Abdominal pain is one of the commonest presentations encountered in both the outpatient clinics and in emergency rooms (Dominitz, Sekijima, & Watts, 2009). The magnitude of the burden, both economical and social, of this presenting feature can be gauged from the fact that the total number of hospital visits which can be accounted for due to this complaint amount to almost 2. 5 million per year (Dominitz, Sekijima, & Watts, 2009). Abdominal pain varies in its severity, character, location and cause and thus it becomes of vital importance to correctly discern the etiology of the pain in order to provide effective treatment.
Pathophysiology of Abdominal Pain Diffuse abdominal pain can be defined as pain located in the abdomen which is the region bounded by the thoracic cavity above and the pelvic cavity below (Virtual Medical Centre, 2008). Pain in the abdomen can arise from various different mechanisms and varies in its nature depending on where it arises from. The four main mechanisms leading to abdominal pain include inflammation, ischemia, stretching and nerve stimulation (Virtual Medical Centre, 2008).
Inflammation refers to the activation of inflammatory cascades such as the arachadonic acid pathway which leads to the formation of several inflammatory mediators. These mediators lead to the activation of pain receptors and thus produce the sensation of pain (Virtual Medical Centre, 2008). Ischemia refers to the lack of blood supply to an organ which eventually due to the lack of adequate nutrients and oxygen and accumulation of waste products leads to the production of pain (Virtual Medical Centre, 2008).
Similarly, stretching of the capsules of the viscera or the surrounding musculature and the stimulation of nerves may trigger pain sensations. Based in the origin and pathophysiology of pain, abdominal pain can b classified into visceral, somatic, referred or pain arising due to peritonitis (Ansari, 2007). There are two kinds of peritoneal linings present in the abdomen, viz. the visceral peritoneum, which encloses the abdominal viscera and the parietal peritoneum. The origin of visceral pain is from the abdominal viscera which produce pain via activation of the autonomic nervous system (Edwards).
The abdominal viscera are only sensitive to the distension of the visceral peritoneum or contractions and any pathology resulting in either of the two aforementioned states results in the production of visceral pain (Ansari, 2007). This pain is dull in nature and instead of localizing to the specific organ in question, it diffusely spreads over the area which corresponds to the embryonic origin of the structure concerned. In general, upper abdominal pain is caused by pathology in structures derived from the foregut including the stomach, duodenum, pancreas and the liver.
On the other hand, pain in the periumblical region can be accounted for by structures arising from the midgut while hindgut structures such as the colon and the genitourinary tract structures give rise to lower abdominal pain (Ansari, 2007). As opposed to visceral pain, somatic pain is caused by the irritation of the parietal peritoneum which derives its nerve supply from the somatic nervous system and is thus well localized. This type of pain is sharp in character and can arise due to infectious, chemical or inflammatory causes (Ansari, 2007).
Referred pain is pain arising in a location other than or distant from the location of the perceived pain and results from the co-stimulation of the different fibers from the spinal cord when they converge. For example, pain due to renal colic often radiates to the groin while that from biliary colic radiates to the scapular region (Ansari, 2007). Peritonitis, which is defined as ‘the inflammation of the peritoneal cavity’ (Ansari, 2007), also results in abdominal pain. This can occur due to several reasons such as perforation of the gut, inflammation of the abdominal viscera (e. g.
appendicitis and pancreatitis) or intraperitoneal blood (Ansari, 2007). Thus, pain in the abdominal cavity can arise via any of the above discussed mechanisms and pathophysiologies and these might overlap in a variety of conditions. Thus, it becomes imperative to correctly identify the etiology of the pain as this guides the subsequent management. Differential Diagnosis • Ectopic Pregnancy • Pelvic Inflammatory Disease • Urinary Tract Infection • Gastroenteritis • Typhoid Fever • GERD (Gastroesophageal Reflux Disease) • Peptic Ulcer Disease • Constipation • Early-stage appendicitis
• Acute pancreatitis • Ruptured Aortic Aneurysm • Intestinal obstruction • Diabetic ketoacidosis (DKA) • Peritonitis • Sickle Cell Crisis • Mesenteric Ischemia • Somatization Disorder (Ansari, 2007; Heller, 2009) Assessment Since the etiology of abdominal pain can be very diverse and difficult to discern, the first step in assessing a patient and formulating a differential diagnosis is a proper history and physical examination. Abdominal pain can result from fairly benign causes such as GERD or constipation to potentially life-threatening, catastrophic causes such as a ruptured aortic aneurysm.
The history would reveal whether the pain is acute or chronic, will give clues about its onset, character, radiation and severity. In a 24 year old female presenting with abdominal pain, it is of foremost importance to rule out pregnancy and its related complications. A ruptured ectopic pregnancy can present with abdominal pain but this would be accompanied by other signs and symptoms such as amenorrhea, symptoms of early pregnancy such as morning sickness, cervical motion tenderness on examination, etc (McPhee, Papadakis, & Tierney, 2008). The diagnosis of an ectopic pregnancy may be confirmed by a positive ?
– hCG test and a pelvic ultrasound (Dominitz, Sekijima, & Watts, 2009). Similarly, other important causes of abdominal pain in a young, sexually active female include pelvic inflammatory disease (PID) which might be chronic in nature and may have abdominal pain as the only symptom and urinary tract infection (UTI) (Dominitz, Sekijima, & Watts, 2009). However, there may be other associated symptoms such as vaginal discharge, menstrual abnormalities and infertility in the case of PID and fever, vomiting, burning micturation, dysuria and nocturia in the case of a UTI (McPhee, Papadakis, & Tierney, 2008).
Other more common causes of diffuse abdominal pain include acute gastroenteritis which manifests with watery diarrhea, vomiting, fever and abdominal cramps and can be diagnosed clinically on the basis of a history and confirmed via a stool culture (McPhee, Papadakis, & Tierney, 2008). Similarly, other infections such as typhoid fever may present with similar symptoms with fever being the predominant complain. The diagnosis of this condition can be confirmed on the basis of a positive blood culture or a bone marrow smear and culture (McPhee, Papadakis, & Tierney, 2008).
Conditions such as GERD and peptic ulcer disease may also cause abdominal pain. The patient might give a history of recurrent episodes of such symptoms, use of NSAIDs and relation of the symptoms with meals. The abdominal pain might be diffuse but may also be localized to the epigastric region and might be severe enough to arouse the patient from sleep (Bliss, Moseley, Valle, & Saint, 2003). Similarly, the complaint of constipation may also be long standing and any new onset constipation might suggest the possibility of a malignancy, obstructive causes or neurologic abnormalities (McPhee, Papadakis, & Tierney, 2008).
Acute appendicitis presents with pain, which is gradual in onset and migratory in nature. The pain begins in the periumblical region, when the onset of inflammation occurs and as the inflammation gradually involves the parietal peritoneum, the pain localizes in the right lower quadrant (Ansari, 2007). On the other hand, abdominal pain associated with pancreatitis is steady in nature and typically radiates to the back. There may be associated features of nausea and vomiting.
The definitive diagnosis of pancreatitis is based on laboratory findings of elevated levels of amylase or lipase (Dominitz, Sekijima, & Watts, 2009). Abdominal pain associated with vomiting is also a common manifestation of intestinal obstruction. The findings on clinical examination which point towards the diagnosis of intestinal obstruction include the absence of bowel sounds and the failure to pass flatus (in the case of a complete obstruction).
There may also be associated fever and signs of hemodynamic instability such as tachycardia, and orthostatic hypotension secondary to dehydration (Dominitz, Sekijima, & Watts, 2009). A very important and potentially catastrophic cause of abdominal pain is a dissecting aortic aneurysm which presents with tearing pain which commonly begins in mid-abdomen and radiates to the back and the left flank (Ansari, 2007; Dominitz, Sekijima, & Watts, 2009).
Moreover, due to the rapid blood loss, the patient inevitably becomes rapidly hemodynamically unstable and presents with symptoms of shock (Dominitz, Sekijima, & Watts, 2009). Other less common causes of abdominal pain include metabolic conditions such as DKA, systemic manifestations of other diseases such as sickle cell crisis and psychiatric conditions such as somatization disorder which can be diagnosed on the basis of the associated signs and symptoms and laboratory findings. Treatment Modalities
The management of abdominal pain depends on the specific cause identified. The first and the foremost step in the management of a patient with abdominal pain is ensuring that the patient is vitally and hemodynamically stable and if the pain is severe, providing pain relief using either NSAIDs or opioids (Virtual Medical Centre, 2008). In all cases in which the patient is hemodynamically unstable, the patients need to be monitored in an ICU and appropriate and prompt management for any signs of instability should be provided.
Conditions such as gastroenteritis and infectious conditions can be fairly easily managed with antibiotics, constipation with the use of laxatives and the GERD or peptic ulcer disease with the use of proton pump inhibitors or H2 receptor blockers (Virtual Medical Centre, 2008). Patients with an ectopic pregnancy can be managed either with medical or surgical intervention. Medical management with methotrexate is recommended only in the case of an uncomplicated, unruptured ectopic pregnancy (Dominitz, Sekijima, & Watts, 2009).
In all other cases, surgical intervention in the form of a laparoscopy or laparotomy and removal of the ectopic pregnancy is required (Dominitz, Sekijima, & Watts, 2009). The patient needs to be vigilantly monitored in the ICU and hemodynamic stability should be ensured. Infectious conditions of the genitourinary tract such as UTI and PID require treatment with appropriate antibiotics which can be provided either as outpatient therapy or the patient may be hospitalized depending on the severity of the condition.
Indications for hospitalization in patients with PID include pregnancy, unresponsiveness to antimicrobial therapy, severe disease such as a tubo-ovarian abscess (Dominitz, Sekijima, & Watts, 2009). In the case of more severe conditions such as appendicitis and pancreatitis, hospitalization is necessary. Acute appendicitis is managed surgically with resection of the inflamed appendix either laparoscopically or via a laparotomy. Patients who are diagnosed to have severe pancreatitis need to be admitted in the ICU and aggressive management should be provided especially.
Important interventions in this condition include provision of intravenous fluid support and serial and vigilant monitoring of serum calcium (Dominitz, Sekijima, & Watts, 2009). Moreover, administration of prophylactic antibiotics such as Impenem or a fluoroquinolone should be initiated (Dominitz, Sekijima, & Watts, 2009). Conditions such as a dissecting aortic aneurysm present as a medical and surgical emergency. If a ruptured aortic aneurysm is diagnosed, the patient should be admitted in the ICU and the hypovolemia should be promptly corrected using either crystalloids or blood products (Dominitz, Sekijima, & Watts, 2009).
If bowel obstruction is suspected, the patient should be kept NPO (nothing per oral). Moreover, insertion of an NG tube with removal of gastric contents to reduce the symptoms of nausea and vomiting, may be required (Dominitz, Sekijima, & Watts, 2009). In addition to these measures, surgical consultation should be obtained as any delays in management can lead to ischemia and infarction of bowel. The specific cause of the obstruction can then be treated surgically (Dominitz, Sekijima, & Watts, 2009).
References
Ansari, P.(2007, September). Acute Abdominal Pain . Retrieved July 23, 2009, from The Merck Manual for Healthcare Professionals: http://www. merck. com/mmpe/sec02/ch011/ch011b. html Bliss, S. J. , Moseley, R. H. , Valle, J. D. , & Saint, S. (2003). A Window of Opportunity. The New England Journal of Medicine , 1848-1853. Dominitz, J. A. , Sekijima, J. H. , & Watts, M. (2009). Abdominal Pain. Retrieved July 23, 2009, from University of Washington, Dperatment of Gastroenterology: http://www. uwgi. org/guidelines/ch_06/CH06TXT. HTM Edwards, H. C.
(n. d. ). The interpretation of pain in the abdomen. British Medical Journal , 779-781. Heller, J. L. (2009, June 26). Abdominal Pain. Retrieved July 23, 2009, from Medline Plus: http://www. nlm. nih. gov/medlineplus/ency/article/003120. htm McPhee, S. J. , Papadakis, M. A. , & Tierney, L. M. (2008). Current Medical Diagnosis and Treatment 2008. McGraw Hill. Virtual Medical Centre. (2008, April 22). Abdominal Pain. Retrieved July 2009, 2009, from virtualmedicalcentre. com: http://www. virtualmedicalcentre. com/symptoms. asp? sid=4