9.2 GI Emergencies Flashcards
What is peritonitis?
Inflammation of the serosal membrane that lines the abdominal cavity. Can be infective or sterile.
How should the peritoneal cavity normally be?
Sterile environment with no bacteria, only filled with a small amount of serosal fluid
What is primary peritonitis?
Spontaneous with no breakdown of the peritoneal membrane
What is secondary peritonitis?
Breakdown of the peritoneal membranes leading to foreign substances entering the cavity
What is the peritoneal cavity
The space between the visceral and parietal peritoneum
What is visceral peritoneum?
Serosal membrane that is not lining the abdominal wall. Forms mesenteries and surrounds viscera
What is the parietal peritoneum
Any part of the serosal membrane that lines the abdominal wall.
What is the posterior abdominal wall?
The posterior aspect of the peritoneal cavity. Retroperitoneal viscera sits behind
What are the 2 sections of the peritoneal cavity?
Greater sac
Lesser lac
Where is the great sac?
Lies in front of the stomach, greater omentum and transverse colon.
Where is the lesser sac?
Behind the stomach, lesser omentum, left lobe of liver
How are the greater sac and lesser sac connected?
Through the foramen of Winslow
Where is the foramen of Winslow?
Posterior to the free edge of the lesser omentum
Give an example of primary peritonitis
Spontaneous bacterial peritonitis
What is spontaneous bacterial peritonitis?
Infection of ascitic fluid that cannot be attributed to any intra-abdominal, ongoing inflammatory or surgical correctable conditions.
When is primary peritonitis commonly seen?
In patients with end stage liver disease
What is ascites?
Pathological collection of fluid within the peritoneal cavity
How does cirrhosis cause ascites?
- Portal hypertension - Causing increased hydrostatic pressure in the veins draining the gut, fluid movement from vasculature into the peritoneal cavity.
- Decreased liver function resulting in less albumin production - Decreased intravascular oncotic pressure
The result is the net movement of fluid into the peritoneal cavity
What are symptoms of primary peritonitis?
Abdominal pain, fever, vomiting
Symptoms commonly milder than secondary peritonitis
How is primary peritonitis diagnosed?
Aspirating ascitic fluid - neutrophil count of greater than 250 cells/mm^3
What is secondary peritonitis?
Secondary (surgical) peritonitis is a result of an inflammatory process in the peritoneal cavity secondary to inflammation, perforation, or gangrene of an intra-abdominal or retroperitoneal structure
What are common causes of secondary bacterial peritonitis?
- Peptic ulcer disease (perforated)
- Appendicitis (perforated)
- Diverticulitis (perforated)
- Post surgery
What are non-bacterial cause of secondary peritonitis?
- Tubal pregnancy that bleeds (the peritoneal cavity is not enclosed in females)
- Ovarian cyst
- Blood is highly irritant to the peritoneal cavity
How does secondary peritonitis present?
Abdominal pain (gradual/acute)
Patients often lie very still as any movement makes the pain worse
Often have knees flexed
Shallow breathing
How is peritonitis treated?
Control the infectious source • Surgery Eliminate bacteria and toxins • Antibacterial therapy Maintain organ system function (stop sepsis) • Intensive care
What is a common complication of peritonitis?
Sepsis
What is bowel obstruction?
Mechanical or functional problem that inhibits the normal movement of gut problems?
Where does bowel obstruction affect?
Small and large intestine
What are common causes of bowel obstruction in adults?
Adhesions
Incarcerated hernias
What are common causes of bowel obstruction in children?
Intussusception
Intestinal atresia
What is intussusception?
When part of the gut tube telescopes into an adjacent section
What is the cause of intussusception?
The cause is not well known
• Potential motility issues
• ‘Lead point’ (a mass that precipitates the telescoping action) - Meckel’s diverticulum, Enlarged lymph node
What are the complications of bowel intussusception?
Lymphatics and venous drainage in gut impaired resulting in oedema
Oedema impairs arterial supply causing infarction
Can result in peritonitis, sepsis
How do patients with intussusception present?
Abdominal pain
Vomiting
Haematochezia
What is haematochezia?
Bright red blood passed per rectum
What is the treatment for intussusception?
Air enema - air pumped into bowel per rectum to decompress.
Surgery - if bowel is very stuck (due to oedema)
What are the symptoms of small bowel obstruction?
Vomiting (bilious)
Nausea
Later on get abdominal distension, absolute constipation
What causes small bowel obstruction?
Intra-abdominal adhesions
Hernias (groin especially)
IBD - crohns
What are intra-abdominal adhesions?
abnormal fibrous bands between organs or tissues or both in the abdominal cavity that are normally separated
What causes intra-abdominal adhesions?
• Arise after more than 50% of abdominal surgeries (Greater omentum involved in 80%, bowel in 50%)
• Damage to mesothelium (direct trauma, post operative infection)
Capillary bleeding leads to exudation of fibrinogen
What are the consequences of intra-abdominal adhesions?
Bowel obstructions - limit peristalsis of bowel, narrow bowel
Abdominal pain - bowel cant expand and move freely
Secondary infertility
How do hernias cause small bowel obstruction?
Hernias can have a narrowed lumen which leads to obstruction. Most common in incarcerated groin hernias
How does Crohn’s disease cause small bowel obstruction?
Crohn’s disease is transmural process of inflammation. Can result in narrowing in bowels by strictures, fistulas due to repeated episodes of inflammation and healing
How do we diagnose small bowel obstruction?
History- abdominal pain is crampy, intermittent (on and off every 3 to 5 mins) pain called colicky pain.
Physical examination- abdominal distension, increased/absent bowel sounds, presence of hernia
Imaging - central distended small bowel ( > 3cm in width ) on x-ray. Know its small bowel by the presence of plicae circulares
Who is typically affected in large bowel obstruction?
Older people
What are common causes of large bowel disease?
- Colon cancer (60% of mechanical obstructions)
- Diverticular disease (20%)
- Volvulus- Sigmoid, Caecal (5%)
What are the presenting symptoms of large bowel obstruction?
Symptoms often appear gradually if caused by cancer but are abrupt with volvulus
• Change in bowel habit (cancer) - blockage/diarrhoea/constipation
• Abdominal distension
• Crampy abdominal pain
• Nausea/vomiting (later)
What is a volvulus?
Part of the colon that twists around its mesentery
Where do we often see volvulus?
Sigmoid colon
Caecum
What does volvulus result in?
Large bowel obstruction, constipation
Distended abdomen
Caecal volvulus causes small and large bowel obstruction
What is the coffee bean sign?
An x-ray sign of a sigmoidal volvulus
What are risk factors for volvulus?
- High fibre diets can also lead to sigmoid overload and twisting
- Extra mass predisposes elongates the sigmoid (relatively smaller mesenteric attachment)
How does the colicky pain vary between large and small bowel obstruction?
Small bowel = colicky (3 - 5 mins)
Large bowel = colicky (10-15mins)
Why is the competency of the ileo-caecal valve of great importance when considering bowel obstruction?
If competent then the colon will not be able to decompress proximally if obstructed
This will cause a closed loop obstruction. There is greater swelling and increased ischaemia and chance of perforation
What imaging is used to determine bowel obstruction?
X-ray
CT
How does imaging of a small bowel obstruction and a large bowel obstruction vary?
LBO = more peripheral distended bowel, wider bowel ( greater than 6cm), presence of haustra SBO = more central, narrower distended bowel ( 3cm), plicae circulares
What is acute mesenteric ischaemia?
Symptomatic reduction in blood supply to the GI tract
Wha are risk factors of acute mesenteric ischaemia?
Female
History of peripheral vascular disease
Elderly
CVS risk factors
What causes acute mesenteric ischaemia?
Arterial embolisms (usually in SMA) Non-occlusive = low cardiac output Mesenteric venous thrombosis = systemic coagulopathy, malignancy
How does acute mesenteric ischaemia present?
- Abdominal pain (if present) is disproportionate to the clinical findings. Classically pain comes on 30 minutes after eating (and last 4 hours)
- Nausea and vomiting are often present
- Pain can often left sided because the blood supply to the splenic flexure is most fragile
What is the splenic flexure?
The area of the large bowel where the transverse colon turns into the descending colon
Why is the splenic flexure called the watershed area?
As blood supply is between the regions supplied by the SMA and IMA
What investigations can be used to help diagnose acute mesenteric ischaemia?
Blood tests - Metabolic acidosis/increased lactate levels
Erect chest x-ray (to check for perforation, gas under diaphragm)
CT angiography is used (sensitivity is >90%) –intravenous contrast
How is acute mesenteric ischaemia treated?
Surgery- resection of ischaemic bowel (bypass graft) Thrombolysis/angioplasty
What is peptic ulceration?
Disruption of the gastric/duodenal mucosa, going through the muscularis mucosa to the submucosa. Usually greater than 5mm diameter
Where are peptic ulcers most common?
In thirst part of the duodenum
Why is a posterior peptic ulcer of the duodenum a cause for concern?
As the gastro-duodenal artery, a branch of the common hepatic artery lies behind the first part of the duodenum. A posterior peptic ulcer of the duodenum can erode into this artery
Where are common locations for gastric ulcers?
Lesser curve and antrum
What artery may be at risk in a gastric ulcer?
Splenic artery, lies behind the stomach
What are causes of upper GI bleeds?
Peptic ulcers
Oesophageal varices
What are oesophageal varices?
Distended varices of Porto-systemic anastomosis in the oesophagus caused by portal hypertension
What are the 3 different categories of portal hypertension?
- Pre-hepatic (portal vein thrombosis)
- Hepatic (cirrhosis, schistosomiasis)
- Post hepatic causes (hepatic vein thrombosis, RHF)
What is portal hypertension?
Increased blood pressure ( over 10mmHg ) in the venous portal system
What is the venous drainage of the oesophagus?
Portal drainage- Oesophageal veins drain into left gastric vein, drains into portal vein
Systemic drainage- Oesophageal veins drain into azygous vein, drains into superior vena cava
What is the normal blood pressure of the portal vein?
5 - 10 mm Hg
Where are the Porto-systemic anastomoses that cause oesophageal varices?
Between the left gastric vein and the azygos vein
How are oesophageal varices treated?
Band ligation - bands put around bases of varices to stop them bleeding
Injection sclerotherapy - inject adrenaline near base of varices.
If bleeding not controlled:
TIPS (Transjugular intrahepatic portosystemic shunt)
Drug treatment = Terlipressin (Reduces portal venous pressure)
What is a transjugular intrahepatic portosystemic shunt?
Used to treat oesophageal varices.
An expandable metal is placed within the liver
Bridges the portal vein to an hepatic vein
Decompresses the portal vein pressure
Reduction in variceal pressure
Reduction in ascites
Where does the abdominal aorta come through the diaphragm?
At spina level T12
What is an abdominal aortic aneurism?
permanent pathological dilation of the aorta with a diameter >1.5 times the expected anteroposterior (AP) diameter of that segment, given the patient’s sex and body size.
The most commonly adopted threshold is a diameter of 3 cm or more
Where do most AAA occur?
Below the renal arteries (infrarenal)
Why do AAA occur?
Usually due to the degeneration of the media layer of the arterial wall
Media- smooth muscle cells with elastin & collagen
AAAs form due to degradation of elastin and collagen causing the lumen to gradually start to dilate
What are risk factors of AAA?
Male
Inherited risk
Increasing age
Smoking
How do most AAAs present?
Asymptomatic until acute expansion or rupture
Can cause nausea, urinary frequency, back pain (by compressing other near by structures)
What are the usual symptoms of a ruptured AAA?
Abdominal pain (+/-flank and groin pain)
• Back pain
• Pulsatile abdominal mass ( need urgent surgical referral)
• Transient hypotension
• Syncope
• Retroperitoneum can temporarily tamponade the bleed
• Sudden cardiovascular collapse (65% of ruptured AAAs die before hospital)
How do we diagnose AAA?
Physical examination
• Presence of a pulsatile abdominal mass (less than 50% of cases)
•Ultrasonography
• Non invasive and in the right hands very sensitive and specific
• Can also detect free peritoneal blood • Computed Tomography (CT)
• Can detect a lot of surrounding anatomy that may be relevant
• Planning for elective surgery
•Plain x-rays
• If aneurysm has calcified then can be seen on plain x-rays
How is AAA treated?
Non surgical
• Smoking cessation
• Hypertension control
•Surveillance of AAA
• Less than 5.5cm (most grew slowly enough to not need treatment)
• More than 5.5 cm- refer to vascular surgeons
Surgery
What surgery is used to treat AAA?
1) Endovascular repair- relining the aorta using an endograft (an exoskeleton of metallic stents over a fabric lining)
Inserted through the femoral artery (seals below renal arteries and above common iliacs)
2) Open surgical repair - Clamp aorta, Open the aneurysm (remove thrombus and debris), Suture in a synthetic graft to replace diseased segment
