abdominal ultrasound was performed revealing mild ascites and pneumoperitoneum that were assumed to be most likely consistent with expected postoperative changes. Because the amount of abdominal fluid was scarce, the Jackson Pratt drain was removed. The patient was discharged 6 days after the surgery, showing a favorable progression with the same medical treatment that was established after surgery.

Follow-up 4 days after discharge revealed that the patient was bright and eating well and that the surgical wound was clean. Biochemistry at that time revealed significant decrease in ALT and ALP to the values of 111 IU/L (reference range 13–88 IU/L) and 397 IU/L (14–105 IU/L), respectively. The patient was still on marbofloxacin, omeprazole, and sucralfate.

On last presentation, 1 mo after surgery, the patient was still bright, showing an unremarkable physical examination and a slight increase in body weight. At that stage, considering the clinical improvement, the 4 wk of marbofloxacin administration were completed, and the patient was discharged without any medication.

Discussion

Bacterial cholangitis and cholangiohepatitis is a well-known disease in dogs and may be more prevalent than previously suggested.⁷ Cholangitis has been classified as neutrophilic, lymphocytic, and destructive, and, for chronic cholangitis, with bacterial infections most commonly associated with a neutrophilic classification.⁸ Neutrophilic cholecystitis, although uncommon in dogs, has been described concurrently with neutrophilic cholangitis, but it is unclear if any relationship occurs between them.^7,8 Etiopathogenesis of these diseases are still poorly understood. However, it has been suggested that bacteria can reach the biliary tract hematogenously by translocation from the portal circulation or ascending from the small intestine.⁹ The most common bacteria implicated are E coli followed by Streptococcus spp, Enterococcus spp, Klebsiella spp, and Clostridium spp.⁷ This case report highlights the major importance of performing cultures when these diseases are suspected. In this case, different bacteria were isolated from the bile and from the gallbladder wall, which is a fact that can be important in cases in which a resistant sensitivity pattern is detected or monitoring of the response to antibiotics is performed.⁷ However, liver and abdominal effusion cultures were not performed in the present case, because it would not be possible to conclude if the bacteria identified in the effusion are related to the ones isolated in the bile, the gallbladder wall, or liver. Biliary tract bacterial infections have been related to gallbladder disease and its consequent rupture due to biliary stasis, ischemia, necrosis of the gallbladder, or distension.^10,11 In a recent study, gallbladder rupture was associated with necrosis of the wall and cholecystitis in a large number of cases.¹¹

Gallbladder rupture is a surgical emergency, and the timing before surgery is crucial for the outcome of gallbladder diseases.⁵ However, diagnosis of gallbladder rupture can be challenging. Traumatic causes, cholecystitis, biliary tract obstruction (e.g., gallbladder mucocele), and gallbladder infarction or torsion can potentially lead to gallbladder rupture.^5,10 Furthermore, some of these conditions (e.g., acute cholecystitis without rupture) can share some similarities in regard to clinical presentation and ultrasonographic findings; therefore, early diagnosis needs to be achieved in order to establish surgical treatment.^5,10

Ultrasonography is an effective tool to assess the biliary tract, and it is considered the first imaging modality in humans. In veterinary medicine, some studies have suggested that the detection of gallbladder wall discontinuity, wall thickening or distended gallbladder, hyperechoic cranial abdominal fat, abdominal free fluid, and/or a free stellate echogenic structure could be compatible with a gallbladder rupture.^5,10,11 However, studies in dogs have described a sensitivity and specificity of this technique that is considerably lower in terms of diagnosis, because in dogs the sensitivity and specificity ranges between 56 and 85% and 91 and 100%, respectively.^1,10,11 In humans, sonographic “Murphy sign” and “hole sign” are two main indicators of gallbladder rupture, the latter being considered more specific.^13,14 However, the utility of both is not well reported in veterinary medicine. The use of computed tomography (CT) as a imaging modality, either in dogs or humans, is reported,^15,16 suggesting that CT could be a better diagnostic tool in detecting gallbladder rupture compared to conventional ultrasonography in both humans and dogs.^15,16 However, further studies are needed in order to determine CT sensitivity and specificity in veterinary medicine. One study in veterinary medicine suggested that contrast-enhanced ultrasonography (CEUS) has a better sensitivity and specificity than traditional ultrasonography to diagnose gallbladder rupture, because CEUS was able to diagnose 10/10 dogs with gallbladder rupture.¹² CEUS enhances vascularized zones in the gallbladder wall, and, as a consequence, it is able to detect a necrotic area or a discontinuity of the gallbladder wall due to the absence of enhancement. However, this technique is not able to differentiate a necrotic area from a discontinuity in the gallbladder wall.¹² In the present case, the ultrasonographic changes were nonspecific, and even though a strong suspicion of gallbladder wall rupture was hypothesized in the light of the clinical history, it could not be confirmed before surgical exploration.

As mentioned before, bile peritonitis has traditionally been diagnosed when bile pigment is reported in the abdominal fluid or the abdominal fluid bilirubin is significantly higher than in the serum or twice the serum concentration.^1–3 However, evidence for the cutoff values and the diagnostic performance of this approach is lacking in the literature. At the time of surgery in the present case, the patient was not icteric, no bile pigment was detected in abdominal effusion, and serum and abdominal effusion bilirubin levels did not highlight cause for concern. Septic peritonitis was detected, and exploratory laparotomy was performed in view of this, which confirmed the presence of gallbladder rupture. At that stage, anicteric gallbladder rupture was concluded in our patient.

Anicteric gallbladder rupture is defined as the presence of rupture in the absence of icterus, hyperbilirubinemia, and significant bilirubin concentration in the abdominal fluid.¹ In this case, at the time of surgery, the dog was presented as a case of anicteric gallbladder rupture. At this point, the dog was not icteric, and the measurement of bilirubin in the free fluid was unremarkable. However, because no bile acid determination or exploratory surgery was performed on admission, the possibility of an earlier icteric rupture cannot be completely ruled out. There are reported canine cases of anicteric gallbladder rupture, more commonly associated with gallbladder mucoceles.^4,7,17 From a pathophysiologic point of view, it has been suggested that bilirubin can diffuse through the peritoneum to the blood, and it can be transported to the intestines for excretion, a mechanism which could explain the lack of hyperbilirubinemia and abdominal fluid bilirubin in these cases.⁴ It has also been hypothesized that other components of the bile may not diffuse freely and may remain in the peritoneal effusion as bile acids, and this analyte may be useful in those cases.¹⁸ In the present case, as mentioned above, bilirubin values were normal in the serum and abdominal fluid at the time of diagnosis of the gallbladder rupture, but the bile acid concentration in the abdominal fluid was elevated above serum levels. The lack of evidence supporting the use of abdominal fluid bilirubin concentration makes further studies evaluating the use of bile acids concentration in the abdominal effusion of dogs (or other components of the bile) necessary for diagnosis of bile peritonitis. Similarly, evaluation of the sensitivity and specificity of abdominal fluid bilirubin is needed. It is also important to evaluate whether the underlying cause of a gallbladder rupture (e.g., mucoceles, cholecystitis) has an impact on the concentration of bilirubin and bile acids in the abdominal fluid in these cases because the composition of the bile may be different between diseases. Finally, there is a study in the literature that describes the presence of mucous material instead of bile pigment in abdominal effusion in three cases and concludes that this material can be also a diagnostic tool for bile peritonitis. However, the sample was small, and the authors suggest interpreting this finding together with fluid bilirubin concentration.¹⁹

Some limitations have been identified in this case report. Measurement of bile acids in the abdominal effusion at the time of admission was not performed because, at that stage, the suspicion of biliary tract rupture was low and no other criteria or findings were present to support this. However, as mentioned previously, in some situations, bile peritonitis does not fulfill the traditional criteria, a fact that makes it difficult to rule out the presence of bile peritonitis at an earlier stage. Furthermore, it was not possible to conclude if the gallbladder rupture was related to gallbladder disease (cholecystitis) and/or the performance of cholecystocentesis. In most circumstances, gallbladder rupture has been related to the presence of gallbladder wall necrosis.¹⁰ However, in the present case, only severe neutrophilic inflammation and fibrosis have been detected in the rupture site without evidence of necrosis. Reported complications of cholecystocentesis have been described, and these include hemorrhage, gallbladder wall odema, intraluminal hemorrhage, vago-vagal reactions, bile leakage, and bile peritonitis.^11,20,21 According to a recent study, complications occur in 5/201 dogs, and bile peritonitis represents 2/210 dogs in the study.²¹ Complications of cholecystocentesis can be challenging to diagnose because of the limitations of ultrasonography.⁵ Regarding the cause of the septic peritonitis, it was assumed to be due to the gallbladder rupture and reported bacterial cholecystitis, even though it was not possible to rule out cholecystocentesis as a cause of the rupture.

Conclusion

This case report emphasizes the fact that abdominal ultrasound and the evaluation of serum and abdominal fluid bilirubin cannot exclude a gallbladder rupture and bile peritonitis. Also, it is the authors’ opinion that further studies are needed to conclude whether the determination of bile acids could potentially be a better diagnostic tool for gallbladder rupture and bile peritonitis regarding sensitivity and specificity compared to ultrasound and bilirubin fluid-to-serum ratio. Finally, the authors raise the importance of bearing in mind the possibility of an anicteric gallbladder rupture and suggest considering the measurement of bile acids in abdominal effusion when gallbladder rupture is strongly suspected but not fulfilling the current poorly validated traditional criteria.

All animal use was consistent with acceptable practices as described in AAHA policy statement.