Intestinal Obstruction: Causes, Symptoms, and Diagnosis PDF

Intestinal obstruction ---------------------- Intestinal obstruction occurs when the normal propulsion and passage of intestinal contents does not occur. An intestinal obstruction may partially or completely block this natural process. 80% of bowel obstructions are in the small intestines while th...

Intestinal obstruction ---------------------- Intestinal obstruction occurs when the normal propulsion and passage of intestinal contents does not occur. An intestinal obstruction may partially or completely block this natural process. 80% of bowel obstructions are in the small intestines while the large bowel constitutes the remaining 20%. Males and females have an equal incidence and incidence increases with age. Intestinal obstruction is divided into mechanical obstruction and functional obstruction. Mechanical obstruction is when a physical blockage is preventing the movement of intestinal contents whereas functional obstruction there is no physical blockage, however, the bowels are not moving food through the digestive tract. [Causes of intestinal obstruction] ***Small bowel*** - Extramural causes 1. Adhesions: they are the most common causes of small bowel obstruction. Adhesions are fibrous bands that form between intestinal loops which are normally not bound together. The band of tissue develops when healing from injury occurs secondary to surgery, infection, trauma, or radiation. Prior abdominal surgery is the most likely source of abdominal adhesions. 2. Hernia: they are weaknesses in the abdominal wall which can allow intestines to bulge through. Inguinal and femoral hernias in particular cause small intestine obstruction. When a segment of the small intestine is stuck and can't move back, food and gas are unable to pass. 3. Neoplasm: small bowel cancer is rare, therefore, external tumors not within the small intestine but from adjacent organs if big enough may press against the small intestine and cause an obstruction. - Mural causes 1. Strictures: they are an abnormal narrowing in the intestine. A stricture is caused by scarring after surgery or when one has Crohn's disease. Depending on there severity it can make it difficult for food or even fluid to pass. 2. Intussusception: part of the intestine invaginates into an adjacent part of the intestine. The telescoping action often blocks food or fluid from passing through. Common site of intussusception is the ileocecal valve. It is a rare disorder but is the most common cause of intestinal obstruction in children younger than 3 years. Most cases in adult result from underlying conditions such as tumors. 3. Meckel's diverticulum: it is the most common birth defect of the digestive system. 4. Paralytic ileus: inhibition of gastrointestinal propulsion without signs of mechanical obstruction. It is mostly caused by peritonitis, lower gastrointestinal surgery, hypokalemia and opioid use. - Intraluminal causes 1. Gallstone ileus: it is a rare complication of chronic cholecystitis and occurs when a large gallstone passes through a fistula between the gallbladder and small bowel before becoming impacted at the ileocecal valve. 2. Foreign body: occasionally an ingested object is likely to pass into the small bowel where they may become entrapped and cause an obstruction. - Extramural causes 1. Volvulus: occurs when a segment of the intestine twists around itself and its supporting mesentery, causing bowel obstruction and potentially cutting off blood supply. Most common site for a volvulus is the sigmoid colon followed by the cecum. It is associated with intestinal malrotation, an enlarged colon, a long mesentery, Hirschsprung disease, pregnancy, abdominal adhesions, and chronic constipation. 2. Diverticular disease: it is a group of conditions in which tiny pouches form in the colon. Small pouches form and push outward through weak spots in the wall of your colon. - Mural causes 1. Neoplasm: colorectal adenocarcinoma constitutes 98% of all cancers in the large intestine. Left sided carcinomas tend to be annular, encircling lesions with early symptoms of obstruction while right sided carcinomas tend to grow as polyploid, fungating masses but obstruction is uncommon. [Signs and symptoms of intestinal obstruction] Small bowel obstruction typically presents with acute symptoms. Patients often experience abdominal cramps, primarily located around the umbilical area or in the epigastric region. Vomiting is common, and in cases of complete obstruction, constipation (obstipation) ensues. Those with partial obstruction might experience diarrhea. The onset of severe, persistent pain usually indicates strangulation. In the absence of strangulation, the abdomen generally remains non-tender. Characteristic findings include hyperactive, high-pitched bowel sounds coupled with peristaltic rushes in alignment with cramping. Occasionally, one might palpate distended bowel loops. When infarction occurs, the abdomen becomes tender, and auscultation may reveal a silent abdomen or minimal peristalsis. The presence of shock and oliguria are grave indicators, often signifying late-stage simple obstruction or strangulation. Large bowel obstruction typically manifests with more gradual and milder symptoms compared to small bowel obstruction. Progressive constipation leads to obstipation and abdominal distention. Although vomiting can occur, it usually does so several hours after the onset of other symptoms and is relatively uncommon. Patients often experience lower abdominal cramps without fecal output. Systemic symptoms are generally mild, with fluid and electrolyte imbalances being rare. During physical examination, a distended abdomen with pronounced bowel sounds (borborygmi) is commonly observed. The abdomen is typically non-tender, and the rectum is often empty. In some cases, a mass corresponding to the location of an obstructing tumor may be palpable. [Complications of intestinal obstruction] In simple mechanical obstruction, a blockage occurs without vascular compromise. Above the obstruction, ingested food, fluids, digestive secretions, and gas accumulate. This causes the proximal bowel to distend and the distal segment to collapse. The normal secretory and absorptive functions of the mucosa are impaired, leading to edema and congestion of the bowel wall. Severe intestinal distention is a self-perpetuating and progressive process, which exacerbates peristaltic and secretory dysfunction and heightens the risk of dehydration and the development of strangulating obstruction. Strangulating obstruction, where blood flow is compromised, occurs in nearly 25% of small bowel obstruction cases. It is commonly associated with conditions such as hernia, volvulus, and intussusception. Strangulating obstruction can quickly lead to infarction and gangrene, sometimes within as little as six hours. Initially, venous obstruction occurs, followed by arterial occlusion, causing rapid ischemia of the bowel wall. This leads to edema, infarction, gangrene, and potential perforation. Strangulation is rare in large bowel obstruction, except in cases of volvulus. Perforation can occur in ischemic segments, typically of the small bowel, or when marked dilation is present. The risk of perforation is particularly high if the cecum is dilated to a diameter of 13 cm or more. Additionally, perforation of a tumor or diverticulum may occur at the site of obstruction. [Diagnosis ] There are several tests for diagnosing an intestinal obstruction, including: - Blood test: blood tests such as full hemogram, basic metabolic panel, CRP can help determine if you have an infection or other illness causing the obstruction. - Radiography: techniques such as X-rays, CT scan images can indicate the location and severity of the blockage. - Capsule endoscopy: a tiny camera embedded in a capsule takes pictures of your digestive tract. - Barium enema: a series of x-rays are taken after one receives an enema containing barium which coats your colon nad shows up well on X-rays. - Colonoscopy: it allows the physician to view the lining of the colon using an endoscope. [Treatment ] Treatment of acute intestinal obstruction must proceed simultaneously with diagnosis. - Nasogastric suction and iv fluids (0.9% saline or lactated ringer's solution). It should be guided by test results but in cases of repeated vomiting serum sodium and potassium are likely to be depleted. - IV antibiotics if bowel ischemia or infarction suspected before operative exploration. - While surgery can be postponed for two or three hours to restore fluid status and urine output in a severely sick, dehydrated patient, early laparotomy is the preferred treatment for complete obstruction of the small bowel. Whenever feasible, the obstructive lesion is removed. - Cholecystectomy is not required if a gallstone is the source of the obstruction; instead, it is removed using an enterotomy. - Procedures such as hernia repair, foreign body removal, and lysis of the problematic adhesions should be carried out in order to prevent recurrence. - Obstructing colon cancers can be treated by a single stage resection and anastomosis, with or without temporary colostomy or ileostomy. When this procedure is not possible, a diverting colostomy with delayed resection is recommended. - Fecal concretion that causes complete obstruction requires laparotomy. - Treatment of volvulus consists of resection and anastomosis of the involved segment. Omenta ------ Omentum is a large adipose fold of the peritoneum connecting the stomach with other abdominal organs. There is a greater omentum and a lesser omentum. [Greater omentum] - It is a peritoneal fold connecting the stomach to the transverse colon. It descends as an apron from the greater curvature of the stomach to cover the intestine separating it from the anterior abdominal wall. - It is made up 2 anterior and 2 posterior layers that are fused together to form a fenestrated membrane with variable amounts of fat. - The 2 anterior layers are attached at the greater curvature of the stomach and the first inch of the duodenum. The 2 posterior layers ascend in front of the small intestine to reach the transverse colon. - It contains the gastroepiploic blood vessels and the right gastroepiploic lymphatic vessels along the greater curvature of the stomach. It also contains an aggregation of macrophages, which form dense patches called milky spots. - Its functions: i. Serves as a heat insulator covering the intestine ii. Reservoir of fat iii. It contains fixed macrophages which can be mobilized for defense against pathogens iv. It moves towards inflamed abdominal organs to surround them and prevent the spread of inflammation(policeman of the abdomen) v. It is sometimes used a grafting material by surgeons. vi. It protects the abdominal viscera from blow on the anterior abdominal wall. vii. It forms a partition between the supracolic and the infracolic compartments of the greater sac [Lesser omentum] - It is a peritoneal fold formed by two layers connecting the lesser curvature of the stomach and the first part of the duodenum to the inferior aspect of the liver. - It consists of two ligaments: hepatogastric ligament located medially and hepatoduodenal ligament located laterally. They connect the lesser curvature of the stomach to the liver and duodenal bulb respectively. - It transports the gastric blood vessels of the lesser curvature of the stomach. Stomas ------ A stoma is an artificial opening on the abdomen that can be connected to either your digestive or urinary system to allow waste(urine/faeces) to be diverted out of your body. Stomas can be temporary or permanent depending on the clinical situation and are constructed in different ways including as an end stoma or loop stoma. A permanent stoma is necessary when there is no distal bowel segment remaining after resection or when for some reason the bowel cannot be rejoined. Temporary stoma relieve complete distal large bowel obstruction causing proximal dilatation. The main types of stomas include; colostomy, ileostomy, urostomy. The most common conditions resulting in stoma surgery include colorectal cancer, bladder cancer, inflammatory bowel disease, and accidental injury. [Indications for a stoma] **End Colostomy Indications**  - Rectal resection with no restoration of continuity in below peritoneal reflection malignancy - Perforating diverticulitis with fecal peritonitis - Abdominoperineal rectal resection **Loop Colostomy Indications ** - Unresectable rectal carcinoma - Protective stoma in deep anterior rectal resection - Radiation proctitis - Incontinence - Complicated rectal carcinoma with stenosis - Complex perianal fistulas in the setting of inflammatory processes **End or Loop-end Ileostomy Indications ** - Failure of an ileal pouch-anal anastomosis - Emergency colectomy or proctocolectomy - Massive intestinal resection in bowel ischemia - Total proctocolectomy for familial adenomatous polyposis (FAP) - Hereditary nonpolyposis colon cancer (Lynch syndrome) with low rectal cancer - Total colectomy for refractory ulcerative colitis with medical management - Total proctocolectomy for Crohn disease ** Loop Ileostomy Indications ** - Protective stoma after proctocolectomy in FAP and chronic inflammatory bowel disease (CIBD) - Fecal incontinence - Fournier gangrene - Fulminant toxic colitis - Low rectal or coloanal anastomosis - Perineal necrotizing fasciitis - Severe Crohn perianal sepsis - Rectal trauma or sphincter injury - Complex rectovaginal or rectourethral fistula - Treatment of anastomotic leak [Colostomy] A colostomy is when part of your large bowel or colon is pulled through from an incision made on your abdomen to form a stoma. The position of the stoma depends on the section of the colon that's diverted, most commonly on the descending colon. *Loop colostomy* In a loop colostomy, a loop of colon is pulled out through an incision in the abdominal wall. The loop is opened up and stitched to the skin and temporarily held in place by a plastic rod slipped beneath it. A loop colostomy is most often preferred for a temporary colostomy, as it's easier to reverse, to divert stool away from an area of intestine that has been blocked or ruptured. *End colostomy* With an end colostomy, part of the colon is divided and the proximal segment is pulled out through an incision in the abdomen while the distal segment is closed off An end colostomy is often permanent, resulting from trauma or cancer. Tempoaray end colostomies are sometimes used in emergencies. [Ileostomy ] An ileostomy is when part of your small bowel(ileum) is pulled through an incision made on abdomen. *Loop ileostomy* This is when a looped portion of the ileum is pulled through abdomen. The loop is opened up and stitched to the skin and temporarily held in place by a plastic rod slipped beneath it. It is usually a temporary measure performed in emergency operation and will be reversed. *End ileostomy* Where one end of the ileum is pulled through and sewn to the abdomen. The other part of the diseased bowel is usually either removed or allowed to heal before being joined back. [Urostomy] A urostomy is formed when the bladder is removed due to disease such as cancer. A segment of the bowel will be pulled through an incision in the abdomen to form a stoma then the ureters will then be detached from the bladder and attached to the section of bowel to form a urostomy that diverts urine into a ostomy pouch. [Complications of a stoma] The most commonly occurring complications of intestinal stoma include the following: - Cutaneous irritation. - Ostomy retraction. - Ostomy prolapse. - Ostomy stenosis - Ostomy ischemia - Parastomal hernia - Fistula Preoperative and postoperative stoma education is critical so that patients ensure proper care of their ostomies to avoid suffering a complication. ***References;*** - Ansari, P. (2024, July 9). *Intestinal obstruction*. MSD Manual Professional Edition. - Mulita, F., & Lotfollahzadeh, S. (2023, June 3). Intestinal stoma. StatPearls - NCBI Bookshelf. - Zero To Finals. (2023, January 16). Understanding bowel obstruction \[Video\]. YouTube. - Savory, G. (2024, December 4). What is a stoma? Bladder & Bowel Community. - Singh, V. (2014). Textbook of Anatomy Abdomen and Lower Limb; Volume II. Elsevier Health Sciences.