Acute Abdominal Pain

ABDOMINAL PAIN Recent onset of pain requiring medical attention History in Patients with Acute Abdominal Pain Question

Potential Responses and Indications

Where is the pain?

Depends on location

What is the pain like?

Acute waves of sharp constricting pain that “take the breath away” (renal or biliary colic) Waves of dull pain with vomiting (intestinal obstruction) Colicky pain that becomes steady (appendicitis, strangulating intestinal obstruction, mesenteric ischemia) Sharp, constant pain, worsened by movement (peritonitis) Tearing pain (dissecting aneurysm) Dull ache (appendicitis, diverticulitis, pyelonephritis)

Have you had it before?

Yes suggests recurrent problems such as ulcer disease, gallstone colic, diverticulitis, or mittelschmerz

Was the onset sudden?

Sudden: “like a light switching on” (perforated ulcer, renal stone, ruptured ectopic pregnancy, torsion of ovary or testis, some ruptured aneurysms) Less sudden: most other causes

How severe is the pain?

Severe pain (perforated viscera, kidney stone, peritonitis, pancreatitis) Pain out of proportion to physical findings (mesenteric ischemia)

Does the pain travel to any other part of the body?

Right scapula (gallbladder pain) Left shoulder region (ruptured spleen, pancreatitis) Pubis or vagina (renal pain) Back (ruptured aortic aneurysm)

What relieves the pain?

Antacids (peptic ulcer disease) Lying as quietly as possible (peritonitis)

What other symptoms occur with the pain? Vomiting precedes pain and is followed by diarrhoea (gastroenteritis) Delayed vomiting, absent bowel movement and flatus (acute intestinal obstruction; the delay increases with a lower site of obstruction) Severe vomiting precedes intense epigastric, left chest, or shoulder pain (emetic perforation of the intra-abdominal oesophagus)

Extra-abdominal causes of abdominal pain

Abdominal Pain

Mechanisms and physiology of abdominal pain Nociceptors: - Group III of A (fast pain fibres): o cause bright, sharp, localised pain and - Group IV or C fibres (slow pain fibres): o Follows sharp pain with a dull, intense, diffuse, unpleasant sensation caused by the latter fibres also called slow pain fibres. The further from the brain the stimulus is applied; greater is the temporal separation of the two components. Types of pain stimuli are mechanical, thermal, electrical, and chemical. Nociceptive pain may be classified further in three types: - Somatic pain o conducted by somatic nerves which are made up of both A and C fibres o may be superficial pain which is sharp, distinct and well localised  Caused by injury to the skin or superficial tissues.  Cutaneous nociceptors terminate just below the skin, and due to the high concentration of nerve endings, produce a sharp, well-defined, localized pain of short duration.  e.g. minor wounds, and minor (first degree) burns.

o or deep pain from muscles, joints, parietal peritoneum which is poorly

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localised  originates from ligaments, tendons, bones, blood vessels, parietal peritoneum, and muscles  The scarcity of pain receptors in these areas produces a dull, aching, poorly-localized pain of longer duration than cutaneous pain  The C fibres conducting the deep pain are connected to both somatic motor as well as the ANS • associated with reflex contraction or spasm of the overlying skeletal muscle as well as autonomic symptoms such as sweating, nausea and changes in blood pressure  e.g. sprains, broken bones; irritation of parietal peritoneum is associated with sweating, vomiting, hypotension • Abdominal guarding occurs due to a reflex contraction of the abdominal wall muscles, in response to a noxious stimulus to the pain fibres of the same dermatome Visceral pain o Conducted by the autonomic nerves (C fibres – symp. and parasymp.) o no pain receptors in the visceral peritoneum, located within the capsule of solid organs or submucous and myenteric plexus of the hollow organs and are sensitive to distension greater o Pain is always dull, poorly localised, unpleasant and associated with nausea, vomiting and autonomic symptoms like sweating and changes in blood pressure. o Reflex spasmodic contractions of the local visceral smooth muscles results in the colicky pain

Since deep somatic pain and visceral pain is poorly localised it may not be felt in the viscera but in some somatic structure that may be a considerable distance away. Referred Pain: -

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The axons of primary afferent nociceptors enter the spinal cord via the dorsal root. Terminate in the dorsal horn of the spinal grey matter. The terminals of primary afferent axons contact spinal neurons that transmit the pain signal to brain sites involved in pain perception. When primary afferents are activated by noxious stimuli, they release glutamate from their terminals that excite the spinal cord neurons o Primary afferent nociceptor terminals also release peptides, including substance P and calcitonin gene-related peptide, which produce a slower and longer-lasting excitation of the dorsal horn neurons. The axon of each primary afferent contacts many spinal neurons, and each spinal neuron receives convergent inputs from many primary afferents.

Pain experienced at a distance from the site of the damaged area. The affected somatic structure developed from the same embryonic segment or dermatome as the structure in which the pain originates. -

Dermatomal Rule o Pain felt at the tip of the shoulder, when the parietal peritoneum on the inferior surface of the diaphragm is irritated (like cholecystitis). This area of peritoneum is innervated by somatic nerves (C4) as is the skin over the tip of the shoulder. o pain from distension of the midgut is referred to the peri-umbilical area

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Sometimes the initial pain is due to hyperaemia (increased blood flow) or distension of the viscera but as the pathology extends it may result in stimulation of the adjacent parietal peritoneum. The nature and site of the pain may then shift from one site to another, e.g. shifting pain in appendicitis which may initially start as a dull pain around the umbilicus and then may shift and localise as a sharp severe pain at McBurney’s point in the right iliac fossa. When visceral pain is both local and referred, it may appear to spread or radiate from the viscera to the referred area e.g. radiation of pain from the loin to groin following distension of the ureter.

Referred pain (error of projection) may be explained by the principles of convergenceprojection hypothesis. Convergence of sensory inputs to a single spinal paintransmission neuron is of great importance because it underlies the phenomenon of referred pain. -

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All spinal neurons that receive input from the viscera and deep musculoskeletal structures also receive input from the skin. The convergence patterns are determined by the spinal segment of the dorsal root ganglion that supplies the afferent innervations of a structure. e.g. the afferents that supply the central diaphragm are derived from the third and fourth cervical dorsal root ganglia. Primary afferents with cell bodies in these same ganglia supply the skin of the shoulder and lower neck. Thus, sensory inputs from both the shoulder skin and the central diaphragm converge on pain-transmission neurons in the third and fourth cervical spinal segments.

Because of this convergence and the fact that the spinal neurons are most often activated by inputs from the skin, activity evoked in spinal neurons by input from deep structures is mislocalised by the patient to a place that is roughly coextensive with the region of skin innervated by the same spinal segment. The brain has no way of knowing the actual source of input and mistakenly "projects" the sensation to the somatic structure. Thus, inflammation near the central diaphragm is usually reported as discomfort near the shoulder. This spatial displacement of pain sensation from the site of the injury that produces it is known as referred pain. NB:

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For history-taking o Pain referred to abdomen from thorax, spine or genitalia is important to clarify because diseases of upper abdominal cavity such as acute cholecystitis or perforated ulcer are frequently associated with intrathoracic complications o The possibility of intrathoracic disease must be considered in every patient with abdominal pain, especially if the pain is in the upper part of the abdomen.  Myocardial or pulmonary infarction, pneumonia, pericarditis, or esophageal disease (the intrathoracic diseases that most often masquerade as abdominal emergencies) will often provide sufficient clues to establish the proper diagnosis. • Diaphragmatic pleuritis resulting from pneumonia or pulmonary infarction may cause pain in the right upper quadrant and pain in the supraclavicular area, the latter radiation to be distinguished from the referred subscapular

pain caused by acute distention of the extrahepatic biliary tree. o Palpation over the area of referred pain in the abdomen also does not usually accentuate the pain and in many instances actually seems to relieve it. o Referred pain from the spine, which usually involves compression or irritation of nerve roots, is characteristically intensified by certain motions such as cough, sneeze, or strain and is associated with hyperesthesia over the involved dermatomes. o Pain referred to the abdomen from the testes or seminal vesicles is generally accentuated by the slightest pressure on either of these organs. The Acute Abdomen – pathological causes of pain (4): Acute inflammation, obstruction, ischaemia, and increased pressure within a solid organ. 1. ACUTE

INFLAMMATION:

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The common processes leading to intra-abdominal inflammation are bacterial invasion, chemical irritation and ischaemia.

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Features of pain causes by inflammation depend on whether the organ affected is intraperitoneal or extraperitoneal.

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Inflammation of intraperitoneal organs o

Results in localised peritonitis, caused by irritation of pain receptors in the parietal (not visceral) peritoneum (peritoneal pain)

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Well localised, patient indicates position of pain with palm of hand or finger

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Aggravated by sudden movement – coughing; minimised by little movement – lying still or using diaphragm not abdominal muscles for breathing 

E.g. involvement of a segment of bowel with Crohn’s disease (transmural inflammatory process) results in peritoneal pain

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Acute salpingitis (develops over period of hours)

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Acute appendicitis (intraperitoneal inflammation caused by obstructive process): periumbilical due to obstruction of appendix (visceral pain), then as inflammation becomes transmural pain becomes peritoneal and moves to R iliac fossa over inflamed organ.

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Consequence of perforation of hollow viscera. Leakage of visceral contents causes pain by chemical irritation. Degree of irritation – depends on nature of leaking material. e.g. Gastric juice from a perforated peptic ulcer or gas from perforated sigmoid colon diverticulum (less irritation and less pain). Onset of pain in response to chemical irritation is rapid. Whether pain is localised or generalised depends on extent of spillage. i.e. max irritation is around site of leakage (epigastric for peptic ulcer, and L iliac fossa for perforated sigmoid diverticulum). Other causes of perforation are ischaemia (progressing to infarction) and malignancy (perforated gastric cancer)

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Ischaemic bowel – peritoneal part of pain is minor. Major component of the pain is of visceral type. Peritoneal inflammation occurs only if pain is transmural (most sensitive component of bowel wall to

ischaemia is mucosa). Except splenic infarct – pain is peritoneal in type, not really visceral. o

Inflammation restricted to bowel mucosa, seen in Ulcerative Colitis, doesn’t result in peritoneal pain.

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Inflammation of non-intraperitoneal organs: acute pancreatitis – chemical irritation of retroperitoneal tissues and irritation of visceral nerves. Pain is constant, severe, not aggravated by movement. If inflammatory process of acute pancreatitis spreads anteriorly, patient will complain of peritoneal pain

2. OBSTRUCTION •

Bowel obstruction causes colicky pain unless there is a complication (gangrene, 2° infection or perforation causing pain to be continuous) o

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Colic – severe, midline position. 

Epigastric if organ originated from foregut (down to the 2nd part of the duodenum), periumbilical if the organ came from midgut (down to splenic flexure of colon), and hypogastric if organ came from hindgut (left colon and rectum)

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Sudden distension of the biliary tree produces a steady rather than colicky type of pain; hence the term biliary colic is misleading.

Onset of obstruction pain is related to speed of obstruction: o

Sudden occlusion (gall bladder outlet obstruction due to a stone or volvulus of sigmoid colon) means onset of pain is over minutes.

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Slow progressing occlusion (obstructing cancer of sigmoid colon) means onset is much slower.

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Intermittent occlusion (gall bladder outlet obstruction due to stone) means intermittent pain

Obstruction caused by luminal lesion (calculus), mural lesion (benign or malignant tumour or fibrous stricture) or extraluminal lesion (fibrous band or neck of hernia)

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Obstruction can occur anywhere along the lumen of GIT, resulting in proximal distension and stasis; if obstructed bowel is open ended proximally, distension progresses proximally. If lumen is closed proximally, luminal contents and organ itself become infected (cholecystitis – inflammation of gall bladder, cholangitis – inflammation of bile duct, appendicitis) or progressive distension can lead to venous obstruction followed by arterial obstruction, then gangrene and perforation (e.g. closed loop obstruction of bowel) 3. ISCHAEMIA AND OTHER VASCULAR DISTURBANCES •

Inadequate blood flow resulting in tissue death (infarction) o

Arterial ischaemia caused by arterial embolus to the bowel, thrombosis or low output state. 

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Sudden onset pain (over few min) and continuous (visceral pain)

Venous ischaemia slower in onset

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The pain of embolism or thrombosis of the superior mesenteric artery or that of impending rupture of an abdominal aortic aneurysm certainly may be severe and diffuse.

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Yet, just as frequently, the patient with occlusion of the superior mesenteric artery has only mild continuous diffuse pain for 2 or 3 days before vascular collapse or findings of peritoneal inflammation appear. The early, seemingly insignificant discomfort is caused by hyperperistalsis rather than peritoneal inflammation. Indeed, absence of tenderness and rigidity in the presence of continuous, diffuse pain in a patient likely to have vascular disease is quite characteristic of occlusion of the superior mesenteric artery.

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Abdominal pain with radiation to the sacral region, flank, or genitalia should always signal the possible presence of a rupturing abdominal aortic aneurysm. This pain may persist over a period of several days before rupture and collapse occur.

4. TENSION •

When venous occlusion is complete, as occurs to a loop of bowel strangulated by the neck of a hernia, the tissue drained by the occluded vein becomes oedematous and engorged with blood, and arterial obstruction and thrombosis may follow. With larger vein occlusion by a thrombus (e.g. portal or superior mesenteric vein, or occasionally volvulus of bowel), the occlusion may be incomplete and alternative venous drainage may save the tissue from necrosis. Acute major mesenteric venous obstruction causes transudation of fluid into peritoneal cavity, which may be evident as ascites.

IN SOLID ORGAN

Sudden swelling – pain of visceral type due to stretching of capsule of organ o

Dull and constant

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Severity depends on degree of swelling

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Haemorrhage into ovarian cyst, necrosis of hepatic metastasis and hepatic venous engorgement due to acute R heart failure

Generalised abdominal pain First issue: address whether patient has abdominal catastrophe – generalised peritonitis, generalised tenderness, guarding, rebound tenderness, absence of bowel sounds. Signs of shock (blood loss or hypovolemic shock) – tachycardia, hypotension, oliguria, peripheral vasoconstriction (cool blue peripheral tissues and thready pulse), pallor indicating blood loss Signs of dehydration – • • • • • • • • • • • • • •

dry tongue reduced skin turgor decreased eye turgor tachycardia possible arrhythmias Increased respiration Decreased sweating and decreased capillary return Decreased urination Increased body temperature Extreme fatigue Muscle cramps Headaches Nausea Tingling of the limbs

Conditions: Glossary Gastroenteritis The typical syndrome will consist of diffuse, cramping abdominal pain, fever, and nausea, with hyperactive bowel sounds and mild diffuse abdominal tenderness. Bacterial infections will cause higher fever, watery diarrhea, and foul-smelling, often bloody stools. Obstipation The patient is distended with stool palpable through the abdominal wall and only mild abdominal tenderness. There will usually be a history of absence of bowel movements for several days although a small amount of diarrhea may pass around the fecal obstruction. Small bowel obstruction The pain is colicky, severe, and poorly localized. Cramping pain occurs in short, intense waves followed by complete absence of pain. Short pain-free intervals occur in proximal obstruction and longer ones in distal. The patient is restless. Vomiting, which may become feculent, is common in proximal obstruction. The abdomen is distended in distal obstruction, and the rectum has an empty, “ballooned” feel. Tenderness to palpation is not impressive unless perforation has occurred. High-pitched hyperactive bowel sounds are characteristic, but they may be hypoactive or absent in 25%. Most patients (80%) have a history of prior abdominal surgery. Large bowel obstruction

Constipation or change in bowel habits often precedes complete obstruction. Pain is felt below the umbilicus. Distension is prominent, but pain is less severe than with small bowel obstruction. Mesenteric ischemia Acute vascular occlusion usually presents with severe midabdominal pain out of proportion to the physical findings. The pain begins as colic, then progresses. In later stages, fever and hypotension occur. An embolic substrate (atrial fibrillation or acute MI) is a key clue. The stool should be hemoccult positive. “Intestinal angina” presents with recurrent colicky abdominal pain and distension occurring 20 to 30 minutes after a meal and lasting 2 to 3 hours. This may manifest itself as food aversion or a malabsorptive diarrhea/steatorrhea with prominent weight loss. There is often a bruit in the upper abdomen. Peritonitis There will be early vomiting, board-like abdominal rigidity, rebound tenderness, fever, and a silent abdomen. The patient will lie absolutely still. The pain is often localized (e.g., appendicitis) before becoming generalized. Abdominal aortic dissection The pain is migrating, severe, tearing, and radiating to the back. The patient will often be in early shock, hypotensive, and restless. There may be a pulsating, enlarged, tender aorta palpable through the abdomen. The femoral pulse may be absent. Loss of motor function and sensation in one leg suggests dissection with spinal artery compromise. Sickle cell crisis Diffuse abdominal pain with peritoneal signs develops in a patient with sickle cell anemia. Hepatitis Following a prodromal phase of anorexia and malaise, the icteric phase is dominated by right upper quadrant pain and tenderness, fever, jaundice, nausea, dark urine, and light stools. Biliary colic Sudden onset of steady and severe pain lasting 15 minutes to hours occurs with acute obstruction of the common bile or cystic duct. Cystic duct obstruction causes right upper quadrant pain whereas common bile duct obstruction causes epigastric pain, early jaundice, and prominent emesis. Pain may radiate to the scapula. Peptic ulcer disease Gnawing, aching, burning, or hunger pain in the epigastrium, relieved temporarily by food or antacids, suggests this diagnosis. Radiation to the back suggests perforation into the pancreas. Duodenal ulcer causes pain 1 to 2 hours after meals and at night. Pyelonephritis Typically, the patient has dysuria, fever, nausea, and costovertebral angle tenderness although presentation with poorly localized abdominal pain is not uncommon either. Acute cholecystitis Right upper quadrant pain radiates to the scapula and is accompanied by nausea, vomiting, and fever. Murphy sign (inspiratory arrest on palpation over the gallbladder) is present, and a distended gallbladder is palpable in 30%. There is often a background of biliary colic. Fever and rigors herald a suppurative cholangitis. Appendicitis Classically, it begins as poorly localized visceral pain in the periumbilical region, moving to the right lower quadrant, where somatic pain is steadily progressive. There is localized tenderness over McBurney’s point, with or without rebound tenderness. Anorexia/nausea and low-grade fever are usually present. Inflammatory bowel disease Pain, fever, and diarrhea with blood or mucus accompany flares. Terminal ileitis in young adults may simulate acute appendicitis. Crohn may be recognized by systemic signs, such as arthritis. Salpingitis A sexually active woman presents with lower abdominal pain. Pelvic examination reveals yellow discharge from the cervix, cervical motion pain (chandelier sign), or tender adnexa. An exquisitely tender adnexal mass indicates a tubo-ovarian abscess. Rectus abdominus muscle strain

The history will suggest strain or overuse. The pain is constant and aching and is exacerbated by movement. There will be superficial tenderness over the rectus abdominis, and spasm may mimic guarding. A hematoma may simulate a localized mass. Ureteral calculus Severe cramping flank pain radiates to the groin. The patient is pale and unable to find a comfortable position. The urine will be dipstick positive for blood. Ruptured corpus luteum cyst Around the time of the menses, there occurs a sudden-onset, transient (hours), unilateral, lower abdominal and adnexal pain and tenderness. It is less severe and more diffuse than appendicitis, and it steadily improves on serial examination rather than worsening. A similar presentation during midcycle occurs with rupture of a graafian follicle (mittelschmerz). Ruptured ectopic pregnancy A missed or late period (85%) with an adnexal mass may be the only clue; thus, a high index of suspicion is needed. Rupture is accompanied by acute pain that may project to the shoulder, accompanied by cervical bleeding, shock, and a full, boggy cul-de-sac. There is a prior history of PID in 25%. Ovarian torsion The usual presentation is a young woman with acute onset of pain and a tender adnexal mass but no fever. Pancreatitis Left upper quadrant pain boring through to the back, prominent nausea and vomiting, and a history of heavy alcohol use or cholelithiasis are important clues. The patient sits up and leans forward, or lies on the side in a knee-chest position. Rebound will be present just above the umbilicus, and costovertebral angle tenderness occurs with inflammation of the tail of the pancreas. Hiccups are often present. Splenic infarction Left upper quadrant pleuritic pain and tenderness occur in the setting of atrial fibrillation, endocarditis, sickle cell anemia, or neoplastic splenic enlargement. There may be a localized friction rub. Myocardial infarction Ischemia should be considered with upper abdominal pain although chest pain is usually present. Nausea can be seen with inferior ischemia. Diverticulitis It presents subacutely with low-grade fever and left lower quadrant abdominal pain. A tender mass with indistinct borders may be palpable on abdominal or rectal examination. Sigmoid volvulus Severe pain will suddenly occur while the patient is straining to defecate. Rapid, extreme left upper quadrant distension occurs, with vertical peristalsis.