Introduction

Post-necrotic pancreatic pseudocyst is the most common complication of acute destructive pancreatitis. Most authors agree that acute pancreatitis is complicated by pseudocyst in 8-78% of cases [1, 2]. Incidence of complications in patients with pseudocysts is 15-88%, infection of cyst – 10-35% [1–5].

Optimal treatment strategy for pseudocyst is still debatable. Many pancreatologists prefer active surgical approach for large and giant cysts. Management of infected pseudocysts with sequesters still presents certain challenges. Sequestration in infected pseudocysts is ubiquitous and occurs in 30-60% of patients. Management of such cysts remains controversial [1, 3, 6–9].

Specialists have no a unified approach to surgical treatment of infected pseudocysts. Nevertheless, there are various surgeries interrupting infectious inflammation (external drainage of via laparotomy or percutaneous drainage under guidance of transabdominal ultrasound, pancreatectomy, endosonography-guided transgastric or transduodenal drainage) [7, 8-10]. Minimally invasive treatment of pseudocysts is perspective for giant infected pseudocysts with sequesters [8–15].

Clinical observation

Patient P. admitted with complaints of recurrent abdominal pain, bloating and general weakness. He fell ill acutely and underwent emergency laparoscopy, omentobursotomy, debridement and drainage of abdominal cavity in October 2020. In postoperative period, the patient was diagnosed with a new coronavirus infection complicated by bilateral pneumonia. After discharge, the patient complained of modern pain in upper abdomen, heaviness in epigastrium and left hypochondrium, general weakness, no appetite, weight loss of more than 10 kg and occasional fever. Despite conservative outpatient treatment, complaints persisted for more than 3 months. After examination, the patient was hospitalized to the surgical department of the regional infectious center.

Status localis at admission

The tongue was wet with white coating. The abdomen was symmetrical, moderately swollen, enlarged and participated in breathing. Postoperative scars in the right iliac region after previous appendectomy, in the right and left hypochondrium, hypogastrium after laparoscopy and omentobursostomy had no signs of inflammation. There was a palpable slightly painful dense elastic induration from the left hypochondrium to the ilium.

Diagnostic data at admission

Complete blood count: leukocytosis up to 12.3 x 10⁹/l.

Biochemical blood test: moderate increase of amylase up to 176 U/l, lipase up to 198 U/l, C-reactive protein (CRP) up to 198 mg/l, decrease of total serum protein (54 g/l) and albumin (26 g/l) as a sign of nutritional deficiency. Ultrasound revealed fluid (anechoic) accumulation with liquid component and parietal echogenic masses 9.5 × 6.0 cm within the pancreatic head. Similar retroperitoneal fluid accumulation 30.0×9.0×14.0 cm with heterogeneous structure due to liquid part and fibrinous component filled with sequesters was found on the left. There was also retroperitoneal fluid accumulation 14.5 × 6.5 × 9.5 cm on the right.

Contrast-enhanced CT of the abdomen revealed atrophic and thinned pancreas with weak accumulation of contrast agent. In parapancreatic space, we observed massive fluid accumulations spreading to the lower floor of the abdominal cavity on both sides, as well as along the left crus of diaphragm. Focal impairment of perfusion in pancreatic body and tail, as well as fluid in pelvic cavity was found (Fig. 1).

Fig. 1. CT of the abdomen, axial scan, giant pancreatic pseudocyst. Thus, giant post-necrotic pancreatic cyst with nutritive insufficiency was diagnosed at admission.

Treatment

After examination with appropriate preoperative preparation, the patient underwent endosonography-guided transgastric drainage of pancreatic pseudocyst after 7 days. Self-expanding metal stent with a diameter of 14 mm and a length of 40 mm was installed under X-ray control. A large amount of heterogeneous infected content of the pseudocyst was obtained through the endoprosthesis into stomach. Double pigtail plastic stent was additionally installed through the metal stent into the cyst for faster evacuation of content. During cystoscopy, we observed a large number of different sequesters, walls with necrotic tissues and detritus (Fig. 2).

Fig. 2. Endoscopic images of transgastric drainage of post-necrotic pancreatic cyst using a metal self-expanding stent.

In 9 days after admission, contrast-enhanced CT of the abdomen was performed. Shrinkage of fluid accumulations and appearance of gas bubbles probably due to air from the stomach were found. We observed fragments of pancreatic tissue with mild contrast-enhancement. No free gas in abdominal cavity was detected (Fig. 3).

Fig. 3. CT of the abdomen, axial scans, significant shrinkage of pseudocyst after transgastric drainage.

After 12 days, the patient complained of fewer up to 38°C. We found increment of serum CRP up to 256 mg/l and negative ultrasound data with larger abdominal effusion and peritoneal symptoms. Emergency laparoscopy, dissection of adhesions, debridement and drainage of abdominal cavity were carried out for advanced enzymatic peritonitis. We intraoperatively evacuated about 1500 ml of serous effusion from abdominal cavity. Biochemical analysis of exudate revealed high concentration of amylase (4890 U/l).

After 15 days, elective staged debridement of post-necrotic pancreatic cyst and partial sequestrectomy were performed. Then, we installed a pigtail stent 5 cm long into the lumen of pseudocyst to improve passage of exudate to the stomach. Simultaneous endoscopic sequestrectomy using Dormia basket and lavage of the cyst with saline and dioxidine were performed.

Endoscopic debridement after 26 days revealed positive clinical and laboratory dynamics. Almost the entire cystic wall was covered with granulations and fibrin. There were few sequesters. Laboratory analyses demonstrated stable positive trend with decrease of acute phase proteins (CRP 56 mg/l), normal WBC count (7.8∙10⁹ /l), serum total protein and albumin. Considering CT and ultrasound data, as well as endoscopic findings, we concluded that pseudocyst was not a single cavity, but there was at least 2 chambers. These were the left part of the pseudocyst (transgastric internal drainage and percutaneous external drainage), as well as central and right-sided parts retaining the same volume of content. Cystography through external percutaneous drainage confirmed this conclusion.

After 30 days, we performed a two-stage minimally invasive treatment. The first stage included ultrasound-guided percutaneous drainage of the right part of the pseudocyst. The second stage implied debridement of the pancreatic pseudocyst and partial sequestrectomy. Endoscopic image is presented in Fig. 4. Amount of purulent exudate significantly decreased. There were few sequesters and small amount of detritus.

Fig. 4. Endoscopic images during cystoscopy, staged sequestrectomy and debridement of cyst.

After 34 days, blood tests revealed serum CRP increment from 54.80 to 136 mg/l. Ultrasound revealed pseudocyst in mesogastrium on the right above the level of drainage tube. Pseudocyst was characterized by heterogeneous hypoechoic structure with maximum thickness up to 2.9 cm. Below the level of drainage tube, we also found hypoechoic homogeneous fluid accumulation 4.6 × 1.6 cm. There was significant abdominal effusion. Dilated intestinal loops up to 4.6 cm without active peristalsis were mainly observed in the right half of abdominal cavity.

Considering increase in serum inflammatory markers, we performed cystography through external retroperitoneal drainage to exclude cyst perforation. There was no contrast agent leakage into abdominal cavity. However, we found leakage into the left part of pancreatic pseudocyst (Fig. 5).

Fig. 5. Cystography, sequential filling of residual cyst with contrast agent.

The prescribed antibiotics were changed in accordance with sensitivity of bacterial flora. Bacteriological data (04/09/2021): Klebsiella pneumoniae 1.00∙10⁷ CFU/ml, Enterococcus faecium 1.00∙10⁷ CFU/ml. We increased the dose of "Bakcefort" to 8.0 g daily and added "Linezolid" 600 mg twice a day.

After 47 days, we removed the destroyed stent from the middle third of the stomach, performed sequestrectomy from post-necrotic cyst, repeated stenting of post-necrotic cavity with a metal self-expanding stent and debridement with dioxidine solution.

Throughout the treatment, the patient underwent 7 consecutive endoscopic staged debridement procedures with partial sequestrectomy.

The last cystoscopy before discharge visualized small amount of exudate inside the cyst, no detritus and necrotic masses. Cystic walls were covered with pink granulations and focal fibrin depositions (Fig. 6).

Fig. 6. Endoscopic images of staged cystoscopy and debridement of cyst.

Ultrasound and CT of the abdomen before discharge revealed positive dynamics with significant shrinkage of cyst. Metal self-expanding stent was visualized between the stomach and collapsed pseudocyst (Fig. 7).

Fig. 7. Contrast-enhanced chest CT, axial scans. Shrinkage and obliteration of cyst at discharge.

Blood tests at discharge revealed normal serum CRP (4 mg/l) and WBC count (6.3 x 10⁹/l). There was no hyperthermia after the last endoscopic debridement. Abdominal pain regressed at discharge. After 60 days, nutritional insufficiency was compensated (total serum protein 72 g/l, albumin 35 g/l), appetite recovered, oral feeding was completely restored.

The patient was discharged after 63 days.

Conclusion

Interventional minimally invasive technologies require certain consumables. However, absence of traditional laparotomy in our case prevented wound complications and severe systemic inflammatory reactions. Combined minimally invasive treatment of giant infected postnecrotic pancreatic cysts requires further study.

The authors declare no conflicts of interest.