approach to abdominal pain

1. Abdominal Pain

2. Introduction
The abdomen has many organs and complex structures.
Determining the cause of an abdominal complaint is
challenging even for experienced health professionals.

3. Introduction
⚫Abdominal surface anatomy can be described when
viewed from in front of the abdomen in 2 ways:
⚫divided into 9 regions by two vertical and two horizontal
imaginary planes
⚫divided into 4 quadrants by single vertical and horizontal
imaginary planes
⚫These regions and quadrants are of clinical importance
when examining and describing pathologies related to the
abdomen

5. Pathophysiology of pain
⚫ Pain is defined as an unpleasant sensory and emotional
experience associated with actual or potential tissue damage.
⚫ It can be explained by
1. Peripheral Mechanism
2. Central mechanism
Merskey H, Bogduk N, editors. Classification of Chronic Pain. 2nd ed. Seattle: IASP press; 1994.

6. Peripheral mechanism
1.Nociception/Transduction
⚫ Painful stimuli are detected by nociceptors, which are free
nerve endings located in tissues and organs. They have high
thresholds and, under normal circumstances, only respond to
noxious stimuli.

7. ⚫ There are two distinct types of nociceptors:
⚫ High threshold mechanoreceptors stimulate myelinated Aδ-
fibres and transmit well-localised sharp pain that lasts as long
as the stimulus.
⚫ Polymodal nociceptors stimulate un-myelinated slowly
conducting C fibres which respond to mechanical, thermal and
chemical stimuli e.g. H+, K+ bradykinin, serotonin, ATPand
prostaglandins.

8. 2. Conduction
⚫ Aδ-fibres are fast conducting and transmit sharp pain till
stimulus is present.
⚫ C-fibres transmit a less well localised persistent aching pain
that persist even after the initial stimulus has gone.
⚫ C fibres express several presynaptic receptors that modulate
transmitter release. These include CCK, opioid and GABA-B
receptors.
⚫ Aβ-fibres conduct low intensity mechanical stimuli which
convey touch and not pain, however in chronic pain states they
are involved in the transmission of pain also.

9. Central mechanism
1.Ascending system
⚫ Spinothalamic tract: carries sensations from C/L side and
terminates in somatosensory cortex where pain is perceived and
localised.
⚫ Spinoreticular tract: It terminates in the pons, medulla and PAG
through reticular formation. It is involved in descending inhibition
of pain.
⚫ Spinomesencephalic tract: Involved in the modulation of
descending control.
Millan MJ. The induction of pain: an integrative review. Prog Neurobiol 1999; 57: 1–164

11. 2. Descending control
⚫ The dorsal horn receives inputs from higher centres that
modulate the response to nociceptor input.
⚫ Inhibitory tracts descend from the brainstem (PAG, raphae
nuclei and LC) and synapse in the dorsal horn.
⚫ The key neurotransmitters involved are NA, 5HT3 &
endogenous opioids.
D’Mello R, Dickenson AH. Spinal cord mechanisms of pain. Br J Anaesth 2008; 101: 8–16.

12. Factors for poor localization of visceral pain:
1. Splanchnic afferents spread across broad range of DRG.
2. Spinal afferents have B/L generalised & overlapping visceral
distribution.
3. Low afferent fibres : cell bodies in DRG
4. Overlap between visceral afferents and somatic pain neurons
in the dorsal horn.

14. Types of Pain
• Caused by stimulation of
visceral spinal nerves.
• Described as crampy , colicky
• Tends to be diffuse and difficult
for a patient to pinpoint
• Commonly seen with other
signs and symptoms such as
sweats, vomiting, nausea and
tachycardia.
Visceral

15. Types of Pain, continued
• A focal pain that occurs when
nerve fibers within the
peritoneum are irritated by
chemical or bacterial
inflammation
• More localized and is usually
described as sharp
• Constant and made worse by
coughing or movement
somatic

16. Types of Pain, continued
• Radiating pain that is felt at a
location away from the point of
origin
• Poorly localized, dull, aching
sensation
• e.g acute cholecystitis,
pancreatitits & renal stones etc.
Referred

19. Approach to acute abdomen
⚫ABC
⚫HISTORY TAKING
⚫EXAMINATION
⚫BLOOD INVESTIGATIONS
⚫RADIOLOGICAL INVESTIGATIONS

20. HISTORY
⚫S – site
⚫O – onset
⚫C – character
⚫R – radiation
⚫A – associated symptoms
⚫T – timing
⚫E – exacerbating & relieving factors
⚫S – severity

21. Physical Exam
⚫ Vital signs
⚫ General physical examination
⚫ Abdomen- inspection, palpation, percussion, auscultation
⚫ Pelvic & Rectal exam
⚫ Cardiac/respiratory exam

22. ⚫ Blood investigations: CBC, LFT,KFT etc
⚫ Some specific investigations like:
amylase/lipase for pancreatitis
SGOT/SGPT/ALP/Bilirubin for biliary disorders
UPT
Radiological investigations:
1. X-ray abdomen-erectand supine
2. USG abdomen
3. CT/MRI

24. Acute appendicitis
⚫ Present with prodromal symptoms of anorexia, nausea, low
grade fever and vague periumblical pain.
⚫ Then pain migrates to RLQ within 6-8hrs due to peritoneal
involvement.
⚫ Alvarado Score- MANT2REL2L
⚫ Score <5 – excludes
5-6 - suggestive
7-8 - probable
9-10 - likely

25. Acute Biliary Disease
⚫ Acute Biliary pain is synd of RUQ or epigastric pain, usually
post-prandial.
⚫ Caused by transient obstruction of cystic duct by gallstone,
self-limited and last for <6hrs.
⚫ If persistent for >6hrs – cholecystitis
⚫ Dull aching pain, can radiate to lower end of scapula
⚫ Associated with nausea, vomiting and low grade fever
⚫ Murphy’s sign
⚫ Charcot’s triad

26. Acute pancreatitis
⚫ Acute epigastric pain that is constant, unrelenting, boring
radiating to back and left scapula.
⚫ Associated with fever, nausea, vomiting
⚫ Comfortable with sitting upright and leaning forward
⚫ h/o alcohol intake or gallstones
⚫ Grey turner sign
⚫ Cullen sign

27. Small bowel obstruction
⚫ Characterised by sudden colicky periumblical abdominal pain.
⚫ Associated with nausea/vomiting which causes temporary
relief of symptoms.
⚫ Frequent bilious vomiting with epigatric pain – proximal
bowel obstruction
⚫ Cramy periumbilical pain with infrequent feculent vomiting
S/O distal intestinal obstruction
⚫ Leucocytosis and lactic acidosis suggest intestinal ischemia or
infarction.

28. Acute diverticulitis
⚫ Approx 80% patients >50yrs
⚫ Present with constant, dull aching pain in LLQ along with
fever.
⚫ h/o constipation or obstipation
⚫ O/E - LLQ tenderness or mass can be felt
⚫ CT is reliable inv for diagnosis
⚫ Hinchey grading

30. Abdominal compartment syndrome
⚫ Defined as pathological elevation of intra-abdominal pressure.
⚫ Normal abdominal pressure – 5-7 mmhg
⚫ may be higher in obese individuals
⚫ Intra-abdominal HTN is defined as abdominal pressure
≥12mmhg
⚫ Abdominal compartment syndrome is defined when visceral
perfusion is compromised by increased intra abdominal
pressure.
⚫ Most prone organ is kidney

33. ⚫ One should not miss extra-abdominal causes which can
present with abdominal pain.
⚫ Some of important causes are:
1. MI
2. DKA
3. Pneumonitis
4. Esophagitis
5. Porphyria
6. Uremia
7. Herpes zoster

35. Chronic abdominal pain
⚫ Pain is defined chronic when duration is >6 months
⚫ It can be divided into:
1. Abdominal wall pain
-anterior cutaneous nerve entrapment and
myofascial pain syndrome
-slipping rib syndrome
2. Functional abdominal pain syndrome
3. Narcotic bowel syndrome

36. Anterior Cutaneous Nerve Entrapment Syndrome
⚫ Abdominal wall shd be suspected when there is chronic &
unremitting abdominal pain which is unrelated to eating and
bowel function but clearly related to movement.
⚫ Occurs due to entrapement of a cutaneous branch of a sensory
nerve(spinal level T7-T12).
⚫ Pain emanating from abd wall is discrete and localised.
⚫ Patient can pinpoint pain location with one finger
⚫ Hover sign
⚫ Carnett’s sign

37. Myofascial Pain Syndrome
⚫ In MFPS, pain arises from myofascial trigger points in skeletal
muscle.
⚫ Causative factors include musculoskeletal trauma, vertebral
column disease, intervertebral disc disease, osteoarthritis,
overuse etc.
⚫ Exact pathophysiology of pain in MFPS is not known

38. Slipping Rib Syndrome
⚫ Cause of chronic lower chest and upper abdominal pain
⚫ Causes unilateral sharp, often lancinating pain in subcostal
region.
⚫ The synd is associated with hypermobility of the costal
cartilage at the anterior end of a false rib (rib 8,9,10), with
slipping of the affected rib behind the superior adjacent rib
during contraction of abdominal musculature.

39. ⚫ This slipping causes pain by different mech including costal
nerve impingement & localised tissue inflammation.
⚫ Hooking maneuver: Examiner hooks his fingers underneath
the patient’s lowest rib and as the rib is moved anteriorly, pain
is reproduced and an audible pop or click is heard.

40. Functional Abdominal Pain Syndrome
⚫ Occurs because of abnormal perception of normal bowel function
rather than a motility disorder.
⚫ More common in young to middle aged females
⚫ Characterized by continuous, severe and diffuse pain with poor
relation to bowel habbits.
⚫ Patient often have some psychiatric illness like anxiety, depression
or somatization.
⚫ History of multiple hospital visits/previous surgeries.
⚫ Closed eye sign

43. Narcotic Bowel Syndrome
⚫ Characterized clinically by paradoxical increase in abd pain
associated with continuous or escalating doses of narcotics.
⚫ Typically seen in well educated young to middle aged women.
⚫ Can also be seen in post-op patients
⚫ Associated history of some psychiatric illness
⚫ Narcotic bowel/Opioid bowel disorder