Intestinal Obstruction – Overview, Diagnosis, and Treatment Guide

Intestinal Obstruction – Overview, Diagnosis, and Treatment Guide

1. Concept & Classification:

• Intestinal obstruction (IO) is a condition where the passage of gas and fluids through the intestines is halted, starting from the Treitz angle (duodenojejunal angle) to the anus.

• Classification:

• Mechanical IO: There is an actual physical obstruction causing narrowing of the intestinal lumen.

• Functional IO: Disturbances in intestinal motility cause stagnation of flow despite an unobstructed intestinal lumen.

• Occlusive IO: Only the intestinal lumen is blocked, while the mesentery is normal.

• Strangulated IO: The mesentery is also twisted or strangulated, leading to necrosis and intestinal ischemia.

2. Causes of Intestinal Obstruction:

• Inside the intestines (Occlusive IO):

• Common: Small intestine: roundworm infestation, food debris, gallstones.

• Rare: Large intestine: due to fecal impaction (elderly patients with prolonged constipation, patients using anti-motility drugs).

• Note: Consuming a lot of bamboo shoots, jackfruit fibers, and black berries can lead to occlusive intestinal obstruction (TRUE).

• Note: Gallstones causing inflammation and perforation into the duodenum, migrating down to the intestines causing obstruction is very rare in Vietnam (FALSE).

• At the intestinal wall (Occlusive IO):

• Cancer: Left colon cancer is most common, large benign tumors (GIST).

• Infections/fibrosis: Intestinal tuberculosis, Crohn’s disease, diverticulitis, post-radiotherapy colitis, anastomosis stenosis, post-trauma intestinal stricture.

• Outside the intestinal wall (Occlusive IO):

• Intestinal adhesions (most common): Due to abdominal surgery, infections, injuries, congenital conditions…

• External masses pressing on the intestines, peritoneal metastases compressing…

• Note: 80% of intestinal adhesions are due to previous abdominal surgeries (TRUE).

• Strangulated IO:

• Intestinal volvulus: Intestinal loops twist continuously around the mesenteric axis.

• Strangulated hernia.

• Acute intussusception in infants.

• Note: The most severe case of strangulated IO is intestinal volvulus (TRUE).

• Note: The most common location for intussusception is ileocecal intussusception.

3. Mechanisms of Intestinal Obstruction:

• Paralytic ileus: The intestines lose their motility and tone.

• Causes:

• Reflex ileus: Biliary/renal colic, ovarian cyst torsion, testicular torsion, greater omentum torsion, spinal cord injury, pelvic hematoma after surgery.

• Peritonitis: Gastric perforation, ruptured appendix, acute pancreatitis, intra-abdominal bleeding.

• Acute anemia and thromboembolism.

• Internal diseases: Metabolic disturbances (low potassium, high calcium, metabolic acidosis), medications (opioid derivatives, anticholinergics), Systemic diseases (diabetes mellitus, hypothyroidism).

• Spastic ileus: Increased tone, the intestines contract tightly and cannot expand.

• Causes: Lead poisoning, alkaloids, electrolyte imbalances…

• Occlusive and Strangulated IO:

• Occlusive IO: Pressure inside the intestines gradually increases with the progression of the disease > Intestinal blood flow is gradually disrupted, increasing progressively.

• Strangulated IO: In addition to increased intestinal pressure, the mesentery is strangulated > ischemia, intestinal necrosis usually progresses rapidly.

• Disruption of intestinal wall circulation: Due to excessive pressure inside the intestines exceeding capillary pressure > Disruption of intestinal wall circulation, lack of oxygen, necrosis of the intestinal wall.

• Systemic disturbances:

• Fluid retention + vomiting > dehydration, electrolyte loss (mainly Na+, K+, Cl-) > kidney failure, hypovolemic shock.

• Bacterial overgrowth + damage to the intestinal barrier > Bacteria, toxins enter the bloodstream > severe infection, sepsis.

• Late IO, strangulated IO > intestinal necrosis, rupture causing generalized peritonitis, bacterial endotoxins enter the peritoneal cavity > severe sepsis, high mortality rate.

4. Clinical Manifestations:

• 3 main functional symptoms:

• Pain: Typical intermittent episodes, starting gradually/suddenly, severe. Beginning around the navel/costal margin, spreading to the entire abdomen.

• Vomiting: Occurs simultaneously but does not relieve pain. Vomiting food > bile > feces.

• Constipation: May occur immediately after the onset. Sometimes not clear (mild obstruction).

• Note: In intestinal obstruction, after vomiting, the patient’s pain will not subside (FALSE).

• Distinguishing vomiting manifestations:

• Low IO: Frequent vomiting, early onset.

• High IO: Late vomiting/only nausea.

• Note: In cases of low intestinal obstruction, there may be bowel movements as waste and feces are discharged below the obstruction (FALSE, High IO).

• Systemic symptoms:

• Late IO, high obstruction: Signs of dehydration: thirst, sunken eyes, dry lips, wrinkled skin, reduced urine output. Signs of shock due to reduced circulatory volume.

• Strangulated IO: Shock can occur immediately, accompanied by signs of sepsis.

• Physical examination:

• Abdominal distention: Usually not distended immediately, highly variable.

• Visible intestinal loops: Abdominal bulge, palpable tension, clear borders, tympanic percussion.

• “Snake-like” movement: During pain episodes, see intestinal loops bulging, moving on the abdominal wall.

• Palpation reveals a soft abdomen, sometimes localized abdominal tenderness.

• Tympany in the middle of the abdomen (gas distention), dullness in the lower abdomen (peritonitis).

• Auscultation: Moving sounds of gas and fluids.

• Examination of hernial orifices.

• Rectal examination: Detects some causes.

• Distinguishing abdominal distention:

• High IO vs Low IO: High IO distends less/not distended/abdomen may be flat, Low IO distends significantly.

• Occlusive IO vs Strangulated IO: Occlusive IO distends evenly, Strangulated IO distends asymmetrically.

• Vol Wahl’s sign: Palpation reveals a very tense, painful intestinal loop, immobile. This sign is very valuable for diagnosing volvulus or strangulation.

• Note:

• The “snake-like” movement is the most characteristic sign of mechanical IO (TRUE).

• If the “snake-like” movement is not present, intestinal obstruction can be ruled out (FALSE).

• Hearing the moving sounds of gas and fluids in the intestines is also a valuable sign equivalent to the “snake-like” movement in diagnosing mechanical IO (TRUE).

• On plain abdominal X-rays, the two images of fluid levels and the “string of beads” sign are of equivalent value in diagnosing intestinal obstruction (TRUE).

5. Diagnosis:

• Determining the location of the obstruction via fluid levels:

• Small intestine obstruction: Multiple levels, concentrated in the middle of the abdomen, low arch, wide base, thin walls, presence of horizontal mucosal folds.

• Large intestine obstruction: Few levels, narrow base, high arch, more gas than fluid, located at the edge of the abdomen.

• “String of beads” sign: Images of small air bubbles arranged side by side in a chain, located in the space between adjacent mucosal folds.

• Plain abdominal X-ray:

• High fluid content: “String of beads” sign.

• High gas content: Fluid levels.

• Barium enema:

• Indication: Suspected large intestine obstruction.

• Contraindication: Suspected intestinal perforation.

• Images:

• Sigmoid volvulus: Contrast stops at the rectum, with a bird’s beak image.

• Large intestine obstruction due to tumor: Contrast stops at the tumor location, with a blunt cut image or a ragged defect with missing contrast.

• Intussusception: “Cup-like” image, “crab claw” image.

• Small bowel follow-through:

• Indication: Partial IO after repeated surgeries.

• Contraindication: Acute IO.

• Note: Small bowel follow-through can show dilated intestinal loops above the obstruction, but it cannot reliably pinpoint the location of the obstruction or its cause (FALSE).

• Abdominal ultrasound:

• Information:

• Images of IO: Dilated intestinal loops, fluid-filled, increased peristalsis, reversed peristalsis, transition zone of dilated/collapsed loops.

• Causes of IO: Tumor, intussusception, food debris, Crohn’s disease.

• Severe signs: Loss of peristalsis (increased in the early stages), free peritoneal fluid, thickened intestinal wall.

• Criteria for diagnosis:

• Dilation: Diameter > 3 cm.

• Wall thickness > 4 mm.

• Images of intussusception:

• “Sandwich” image on longitudinal sections.

• “Beer shot” image on cross-sections.

• Abdominal CT scan:

• Information:

• Signs of IO: Images of fluid levels, dilated intestinal loops…

• Diagnosing the cause: Tumor, food debris, metastases, roundworm infestation, internal hernias…

• Severe signs:

• Intestine loops not enhancing/poor enhancement with contrast.

• Diameter: Small intestine > 4 cm, cecum > 10 cm.

• Small intestine wall thickness > 4 mm or less than 1 mm.

• Gas: Present in the intestinal wall/mesentery/portal vein.

• Images:

• Images of gas in the intestinal wall and portal vein: Signs of necrosis of intestinal loops.

• Images of intestinal loops not enhancing/poorly enhancing with contrast: Indicates that intestinal loops are no longer well-perfused.

• Hematological and Biochemical examinations:

• Hematological examination: Increased red blood cells, increased hematocrit.

• Biochemical examination:

• Early stage: Decreased K+, increased pH, normal/slightly increased urea/creatinine.

• Late stage: Significant decrease in Na+, increased K+, decreased pH, significantly increased urea/creatinine, decreased Cl-.

6. Differential Diagnosis:

• The most specific symptom of intestinal obstruction is constipation (TRUE).

• The Bauhin valve is the landmark used to differentiate high/low IO; another name for the Bauhin valve is the ileocecal valve.

• High IO:

• Clinical:

• Pain: Severe, intermittent.

• Vomiting: Frequent, early onset.

• Constipation: Unclear in the initial hours, may have bowel movements.

• Abdominal distention: Around the navel/no distention/may be flat if obstruction is high near the Treitz angle.

• Dehydration and electrolyte disturbances: Early onset and severe.

• Paraclinical:

• Plain abdominal X-ray: Fluid levels: Multiple, concentrated in the middle of the abdomen, small, wide base, high arch, thin walls, arranged from the lower T rib to the pelvic cavity, with images of horizontal mucosal folds. Obstruction near the Treitz angle: A single level below the left rib or in front of the spine. High intestinal fluid content: “String of beads” image.

• CT scan: Location of obstruction (transition zone of dilated and collapsed intestinal loops), cause of obstruction.

• Low IO:

• Clinical: The disease usually starts gradually.

• Pain: Mild, infrequent.

• Vomiting: Late, sometimes only nausea; if present, vomit is foul-smelling.

• Constipation: Early onset.

• Abdominal distention: Significant, along the large intestine. Distention of the entire abdomen if obstruction is late. Asymmetric distention if large intestine volvulus.

• Dehydration and electrolyte disturbances: Late onset.

• Paraclinical:

• Plain abdominal X-ray: Fluid levels: Few, narrow base, high arch, more gas than fluid, located at the edge of the abdomen, late stages may have accompanying fluid levels of the small intestine. Sigmoid volvulus: A single dilated loop, shaped like an inverted U, with the base at the left iliac fossa extending upward towards the right costal margin. May have 2 fluid levels within the loop.

• Barium enema: Determining the location of obstruction.

• CT scan: Determining the location and cause of obstruction.

• Note: Large intestine obstruction can also reveal images of fluid levels in the small intestine (TRUE).

• Functional IO:

• Clinical: Gradual onset. Mild abdominal pain, rarely vomiting. The abdomen is usually significantly distended, with absent bowel sounds.

• Paraclinical:

• Plain abdominal X-ray: Dilation of the entire intestinal tract.

• Barium enema: Images of large intestine stenosis.

• CT scan: No location or cause of obstruction can be identified.

• Special cases: Ogilvie’s syndrome: Dilation of the entire large intestine, mainly gas dilation, commonly seen in patients with multiple traumas, patients on mechanical ventilation, the elderly and frail, patients using sedatives. CT scan helps to diagnose the disease.

• Note: CT scan does not help to diagnose functional IO, except in Ogilvie’s syndrome (TRUE).

• Occlusive IO:

• Clinical: Gradual onset.

• Typical intermittent episodes of pain.

• Even abdominal distention.

• “Snake-like” movement.

• Increased bowel motility during pain episodes.

• Gradual development of systemic signs.

• Paraclinical:

• Plain abdominal X-ray: Multiple fluid levels arranged in layers, depending on the location of the obstruction.

• CT scan: Determining the location and cause of obstruction.

• Strangulated IO:

• Clinical: Sudden, severe onset.

• Pain: Severe, constant, no episodes, no relief.

• Vomiting: Early, frequent.

• Abdominal distention: Usually tight, may be absent.

• Vol Wahl’s sign.

• Absent bowel sounds.

• Rectal examination: Full and painful Douglas pouch.

• General condition: Rapid decline, signs of dehydration, early onset of shock.

• Paraclinical:

• Plain abdominal X-ray: Image of a single dilated intestinal loop shaped like a solitary arch with two fluid levels on either side.

• CT scan: Determining the location and cause of obstruction.

• Intestinal obstruction in newborns: Usually associated with congenital malformations such as: Imperforate anus – rectum, anal stenosis, intestinal atresia, Hirschsprung’s disease (TRUE).

• Intussusception in infants:

• Diagnosis: Sudden onset. The infant screams in episodes, refuses to feed, vomits, and passes blood in the stool. Abdominal examination reveals an intussusception mass below the right costal margin/above the navel/below the left costal margin. Rectal examination reveals blood.

• Ultrasound helps to make a definitive diagnosis.

• Treatment: Air insufflation for intussusception reduction. Surgery if reduction fails or the disease presents late.

• Volvulus of the small intestine:

• Cause: Due to ligaments, fissures/holes appearing after abdominal surgery, congenital openings: Wilslow’s fissure, foramen of Winslow, esophageal hiatus.

• Clinical: Sudden, severe onset. Typical: Sudden, severe pain like continuous twisting, no episodes, localized and spreading to the back. Asymmetric abdominal distention, localized abdominal tenderness. Palpation reveals a tense, fixed intestinal loop, very painful. No “snake-like” movement, silent abdomen on auscultation. Shock usually occurs early.

• Paraclinical: Plain abdominal X-ray: Image of a single dilated loop shaped like a solitary arch with two fluid levels on either side. CT scan with contrast: Determining the definitive diagnosis, assessing the severity.

• Note: On CT scan, the “double bird’s beak” image may be observed at the base of the twisted intestinal loop.

• Examination of a strangulated abdominal wall hernia: The hernial mass descends, does not spontaneously return, pain when palpating the hernial sac neck.

• Note: Femoral hernias in obese women are easily missed during examination (TRUE).

• Intestinal obstruction due to roundworm infestation:

• Target population: Common in children, especially schoolchildren.

• Clinical: Abdominal palpation may reveal a roundworm mass like a bundle of sticks, firm, curved along the intestinal loop, mild pain.

• Plain abdominal X-ray: The roundworm mass creates long streaks or holes when the mass is cut transversely.

• Intestinal obstruction due to food debris:

• Target population: Common in the elderly with missing teeth, patients with exocrine pancreatic insufficiency, patients with bypass surgery, schoolchildren. Prior consumption of food high in fiber/astringent fruits.

• Clinical: Signs of small intestine obstruction are not typical, abdominal distention may be minimal/significant depending on the location, may still have bowel movements.

• Paraclinical: X-ray: Multiple small intestine fluid levels, possibly with gas in the large intestine. CT scan: Helps to make a definitive diagnosis.

• Intestinal obstruction due to a small intestine tumor:

• Clinical: Gradual progression. Initial signs of partial obstruction: Intermittent episodes of abdominal pain, bowel sounds heard during pain episodes, pain subsiding after bowel movements (Koenig’s sign). Large tumors causing complete obstruction > typical signs of occlusive IO. Palpation may reveal a tumor around the navel.

• Paraclinical: CT scan helps to make a definitive diagnosis.

• Intestinal obstruction due to gallstones:

• Cause: A rare complication of cholelithiasis, creating a fistula from the gallbladder to the duodenum, gallstones move down to the small intestine, become lodged in the terminal ileum, near the Bauhin valve.

• Clinical: Typical signs: High occlusive intestinal obstruction occurring after an episode of right costal pain accompanied by fever (cholecystitis).

• Paraclinical: X-ray and CT: Images of small intestine obstruction, gas in the biliary tract, images of gallstones in the terminal ileum.

• Intestinal obstruction due to colon cancer:

• Most common location: Colon, especially the sigmoid colon (tendency to narrow the colon lumen).

• Clinical: Gradual onset of the disease with signs of low IO. Disease presentation: Middle-aged patients, progressive changes over several months: Intermittent episodes of abdominal pain, alternating constipation and diarrhea, loose, unformed stools, mucous blood in the stool, altered bowel habits. Rarely palpable tumors on the abdomen, except for large right colon tumors, rectal examination detects tumors if they are less than 10 cm from the anal margin.

• Paraclinical: CT scan: Helps to make a definitive diagnosis, determining the stage of the disease.

• Contraindication: Colonoscopy.

• Sigmoid volvulus:

• Cause: The sigmoid colon is long, its mesentery is mobile, and the two limbs of the sigmoid loop are close to each other.

• Target population: Common in older adults, with a history of constipation and episodes of semi-obstructive abdominal pain that resolve spontaneously.

• Vohl Wahl’s triad: Asymmetric abdominal distention, palpation reveals a dilated, tense intestinal loop extending from the left iliac fossa to the right costal margin, immobile, tympanic percussion.

• Clinical: Vohl Wahl’s triad.

• Paraclinical:

• Plain abdominal X-ray: Image of a single dilated loop, shaped like an inverted U, with the base at the left iliac fossa extending upward towards the right costal margin. May have 2 fluid levels within the loop.

• Barium enema (X-ray or CT): Contrast stops at the junction of the sigmoid colon and rectum, with a bird’s beak image.

• CT scan: Excluding colon cancer.

• Cecal volvulus:

• Cause: The right colon is not attached to the abdominal wall posteriorly.

• Target population: Younger adults, with a history of right costal pain that resolves spontaneously.

• Clinical: Sudden onset of severe pain in the right periumbilical region. Early, frequent vomiting. Constipation. Asymmetric distention in the upper, left abdomen. Palpation reveals a dilated, tense intestinal loop, tender to the touch.

• Paraclinical:

• Plain abdominal X-ray: Image of a single dilated loop, with fluid levels, located below the left rib, rarely in the middle of the abdomen, accompanied by images of small intestine obstruction.

• CT scan with contrast: Helps to make a definitive diagnosis.

• Intestinal obstruction due to fecal impaction:

• Disease presentation: Low intestinal obstruction in elderly, frail patients with chronic constipation.

• Rectal examination: A firm, hard fecal mass is palpable.

• CT scan: Helps to make a definitive diagnosis.

• Early intestinal obstruction after surgery:

• Commonly occurs: 4-6 weeks after surgery.

• Classification:

• Mechanical IO: The patient has regained bowel movements. Signs of sudden obstruction appear, no fever. Causes are usually metastases, internal hernias.

• Postoperative paralytic ileus: In the first few days, the patient has not regained bowel movements, significant abdominal distention, no/minimal pain on palpation, minimal/only nausea, no “snake-like” movement and silent abdomen, no signs of inflammation. Plain abdominal X-ray shows images of dilation of the entire intestine.

• Intestinal obstruction due to intra-abdominal infection (peritonitis, abscess): After surgery, the patient has delayed/no bowel movements, high fever, abdominal distention, and pain.

7. Treatment:

• Irreversible damage in strangulated IO: Occurs after 6-12 hours. Signs: Shock, infection, sepsis, diffuse abdominal tenderness > Emergency surgery.

• Occlusive IO: Usually progresses gradually and progressively, but if left untreated, it can lead to a serious condition: Decreased pain episodes, increased vomiting, vomit resembling feces, increasing heart rate, shortness of breath, gradual fever, emaciated face. Development of diffuse abdominal tenderness, signs of peritonitis, no more moving gas and fluid sounds in the intestines. After 24-36 hours, it can lead to: Kidney failure, circulatory failure, respiratory failure.

• Preoperative preparation:

• Gastric decompression (inserting a nasogastric tube through the pylorus).

• Fluid and electrolyte replacement.

• Antibiotics.

• Shock management (if necessary).

• Surgical approach: Midline incision above and below the navel.

• Initial exploration after laparotomy: Checking the cecum: Collapsed (small intestine obstruction) – dilated (large intestine obstruction).

Note:

• This article provides general information and is not a substitute for professional medical advice.

• If you have any health concerns, consult a specialist for advice and timely treatment.