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Sigmoid volvulus, acquired megacolon and pseudo-obstruction
INTESTINAL SURGERY II
Sigmoid volvulus, acquired megacolon and pseudoobstruction
Aetio-pathology Sigmoid volvulus is permitted by an elongated segment of bowel accompanied by a lengthy mesentery with a narrow retroperitoneal attachment. This allows the two ends of the mobile colon to come together and twist around the narrow mesenteric base (Figure 1). Chronic constipation and treatment with psychotropic drugs may predispose to volvulus by affecting intestinal motility. High dietary fibre intake has been attributed to volvulus in developing nations. A twist of greater than 180 in the sigmoid mesentery can result in closed loop colonic obstruction if the patient has competent ileo-caecal valve. Volvulus impairs blood supply to the affected bowel leading to ischaemia. Bacterial fermentation of colonic contents in the closed loop results in further gas production and worsening colonic distension thus setting in a cascade of progressive ischaemia, bacterial translocation, systemic sepsis, segmental infarction, gangrene and perforation leading to generalized peritonitis and death.
Ramana R Kallam Dibyendu Bandyopadhyay
Abstract This article is aimed at describing three common colorectal surgical emergencies that present as large bowel obstruction. Emphasis is given to sigmoid volvulus, acquired megacolon/megarectum and colonic pseudoobstruction with respect to their clinical presentation and management including emergency treatment and any further elective treatment options once the emergency situation is resolved. In western society, these conditions are commonly associated with elderly and institutionalized patients posing significant management challenges. With increasing emphasis on emergency sub-speciality care provision, thorough understanding of these clinical conditions is essential to appropriately tailor the management to individual patient needs.
Clinical presentation Patients with sigmoid volvulus may present as acute or sub-acute intestinal obstruction. There is usually sudden onset of severe abdominal pain, obstipation and abdominal distension more dramatic than would be associated with other causes of colonic obstruction. Vomiting is usually a late feature. In the majority of patients, there may be a history suggestive of similar episodes which have spontaneously resolved with the passage of large quantities of flatus and faeces or hospitalization and various interventions to resolve the volvulus. The abdomen is usually markedly distended and tympanic. Severe abdominal pain, rebound tenderness and tachycardia are ominous signs as they are usually associated with either mural ischaemia from increased tension in excessively distended bowel wall or arterial occlusion caused by torsion of the mesenteric arterial supply. Plain radiographic findings often enable prompt diagnosis in at least 75% of cases. Radiographs reveal a markedly distended airfilled sigmoid colon with its apex in the right upper quadrant e classically described as the ‘coffee bean’ sign (Figure 2). Proximal colon is usually dilated and if the ileo-caecal valve is incompetent there will be associated small bowel dilatation. Gas is usually absent in the rectum. An erect chest X-ray helps to exclude perforation if there is no pneumoperitoneum. In the case of any diagnostic uncertainty based on plain radiographs, a CT scan is recommended for a more certain diagnosis. CT scans reveal a characteristic mesenteric whirl. Even though not routinely used, a contrast enema typically demonstrates the point of obstruction with the pathognomonic ‘bird’s beak’ deformity. Flexible endoscopy will help to confirm the diagnosis, treat the condition and more importantly, it will help to rule out other causes of large bowel obstruction.
Keywords Acquired megacolon/megarectum; colonic obstruction; large bowel obstruction; Ogilvie’s syndrome; pseudo-obstruction; sigmoid volvulus
Sigmoid volvulus Definition In general, volvulus describes the condition in which the bowel becomes twisted on its mesenteric axis resulting in partial or complete obstruction of the bowel lumen and a variable degree of impairment of its blood supply. Volvulus commonly affects: a redundant sigmoid colon (61%) due to its anatomy of long sigmoid mesentery with a narrow base, the right colon (34.5%) described as caecal volvulus (a misnomer), the transverse colon (3.5%) and very rarely the splenic flexure (1%).1,2 Epidemiology Accounting for 5e7% of emergency hospital admissions with colonic obstruction, sigmoid volvulus is relatively rare in North America and Europe. In Russia, sigmoid volvulus accounts for 50% of emergency admissions with a large bowel obstruction. In Iran, India and Africa, sigmoid volvulus is the most common cause for a large bowel obstruction. A typical European or North American patient with sigmoid volvulus is usually elderly, institutionalized and with multiple medical co-morbidities like dementia, Parkinson’s disease, Alzheimer’s and longstanding electrolyte imbalances and frailty. Sigmoid volvulus is more prevalent in males.
Management Once the diagnosis of sigmoid volvulus is established, initial management is aimed at resuscitation with correction of hypovolaemia and electrolyte imbalance. In almost all the patients in absence of perforation initial treatment is non-surgical intervention with a view to resolve the twist.3 This can be attempted either with a rigid or a flexible sigmoidoscope with controlled insufflation and advancement of scope beyond the point of obstruction to decompress the obstructed sigmoid colon. Sigmoidoscopic decompression is successful in 70e80% of cases in conventional practice.1,3
Ramana R Kallam FRCS is a Specialist Registrar in Surgery in Yorkshire Deanery, UK. Conflicts of interest: none declared. Dibyendu Bandyopadhyay MS FRCS FRCS (Gen Surg) is a Consultant Colorectal Surgeon at York Teaching Hospital, UK. Conflicts of interest: none declared.
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Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
Figure 1 Sigmoid volvulus.
semi-elective or elective setting for suitable patients. The operation could be conducted through a small left lower quadrant incision or laparoscopic approach. As the elongated colon and mesentery require virtually no mobilisation, sigmoid resection with primary anastomosis is easily accomplished. However, the authors feel that it is important to excise the sigmoid loop and anastomose at the upper rectum to prevent recurrent volvulus following surgery. Colonoscopy should be considered before elective resection if there is any suspicion of an associated neoplasm. In fit patients it is feasible to proceed to surgery at the index admission once endoscopic decompression is successful. When there is clinical peritonitis, endoscopic decompression is contra indicated and main stay of treatment is surgical intervention. Options in the emergency setting depend on the viability of the bowel, the patient’s general and nutritional status and local expertise. Surgical options include the following. A primary sigmoid resection with anastomosis is the best option. A sigmoid resection with end colostomy and closure of rectal stump (Hartmann’s resection), if conditions for a safe primary anastomosis are unfavourable. A double-barrel stoma as in Paul-Mikulicz’s procedure. A subtotal colectomy with end ileostomy or ileo-rectal anastomosis, in case of non-viable colon (closed loop obstruction). If the patient’s general condition does not permit resection surgery or general anaesthesia, percutaneous endoscopic sigmoidopexy is a preferred option once sigmoid volvulus is decompressed. Elongated loop of sigmoid is triangulated and fixed using three-point endoscopic fixation using percutaneous endoscopic gastrostomy (PEG) tubes or button devices.
Once decompressed it is advisable to leave a flatus tube to maintain continuous drainage for 24e48 hours; this will also help to prevent immediate recurrence. It is strongly advised for the operator to wear protective clothing whilst attempting endoscopic decompression as de-rotation is associated with rapid egress of flatus and liquid stool. In patients with clinical, radiological or biochemical signs of peritonitis from perforation or gangrene of the colon if the patient is fit enough to withstand the surgical stress, treatment should be emergency surgery with simultaneous resuscitation. Emergency operative interventions in this group of patients are associated with higher morbidity and mortality. In one of the larger case series from Veterans’ Affairs Hospitals, emergency surgery was associated with 24% mortality when compared to 6% in elective setting after emergency decompression of volvulus.1 Surgical options Recurrent sigmoid volvulus is common and can recur in 90%1 of patients after first successful conservative de-rotation and decompression. Due to this high rate of recurrence, once the emergency is over surgical treatment should be considered in the
Idiopathic megabowel/acquired megacolon/megarectum Definition A subgroup of patients with intractable constipation has persistent dilatation of the bowel. In the absence of an organic cause this is termed idiopathic megabowel (IMB). This is associated with chronic abnormal dilatation of colon and rectum down to the level of anal sphincters. Dilatation may affect various parts of colon. If dilatation is confined to colon it is described as megacolon, if dilatation is confined to rectum it is described as megarectum and if dilation involves both colon and rectum the condition is described as idiopathic megabowel.
Figure 2 The ‘coffee bean’ sign.
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Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
in 83% of patients in a small series.5 Pelvic floor procedures described are internal sphincterotomy or puborectalis division with limited success. The final option would be creation of a stoma proximal to non-functioning segment.5
Incidence and aetiology True incidence of IMB is unknown as majority of these patients are asymptomatic. Males and females are equally affected.4 This condition is characterized by recurrent faecal impaction usually beginning in childhood or early adult life.5 Despite the aetiology being unknown, evaluation of anorectal function has revealed that patients with IMB have excessive laxity (increased compliance), hypomotility, and sensory dysfunction of the rectum.5 Furthermore, patients also have impaired rectal evacuatory function, often with secondary delay in colonic transit.5
Colonic pseudo-obstruction Definition Colonic pseudo-obstruction is a term used to characterize a clinical syndrome with symptoms, signs, and a radiographic appearance of large bowel obstruction without a mechanical cause.6 According to presentation, pseudo-obstruction syndromes can be subdivided into acute and chronic forms. Acute colonic pseudoobstruction (ACPO) is characterized by massive colonic dilatation in the absence of mechanical obstruction. ACPO is also referred to as acute colonic ileus or Ogilvie’s syndrome.6
Clinical presentation Commonly presents with features suggestive of large bowel obstruction with abdominal distension and obstipation; this may or may not be associated with pain. Often no significant previous history of bowel disturbance is reported although a history of regular laxative use for constipation can be elicited. Progressive proximal colonic distension and faecal loading of rectum predisposes to acute presentation as sigmoid volvulus.5 On clinical examination one can observe gross abdominal distension with tympanic resonance on percussion. Digital rectal examination provides adequate clues to differentiate from volvulus as in IMB, rectum is usually voluminous and empty or faecally impacted.5 Plain radiographs will reveal a grossly distended colon and rectum. Formal diagnosis is made on contrast enema when the rectal diameter is greater than 6.5 cm at the level of pelvic brim.5 Histology of megacolon confirms the presence of ganglion cells in contrast to the absence of ganglions as seen in Hirschsprung’s disease.5
Incidence and aetiology The exact incidence of colonic pseudo-obstruction is unknown but may be inferred from the incidence of large bowel obstruction, where it is responsible for 20% of cases.6 The highest prevalence of ACPO is observed during the late middle age and men are more commonly affected than women.6 ACPO occurs in 1% of hospitalized orthopaedic patients undergoing hip, knee and spinal surgery. Although a few patients without any associated disease are affected, most develop ACPO in association with a wide spectrum of illnesses.6 Common associations are listed in Box 1.7 The cause of ACPO is thought to be due to an alteration in the normal autonomic regulation of colonic motor function. This could be either by excess parasympathetic suppression reducing colonic contractility or excessive sympathetic stimulation decreasing colonic motility.6 Nitric oxide, an inhibitory neurotransmitter, has also been shown to be overproduced in experimental models of ACPO.6
Management The majority of patients with IMB are managed conservatively to control symptoms. Basic measures include appropriate hydration and correction of electrolyte disturbances. Regular rectal evacuation should be encouraged with the help of stimulant laxatives, suppositories, enemas and rectal irrigation. Even though it has been claimed that the majority of these patients can be managed conservatively, 50e70% of patients may not tolerate medical treatment and represent with recurrent symptoms.5 Those who respond will require lifelong treatment. Medical therapy fails to achieve restoration of rectal calibre to normal even after prolonged treatment.5 More recently, the role of behavioural retraining incorporated with biofeedback has been explored.5
Clinical presentation Acute colonic pseudo-obstruction is characterized by abdominal distension, pain, nausea and/or vomiting, with a failure to pass flatus and stool. Symptoms tend to develop gradually over a period of time. Clinical examination reveals distended tympanitic
Predisposing conditions associated with acute colonic pseudo-obstruction
Surgical options Primary treatment for IMB is medical. However, when medical therapy fails surgical options should be carefully considered in selected patients with intractable symptoms impinging on quality of life. This should preferably be performed in a specialist surgical unit with multi disciplinary team approach. Patients should be carefully counselled, as surgery may only partially improve symptoms and may not provide a cure. In patients with megacolon and normally functioning normal capacity rectum, the operation of choice would be subtotal colectomy with ileo-rectal anastomosis, as segmental resections are associated with higher failure rates of up to 50%.5 In patients with IMB procedure of choice would be restorative proctocolectomy with ileo-anal pouch with up to a 73% success5 or total colectomy with end ileostomy. Vertical resection rectoplasty has been suggested for megarectum alone with normal colon with successful resolution of symptoms
SURGERY 32:8
C C
C C
C C
C
C C
Trauma (long bone, spinal injuries) Infection (pneumonia, urinary tract infection, pyrexia of unknown origin, abdominal sepsis) Cardiac (myocardial infarction, cardiac failure) Obstetric and gynaecological (lower segment Caesarean section, child birth, hysterectomy) Abdominal or pelvic surgery Neurological (stroke, Parkinson’s disease, multiple sclerosis, Alzheimer’s) Electrolyte imbalances (low sodium, potassium, phosphate, magnesium and calcium) Uraemia and renal failure Drugs (antidepressants, phenothiazines, opiates and antiparkinsonian agents)
Box 1
429
Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
than 10 minutes. Recurrence rates of ACPO after neostigmine administration appears to be lower (11%), than after colonoscopic decompression without flatus tube placement (40%).6 A significant side effect of neostigmine is bradycardia. Atropine must be immediately available. Nevertheless, caution with neostigmine is needed in patients with a history of myocardial infarction, active bronchospasm, renal failure and who are receiving b-blockers. Alternatively neostigmine can be given orally at a dose of 15 mg twice a day, until a regular bowel habit is established. Other agents tried with limited success include, erythromycin, cisapride and ondansetron as prokinetic agents. Administration of polyethylene glycol electrolyte-balanced solution after initial resolution of ACPO either with neostigmine or colonoscopy is associated with marked reduction in recurrence of ACPO.11
abdomen with bowel sounds. Massive colonic dilatation may cause ischaemia and spontaneous perforation in 3% of patients,6 with subsequent findings of peritonitis, tachycardia and raised C-reactive protein and white blood cell count. Spontaneous perforation is associated with 40% mortality when compared to 15% in patients with viable non-perforated bowel.6 A plain abdominal radiograph will reveal a dilated large bowel with or without associated small bowel dilatation (Figure 3). The differential diagnosis in hospitalised or institutionalised patients includes mechanical obstruction from rectal lesion and toxic megacolon due to Clostridium difficile infection. An erect chest Xray helps to look for free air under the diaphragm in suspected perforation. A water-soluble contrast enema or CT should be performed to differentiate a mechanical obstruction from a pseudo-obstruction. CT also helps to accurately measure the caecal diameter as a diameter greater than 12 cm is associated with risk of perforation.6
Surgical management CT-guided percutaneous caecostomy has been reported in suitable high-risk patients who failed to respond to optimal medical treatment with high success rate.6 Surgery is either reserved for patients with imminent perforation or inpatients who have not responded to maximum nonsurgical measures. Surgery is associated with high morbidity (30%)6 and mortality (6%).6 If the colon is viable, a venting caecostomy or a colostomy is preferred option with. If the colon is nonviable or perforated, subtotal colectomy or segmental resection with double barrel stoma should be considered. A
Management Once the diagnosis of acute pseudo-obstruction is suspected, treatment should accompany the diagnostic evaluation. Initial treatment is conservative including correction of fluid and electrolyte loss, naso-gastric decompression (in case of incompetent ileo-caecal valve) and discontinuing all opiates and motility inhibitors. Patients should be monitored closely for response with serial abdominal examinations and plain radiographs. Spontaneous resolution can be observed in 77% of patients with conservative measures.6 If the situation deteriorates or does not resolve, colonoscopic decompression, mucosal inspection for ischaemia and placement of flatus tube for continuous decompression should be considered.6
REFERENCES 1 Gingold D, Murrell Z. Management of colonic volvulus. Clin Colon Rectal Surg 2012; 25: 236e44. 2 Martin MJ, Steele SR. Twists and turns: a practical approach to volvulus and intussusception. Scand J Surg 2010; 99: 93e102. 3 Lou Zheng, Yu En-Da, Zhang Wei, Meng Rong-Gui, Hao Li-Qiang, Fu Chuan-Gang. Appropriate treatment of acute sigmoid volvulus in the emergency setting. World J Gastroenterol 2013; 19: 4979e83. 4 Gattuso JM, Kamm MA. Clinical features of idiopathic megarectum and idiopathic megacolon. Gut 1997; 41: 93. 5 Gladman MA, Scott SM, Lunniss PJ, Williams NS. Systematic review of surgical options for idiopathic megarectum and megacolon. Ann Surg 2005; 241: 562e74. 6 Saunders MD, Kimmey MB. Systematic review: acute colonic pseudoobstruction. Aliment Pharmacol Ther 2005; 22: 917e25. 7 De Giorgio R, Knowles CH. Acute colonic pseudo-obstruction. Br J Surg 2009; 96: 229e39. 8 Kayani B, Spalding DR, Jiao LR, Habib NA, Zacharakis E. Does neostigmine improve time to resolution of symptoms in acute colonic pseudo-obstruction? Int J Surg 2012; 10: 453e7. 9 Elsner JL, Smith JM, Ensor CR. Intravenous neostigmine for postoperative acute colonic pseudo-obstruction. Ann Pharmacother 2012; 46: 430e5. 10 Loftus CG, Harewood GC, Baron TH. Assessment of predictors of response to neostigmine for acute colonic pseudo-obstruction. Am J Gastroenterol 2002; 97: 3118e22. 11 Sgouros SN, Vlachogiannakos J, Vassiliadis K, et al. Effect of polyethylene glycol electrolyte balanced solution on patients with acute colonic pseudo obstruction after resolution of colonic dilation: a prospective, randomised, placebo controlled trial. Gut 2006; 55: 638e42.
Medical management In unresolved cases of ACPO, neostigmine, a parasympathomimetic agent has been successfully used to enhance colonic motility in up to 90% of patients.6 It is imperative that mechanical obstruction be excluded prior to neostigmine administration, or the subsequent high pressure generated in the colon against a distal obstruction could cause colonic perforation. Neostigmine enhances parasympathetic activity by competing with acetylcholine for acetylcholinesterase-binding sites.8e10 Neostigmine is administered intravenously at a dose of 2e2.5 mg over 3e5 minutes with close cardiac monitoring.9 The resolution of ACPO is indicated by passage of stool and flatus in less
Figure 3 Small bowel dilatation.
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Ó 2014 Elsevier Ltd. All rights reserved.
Sigmoid volvulus, acquired megacolon and pseudoobstruction
Aetio-pathology Sigmoid volvulus is permitted by an elongated segment of bowel accompanied by a lengthy mesentery with a narrow retroperitoneal attachment. This allows the two ends of the mobile colon to come together and twist around the narrow mesenteric base (Figure 1). Chronic constipation and treatment with psychotropic drugs may predispose to volvulus by affecting intestinal motility. High dietary fibre intake has been attributed to volvulus in developing nations. A twist of greater than 180 in the sigmoid mesentery can result in closed loop colonic obstruction if the patient has competent ileo-caecal valve. Volvulus impairs blood supply to the affected bowel leading to ischaemia. Bacterial fermentation of colonic contents in the closed loop results in further gas production and worsening colonic distension thus setting in a cascade of progressive ischaemia, bacterial translocation, systemic sepsis, segmental infarction, gangrene and perforation leading to generalized peritonitis and death.
Ramana R Kallam Dibyendu Bandyopadhyay
Abstract This article is aimed at describing three common colorectal surgical emergencies that present as large bowel obstruction. Emphasis is given to sigmoid volvulus, acquired megacolon/megarectum and colonic pseudoobstruction with respect to their clinical presentation and management including emergency treatment and any further elective treatment options once the emergency situation is resolved. In western society, these conditions are commonly associated with elderly and institutionalized patients posing significant management challenges. With increasing emphasis on emergency sub-speciality care provision, thorough understanding of these clinical conditions is essential to appropriately tailor the management to individual patient needs.
Clinical presentation Patients with sigmoid volvulus may present as acute or sub-acute intestinal obstruction. There is usually sudden onset of severe abdominal pain, obstipation and abdominal distension more dramatic than would be associated with other causes of colonic obstruction. Vomiting is usually a late feature. In the majority of patients, there may be a history suggestive of similar episodes which have spontaneously resolved with the passage of large quantities of flatus and faeces or hospitalization and various interventions to resolve the volvulus. The abdomen is usually markedly distended and tympanic. Severe abdominal pain, rebound tenderness and tachycardia are ominous signs as they are usually associated with either mural ischaemia from increased tension in excessively distended bowel wall or arterial occlusion caused by torsion of the mesenteric arterial supply. Plain radiographic findings often enable prompt diagnosis in at least 75% of cases. Radiographs reveal a markedly distended airfilled sigmoid colon with its apex in the right upper quadrant e classically described as the ‘coffee bean’ sign (Figure 2). Proximal colon is usually dilated and if the ileo-caecal valve is incompetent there will be associated small bowel dilatation. Gas is usually absent in the rectum. An erect chest X-ray helps to exclude perforation if there is no pneumoperitoneum. In the case of any diagnostic uncertainty based on plain radiographs, a CT scan is recommended for a more certain diagnosis. CT scans reveal a characteristic mesenteric whirl. Even though not routinely used, a contrast enema typically demonstrates the point of obstruction with the pathognomonic ‘bird’s beak’ deformity. Flexible endoscopy will help to confirm the diagnosis, treat the condition and more importantly, it will help to rule out other causes of large bowel obstruction.
Keywords Acquired megacolon/megarectum; colonic obstruction; large bowel obstruction; Ogilvie’s syndrome; pseudo-obstruction; sigmoid volvulus
Sigmoid volvulus Definition In general, volvulus describes the condition in which the bowel becomes twisted on its mesenteric axis resulting in partial or complete obstruction of the bowel lumen and a variable degree of impairment of its blood supply. Volvulus commonly affects: a redundant sigmoid colon (61%) due to its anatomy of long sigmoid mesentery with a narrow base, the right colon (34.5%) described as caecal volvulus (a misnomer), the transverse colon (3.5%) and very rarely the splenic flexure (1%).1,2 Epidemiology Accounting for 5e7% of emergency hospital admissions with colonic obstruction, sigmoid volvulus is relatively rare in North America and Europe. In Russia, sigmoid volvulus accounts for 50% of emergency admissions with a large bowel obstruction. In Iran, India and Africa, sigmoid volvulus is the most common cause for a large bowel obstruction. A typical European or North American patient with sigmoid volvulus is usually elderly, institutionalized and with multiple medical co-morbidities like dementia, Parkinson’s disease, Alzheimer’s and longstanding electrolyte imbalances and frailty. Sigmoid volvulus is more prevalent in males.
Management Once the diagnosis of sigmoid volvulus is established, initial management is aimed at resuscitation with correction of hypovolaemia and electrolyte imbalance. In almost all the patients in absence of perforation initial treatment is non-surgical intervention with a view to resolve the twist.3 This can be attempted either with a rigid or a flexible sigmoidoscope with controlled insufflation and advancement of scope beyond the point of obstruction to decompress the obstructed sigmoid colon. Sigmoidoscopic decompression is successful in 70e80% of cases in conventional practice.1,3
Ramana R Kallam FRCS is a Specialist Registrar in Surgery in Yorkshire Deanery, UK. Conflicts of interest: none declared. Dibyendu Bandyopadhyay MS FRCS FRCS (Gen Surg) is a Consultant Colorectal Surgeon at York Teaching Hospital, UK. Conflicts of interest: none declared.
SURGERY 32:8
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Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
Figure 1 Sigmoid volvulus.
semi-elective or elective setting for suitable patients. The operation could be conducted through a small left lower quadrant incision or laparoscopic approach. As the elongated colon and mesentery require virtually no mobilisation, sigmoid resection with primary anastomosis is easily accomplished. However, the authors feel that it is important to excise the sigmoid loop and anastomose at the upper rectum to prevent recurrent volvulus following surgery. Colonoscopy should be considered before elective resection if there is any suspicion of an associated neoplasm. In fit patients it is feasible to proceed to surgery at the index admission once endoscopic decompression is successful. When there is clinical peritonitis, endoscopic decompression is contra indicated and main stay of treatment is surgical intervention. Options in the emergency setting depend on the viability of the bowel, the patient’s general and nutritional status and local expertise. Surgical options include the following. A primary sigmoid resection with anastomosis is the best option. A sigmoid resection with end colostomy and closure of rectal stump (Hartmann’s resection), if conditions for a safe primary anastomosis are unfavourable. A double-barrel stoma as in Paul-Mikulicz’s procedure. A subtotal colectomy with end ileostomy or ileo-rectal anastomosis, in case of non-viable colon (closed loop obstruction). If the patient’s general condition does not permit resection surgery or general anaesthesia, percutaneous endoscopic sigmoidopexy is a preferred option once sigmoid volvulus is decompressed. Elongated loop of sigmoid is triangulated and fixed using three-point endoscopic fixation using percutaneous endoscopic gastrostomy (PEG) tubes or button devices.
Once decompressed it is advisable to leave a flatus tube to maintain continuous drainage for 24e48 hours; this will also help to prevent immediate recurrence. It is strongly advised for the operator to wear protective clothing whilst attempting endoscopic decompression as de-rotation is associated with rapid egress of flatus and liquid stool. In patients with clinical, radiological or biochemical signs of peritonitis from perforation or gangrene of the colon if the patient is fit enough to withstand the surgical stress, treatment should be emergency surgery with simultaneous resuscitation. Emergency operative interventions in this group of patients are associated with higher morbidity and mortality. In one of the larger case series from Veterans’ Affairs Hospitals, emergency surgery was associated with 24% mortality when compared to 6% in elective setting after emergency decompression of volvulus.1 Surgical options Recurrent sigmoid volvulus is common and can recur in 90%1 of patients after first successful conservative de-rotation and decompression. Due to this high rate of recurrence, once the emergency is over surgical treatment should be considered in the
Idiopathic megabowel/acquired megacolon/megarectum Definition A subgroup of patients with intractable constipation has persistent dilatation of the bowel. In the absence of an organic cause this is termed idiopathic megabowel (IMB). This is associated with chronic abnormal dilatation of colon and rectum down to the level of anal sphincters. Dilatation may affect various parts of colon. If dilatation is confined to colon it is described as megacolon, if dilatation is confined to rectum it is described as megarectum and if dilation involves both colon and rectum the condition is described as idiopathic megabowel.
Figure 2 The ‘coffee bean’ sign.
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Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
in 83% of patients in a small series.5 Pelvic floor procedures described are internal sphincterotomy or puborectalis division with limited success. The final option would be creation of a stoma proximal to non-functioning segment.5
Incidence and aetiology True incidence of IMB is unknown as majority of these patients are asymptomatic. Males and females are equally affected.4 This condition is characterized by recurrent faecal impaction usually beginning in childhood or early adult life.5 Despite the aetiology being unknown, evaluation of anorectal function has revealed that patients with IMB have excessive laxity (increased compliance), hypomotility, and sensory dysfunction of the rectum.5 Furthermore, patients also have impaired rectal evacuatory function, often with secondary delay in colonic transit.5
Colonic pseudo-obstruction Definition Colonic pseudo-obstruction is a term used to characterize a clinical syndrome with symptoms, signs, and a radiographic appearance of large bowel obstruction without a mechanical cause.6 According to presentation, pseudo-obstruction syndromes can be subdivided into acute and chronic forms. Acute colonic pseudoobstruction (ACPO) is characterized by massive colonic dilatation in the absence of mechanical obstruction. ACPO is also referred to as acute colonic ileus or Ogilvie’s syndrome.6
Clinical presentation Commonly presents with features suggestive of large bowel obstruction with abdominal distension and obstipation; this may or may not be associated with pain. Often no significant previous history of bowel disturbance is reported although a history of regular laxative use for constipation can be elicited. Progressive proximal colonic distension and faecal loading of rectum predisposes to acute presentation as sigmoid volvulus.5 On clinical examination one can observe gross abdominal distension with tympanic resonance on percussion. Digital rectal examination provides adequate clues to differentiate from volvulus as in IMB, rectum is usually voluminous and empty or faecally impacted.5 Plain radiographs will reveal a grossly distended colon and rectum. Formal diagnosis is made on contrast enema when the rectal diameter is greater than 6.5 cm at the level of pelvic brim.5 Histology of megacolon confirms the presence of ganglion cells in contrast to the absence of ganglions as seen in Hirschsprung’s disease.5
Incidence and aetiology The exact incidence of colonic pseudo-obstruction is unknown but may be inferred from the incidence of large bowel obstruction, where it is responsible for 20% of cases.6 The highest prevalence of ACPO is observed during the late middle age and men are more commonly affected than women.6 ACPO occurs in 1% of hospitalized orthopaedic patients undergoing hip, knee and spinal surgery. Although a few patients without any associated disease are affected, most develop ACPO in association with a wide spectrum of illnesses.6 Common associations are listed in Box 1.7 The cause of ACPO is thought to be due to an alteration in the normal autonomic regulation of colonic motor function. This could be either by excess parasympathetic suppression reducing colonic contractility or excessive sympathetic stimulation decreasing colonic motility.6 Nitric oxide, an inhibitory neurotransmitter, has also been shown to be overproduced in experimental models of ACPO.6
Management The majority of patients with IMB are managed conservatively to control symptoms. Basic measures include appropriate hydration and correction of electrolyte disturbances. Regular rectal evacuation should be encouraged with the help of stimulant laxatives, suppositories, enemas and rectal irrigation. Even though it has been claimed that the majority of these patients can be managed conservatively, 50e70% of patients may not tolerate medical treatment and represent with recurrent symptoms.5 Those who respond will require lifelong treatment. Medical therapy fails to achieve restoration of rectal calibre to normal even after prolonged treatment.5 More recently, the role of behavioural retraining incorporated with biofeedback has been explored.5
Clinical presentation Acute colonic pseudo-obstruction is characterized by abdominal distension, pain, nausea and/or vomiting, with a failure to pass flatus and stool. Symptoms tend to develop gradually over a period of time. Clinical examination reveals distended tympanitic
Predisposing conditions associated with acute colonic pseudo-obstruction
Surgical options Primary treatment for IMB is medical. However, when medical therapy fails surgical options should be carefully considered in selected patients with intractable symptoms impinging on quality of life. This should preferably be performed in a specialist surgical unit with multi disciplinary team approach. Patients should be carefully counselled, as surgery may only partially improve symptoms and may not provide a cure. In patients with megacolon and normally functioning normal capacity rectum, the operation of choice would be subtotal colectomy with ileo-rectal anastomosis, as segmental resections are associated with higher failure rates of up to 50%.5 In patients with IMB procedure of choice would be restorative proctocolectomy with ileo-anal pouch with up to a 73% success5 or total colectomy with end ileostomy. Vertical resection rectoplasty has been suggested for megarectum alone with normal colon with successful resolution of symptoms
SURGERY 32:8
C C
C C
C C
C
C C
Trauma (long bone, spinal injuries) Infection (pneumonia, urinary tract infection, pyrexia of unknown origin, abdominal sepsis) Cardiac (myocardial infarction, cardiac failure) Obstetric and gynaecological (lower segment Caesarean section, child birth, hysterectomy) Abdominal or pelvic surgery Neurological (stroke, Parkinson’s disease, multiple sclerosis, Alzheimer’s) Electrolyte imbalances (low sodium, potassium, phosphate, magnesium and calcium) Uraemia and renal failure Drugs (antidepressants, phenothiazines, opiates and antiparkinsonian agents)
Box 1
429
Ó 2014 Elsevier Ltd. All rights reserved.
INTESTINAL SURGERY II
than 10 minutes. Recurrence rates of ACPO after neostigmine administration appears to be lower (11%), than after colonoscopic decompression without flatus tube placement (40%).6 A significant side effect of neostigmine is bradycardia. Atropine must be immediately available. Nevertheless, caution with neostigmine is needed in patients with a history of myocardial infarction, active bronchospasm, renal failure and who are receiving b-blockers. Alternatively neostigmine can be given orally at a dose of 15 mg twice a day, until a regular bowel habit is established. Other agents tried with limited success include, erythromycin, cisapride and ondansetron as prokinetic agents. Administration of polyethylene glycol electrolyte-balanced solution after initial resolution of ACPO either with neostigmine or colonoscopy is associated with marked reduction in recurrence of ACPO.11
abdomen with bowel sounds. Massive colonic dilatation may cause ischaemia and spontaneous perforation in 3% of patients,6 with subsequent findings of peritonitis, tachycardia and raised C-reactive protein and white blood cell count. Spontaneous perforation is associated with 40% mortality when compared to 15% in patients with viable non-perforated bowel.6 A plain abdominal radiograph will reveal a dilated large bowel with or without associated small bowel dilatation (Figure 3). The differential diagnosis in hospitalised or institutionalised patients includes mechanical obstruction from rectal lesion and toxic megacolon due to Clostridium difficile infection. An erect chest Xray helps to look for free air under the diaphragm in suspected perforation. A water-soluble contrast enema or CT should be performed to differentiate a mechanical obstruction from a pseudo-obstruction. CT also helps to accurately measure the caecal diameter as a diameter greater than 12 cm is associated with risk of perforation.6
Surgical management CT-guided percutaneous caecostomy has been reported in suitable high-risk patients who failed to respond to optimal medical treatment with high success rate.6 Surgery is either reserved for patients with imminent perforation or inpatients who have not responded to maximum nonsurgical measures. Surgery is associated with high morbidity (30%)6 and mortality (6%).6 If the colon is viable, a venting caecostomy or a colostomy is preferred option with. If the colon is nonviable or perforated, subtotal colectomy or segmental resection with double barrel stoma should be considered. A
Management Once the diagnosis of acute pseudo-obstruction is suspected, treatment should accompany the diagnostic evaluation. Initial treatment is conservative including correction of fluid and electrolyte loss, naso-gastric decompression (in case of incompetent ileo-caecal valve) and discontinuing all opiates and motility inhibitors. Patients should be monitored closely for response with serial abdominal examinations and plain radiographs. Spontaneous resolution can be observed in 77% of patients with conservative measures.6 If the situation deteriorates or does not resolve, colonoscopic decompression, mucosal inspection for ischaemia and placement of flatus tube for continuous decompression should be considered.6
REFERENCES 1 Gingold D, Murrell Z. Management of colonic volvulus. Clin Colon Rectal Surg 2012; 25: 236e44. 2 Martin MJ, Steele SR. Twists and turns: a practical approach to volvulus and intussusception. Scand J Surg 2010; 99: 93e102. 3 Lou Zheng, Yu En-Da, Zhang Wei, Meng Rong-Gui, Hao Li-Qiang, Fu Chuan-Gang. Appropriate treatment of acute sigmoid volvulus in the emergency setting. World J Gastroenterol 2013; 19: 4979e83. 4 Gattuso JM, Kamm MA. Clinical features of idiopathic megarectum and idiopathic megacolon. Gut 1997; 41: 93. 5 Gladman MA, Scott SM, Lunniss PJ, Williams NS. Systematic review of surgical options for idiopathic megarectum and megacolon. Ann Surg 2005; 241: 562e74. 6 Saunders MD, Kimmey MB. Systematic review: acute colonic pseudoobstruction. Aliment Pharmacol Ther 2005; 22: 917e25. 7 De Giorgio R, Knowles CH. Acute colonic pseudo-obstruction. Br J Surg 2009; 96: 229e39. 8 Kayani B, Spalding DR, Jiao LR, Habib NA, Zacharakis E. Does neostigmine improve time to resolution of symptoms in acute colonic pseudo-obstruction? Int J Surg 2012; 10: 453e7. 9 Elsner JL, Smith JM, Ensor CR. Intravenous neostigmine for postoperative acute colonic pseudo-obstruction. Ann Pharmacother 2012; 46: 430e5. 10 Loftus CG, Harewood GC, Baron TH. Assessment of predictors of response to neostigmine for acute colonic pseudo-obstruction. Am J Gastroenterol 2002; 97: 3118e22. 11 Sgouros SN, Vlachogiannakos J, Vassiliadis K, et al. Effect of polyethylene glycol electrolyte balanced solution on patients with acute colonic pseudo obstruction after resolution of colonic dilation: a prospective, randomised, placebo controlled trial. Gut 2006; 55: 638e42.
Medical management In unresolved cases of ACPO, neostigmine, a parasympathomimetic agent has been successfully used to enhance colonic motility in up to 90% of patients.6 It is imperative that mechanical obstruction be excluded prior to neostigmine administration, or the subsequent high pressure generated in the colon against a distal obstruction could cause colonic perforation. Neostigmine enhances parasympathetic activity by competing with acetylcholine for acetylcholinesterase-binding sites.8e10 Neostigmine is administered intravenously at a dose of 2e2.5 mg over 3e5 minutes with close cardiac monitoring.9 The resolution of ACPO is indicated by passage of stool and flatus in less
Figure 3 Small bowel dilatation.
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