UBC Objectives: Care of Children + Adolescents, UBC Objectives: Care of the Elderly, UBC Objectives: Surgical + Procedural Skills, & Priority Topic: Abdominal Pain

By the end of postgraduate training, using a patient-centred approach and appropriate selectivity, a resident, considering the patient's cultural and gender contexts, will be able to...

• Describe how the presentation and management of disease in children differs from adults
• Assess and manage atypical presentations of common medical conditions in the elderly
• Diagnose the common acute and non-acute disease entities requiring surgical treatment

Key Feature 1b: Given a patient with abdominal pain, paying particular attention to its location and chronicity: Generate a complete differential diagnosis (ddx).
Skill: Clinical reasoning
Phase: Hypothesis generation, Diagnosis

Key Feature 4: In a patient with acute abdominal pain, differentiate between a surgical and a non-surgical abdomen. 
Skill: Clinical reasoning, Selectivity
Phase: Physical, Diagnosis

Key Feature 5: In specific patient groups (ex: children, pregnant women, the elderly), include group-specific surgical causes of acute abdominal pain in the ddx. 
Skill: Clinical Reasoning, Selectivity
Phase: Hypothesis generation, Diagnosis

A 13 year old female presented to clinic with her mother today concerned about acute abdominal pain. She localised the pain as being midline in the lower abdomen. What is my ddx?

Like my previous post regarding the categorisation of acute vs chronic abdominal pain, sometimes (oftentimes) we encounter patients who challenge our clinical ability to categorise symptoms. Certainly this is true with pediatric patients, as their report of symptoms, if they are even old enough to verbally report symptoms, can be challenging to decode. Their inexperience with the pain of a headache may be entirely new, and perhaps associating feeling sick with feeling sick to their stomach, they may point to their tummy when you ask them where there pain is. Or maybe some kiddos actually feel sick to their stomach when they have a headache. The possibilities are endless, and without a reliable way to confidently know where pain or other manifestations of disease is originating from on history, as treating physicians we need to maintain a healthy dose of suspicion in searching for the culprit(s). As their own demographic, children also present with different probabilities of disease, and when it comes to abdominal pain, this is as true as any other undifferentiated symptom. 

My abbreviated ddx for pediatric abdominal pain (informed by the LMCC learning objectives) depending on the area to which the pain is localised (if they are old enough to be able to localise and communicate this information) is as follows:

• Epigastric pain
  • Gastroesophageal reflux disease
  • Peptic ulcer disease
  • Biliary tract disease
  • Pancreatitis
• Lower abdominal pain
  • Appendicitis
  • Mesenteric adenitis
  • Inguinal hernia (incarcerated)
  • Inflammatory bowel disease
  • Gastroenteritis
  • Constipation
  • Gynaecological causes in pubertal children
  • Urinary tract  infection
• Generalised pain
  • Peritoneal inflammation
  • Bowel (infantile colic, obstruction)
  • Malabsorption
  • Inflammatory bowel disease
• Flank pain
  • Nephrolithiasis
  • Pyelonephritis
• Functional abdominal pain

Of course, this list is not exhaustive, but it does prompt me to consider some of the most common diagnoses in pediatric patients, as well as important ones not to miss, including the ones that require urgent or emergent surgery. And when I encountered that 13 year old female in clinic today who was able to reliably tell me that she was having midline lower abdominal pain, I was able to use this ddx to inform my clinical data collection, my springboard to  collect pertinent negatives to arrive at a working diagnosis (which for this patient was constipation). I don't know that I was correct in reaching this conclusion, or that it was the only thing contributing to the pain, but my attending concurred with this conclusion, and it helped me look for the absence of findings suggesting a worrisome not-to-miss condition. If I cannot feel confident about localisation in a pediatric patient, then I can simply broaden my ddx to include all common and worrisome pediatric diagnoses. And if that still is unsatisfactory, I can consider the more extensive ddx I have for adult abdominal pain (which is still relatively abbreviated, but does take into consideration most bodily systems that may be sources of pain).

For completeness, here is my ddx for acute abdominal pain (adult patient, also informed by the LMCC objectives):

• Upper abdominal pain
  • Acute hepatitis, hepatic abscess
  • Biliary tract disease
  • Gastroesophageal reflux disease
  • Peptic ulcer disease, gastritis
  • Pancreatitis
  • Splenic infarct, splenic abscess
  • Referred cardiothoracic pain
  • Musculoskeletal pain
• Lower abdominal pain
  • Appendicitis
  • Mesenteric adenitis
  • Diverticulitis
  • Incarcerated hernia
  • Inflammatory bowel disease
  • Bowel obstruction
  • Renal colic
  • Urinary tract infection
  • Ectopic pregnancy
  • Pelvic inflammatory disease
  • Ovarian (torsion, ruptured ovarian cyst)
• Diffuse pain
  • Generalised peritonitis
  • Ruptured abdominal aortic aneurysm
  • Ischemic bowel disease
  • Gastroenteritis
  • Irritable bowel syndrome

And my ddx for chronic abdominal pain (adult patient, also informed by the LMCC objectives):

• Upper abdominal pain
  • Hepatic disease
  • Biliary disease
  • Ulcer and nonulcer dyspepsia (ex: heartburn)
  • Gastric cancer
  • Pancreatic disease
  • Referred cardiothoracic pain
• Lower abdominal pain
  • Bowel disease
    • Inflammatory bowel disease
    • Diverticular disease
    • Irritable bowel syndrome
  • Genitourinary disease
    • Pelvic inflammatory disease
    • Benign or malignant tumours
    • Endometriosis
    • Urinary tract disease

To elaborate a bit further on inclusion of surgical causes of acute abdominal pain, it is important to know which diagnoses require surgical referral, be it after a bit of a workup to confirm the diagnosis, or more urgent or emergently if the patient is seriously unwell or with signs of peritonitis*. In the pediatric patient, for example, this could mean first doing an ultrasound** to rule out appendicitis if you think it is possible but not highly likely as the cause of the abdominal pain, or it could mean ordering imaging concurrently as you urgently consult general surgery if you think an acute appendicitis is in fact likely to be the underlying etiology for the pain. For any case in which a patient is presenting with peritonitis and a broad working differential for acute abdominal pain, a consult to general surgery is indicated. If the working differential is more focused, given the clinical presentation and patient-specific risk factors, then the surgeon to consult will depend on suspected etiology and local specialist accessibility, and may warrant consultation with general surgery, gynaecology, urology, cardiac surgery, vascular surgery, or otolaryngology. Of course, consultation with a nonsurgical medical specialist may also be warranted given the working diagnosis, such as a gastroenterologist, nephrologist, or infectious disease specialist, among others. The timing of when to involve such specialists must be driven by the urgency of the situation in combination with the working differential, be it to provide diagnostic clarity when there is confusion or to administer therapy that is not in the general practitioner's scope of practice.

*In a patient presenting with acute abdominal pain, it is particularly important to examine the patient's abdomen to decide if it is "peritonitic" (otherwise known as a surgical abdomen). Peritonitis is the inflammation of the peritoneum, the sac that encases much of our abdominal organs, and is an ominous finding that suggests surgical intervention is needed. Features most suggestive of peritonitis on physical exam that warrant urgent surgical consultation, in the order in which they would be assessed as per the Inspect-Auscultate-Percuss-Palpate (IAPP) approach to the abdominal exam as is standard medical school teaching, include:

• "Bump the stretcher test"
  • Literally you pretend to accidentally bump the stretcher and see if the patients respond with pain. It's not nice if there really is peritonitis, as any sudden movements can cause significant pain, but if it helps you to figure out they have peritonitis, I think the pain caused by bumping their stretcher is far outweighed by the pain of a missed diagnosis of peritonitis.
• Percussion tenderness
  • ​Another test of something that should otherwise not cause any measurable degree of discomfort, in a patient with peritonitis, even gentle percussion on the abdominal wall can produce pain out of proportion to the tap, increasing the likelihood that the patient has a peritonitic process occurring in their abdomen.
• Guarding/rigidity
  • Guarding and rigidity are phenomena whereby patients tense their abdominal wall muscles in order to protect the underlying organs in the abdomen. On examination, the abdominal wall feels firm. The difference between guarding and rigidity is that in the former, the muscle tension is voluntary, such that if you can get a patient distracted, maybe by asking them questions that take their mind ever-so-momentarily off the fact that you're feeling their tender abdomen, the abdominal wall becomes softer. Rigidity, on the other hand, is involuntary contraction of the abdominal wall musculature. With a peritonitic process, the irritation of the peritoneum causes a reflex contraction of the muscles in processes not requiring conscious contraction. So neat. As you may expect, rigidity has a much greater likelihood ratio in predicting the presence of peritonitis than does guarding, but even guarding does increase the likelihood of peritonitis so is important not to overlook if full on rigidity is absent.
• Rebound tenderness
  • ​To elicit this finding, you push down on the abdominal wall as you do when palpating in general, and then you release. In the force of pushing in on a peritonitic abdomen, this will likely cause the patient significant pain already, but the likelihood of the patient with acute abdominal pain having peritonitis is actually greater if the pain on removal of the force inward on the abdomen (the pain on rebound) is worse.

**A tangent on how the management of disease in children differs from adults: A consideration that a  physician must have when working up a pediatric concern is how the potential for harm and benefit of various interventions is different from that of an adult or geriatric patient. For example, the potential for harm from repeated CT scans could increase a person's risk of cancer down the road, and having hopefully much more time to live and bear secondary mutations possibly related to effects of radiation, the risk to benefit ratio of performing CT scans in pediatric patients is not the same as in older patients. Although the harm of a single CT scan is not so significant if it means possibly saving a life, it is something to consider if your pre-test probability of ominous disease is low. The converse is also true for the elderly or other patients that have risk factors for true and serious pathology: where the weight balances on the risk vs benefit scale shifts. The same general rationale regarding management decisions applies to considering interventions in pediatric patients as compared to other demographics, and the wise physician will remember to consider that the benefit to harm ratio of anything we choose to do or abstain from doing will differ depending on the individual before us.