Lower GI

Lower GI

BOWEL OBSTRUCTION

Interuption in the aboral passage of intesrtinal contents

Clinical Picture

Colicky abdominal pain

Abdominal distension

Vomiting

Decreased passage of stool or flatus

Typical radiographic picture- plain AXR, contrast CT, oral contrast with PFA 

  

Adynamic Ileus	Mechanical Obstruction
Gas diffusely through intestine, incl. colon May have large diffuse A/F levels Quiet abdomen No obvious transition point on contrast study Peritoneal exudate if peritonitis	Large small intestinal loops, less in colon Definite laddered A/F levels “Tinkling”, quiet= late Obvious transition point on contrast study No peritoneal exudate

Pathophysiology

Hypercontractility- hypocontractility

Massive third space losses

oliguria, hypotension,  haemoconcentration

Electrolyte depletion

Bowel distension--increased  intraluminal pressure--impedement  in venous return--arterial  insufficiency

Site : small bowel vs large bowel

• Scenario - prior operations, ↑ in bowel habits
• Clinical picture - scars, masses/ hernias, amount of  distension/ vomiting
• Radiological studies - gas in colon?, volvulus?, transition  point, mass
• (Almost) always operate on LBO,  often treat SBO non-operatively

Partial vs. complete

Simple vs. strangulated

Fluid & electrolyte status

Operative vs. non-operative management

Small Bowel vs. Large Bowel

Etiology

Lesions Extrinsic to Intestinal Wall

• Adhesions (usually postoperative)
• Hernia
  • External (e.g., inguinal, femoral, umbilical, or ventral hernias)
  • Internal (e.g., congenital defects such as paraduodenal, foramen of Winslow, and diaphragmatic hernias or postoperative secondary to mesenteric defects)
• Neoplastic - Carcinomatosis, extraintestinal neoplasm
• Intra-abdominal abscess/ diverticulitis
• Volvulus (sigmoid, cecal)

Lesions Intrinsic to Intestinal Wall

• Congenital – Malrotation, Duplications/cysts
• Traumatic -Hematoma, Ischemic stricture
• Infections - Tuberculosis ,Actinomycosis, Diverticulitis
• Neoplastic - Primary neoplasms , Metastatic neoplasms
• Inflammatory  -Crohn's disease
• Miscellaneous -Intussusception, Endometriosis,Radiation enteropathy/stricture

Intraluminal/ Obturator  Lesions

• Gallstone
• Enterolith
• Bezoar
• Foreign body

	Small Bowel Obstrution	Large Bowel Obstructun
Causes	Lesions Extrinsic to Intestinal Wall Adhesions (usually postoperative) Hernia External (e.g., inguinal, femoral, umbilical, or ventral hernias) Internal (e.g., congenital defects such as paraduodenal, foramen of Winslow, and diaphragmatic hernias or postoperative secondary to mesenteric defects) Neoplastic - Carcinomatosis, extraintestinal neoplasm Intra-abdominal abscess/ diverticulitis Volvulus (sigmoid, cecal) Lesions Intrinsic to Intestinal Wall Congenital – Malrotation, Duplications/cysts Traumatic -Hematoma, Ischemic stricture Infections - Tuberculosis ,Actinomycosis, Diverticulitis Neoplastic - Primary neoplasms , Metastatic neoplasms Inflammatory  -Crohn's disease Miscellaneous -Intussusception, Endometriosis,Radiation enteropathy/stricture Intraluminal/ Obturator  Lesions Gallstone Enterolith Bezoar Foreign body	Common causes   Cancer (primary,        anastomotic, metastatic)   Volvulus   Diverticulitis   Hernia   Anastomotic stricture Unusual causes   Intussusception   Fecal impaction   Strictures (from one of the following)    Inflammatory bowel disease    Endometriosis    Radiation therapy    Ischemia   Foreign body   Extrinsic compression by a mass    Pancreatic pseudocyst    Hematoma    Metastasis    Primary tumors
Presentations	Abdominal distension Colicy abdominal pain Vomiting ? Absolute constipation Painful hernia Prev surgery Hx of crohn’s Tachy, Hypotensive Dehydrated Signs of crohn’s Abdominal distension Increased bowel sounds Empty rectum Hernial orifrces/tender	Abdominal distension Colicy abdominal pain Absolute constipation ? Vomiting Tenesmus Altered bowel habit Wgt loss Blood pr Hx of diverticulitis Tachy, Hypotensive Dehydrated Abdominal distension Increased bowel sounds Empty rectum, rectal mass Hernial orifrces/tender Enlarged liver Left supraclavicular LN
Investigation	Bloods:FBC, Renal, AGB, lactate Errect CXR PFA Small bowel follow through (gastrograffin) CT abdomen	FBC, Renal, LFT’s, AGB, Lac, Tumour markers Errect CXR PFA Single Contrast Ba enima CT abdomen
Ddx	Paralytic ileus Large bowel obstruction Ischaemic bowel Pseudo-obstruction	Paralytic ileus Large bowel obstruction Ischaemic bowel Pseudo-obstruction
Treatment	Drip & Suck Aggressive fluid resusitation and correction of electrolyte imbalances N/G tube to decompress bowel Urinary catheter to monitor hydration Conservative Exploratory laparotomy Repair hernia Small bowel resection	Drip & Suck Aggressive fluid resusitation and correction of electrolyte imbalances N/G tube to decompress bowel Urinary catheter to monitor hydration Open or closed loop Exploratory laparotomy Repair hernia Hartmanns proceedure Right hemicolectomy

Common Causes of LBO

• Colon cancer
• Diverticulitis
• Volvulus
• Hernia

Unlike SBO, adhesions very unlikely  to

produce LBO

Causes of Adynamic Ileus

Following laparotomy- small bowel- 24h, stomach- 48h,  colon- 3-5d

Inflammation e.g. appendicitis, pancreatitis

Retroperitoneal disorders e.g. ureter, spine, blood

Thoracic conditions e.g. pneumonia, # ribs

Systemic disorders e.g. sepsis, hyponatremia, hypokalemia, hypomagnesemia

Drugs e.g opiates, Ca-channel blockers, psychotropics

Partial	Complete
Flatus Residual colonic gas above peritoneal reflection /p 6-12h Adhesions 60-80% resolve with non-operative Mx Must show objective improvement, if none by 48h consider OR	Complete obstipation No residual colonic gas on AXR SBFT may differentiate early complete from high-grade partial Almost all should be operated on within 24h

Strangulation

4 Cardinal Signs = fever, tachycardia, localized  abdominal tenderness,  leukocytosis

Cardinal signs shown	% of strangulated bowel
0/4	0
1/4	7
2-3/4	24
4/4	67

process accelerated with closed- loop obstr.

Management of Bowel Obstruction

Fluid resuscitation

• Massive third space losses as fluid  and electrolytes accumulate in  bowel wall and lumen
• Depend on site and duration
  • proximal- vomiting early, with  dehydration, hypochloremia,  alkalosis
  • distal- more distension, vomiting  late, dehydration profound, fewer  electrolyte abnormalities
• Requirements = DEFICIT +  MAINTENANCE + ONGOING  LOSSES

Electrolyte, acid-base correction

Close monitoring

foley, central line

NGT decompression

Antibiotics controversial

Resuscitation

Surgery

Contraindications

• SMALL bowel obstruction if  adhesions suspected etiology i.e.  CANNOT have a “virgin”  abdomen
• No signs of strangulation
• Adynamic ileus

Indications

Incarcerated or strangulated hernia

Peritonitis

Pneumopertioneum

Suspected strangulation

Closed loop obstruction

Complete obstruction

Virgin abdomen

LARGE bowel obstruction

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COLORECTAL CANCER

the occurance of malignant lesions in the mucosa of the colon or rectum

Epidemiology

male:female = 1.3:1

Age 50+ years

Incidence has  increased in western world over last 50 years

Aetiology- risk factor

Prior colorectal carcinoma or adenomatous polyps

Hereditary polyposis syndromes

• Familial adenomatous polyposis (FAP) – 1/30 000, autosomal dominant defect in APC gene, hundreds of adenomatous polyps in large bowels in mid teen years, certain cancer at age 40. Prophylactic surgery- subtotal colectomy + ileorectal anastomosis. Panproctocolectomy -remove all
• Peutz Jeughers syndrome – hamartomatous polyps trpughout GI tract

Hereditary non-poltposis colorectal cancer (HNPCC) – Lynch syndrome 70% lifetime risk

Family history of colorectal carcinoma

Chronic active ulcerative colitis

Diet (low in indigestible fibre, high in animal fat)

Increased faecal bile salts, selenium deficiency

Alcohol excess beer, not wine

Ulcerative colitis- after 10 years of active disease, risk ↑ 1% each year

Pathology

Macroscopic

• Polypoid, ulcerating, annular, infiltrative
• 75% of lesions are within 60cm of the anal margin (rectum, sigmoid, left colon)
• 3% are synchromous (ie a second lesion will be found at the same time) and 3% are metachronous (ie a second lesion will be found later)

Histology

• Adenocarcinoma (10-15% are mucinous adenocarcinoma)

Staging

Modified Duke Classification

Dukes stage	Extent of pathology	5-year survival (%)
A	Tumour confined to bowel mucosa	90
B1	Tumour involves the muscle wall but not completely	70
B2	Involves the serosa	60
C1	Tumour involves the muscle wall but not completely. Local lymph nodes involved.	30
C2	Involves the serosa. Local lymph nodes involved

Spread

lymphatic, haematogenous (via veins to liver), peritoneal

Clinical Features

• Anaemia
• palpable mass in LIF
• Colicky abdominal pain: tumours causing partial obstruction, eg transverse or descending colonic lesions
• Alteration in bowel habit: either constipation or diarrhoea
• Large bowe obstruction – more likely if more distal. Colonic cancers tend to progressively encircle the bowel wall – producing an annular stenosis
• Bleeding or passage of mucus per rectum
• Tenesmus (frequent or continuous desire to defecate): rectal lesions

Investigations

Digital rectal examination and faecal occult blood

FBC: anaemia

U&E: hypokalaemia

LFT : liver metastases

Sigmoidocopy (rigid to 30cm/flexible to 60cm) and colonoscopy (whole colon), observe lesion, obtain biopsy.

?Virtual colonoscopy

Doube-contrast barium enema: 'apple-core' lesion, polyp

Carcinoembryonic antigen is often raised in advanced disease

Management

• Surgery (potentially curative)
• Resection of the tumour with adequate margins to include regional lymoh nodes
• Resection possible for liver metastases if <5

Procedures

• Right hemicolectomy (no bowel preparation) for lesions from caecum to slpenic flexure
• Left hemicolectomy (bowel preparation) for lesions of descending and sigmoid colon.
• Anterior resection for rectal tumours
• Abdominoperineal resection and colostomy for very low rectal lesions.
• Hartmann's procedure for emergency surgery to left colon.

Surgery/interventions (palliative)

• Open resection of tumour (with anastomosis or stoma) for obstructing or symptomatic cancers despite metastases
• Surgical bypass for obstructing inoperable cancers
• Transanal resection for inoperable rectal cancer
• Intraluminal stents for obstructing cancers

Complications

Early

Local

• inadvertent damage to other organs, eg ureter, bladder
• haemorrhage, eg slipped ligature
• Wound infection – cellulitis, abscess, wound edge necrosis
• intra-abdominal abscess- at site of surgery, pelvic or subphrenic

Regional

• Anastomic leak or breakdown- local or general peritonitis
• Stoma problems- sloughing or retraction
• compartment syndrome in legs due to prolonged elevation during surgery (rare)

Systemic

• New onset A-fib or flutter- often indicates anastomic breakdown
• Systemic sepsis leading to multi-organ dysfunction syndrome

Late

• Diarrhoea -due to short bowel
• Division of pelvic parasympathetuc nerves- caused sexual/bladder dysfunction
• Small bowel obstruction- due to pelvic peritoneal adhesion or tangling of small bowel with colostomy or ileostomy, or later as a complication of radiotherapy causing small bowel damage

Inadvertent damage to other organs, eg ureter, bladder

haemorrhage eg. Slipped ligature

Wound infection – cellulitis, abscess or wound edge necrosis

Intra-abdominal abscess- at site  of surgery, pelvic or subphrenic

Other treatment

Radiotherapy may be used to shrink rectal cancers preoperatively or palliate inoperable rectal cancer

Adjuvant chemotherapy (5-fluorouracil + levamisole) to reduce risk of systemic recurrence (Dukes stage C and some Dukes stage B) or to palliate liver metastes

Prognosis

5-year survival depends on staging: A 80%, B 60%, C 35%, D 5%

HERNIAE

Layers of the abdominal wall

• Superficial to deep
• Skin
• Camper’s fascia
• Scarpa’s fascia
• External Oblique
• Internal Oblique
• Transversus abdominus
• Transversalis fascia
• Abdominal peritoneum

Musculature of the abdomen

• External oblique
• Fibres extend downwards and  medially(hands in pockets)
• Internal Oblique muscle
• Fibres run upwards and  laterally(opp to E.O)
• Transversus abdominus- transverse fibres

• Rectus abdominus-pair of  muscles
• Join at the linea alba
• Lies within the rectus sheath
• Attaches to the anterior sheath  of the rectus sheath by three  tendinous insertions-at level of  xiphisternum, umbilicus and 1/2  way between

The rectus sheath

• The joining of the aponeuroses  of the E.O., I.O., T.A.
• Consists of the anterior and  posterior rectus sheaths
• Anterior sheath consists of E.O  and half of the I.O
• Posterior sheath consists of  other half of I.O. and T.A.

• Different above and below the  arcuate line(3cm below  umbilicus)
• Above arcuate line
  • Consists of ant and posterior  sheath
• Below arcuate line
  • No posterior sheath
  • All muscle layers pass anteriorly

Note the conjoint tendon is the  aponeurosis of the internal  oblique and transversus  abdominus muscles

The Inguinal Canal

• Situated between the layers of abdominal wall.
• 2 cm wide
• Runs above and parallel to the inguinal ligament
• Extends from the deep ring to the superficial ring

• Boundaries
  • Anterior- E.O.aponeurosis  reinforced by the I.O.laterally  (superficial ring)
  • Inferior-inrolled edge of the  E.O.
  • Posterior-T.F. reinforced  medially by conjoint tendon  (deep ring)
  • Superiorly-lower edge of the I.O  and the T.A
• Of note
  • The anterior wall is strongest opposite the weakest point of the posterior wall-the deep ring(I.O.laterally)
  • The posterior wall is strongest opposite the weakest point of the anterior wall-the superficial ring( C.T.medially)

• Contents
  • Spermatic cord
  • Round Ligament
  • On top-ilioinguinal nerve

To understand the scrotal and  cord layers, knowledge of the  abdominal wall layers is  necessary

Scrotal layers

Derived from the abdo wall layers

Skin-

Camper’s fascia       Dartos muscle

Scarpa’s fascia        Dartos fascia

External Oblique      External spermatic fascia

Internal Oblique       Cremaster muscle

Transversalis fascia Internal spermatic fascia

Abdo peritoneum     Tunica vaginalis

Contents of Spermatic Cord

• 3 arteries
  • Testicular
  • Cremasteric
  • Artery of the vas deferns
• 3 nerves
  • Symp,parasymp
  • Genital Br of genitofemoral  nerve(supplies cremaster ms and  scrotum)
  • Contents of Spermatic Cord
• 3 others
  • Vas deferens
  • Pampaniform plexus of veins
  • Lymphatic vessels

Note the ilioinguinal nerve lies on top the of the cod and supplies I.O. transversus ms. and the medial thigh

Of note!

• The right testicular vein drains directly into the IVC
• The left testicular vein drains into the left renal vein
• Varicocoeles are more common on the left side as it inserts more vertically  allowing the backflow of blood
• The right has a more oblique entry point stopping this

Definitions

• The mid inguinal point is located halfway between the ASIS and the pubic symphysis(corresponds to the femoral pulse)
• The midpoint of the inguinal ligament- halfway between ASIS and the pubic tubercle(corresponds to the position of the deep ring)

Inguinal anatomy

The inguinal ligament extends  between the ASIS and the  pubic tubercle

The deep ring-oval opening in  the transversalis fascia

Mid-point of the inguinal  ligament

Bounded

• Laterally by the transversus  abdominus
• Medially by t.fascia

The superficial ring is an  opening in the E.O aponeurosis

Herniae

• Indirect herniae extend through  the deep ring thru the canal out  thru the superficial ring
• The hernial sac is the remains  of the processus vaginalis
• It may be complete versus  incomplete
• Complete the testis is found in  the fundus
• Incomplete can be inguino- scrotal or inguino-labial or  limited to the canal
• It commonly extends into the  scrotum
• Note the inferior epigastric  vessels lie medial to the neck

Indirect herniae	Direct herniae
Predisposing factors Males Premature Right side more  common(descends later) Youth Increased intraperitoneal  fluid(ascites)	An acquired weakness in the  posterior wall Note the inferior epigastric  vessels lie lateral to the neck Predisposing factors Age male ↑intraabdominal  pressure(constipation) Aortic aneurysm(collagen defect)

Surgical management

Uncomplicated hernias

• Shouldice repair
• Mesh repair
• Laparoscopic
• McVay

Shouldice repair

• Incision-3cm above medial 2/3rds of the ininguinal ligament
• Haemostasis
• Slit along fibres of external oblique
• Identify spermatic cord and incise ext spermatic fascia
• Preserve the ilioinguinal nerve
• Opening covers of spermatic cord inspect for signs of indirest herniae
• Separate sac from spermatic cord
• Open sac and release contents into abdo cavity
• Transfix sac near deep ring and excise
• Create a “new” posterior wall using mesh
• The lateral borders are placed around the spermatic cord near the deep ring strenghtening the posterior wall.
• Suture inferior end of mesh to inguinal ligament
• The lateral borders are placed  around the spermatic cord near  the deep ring strenghtening the  posterior wall.
• Suture inferior end of mesh to  inguinal ligament
• Medially and superiorly fix  mesh to internal oblique

Consenting for inguinal hernia repair

1) Damage to ilioinguinal nerve- Numbness in lower groin and scrotum

2) damage to cord

• Reduced fertility(damage to vas)
• Ischaemic orchitis(dam to test artery)
• Varicocoele(dam to plexus of veins

3) damage to contents of sac

• Bowel
• Bladder

Femoral herniae

Definitions to know

• Femoral canal
• Femoral sheath
• Femoral ring

Femoral anatomy

Boundaries of the Femoral  canal

Medially- medial border of Add longus

Laterally - medial border of sartorius

Superiorly- inguinal ligament

Contents of the Canal

• Femoral vein
• Femoral artery
• Femoral nerve

The femoral Sheath

• A continuation of the  extraperitoneal fascia
• Anteriorly consists of T. fascia
• Posteriorly consists of  ileopsoas fascia
• Contains
  • Femoral canal
  • Femoral vein
  • Femoral artery

The femoral canal

• The most medial compartment of the femoral sheath contains lymphatic vessels and Cloquet’s node
• Entry superiorly via the femoral ring
• The femoral ring
  • Laterally femoral ring
  • Medially lacunar ligament
  • Anteriorly I.L
  • Posteriorly pectineal ligament

Surgical repair

• Lockwood
• McEvedy
• Lotheissen