Rectus abdominis muscle abscess after performing colonoscopy—A case report

Abstract

Key Clinical Message

Endoscopic removal of premalignant polyps can prevent colorectal cancers. It is considered a safe procedure, yet there are some complications reported. Rectus abdominis muscle abscess (RAMA) is a type of pyomyositis seen as a complication of rectus sheath hematoma. Predisposing factors to RAMA include trauma, diabetes mellitus, alcohol abuse, Intravenous drug abuse and hematologic diseases.In this article, we report a case of a 74-year-old patient with abscess formation in the Rectus Abdominis muscle after colonoscopy and polypectomy with the application of abdominal pressure techniques without any early complications. Diagnosis of RAMA was made after a Computed Tomography scan and ultrasound-guided drainage, in addition to antibiotic therapy, were used as treatment.Although colonoscopy is considered a generally safe procedure, endoscopists should be aware of Rectus Abdominis sheath hemorrhage and RAMA in the following as a complication with the presentation of abdominal pain. Applying abdominal pressure should be done carefully To reduce minor trauma likelihood, owing to it being a predisposing factor of RAMA.

INTRODUCTION

Endoscopic removal of colorectal polyps is used as a first-line treatment for reducing the incidence of colorectal cancer and cancer-related mortality.¹ Colonoscopy is a safe procedure in general, but there is a chance of complications. Complications are more likely to happen in colonoscopy with cautery. As the procedure gets more complex, a higher rate of complications is reported.² Perforation and post-colonoscopy hemorrhage are the most common complications.

Local infection is one of the colonoscopy complications; however, it is rare indeed. Perianal abscess and Fournier's gangrene have been described after colonoscopy. The mechanism is local mechanical trauma.³ Intraperitoneal and retroperitoneal abscess formation are also described in a few case reports as a result of colonoscopy.^4,5 As far as we know, there is no report of Rectus Abdominis muscle abscess after colonoscopy. In this article, we want to present a case of rectus abdominis muscle abscess after a colonoscopy completed by applying abdominal pressure techniques.

CASE PRESENTATION Investigation

A 74-year-old man with a positive fecal immunochemical test (FIT) underwent a screening colonoscopy followed by endoscopic removal of a sigmoidal polyp without any early complication (Figure 1). After 3 days, he came to the clinic with a complaint of mild abdominal pain in the left lower quadrant (LLQ) that started 1 day after the colonoscopy. The pain got worse while bending forward. Eating and defecation did not affect it. At this time, he had a mild tenderness in his left lower abdomen. There were no other findings, so antispasmodics were prescribed for him, and medical follow-up was advised. Four days later, he was admitted to the hospital. Figure 2 contains a timeline of clinical findings. The pain had increased during this period; also, he was ill and feverish. His past medical history merely included chronic hypertension controlled by medical therapy (Losartan tablets 25 mg daily). Before the colonoscopy, he had no history of intervention. On physical examination, low-grade fever and a notable tender swelling in the abdominal LLQ were detected.

FIGURE 1. Polyp in sigmoid part of colon, resected during colonoscopy.

FIGURE 2. Timeline of the clinical findings.

Diagnosis

Laboratory findings include mild leukocytosis (WBC = 10.8 10³/μL). Other remarkable findings include a high ESR level (62 mm/h), high CRP level (103 mg/L) and a microcytic hypochromic anemia. (Hb = 8.7 gr/dL, MCV = 81 fL, MCHC = 32.3 g/dL).

Abdominal ultrasonography showed a heterogenic hypoechoic region containing septa in the left rectus abdominis muscle, suggesting collection.

An abdominal CT scan with and without contrast was performed. As shown in Figure 3, the CT-scan images indicated subfacial multiloculated fluid collection with peripheral enhancement at the hypogastric left side abdominal wall in size of 102 × 63 mm compatible with abscess or rectus sheath hematoma (RSH). Other findings were sliding hiatal hernia.

FIGURE 3. Abdominopelvic MDCT scan shows a subfacial multiloculated collection in the hypogastric left side abdominal wall along the left rectus abdominis in size about 102 × 63 mm compatible with abscess formation or rectus sheath hematoma (arrows).

Treatment and follow-up

He was started on intravenous ceftriaxone and metronidazole as empiric therapy. Then, under the sonographic guide, drainage of the collection was done. The collection volume drained was 50 cc, which was sent to the laboratory for culture—also, a drain was placed at the collection site.

After 72 h, his condition improved. His abdominal tenderness decreased, and the quantity of drainage was insignificant. In addition, the WBC count fell to 5.6103/L. Due to the improvement in condition, the drain was removed. Pus culture result showed growth of Klebsiella pneumoniae. Antibiotic therapy was modified to oral ciprofloxacin and metronidazole due to antibiogram. He preferred to continue medications at home, so he was discharged. The antibiotic therapy continued for 14 days. Further follow-up showed complete resolution of symptoms.

DISCUSSION

RAMA is a pyomyositis seen as a complication of RSH.⁶ Abscess is an accumulation of purulent material associated with signs of infection such as fever and leukocytosis. Patients with abdominal wall abscesses such as RAMA may present with abdominal pain, fever, mass, anorexia, tachycardia, and septic shock.^7,8 Predisposing factors to RAMA and other types of pyomyositis are trauma, diabetes mellitus, alcohol abuse, parenteral drug abuse, HIV infection, cancer, and hematologic diseases.⁹ RAMA has been reported as an adverse effect in laparoscopic appendectomy, peritoneal dialysis, vaginal delivery and perforation of small bowel.^8,10–12 In this case, we presented a report of a 74-year-old patient with RAMA after colonoscopy. Our patient's only factor related to RSH and thus rectus sheath abscess was abdominal pressure we applied during colonoscopy.

CT scan with intravenous contrast and ultrasound are both effective methods to establish or evaluate the diagnosis of the Rectus abdominis muscle abscess.^13,14 In our case, we used both ultrasound and CT scan to confirm RAMA diagnosis according to mild leukocytosis.

The culture result in this case was the growth of Klebsiella pneumonia. Klebsiella is a gram-negative, encapsulate, and nonmotile bacterium that is considered an opportunistic pathogens colonizing mucosal surfaces without causing pathology. In the general population, 5%–38% of individuals carry the organism in their stool and 1%–6% in the nasopharynx.^15,16 It seems that Klebsiella spread hematogenous since no perforation was seen in the CT scan images.

Treatment of RAMA has two parts: open surgical or interventional radiological drainage of abscess and antibiotic therapy.⁹ It is essential to differentiate between RSH and RAMA because treatment of hematoma can be supportive or intervention based on the patient's condition. At the same time, Abscess drainage rapidly after the diagnosis is the key to treatment success.¹³ Treatment of our patient has included radiologically guided drainage combined with fluoroquinolone due to antibiogram result and metronidazole in case anaerobic bacteria were presented in pus that could not grow in the palate.

Colorectal cancer is the second leading cause of cancer death, affecting both men and women. Endoscopic removal of premalignant polyps can prevent colorectal cancers.¹⁷ Since total colonoscopy can be difficult due to looping, the proper abdominal pressure technique is an effective tool applied for assisting endoscopists during colonoscopy.^18–20 There are guidelines for applying safe and effective abdominal pressure techniques.^18,21

Although colonoscopy and polypectomy are considered safe procedures, there is a chance for complications such as perforation, bleeding or death.³ As far as we know, complications of abdominal pressure techniques have not been evaluated; however, Mesenteric tear and RSH are two complications reported after abdominal pressure.^4,19 RSH has been reported as a result of applying abdominal pressure happened immediately in the recovery room, and the patient became hypotensive with a fall in hemoglobin level.¹⁹ It is believed that either RSH occurrence is associated with minor trauma or exertional abdominal wall straining, as well as anti-coagulant consumption and intra-abdominal injections and can lead to abscess formation.^19,20 In our case, the onset of symptoms was late. However, since there is no other apparent predisposing factor in his history or further evaluation, and RAMA can be a result of RSH, the only reasonable cause can be the colonoscopy and the abdominal pressure that has been applied during the procedure in order to approaching complete colonoscopy.

CONCLUSIONS

While colonoscopy is usually a safe procedure, endoscopists must be mindful of rare complications such as RSH and RAMA, especially in patients experiencing abdominal pain. When applying pressure to the abdomen, care should be taken to minimize the likelihood of minor injuries, as these can lead to RAMA. It is crucial to consider a differential diagnosis in such cases and rule out other conditions.

AUTHOR CONTRIBUTIONS

Maryam Soheilipour: Conceptualization; project administration; supervision; writing – original draft. Elham Tabesh: Data curation; investigation; methodology; supervision. Mahshad Afsharzadeh: Project administration; visualization; writing – original draft; writing – review and editing. Amirhossein Tabibian: Writing – review and editing.

FUNDING INFORMATION

There was no funding for this study.

CONFLICT OF INTEREST STATEMENT

We confirm that we have no conflict of interest.

DATA AVAILABILITY STATEMENT

All data underlying the results are available as part of the article and no additional source data are required.

CONSENT

Written informed consent was obtained from the patient to publish this report under the journal's patient consent policy.