Abnormalities in Small Intestine - NEET PG Surgery

The small intestine is a crucial part of the digestive system, responsible for most nutrient absorption from our food. As a result, small intestine disorders can lead to various health problems, including malabsorption syndromes, inflammatory bowel disease, and small bowel obstruction.

Understanding the anatomy, physiology, and surgical management of the small intestine is essential for the NEET PG exam, as it is a common site of disease and surgical intervention in the abdominal cavity.

Let’s learn more about this important surgery topic for NEET PG/NExT exam preparation.

MECKEL'S DIVERTICULUM 

A protrusion or bulging in the lower portion of the small intestine is known as a Meckel's diverticulum. The bulge is a remnant of the umbilical cord and is congenital (existing at birth). The most frequent gastrointestinal tract congenital abnormality is Meckel's diverticulum. In the general population, 2% to 3% of people have it. it is Caused by Persistent VID/OMD this is mainly Congenital. True Diverticulum ( it has both Mucosa and Submucosa Muscularis propria) it is Characterized by Rule of 2.

• 2% population
• 2 inches in length
• Located 2 feet proximal to I/C Junction 
• Symptomatic patients: <2 years of age 

• Ectopic mucosa is Gastric> Pancreatic > Colonic 

Clinical features

• Most common symptom is  bleeding which  generally manifests as lower GI Bleeding. the Most common symptom in Adults is Abdominal pain 
• cramps and pain in the abdomen.
• tenderness in the area of the abdominal button (navel).
• Bowel obstruction refers to a blockage that prevents the passage of intestines' contents. Pain, bloating, diarrhea, constipation, and vomiting may result from this.
• Diverticulitis (intestinal wall edema).

Diagnosis of Meckel's Diverticulum:

• Scan with technetium: This test is a scan. Injections of radioactive technetium are administered. This material, which can be seen using a specialised the camera, is absorbed by stomach cells in the diverticulum.
• A short, flexible tube with a camera on the end is introduced into the colon and rectum during a colonoscopy to check for obstructions and the source of bleeding.
• Endoscopy using a wireless capsule: During this procedure, the patient ingests a tiny camera that can look for signs of bleeding in the small intestine. If your child is too young to swallow a tablet, you can give it to him or her while they are sleeping.

Complications 

• Most common complication in children: Bleeding 
• Most common complication in Adult: Intestinal obstructions 
• Diagnosis: Investigation of choice for diagnosis: Tc-Pertechnnate scan 
• Treatment: Meckel's with Healthy base: Diverticulectomy 
• Meckel's with unhealthy base: RIA → Resection and anastomosis 
• Increased risk of complications: 
  • Narrow mouthed 
  • Ectopic gastric mucosa 
  • Unhealthy base 

Superior Mesenteric Artery Syndrome/ Wilk’s Syndrome/ Cast Syndrome  

It is Characterized by compression of 3^rd part of duodenum by superior mesenteric artery  the Predisposing factors for this condition are:

• Rapid Weight loss
• Rapid gain of height
• Cast application

Clinical features 

• Postprandial Abdominal Pain 
• Weight loss 

Diagnosis

• CECT 
• Hypotonic duodenography

Treatment

• Strong’s procedure
• Treatment of choice: Duodenojejunostomy

GASTRO-INTESTINAL TUBERCULOSIS

Most common organism which causes gastrointestinal tuberculosis is Mycobacterium tuberculosis. First organ to be infected is lungs  and there is production of Infected sputum and then it affects the leum. Earliest lesion seen in Submucosa  Most common site is  Ileum and ileocolic junction.

• Pathological types
  • Ulcerative (60%)
  • Hyperplastic (10%)
  • Sclerotic fibrotic (30%) 
• TB: Transverse ulcers → healing causes stricture 
• In Typhoid there is Longitudinal ulcers 

Clinical features 

• Nonspecific sign and symptoms
• Most common symptom is Abdominal pain
• Most common presentation is SAID (Subacute intestinal obstruction)
• Investigation of choice - diagnosis: Most common lab abnormality: increased ESR (90%) 
• Primary cause for diagnosis: CECT 
• Paracentesis findings
  • Lymphocytosis > 500/mm3
  • Protein > 2.5 gm/dl 
  • SAAG < 1.1 
  • ADA increased 

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Barium Meal Follow-Through Findings  

• Pulled up caecum 
• Obtuse I/C angle 
• Goose neck deformity 

• Sterlein Sign 
• String sign of Kantor: seen in GI TB, Crohn’s Disease 

Treatment

• ATT with management of complications 
• Indications of surgery 
  • Acute intestinal obstructions 
  • Perforation 
  • Bleeding 
  • Fistula 
  • Abscess

SMALL BOWEL TUMOR

• Most common small bowel tumor > stromal tumor > Adenoma 
• Most common small bowel tumor in children: Lymphoma 
• Most common malignant small bowel tumor. Adenocarcinoma > Carcinoid Tumor 
• Chemotherapeutic agent → Folfox → Folinic acid (Leucovorin), SFU, Oxaliplatin 

CARCINOID TUMOR

NET type of neuro-endocrine tumor it Arises from ECL in the small intestine (crypt of Lieberkühn)  and secretes Secrete 5-HT (serotonin). Most common site: (B > I > R > A > C > S) 

• Bronchus 
• Ileum
• Rectum 
• Appendix 
• Colon 
• Stomach 

Most common site’

•  GIT> Respiratory tract
• Small intestine> Bronchus
• Small intestine: Duodenum + Jejunum ileum

Localized carcinoid: L > OA > R (Larynx > Ovary > Appendix > Rectum) 

• Larynx: Best prognosis
• In GIT appendix: Best prognosis seen

Non localized carcinoid: P> C> S 

• Pancreatic > Colonic > Small intestine 
• Worst prognosis seen in Pancreatic carcinoid 

Carcinoid Heart Disease 

• Right side is affected mare 
• TR > PR > TS > PS 

Carcinoid Syndrome

• Most common Manifestation is Flushing 
• Other Manifestation: Wheezing, Bronchospasm, Diarrhea. 

Small Bowel Carcinoid

Most common symptom is Abdominal pain (Intermittent Intestinal obstruction) caused by fibrosis around the tumor and fibrosis due to intense Desmoplastic Reactions

• Labs: ↑↑5 - HIAA → 24 hours urinary Estimation of 5-HIAA 
• Initial investigation used for localization and staging → SRS 

SRS (Somatostatin Receptor Scintigraphy) 

• For Staging
• Best Investigation for localizing: DOPA-PET 
• Plasma Chromogranin A, highly specific for Carcinoid Tumor 

Treatment

• Segmental Resection + En bloc Lymphadenectomy 
• Chemotherapy Regimen
  • D - Dacarbazine 
  • E – Epirubicin
  • F - 5-Fluorouracil 
• Carcinoid Tumor has better prognosis than Adenocarcinoma 

SHORT BOWEL SYNDROME 

• Normal length of Small intestine: 600 cm 
• Short bowel < 200 cm 

Causes (Massive Small intestine Resection) 

• Mesenteric Ischemia
• Crohn's disease
• Midgut volvulus
• Mesenteric Trauma

Manifestations of SBS 

• Megaloblastic Anemia (Due to impaired B₁₂ absorption) 
• Cholesterol gallstones. 
• Choleretic Diarrhea 
• Malabsorption 
• Oxalate Renal Stones 
• Bacterial Overgrowth 
• Diarrhea 

Important Information

• Catabolism of gastrin Occurs in SI mucosa so in SBS there is "Hypergastrinemia"

Management

• TPN (Total Parenteral Nutrition) 
• Treatment of choice - Small Bowel Transplantation 
• BIANCHI procedure (LILT - Longitudinal intestinal Lengthening and Tailoring) 
• STEP (Serial Transverse Enteroplasty Procedure)

Previous Year Questions

Q. Which of the following is wrong regarding superior mesenteric artery syndrome? (AIIMS May 2018)

A. Superior mesenteric artery is compressed by third part of duodenum at the ligament of

Treitz attachment

B. Superior mesenteric artery has a normal angle between 38-65 degree is relation to duodenum

 C. Strong procedure is corrective surgery in which ligament of Treitz is divided

 D. Superior mesenteric artery syndrome is characterized by an angle less than 25 degree due to loss of intervening mescenteric pad of fat

Q. Which of the following is the most common epithelial tumor of stomach? (NEET Jan 2018)

A. Carcinoid tumor 

B. Sarcoma 

C. GIST 

D. Gastric adenocarcinoma

Q. Increased level of 5-HIAA is present in? (NEET Jan 2018)

A. Alkaptonuria 

B. Albinism

C. Carcinoid tumor

D. Phenylketonuria

Q. A 50 years old lady with history of carcinoid syndrome complains of flushing and diarrhea. Which of the following is not true regarding this syndrome? (JIPMER May 2019)

A. Occurs in <10% of carcinoid tumors

B. Octreotide injection reduces symptoms of flushing and diarrhea

C. Attacks precipitated by stress, alcohol and large meal

D. Bright-red patchy flushing is typically seen with ileal carcinoids

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