Summary of Common Conditions Seen in OSCEs
Causes of abdominal pain can be broadly divided into acute and chronic.
Acute Abdominal Pain
Chronic Abdominal Pain
Investigations to Consider for Abdominal Pain
Blood Tests
- Full blood count: anaemia may be present in cases of gastrointestinal malignancy or a perforated peptic ulcer. A raised white cell count would be found in infective or inflammatory conditions.
- Us+Es: renal impairment may be found in pyelonephritis or any other renal/renal tract pathology.
- C-reactive protein: raised in IBD, infections and any other pathologies causing inflammation.
- Liver function tests: deranged in hepatitis, raised alkaline phosphatase in cholecystitis (often follows biliary colic and will be associated with constant pain and fever).
- Amylase: raised levels in pancreatitis.
- Arterial blood gasses: this is very useful in an ‘acute abdomen’. A low base excess and a high lactate level may indicate severe general physiological decompensation. A metabolic acidosis will help narrow down the potential causes (e.g. pancreatitis).
Urine
- Urine dipstick on midstream urine sample: to look for haematuria in renal colic due to renal stones, nitrites if a urinary tract infection or pyelonephritis is present.
- Urine beta-human chorionic gonadotropin: for pregnancy.
Imaging
- Erect chest X-ray: to look for air under the diaphragm due to a perforated viscus.
- Abdominal X-ray: to assess for abnormal fluid air levels, loops of dilated bowel, etc.
- Ultrasound/CT: for any structural hepatobiliary or gynaecological pathologies.
- MRCP: for hepatobiliary pathology.
- Intravenous urogram: for suspected ureteric obstruction due to calculi.
- Mesenteric angiogram for suspected mesenteric ischaemia (remember that this can occur in atrial fibrillation).
Others
- Oesophago-gastro-duodenoscopy/colonoscopy: for cases of suspected gastrointestinal bleeding or any pathology in the lumen of the oesophagus or colon.
- ERCP: for diagnosing cholangiocarcinoma and for close visualisation of the hepatobiliary tract.
- Helicobacter pylori: can be detected either by a stool antigen test or a CLO test (via oesophago-gastro-duodenoscopy); serology is of limited clinical value.
- Vaginal/endocervical swabs: if suspecting pelvic inflammatory disease/genitourinary infection.
Hints and Tips for the Exam
Work Through the Systems
Abdominal pain is potentially more difficult to manage due to the wide variety of systems from which it may originate. To help narrow down your list of differential diagnoses, it may be helpful to work your way through the different organs or systems in your mind. The following list summarises these:
- Oesophagus/stomach
- Small intestine
- Large intestine
- Liver/hepatobiliary tract
- Abdominal aorta
- Kidneys, renal tract, bladder
- Gynaecological/pelvic organs (ovaries, fallopian tubes, uterus)
- Scrotal/testicular
- Metabolic
Don’t Forget Non-Abdominal Causes of Abdominal Pain
These could be as serious and potentially life-threatening as the classical causes that originate from the abdomen – the tables above list them in the ‘Others’ column.
Managing an Acute Abdomen
This is a common surgical emergency that every junior doctor should know inside out. Although there is an absolute plethora of possible causes, the initial management is generic for most of them:
- Make the patient nil by mouth.
- Start intravenous fluids.
- Administer adequate analgesia: remember to prescribe an antiemetic with any opioid-based analgesia.
- Take bloods for the following:
- Full blood count, Us+Es, liver function tests, C-reactive protein level, amylase
- Blood cultures
- Group and save
- Vaginal swabs in women.
- Full blood count, Us+Es, liver function tests, C-reactive protein level, amylase
- Do a pregnancy test.
- Do a urine dipstick.
- Do an erect chest X-ray to look for air under the diaphragm.
- Request a specialist assessment by the general surgical and/or gynaecology on-call team.
Women’s Health
In women, remember to consider pathologies related to obstetric and gynaecological causes – it is unusual to encounter obstetrics and gynaecology-related pathologies in a finals OSCE, but it is still possible.
Pregnancy Test
This should be one of the first tests you do in a woman of child-bearing age presenting with lower abdominal pain. A urinary beta-human chorionic gonadotropin test is quick and easy to do.
Ectopic Pregnancy
A pregnant woman with acute lower abdominal pain is a case of ectopic pregnancy until proven otherwise. Ectopic pregnancies can rupture, bleed, cause peritonitis and ultimately be fatal. Most women will have had their first pregnancy-related scan by around 12 weeks, which will reveal whether or not the baby is in the uterus.
Deciding Where the Pain Originates From
The key to this lies in appreciating some basic anatomy and embryology (as distant in your training as it may sound):
- Visceral pain: This is the pain that the patient feels first. It occurs as a result of stretching of the viscera (such as the intestines, the wall of the stomach, and anything that forms the gastrointestinal or hepatobiliary tract). This pain is usually quite vague and often difficult to localise to a very specific area.
To appreciate the origin of visceral pain, one has to appreciate how the gastrointestinal tract was formed. To cut a long story short, the zygote develops in three layers – the endoderm (the innermost layer), the mesoderm (the middle layer) and the ectoderm (the outermost layer). The only one that is relevant here is the endoderm. This develops into foregut, midgut and hindgut, which later develop into various parts of the gastrointestinal system. This is relevant is because the area of the abdomen where the pain is first felt correlates with these three divisions – abdominal pain in the epigastric area usually originates from structures derived from the foregut, pain in the umbilical area originates from structures derived from the midgut, and pain in the suprapubic area originates from structures derived from the hindgut. Figure 30.1 illustrates this more simply.
- Peritoneal pain: This is the pain that the patient feels later. In contrast to visceral pain, peritoneal pain is more clearly defined and easier to localise. It occurs after the painful organ either touches, stretches or inflames the peritoneal peritoneum, which is why it happens after visceral pain (which is due to stretching of an organ or other structures). To localise where peritoneal pain is coming from, you need to know the structures that underlie the peritoneum, as illustrated in Figure 30.2.
Figure 30.1 Foregut, midgut and hindgut
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