Abdominal compartment syndrome secondary to megarectum and megasigmoid

Abstract

A 31-year-old male patient with chronic constipation of unknown aetiology presented emergently with worsening nausea, vomiting and abdominal distension of one week duration. On examination, his abdomen was distended with minimal tenderness. A plain film of the abdomen demonstrated severe faecal loading. The patient was haemodynamically unstable on admission and appeared sick. An urgent CT abdomen and pelvis was conducted showing extensive rectal dilatation and associated proximal colonic stercoral perforation. The patient proceeded straight to theatre for laparotomy as his general condition was deteriorating rapidly. On transfer to the operating table, the patient suffered cardiopulmonary arrest. Resuscitation was immediately commenced. Abdominal compartment syndrome was suspected. Cardiac output was re-established following a midline laparotomy which acted relieve the abdominal pressure. The rectosigmoid faecal content was decompressed via an enterotomy. The perforated segment of transverse colon was resected and an end colostomy fashioned. A year later, the continuity of the bowel was re-established.

Background

This case report details a life-threatening condition secondary to chronic constipation. Chronic constipation is a common health condition and can have a significant negative impact on health-related quality of life.¹ However, megarectum is a rarely documented complication of chronic constipation.

Case presentation

A 31-year-old man with a history of chronic constipation presented to the emergency department with nausea, vomiting and worsening abdominal distension. The patient had been feeling unwell for one week prior to presentation with a poor appetite, poor oral intake and nausea. One day prior to admission, he began vomiting. The patient had not passed a solid bowel motion in three weeks but he was passing flatus. His abdomen had become more distended in the previous two weeks but he denied any abdominal pain.

This patient suffered from constipation from childhood, with a 28-year history of constipation. At the age of three, he received bowel training from a paediatric gastroenterologist. Prior to this, he had rectal biopsies performed which were negative for evidence of Hirschsprung’s disease. Through his teens and adulthood, the patient had numerous manual evacuations under anaesthetic. At the age of 21, he was further investigated for constipation, receiving a colonoscopy. The colonoscopy was reported normal and the patient was commenced on a long-term laxative regimen. He did not have any more investigations in the interim. Of note, he has mild learning disability.

He presented to the emergency department 10 days previously with unilateral left lower limb painful swelling. He was subsequently diagnosed with a deep vein thrombosis (DVT) and discharged home on rivaroxaban.

He took no regular medication except for the recently commenced rivaroxaban.

Initially, this patient did not have any signs of distress or altered consciousness. His heart rate was 146 beats/min, blood pressure 168/110 mmHg, oxygen saturation 98% on room air with a respiratory rate of 20/min. On examination, his abdomen was moderately tense and distended with an umbilical hernia. However, bowel sounds were audible. He had solid stool palpable on digital rectal examination.

A plain film of the abdomen was performed which displayed extensive faecal loading. Haematological investigations were as shown in table 1.

Table 1.

Bloods result on admission

Full blood count		Urea and electrolytes
White cell count	11.1 x 109/L	Sodium	126 mmol/L
Neutrophils	9.8 x 109/L	Potassium	3.3 mmol/L
Haemoglobin	11.3 g/dL	Urea	11.7 mmol/L
Platelets	416.0 x 109/L	Creatinine	139 µmol/L

Liver function tests		Other investigations
Alkaline phosphate	93 IU/L	Amylase	13 U/L
Gamma-glutamyl transferase	53 IU/L	C-reactive protein	249 mg/dL
Alanine transaminase	7 IU/L	Lactate	2.4 mmol/L
Aspartate transaminase	27 IU/L
Bilirubin	16.4 mmol/L
Albumin	18 g/L

Coagulation profile
Prothrombin time	52.5 seconds
International normalized ratio	5.8
Activated parial thromboplastin time	59 seconds

Blood cultures
Aerobic bottle	Positive for Escherichia coli
Anaerobic bottle	Positive for Eggerthella lenta

He was commenced on intravenous fluids and an urgent CT of the abdomen and pelvis was planned. His condition continued to deteriorate although he continued to deny pain, was alert and orientated.

The CT demonstrated a grossly dilated large bowel, in particular the rectum and sigmoid colon, with the rectosigmoid diameter measuring 17 cm (figure 1). There was extensive faecal impaction and loading throughout the rectum and sigmoid but also throughout the large bowel. There were moderate amounts of free abdominal fluid seen as well as locules of free air in the peritoneal cavity consistent with perforation (figure 2). This was suggestive of a stercoral perforation of the transverse colon due to marked faecal impaction and colonic dilatation.

Figure 1.

CT topogram (coronal section) shows a very distended sigmoid colon.

Figure 2.

CT abdomen (axial section) demonstrates abundant faecal material at the site of the perforation in the transverse colon (arrow).

On transfer from the patient’s bed to the operating table, the patient had a pulseless electrical activity cardiopulmonary arrest with flat lining of the arterial pressure waveform. While CPR was started immediately, it was recognised that significant abdominal distension was compromising venous return, and a raised intra-abdominal pressure (IAP) was suspected. Thus, an immediate laparotomy was performed to decompress the inferior vena cava, resulting in a spontaneous return of circulation.

Exploration revealed distension of the rectum, sigmoid and left colon—appearances in keeping with chronic distension (figure 3). Stercoral perforation in the transverse colon secondary to pressure necrosis and feculent peritonitis was also evident.

Figure 3.

A very distended sigmoid colon intraoperatively.

The rectosigmoid was decompressed via enterotomy and evacuation of the retained faeces. Next, the large bowel was resected from the hepatic flexure to the nearest point of healthy bowel in the left colon with oversewing of the stapled remaining stump. The decision was made to leave the chronically dilated rectosigmoid in situ considering how unwell the patient was at induction. Following copious washout, an end colostomy was fashioned in the right side. The fascia was closed and skin stapled. The patient was ventilated in intensive care unit requiring inotropic support for 5 days. He spent a further 8 days in the high dependency unit during which he was weaned off the ventilator and his inotropic support was withdrawn. Oral feeding was commenced, the stoma began functioning well and the patient was transferred to a surgical ward. Twenty-four days postadmission, the patient was discharged home on full diet.

Outcome and follow-up

The histology did not show any evidence of Hirschsprung’s disease or any other abnormal pathology. The patient had a left colonoscopy done a few months later and multiple full thickness random biopsies were taken from the anal canal and anorectal junction and that did not show any features of Hirschsprung’s disease. He was also found to have a very significant enlarged rectal stump with some large inspissated faeces within the lumen which were washed out and was started on Coloplast water irrigation enemas. A year later, the continuity of the large bowel was re-established with a colocolonic anastomosis and a diverting loop ileostomy was fashioned as a temporary measurement to reduce any serious consequences should an anastomotic leakage happen. However, the ileostomy was closed a few months later.

Discussion

This case report describes the management of a complication arising from intractable constipation and faecal impaction. The raised IAP secondary to a megarectum lead to ischaemia, necrosis and stercoral perforation of the bowel while simultaneously compressing the inferior vena cava obstructing venous return. Interestingly, the patient was diagnosed with a DVT of the left leg 10 days previous to this episode. Careful inspection of the common iliac vein on the subsequent CT imaging demonstrates extrinsic compression of the left common iliac vein at the level of the pelvic brim by the faecally loaded and dilated rectosigmoid. As uncommon as megarectum is, there are even fewer documented cases of such associated complications.

Intractable constipation is most commonly seen in the elderly, opioid dependent and psychiatric population,^{2 3} a cohort to which our patient does not belong. Patients who have chronic constipation can be divided into those who have a normal diameter gut and those who have gut dilatation. The latter includes Hirschsprung’s disease, chronic idiopathic intestinal pseudo-obstruction and idiopathic megacolon and megarectum.⁴ Megarectum, as seen here, is defined by a dilatation of the rectum to width greater than 6.5 cm at the level of the pelvic brim,⁵ has an unknown aetiology and pathology. What is known is that it is uncommon and poorly characterised.⁴ From the literature, it appears that rectal hyposensation with a poor perception of rectal filling may contribute to poor evacuatory function.^{4 6} In this case, the patient has a mild learning disability in terms of low capacity to concentrate and coordinate which might be accountable for his chronic problem.

Megarectum is often poorly managed; the faecal impaction associated with its poor evacuatory function can cause serious consequences such as obstructive uropathy, septic shock, respiratory distress and as seen in this case, colonic perforation, abdominal compartment syndrome (ACS) and compression of surrounding vascular structures.²

Stercoral perforation is a perforation of the large bowel due to pressure necrosis from a faecal mass.⁷ It is reported to account for 3.2% of all colonic perforations⁸ and associated with a 35% mortality rate.⁹ In this instance, the perforation site was situated in the transverse colon which is more proximal than where stercoral perforations are normally situated. This finding is likely a reflection of the level of faecal loading in the rectum and descending colon.

The other major issue seen in this case was ACS arising from the colonic dilatation. Prolonged, unrelieved pressure may lead to respiratory compromise, renal impairment, cardiac failure, shock and death.¹⁰ ACS causes organ failure through direct mechanical effects. Cardiovascular compromise results from decreased venous return from the compression of the heart and the inferior vena cava. This was initially appreciated here by our patient’s high diastolic pressure and tachycardia. Oliguria with a raised creatinine and urea could be explained by the compression of the renal vasculature. Time constraints did not allow for exact pressure measurements. Generally, intracystic pressure is measured and used as a reflection of IAP.¹⁰ An adult with an IAP of 35 mm Hg can suffer consequences of ACS.¹¹ In less acute cases, patients with an elevated IAP need to be monitored closely for evidence of organ dysfunction. Medical strategies to reduce IAP should be attempted but often surgical decompression is required.^{11 12} Untreated, ACS is associated with an 80%–100% mortality; with early decompression, mortality rates are still high at 40%–60%.^{12 13}

Learning points.

• Absence of pain does not mean absence of disease: abdominal pain and tenderness are key indicators of intra-abdominal pathology. Pain often guides management and investigations and the urgency in which they are done. Thankfully, the serious nature of this patient’s condition was recognised, even in the absence of pain.

• Almost always look for signs of abdominal compartment syndrome in any patient who presents with abdominal distension, and remember that even chronic constipation may cause it.

• Close attention to vital signs is essential. Without these indicators, the seriousness of the patient’s clinical condition may have gone unrecognised.

• Timely and precise intervention saves lives. Any further delay in surgical decompression and the outcome may have been fatal.

• Necessary follow-up with early recognition and elective intervention help avoid unnecessary risk.