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24
Manipal Manual of Surgery
Fig. 7.3: Visual analogue scale
Fig. 7.4: Wong-Baker FACES scale
depicting severe pain (Fig. 7.4). This is particularly
useful for older children.
ROUTES OF ADMINISTRATION OF ANALGESIA
Pain medications can be given by various routes.
Oral route: This route is a common method of providing
postoperative analgesia for day care surgeries. A
combination of a mild opioid such as codeine or
tramadol along with paracetamol gives good pain relief
for superficial surgeries such as hernia repair or breast
lumpectomy. The oral route can be used only after the
patient is able to take orally after surgery and thus
would not be feasible in the immediate postoperative
period after surgery on the bowel, etc. It is also not
suitable for patients who are still sedated, not regained
their ability to swallow and are at risk of aspiration.
They may also have postoperative nausea and vomiting.
Intramuscular route: Regular injections of intramuscular
opioids used to be given for postoperative pain relief.
Although the analgesia might last longer than intermittent intravenous opioids, repeated intramuscular
injections are not pleasant and must be avoided.
Subcutaneous route: To avoid the pain of repeated
Section I • Basic Principles of Surgery
intramuscular injections, a cannula can be inserted
subcutaneously, usually in the deltoid region and the
intermittent injections can be given subcutaneously
through this cannula. However, absorption of the
medications can be unreliable.
Intravenous route: For patients who have undergone
major surgery and are in-patients, postoperative
analgesia is given very commonly by the intravenous
route. This may be given intermittently on a regular and
‘as required’ basis by the nurse. A continuous infusion
is better for the immediate postoperative period for a
patient who has undergone major surgeries. These
patients must be closely observed for any complications
including respiratory depression and hypotension.
Epidural analgesia: This involves insertion of a thin
plastic catheter into the epidural space before surgery.
Infusion of dilute solution of local anaesthetic (0.25%
bupivacaine or 0.2% ropivacaine) either alone or in
combination with an opioid (usually fentanyl at 2 µg/
cc) provides excellent analgesia. The patient is not
drowsy, is more comfortable and outcomes are better.
Patient-controlled analgesia (PCA): This method is by
far the most preferred and safest of the different
approaches. By definition, the patient himself/herself
administers the medication when he/she thinks pain
Pain Management
CHRONIC PAIN
When pain persists beyond three months of injury, it is
termed chronic pain. While, in acute pain, the injured
tissue is the source of pain; in chronic pain, the injured
tissue might have ‘healed’ but the pain persists. This is
due to plasticity of the spinal neurons and a phenomenon called wind-up. In this situation, an impulse that
is normally painless also can become painful. Features
of chronic pain include hyperaesthesia, hyperalgesia
(increased sensitivity to touch and pain) and allodynia
(stimuli that are not normally painful are sensed as
painful). It can be debilitating and can affect healthrelated quality of life.
25
Fig. 7.5: Patient with PCA in our hospital
relief is required. This can be used for either intravenous
route or the epidural route, although the drugs and
dosages will differ with the route. This requires an
electronic pump which can be programmed by the pain
nurse or the anaesthetist. They can set the amount of
bolus of the drug to be delivered, the minimum
mandatory interval before which another bolus cannot
be given (lock-out period) and the hourly maximum
dose. The pump is fitted with a trigger button, which
when pressed will deliver the drug to the patient. To
ensure safety, only the patient is allowed to press
the button and no one else (nurse, parent, relative,
etc. not allowed). Thus, if a patient has been administered a bolus, unless he is awake enough to press the
button, he would not get another dose. This increases
safety (Fig. 7.5).
ADVERSE EFFECTS OF ANALGESIC MEDICATIONS
Provision of analgesia after surgery is humane and a
necessity. However, it has to be titrated to the patient.
The type of analgesia given to a patient will vary with
the surgical procedure, patient consent, presence of
comorbidities and facilities available at the hospital.
Superficial and key-hole surgeries are associated with
less pain compared to open major body cavity surgeries.
A multimodal approach helps in reducing the amount
of each medication and adds safety and efficacy to the
treatment.
The patient must be monitored closely for any
adverse effects due to these medications. Common
adverse effects attributable to opioids are respiratory
depression, hypotension and bradycardia. Epidural
narcotics can produce pruritus as well. Local anaesthetics when given epidurally can cause hypotension
and urinary retention. The patients must be monitored
closely postoperatively and documented.
Types of Chronic Pain (Key Box 7.2)
1. Neuropathic pain: This type of pain is burning or
shooting in nature. It can occur due to irritation of a
nerve or due to entrapment of nerves. Diabetic
neuropathy in the foot can produce neuropathic pain
with tingling and numbness. Chronic groin pain after
inguinal hernioplasty and mesh repair is not
uncommon (10 to 15%). It may be due to ilioinguinal
or genitofemoral nerve irritation or entrapment by
mesh fibrosis or sutures. Thus, when performing
mesh removal after a previous Lichtenstein repair, it
is recommended to remove as much of the mesh as
possible (preferably all mesh material) together with
triple neurectomy anterior to the annulus, i.e. outside
of the abdominal cavity without dissection behind
the transversalis fascia.
2. Nociceptive pain: A nociceptor (pain receptor) is a
sensory neuron that sends pain signals to the spinal
cord and the brain as a result of damaging or
potentially damaging stimuli. This pain occurs due
to actual tissue injury, e.g. burns or bruises. These
receptors are present in the skin and in the central
nervous system. As a result of stimuli, the cutaneous
nociceptors are activated leading to exaggerated
response in the dorsal horn of the spinal cord.
3. Psychogenic pain: This is due to depression. This
depression will add to any illness resulting in chronic
pain.
Key Box 7.2
Types of Chronic Pain
1. Neuropathic pain
2. Nociceptive pain
3. Psychogenic pain
4. Musculoskeletal pain
5. Inflammatory pain
6. Mechanical pain
Section I • Basic Principles of Surgery
26
Manipal Manual of Surgery
4. Musculoskeletal pain: This occurs due to excessive
activity of muscles or consequent to injury to muscles
or ligaments, e.g. back pain, myofascial pain.
5. Inflammatory pain: Autoimmune disorders such as
rheumatoid arthritis or gout can be associated with
joint pains as they get involved due to the disease.
6. Mechanical pain: Pain experienced by patients with
malignant conditions is often due to expanding
malignancy and involves stretch or compression of
surrounding tissues, nerves, blood vessels or bone.
Management of Chronic Pain
Patient evaluation: A thorough history must be taken
regarding the onset, characteristics, site, side, severity,
etc. of the pain and associated symptoms. Unlike acute
pain, it is important to also note how much this pain is
interfering with the patient’s daily activities. Structured
questionnaires (McGill Pain Questionnaire) are available
to document all aspects of this assessment. A detailed
physical examination, especially neurologic examination must be done.
Treatment
This includes pharmacologic, nonpharmacologic,
adjunct therapies and interventional treatments when
they do not respond adequately to these.
Pharmacologic Treatment of Chronic Pain
The WHO has advised Step-Ladder pattern for the use
of medications to treat chronic pain.
The WHO three-step analgesic ladder states as follows:
Step 1 (mild pain with NRS 1–4): Treated with
acetaminophen and adjuvants as required.
Step 2 (moderate pain with NRS 5–6): Milder analgesics
such as hydrocodone, oxycodone, tramadol, nonopioid
analgesics and adjuvants can be used.
Step 3. In patients with severe pain (NRS 7–10), strong
opioids such as morphine and fentanyl can be used in
addition to those mentioned above. Morphine is usually
given in the form of tablets or liquid every 4 or 6 hours.
Slow release-enteric coated morphine is also available.
Nausea and constipation are common complications.
Morphine can also be given subcutaneously, if pain is
severe.
First-line therapy for musculoskeletal pain includes
nonsteroidal anti-inflammatory drugs and paracetamol.
NSAIDs act by inhibiting the enzyme cyclooxygenase
(COX), thereby blocking the production of prostaglandins. They may be contraindicated in patients with
stomach ulcers and renal dysfunction. Adjunctive
Section I • Basic Principles of Surgery
therapy includes capsaicin cream or lignocaine.
First-line drug for neuropathic pain is gabapentin or
pregabalin. They prevent the reabsorption of neurotransmitters called serotonin and norepinephrine. They
also reduce spontaneous neuronal activity.
of antidepressants such as amitriptyline can be helpful.
Carbamazepine may be especially helpful in trigeminal
neuralgia.
Second-line drugs include opioids. In more severe
cases—example: Pain of chronic pancreatitis—oral
preparations of morphine can be used. Fentanyl and
buprenorphine cutaneous patches are also available.
When patients have neuropathic and nociceptive
elements, tapentadol can be used. It is an opioid with
norepinephrine reuptake inhibition. Side effects of
opioids such as constipation are less with this drug.
However, the benefit of pain relief must be weighed
against the possible side effects such as dependence,
constipation, respiratory depression, etc. For this reason,
adjunctive therapies must be tried first and opioids must
be used with caution in patients, particularly with nonmalignant conditions.
Nonpharmacological options include heat and cold
therapy, relaxation therapy, ultrasound stimulation,
acupuncture, physical therapy, occupational therapy,
and TENS units. Interventional techniques such as epidural steroid injections, radiofrequency nerve
ablations, nerve blocks and trigger point injections can
be used to treat chronic pain. Transcutaneous nerve
stimulators and acupuncture increase the levels of
endorphin production in the central nervous system.
In trigeminal neuralgia, nerve decompression is a
better option by doing craniotomy than percutaneous
coagulation of the ganglion.
ADJUNCTS
• Neurolysis: It refers to division of neural fibres, e.g.
coeliac plexus blocks with alcohol in pancreatic cancer
and gastric cancer.
• Anti-oestrogen drug such as tamoxifen 20 mg tablet
in carcinoma breast and anti-androgen cyproterone
50/100 mg tablets in carcinoma prostate for
disseminated metastasis are used. They also relieve
bony pain. Both these drugs are antipituitary also,
avoiding pituitary ablation surgery.
• Infusion of diamorphine: Various routes can be
Intravenous, subcutaneous, intrathecal or
used:
epidural.
Pain is a symptom when acute and borders on to
disease when chronic. If acute pain is well-addressed,
the likelihood of chronic pain is much reduced. If chronic
pain occurs, prompt treatment may be sought so that
healing can be faster. Good pain relief will be taken as a
blessing.
The addition
8
Biohazard Disposal/
Biomedical Waste Management
Hazards associated with biomedical waste (BMW)
Steps of BMW management
SU15.1: Describe classification of hospital waste and
appropriate methods of biomedical waste disposal.
INTRODUCTION
Biohazard or biomedical waste (BMW) refers to
hazardous waste generated in the hospital during the
diagnosis or treatment of patients, or in research
laboratories, including experimental activities. Broadly,
this generated waste falls into two categories—general
waste (non-hazardous solid waste, 80%) and biomedical
waste (20%). Biomedical waste includes infectious waste
(10%) and chemical/radioactive waste (5%). Infectious
waste can be from viruses, toxins, blood products, etc.
Examples of chemical waste include solutions used in
biochemistry labs or chemicals used for sterilization/
disinfection in operation theatres. Radioactive materials
are used in the radionuclear department for isotope
scanning or for treating diseases (e.g. thyroid disorders).
HAZARDS ASSOCIATED WITH BIOMEDICAL WASTE
• The WHO issued a statement in 2020 mentioning that
due to improper methods of medical waste disposal,
21 million hepatitis B cases, 2 million hepatitis C
cases, and 2,60,000 HIV cases had occurred.
• Broadly, biomedical waste can be classified as follows:
1. Infectious waste: Example: Badly infected wounds
in the leg or wounds in the perineum. Dangerous
pathogens may cause dangerous infections in
treating doctors or nurses. A few examples are
given in Key Box 8.1.
2. Chemical waste: These can produce corrosive and
physical injuries.
3. Pharmaceutical waste: A few drugs, such as
nicotine, warfarin and epinephrine, can be acutely
Segregation of biomedical waste
BMW rules in India
Key Box 8.1
Sources of Infectious Waste
Cultures of infectious agents from laboratories
Waste from surgeries and autopsies
Waste originating from infected patients in isolation
wards, e.g. feces and urine in cholera
Waste having come in contact with infected hemo-
dialysis patients (e.g. dialysis tubes, filters, disposable
towels, gloves, aprons, etc.)
toxic. Cytotoxic drugs can cause mutations and can
be teratogenic. A few drugs can be carcinogenic.
4. Radioactive waste: These can produce genetic
changes and tissue destruction.
STEPS OF BMW MANAGEMENT
1. Identify points of waste generation—wards, OPDs,
operation theatres, etc.
.
Segregate (at the point of generation) into the
2
appropriate colour-coded containers.
3. Transport to the central collection point.
4. Apply barcode and sticker. This is as per the changes
implemented in 2015.
5. Weigh the BMW to help approximate the amount
generated. For example, in a 1000-bedded hospital,
1 bed may produce 500 g of BMW. Thus, all the waste
in all different coloured containers are weighed.
6. Transport by a vehicle to the final treatment plant
with a GPS system to track the vehicle and ensure
proper disposal of the BMW. Treatment and/or
disposal of waste should be done within 48 hours of
generation.
27
28
Manipal Manual of Surgery
Please note: Liquid BMW is collected from a separate
line from all points and then joined together and
collected in the effluent treatment plant (ETP). About 500
ml of HYPO is put in the sump to disinfect the liquid.
Every month, a sample from this sump is sent to the
pollution board for analysis to determine the efficacy of
the system.
SEGREGATION OF BIOMEDICAL WASTE
According to BMW guidelines (2016), segregation
should be done with containers of four different colours.
Each container is designated for a particular waste
category (Figs 8.1 and 8.2)
. Yellow: Human tissues—pathology specimens,
1
sponges, cotton, dressing materials, any item soaked
with blood, sanitary pads, body fluids, tissue paper,
masks, caps, bedding materials, expired drugs,
cytotoxic drugs, discarded drugs, infected aspirated
fluid from the body, liquids from floor washings or
from laboratories. A separate sticker -C- is put for
cytotoxic materials. Stickers are also put for COVID
materials (Fig. 8.3).
. Red: Disposable plastic materials that can be
2
recycled—wastes generated from gloves, tubes,
catheters, urine bags, etc.
3. Black: Paper, packing material, wrappers, glove
covers, etc. These can be recycled.
4. White: Sharp objects—blades, scalpels, syringes with
needles, suture material needles, etc.
5. Blue: Glass materials—broken ampules, discarded
materials from labs or wards, metallic body
implants.
Fig. 8.1: Waste for incineration
Section I • Basic Principles of Surgery
Fig. 8.2: Collection of biomedical wastes in different containers
Fig. 8.3: Stickers indicating cytotoxic, COVID, and biohazard wastes
Biohazard Disposal/Biomedical Waste Management
29
BMW RULES IN INDIA
The Ministry of Environment and Forests formulated a
BMW rule in 1998 that had classified waste and
segregated them into colour-coded containers. The new
BMW guidelines (2016, with amendments added in 2018
and 2019) describe the following:
1
. Every hospital should have a final disposal and
recycling unit and a common biomedical waste
treatment facility (CBMWTF).
2. Only if there is no CBMWTF within 75 km can a
hospital create its own disposal facility.
3. Hospitals should have a biomedical committee that
meets once in 6 months and submits an annual report
to licensing authorities.
4. Doctors, nurses, and all healthcare workers should
be educated about BMW management services.
5. Hospital committees should inspect the waste
disposal area and functioning of the unit.
6. If required, audits can be done with CCTV cameras.
Section I • Basic Principles of Surgery
9
Investigation and Interpretation
Introduction
Examples
SU9.1: Choose appropriate biochemical, microbiological,
pathological, imaging investigations and interpret the investigative data in a surgical patient.
Refer to the chapter on radiology for details about radiological
investigations and interpretations.
INTRODUCTION
When a surgical patient is investigated for a disease,
many investigations are done. Often many of them may
not help either in the diagnosis or in the treatment (Key
Box 9.1). Ultrasound examination is the most common
non-invasive and simple preliminary investigation in
abdominal conditions, breast, thyroid or any cystic
swellings. It has been called extension of surgeon’s
hand or extension of clinical examination. To avoid
unnecessary investigations, proper history taking
including co-existing diseases such as diabetes, hypertension, allergy, etc. followed by a thorough clinical
examination must be done first. Once a working diagnosis is made, relevant investigations are ordered. One
should then see the results, interpret and give appropriate treatment. As you read further lines, you will get
a better understanding. This topic deals with only a few
examples, but students are expected to apply these
principles to every disease. I have given four examples
to highlight the importance of the investigations.
EXAMPLES
Example 1. Carbuncle (multiple hair follicle
infections) over the nape of the neck
• This is a common problem in diabetic patients. Firstly,
haematological investigations are ordered. Normal
white cell count ranges between 4500 and 11000 cells
Immunohistochemistry (IHC)
Example of acute abdominal pain
Key Box 9.1
Important Points to Remember
1. Investigations can be broadly classified as investigations
that help in the diagnosis (to be done first), investigations
that help in detecting spread of the disease (metastatic
work-up in malignancies), and investigations to assess the
fitness of the patient for surgery.
2. When you order investigations, ask yourself whether
this investigation is necessary and will this patient
benefit from this investigation?
3. Think twice before you order any invasive investigations that can be associated with serious complications.
One example: Colonic perforation during colonoscopy.
If you need to establish the diagnosis to prove
tuberculosis/carcinoma, colonoscopy is certainly
indicated. However, colonoscopy is not recommended
for a patient with a 7-days history of constipation.
4. Need to know the side effects: Example: CECT scan. Expo-
sure of the patient to CECT scan is equivalent to 200 chest
X-rays and contrast used can give rise to renal failure.
5. Junior surgeons and postgraduates especially, who order
investigations must also see the reports and try
interpretation. If you have requested for MRI foot for
diabetic foot, there is no need to obtain X-rays of the foot.
per microliter. If white cell count is elevated, it
indicates significant infection.
• Two important biochemical investigations which are
obtained in a diabetic patient are fasting blood
sugar—FBS, and post-prandial blood sugar—PPBS
and creatinine. If blood sugars are high (FBS more
than 150 mg/dl and PPBS more than 200 mg/dl), the
patient has to be treated for diabetes. If serum
creatinine is high, it indicates renal damage, and one
has to be careful in selecting antibiotics—better to
avoid gentamicin, amikacin, etc.
30
Investigation and Interpretation
31
• If doubtful of the diagnosis, ultrasound imaging can
be requested to confirm the diagnosis. An abscess will
appear hypoechoic.
• Aspiration of pus seen at the ultrasound imaging is
sent for culture and sensitivity.
• It is usually caused by Staphylococcus aureus, and it
responds to cloxacillin or clindamycin. If patient has
toxicity, we may have to start vancomycin.
• Once abscess is drained (Fig. 9.1), the tissue is sent
for microbiological examination again. The wall of
the abscess cavity or tissue can also be sent to
pathology depending upon the nature of the abscess.
Then look at the histopathology report and plan
further treatment, if necessary.
• Thus, in this patient haematological investigations
such as haemoglobin, total count including differential count of neutrophils, blood sugar and creatinine,
imaging (may not be required in all), pus culture
sensitivity are important.
• Ultrasound-guided FNAC is not done in toxic
nodules but is routine in all thyroid swellings
to rule out malignancy. If any mitotic figures or
microcalcifications are present it will suggest
malignancy.
• In large goitres, vital structrues such as trachea,
esophagus, internal jugular vein and common carotid
arteries are displaced or infiltrated as in malignant
goitres. To identify these anatomical structures and
to avoid injuries to these strictures, CECT scan can
also be done.
• A few other investigations are done to assess fitness
of the patient, to control comorbidity, if any, in this
patient. Cardiac status—echocardiogram to know the
ejection fraction, and if necessary, coronary angiogram in cases of myocardial ischemia.
Example 3. Obstructive jaundice: As you can see here,
sclera are stained with bilirubin—deep yellow coloured
almost with greenish tinge due to biliverdin deposition.
Following investigations are done and interpretations
are given below. The patient had carcinoma head of
the pancreas with palpable gallbladder (Fig. 9.2).
Fig. 9.1: Carbuncle on the back is incised by cruciate incision.
Slough is removed. The pus is sent for culture sensitivity
Example 2. Toxic multinodular goitre
• Haematological investigations are ordered. 4,500 to
9
11,000 WBCs per microliter (4.5 to 11.0 × 10
/l) is
normal white blood cells count or leucocyte count.
• If leucocyte counts are low (4,000 cells/µl), it indicates
leukopenia. It may be side effect of drugs used to
control toxicity. Example: Carbimazole, in this case.
• Thyroid hormone levels: T
and T4 levels are elevated
3
suggesting thyrotoxicosis. Usually, T4 toxicosis is
common. When these hormones are elevated,
thyroid-stimulating hormone (TSH) is very low due
to feedback mechanism. In Hashimoto’s thyroiditis or
in cases of hypothyroidism, TSH is elevated but T
and T4 are usually low. Hence, they need thyroid
hormone supplementation.
• Ultrasound imaging is the first investigation. Look
for nodules, nature of nodules, suggestion of malignancy (details are given in thyroid chapter).
a
Fig. 9.2: (a) Deep yellow sclera; (b) Palpable gallbladder
b
• Liver function test: Bilirubin, alanine transaminase
(ALT), aspartate transaminase (AST), alkaline
phosphatase (ALP), albumin and total protein,
gamma-glutamyl transferase (GGT), L-lactate
dehydrogenase (LD), prothrombin time (PT).
. Normal bilirubin levels are 0.2 to 0.6 mg/dl.
a
Elevation beyond 2 mg/dl will be visible in the
sclera. Very high values are often found in obstructive jaundice. If more than 50% of the total bilirubin
is direct bilirubin, it is obstructive in origin. If more
3
than 50% is indirect, it could be hemolytic jaundice.
b. ALT and AST levels are elevated in hepatitis
because they represent hepatocellular damage.
c. ALP is elevated when there is obstruction to the
biliary tree—classically in a patient with obstructive
jaundice. (More details in Chapter 42, page 616).
Section I • Basic Principles of Surgery
32
Manipal Manual of Surgery
d. Albumin is synthesised only in the liver. Hence low
levels of albumin is a feature of chronic liver disease
or chronic malnutrition.
e. GGT: The main role of GGT is helping the liver in
metabolising drugs or toxins. High levels of GGT
are seen in liver diseases including chronic
alcoholic liver damage and fatty liver.
f. LDH: Normal levels: 140 units per litre (U/L) to
280 U/L. Increased levels are seen in high tumour
burden cases which means tumour is spreading. It
can also be seen in benign conditions with increased
tissue breakdown.
g. INR and prothrombin time will be prolonged.
• Culture and sensitivity: If patient has high grade fever
with chills and rigors, it indicates cholangitis— send
blood for culture and sensitivity. Invariably gramnegative organisms dominate along with other
organisms.
• Imaging: When ultrasound probe is kept in the right
hypochondrium, one can see dilated biliary radicles—
which is the first indication of distal obstruction. If
gallbladder is also enlarged, it will suggest lower bile
duct obstruction.
• CT scan is done not only to confirm ultrasound
findings but also to know the resectability by
demonstrating plane between superior mesenteric
vein/superior mesenteric artery—if it shows hypodense lesions, they suggest secondaries in the liver.
• Tumour markers such as CEA (carcinoembryonic
antigen) and CA 19-9 were normal. Details about
tumour markers are given in the respective topics
such as gallbladder cancer, pancreatic head cancer
and carcinoma colon, etc.
• One example of a typical patient with obstructive
jaundice has been given here.
Total bilirubin (serum) (H) 20.94 mg/dl
Direct bilirubin (serum) (H) >17 mg/dl
Total protein (serum) 6.40 g/dl
Albumin (serum) 3.50 g/dl
Globulin 2.90 g/dl
Aspartate transaminase (AST) (serum) (H) 51 IU/L
Alanine transaminase (ALT) (serum) 32.0 IU/L
Alkaline phosphatase (ALP) (serum) (H) 568 U/L
• If you see this report of a jaundice patient, direct
bilirubin is more than 50% of total bilirubin with very
high values of alkaline phosphatase—it suggests
obstructive jaundice.
• Tumour markers in this patient done were: CEA:
3.0 ng/ml and
CA 19-9: 21 U/ml. These are done to
find out or to get the clue about possibility of gall-
Section I • Basic Principles of Surgery
bladder cancer or carcinoma head of the pancreas.
Example 4. Carcinoma breast
• Initial triple assessment is done: Clinical examination,
mammogram and tru-cut biopsy are done and
carcinoma is confirmed.
• Then metastatic work-up: If chest X-ray shows
cannon ball metastasis, it is a stage 4 disease.
• CT-PET scan is done to look for metastasis all over
the body depending upon staging and grading of the
tumours, etc. (details are given later).
• Core needle biopsy is subjected for immunohisto-
chemistry. It is required to plan appropriate
chemotherapy or hormonal therapy or therapy with
newer agents including trastuzumab. Details of IHC
are given below.
IMMUNOHISTOCHEMISTRY (IHC)
Immunohistochemistry, also known as IHC, is an important diagnostic modality in the work-up of cancers. It
is widely applied in the field of oncopathology to detect
the presence of specific antigens on the tumour cell, that
help in confirmation of cancers and their subtyping. It
is useful in identifying the cell type and origin of a
metastasis to find the site of the primary tumour. IHC
is also widely used to predict the response to therapy
in various tumours, i.e. carcinoma of breast.
The technique involves fixing tumour tissue using a
chemical such as formaldehyde which stabilises the
structural properties of tissue. The tissue is then
incubated with an appropriate primary antibody against
specific tumour antigens/proteins, followed by a
secondary antibody that is conjugated with a dye or
enzyme. The binding
of antigen on tumour with the
antibody brings about a color reaction which is then
visualized under microscope.
The panel of immunohistochemical antibodies available is substantial that are used as diagnostic, prognostic
and predictive biomarkers. Following are some
examples of commonly used IHC antibodies:
• Estrogen receptor (ER) (Figs 9.3 and 9.4), progesterone
receptor (PR), H
er 2 and Ki 67 (proliferation marker)
in breast cancers for subtyping and predicting
response to therapy.
• Cytokeratin 7 and cytokeratin 20 in the work-up of
metastasis of unknown origin.
• CD15 and CD30 in Hodgkin’s lymphoma (Fig. 9.5).
• CD19, 20 for B cell lymphomas, CD3 for T cell
lymphoma.
• CD117 for gastrointestinal stromal tumours.
• CD99 and FLI 1 for Ewing’s sarcoma.
• Melanoma: S100
• Vascular: CD31, CD34
• Colorectum: Cytokeratin
Investigation and Interpretation
33
Fig. 9.3: Positive staining for oestrogen receptor (seen as brown
nuclear positivity in tumour cells of breast cancer) helps to predict
response to tamoxifen therapy
Fig. 9.5: Positively staining with CD30 of Reed-Sternberg cells
helps to confirm diagnosis of Hodgkin’s lymphoma
• Ovary: CA125, CK20
• Prostate: PSA
• GIST: CD117
• Thus, immunohistochemical stains can detect all
types of tumours and can confirm malignancy. S100
and actin stains can be used to identify the myoepithelial cell layer in a duct or gland.
• IHC may also help in selecting a treatment and
making prognostic predictions. Examples: Carcinoma
Fig. 9.4: Positive staining for Her2 (seen as strong brown
membranous positivity in tumor cells of breast cancer) helps to
predict response to targeted therapy with Trastuzumab (Courtesy:
Dr Kanthilatha Pai, HOD pathology, KMC Manipal for contributing
IHC slides and write up.)
of the breast is assessed for oestrogen receptor,
progesterone receptor, and HER2 status.
• IHC can also detect infections such as cytomegalo-
virus (CMV), Epstein-Barr virus (EBV), etc. and detect
an abnormal accumulation of proteins or amyloid.
Please note: Abdominal investigations and interpretations require theoretical knowledge of both surgical and radiological
investigations. One example of how to arrive at the diagnosis is given below. As you read the entire textbook you will be
in a better position to understand this aspect.
Section I • Basic Principles of Surgery