By Dr. Marcus Judge

OSCE

During any examination in an OSCE it is important to understand the pathology and reasoning behind each of the signs and symptoms elicited. This applies even if the patient being examined is ‘normal’. This article explains how to perform a rectal (PR) examination and the key findings you should look for, showing you what each sign means and what conditions it may indicate.

The rectal examination is written as ‘PR’ for per rectum. It is often called a digital rectal examination (DRE), where ‘digital’ means done with a finger. It allows you to assess the perianal skin (the skin around the anus), the anal canal (the short passage between the rectum and the outside), the rectum and, in men, the prostate gland. It is an intimate examination, so a sensitive, professional approach is essential throughout, and you should offer a chaperone (usually a health professional who acts as an impartial observer).

Contents

  1. Introduction
  2. General Inspection
  3. Inspection of the Perianal Region
  4. Digital Examination: Insertion and Anal Tone
  5. Palpation of the Rectal Walls
  6. Palpation of the Prostate (in Males)
  7. Withdrawal and Inspection of the Glove
  8. Completing the Examination
  9. Quiz

Introduction

Wash your hands and don a pair of non-sterile gloves and an apron. Good hand hygiene reduces the risk of transmitting infection during this intimate examination.

Introduce yourself to the patient, giving your name and grade e.g. 3rd year medical student/junior doctor/registrar.

Confirm the patient’s details taking 3 points of identification; usually full name, date of birth and NHS/hospital number.

Briefly explain the examination in clear, jargon-free language. Say that you need to examine the back passage by gently inserting a gloved, lubricated finger into the anus to feel for any abnormalities. Reassure the patient that it may feel uncomfortable but should not be painful, and that they can ask you to stop at any time. Obtain verbal consent.

Offer a chaperone and explain their role. A chaperone protects both patient and examiner and provides reassurance, and offering one is a key marking point in any OSCE. Document who was present, or that the patient declined the offer.

Ask the patient to remove their lower clothing and underwear in privacy. Then ask them to lie on the couch in the left lateral position with their knees drawn up towards their chest. This position relaxes the gluteal (buttock) muscles and brings the rectum and prostate within easy reach of the examining finger. To preserve their dignity, cover the patient with a sheet until you are ready to begin.

Before starting, ask whether the patient has any pain, particularly around the back passage, as severe perianal pain may make the examination intolerable, for example with an anal fissure (a painful tear in the lining of the anal canal).

General Inspection

Begin with a brief general inspection of the patient and their surroundings. Note whether the patient appears comfortable or is in obvious pain or distress, which may suggest an acutely painful condition such as an anal fissure, a perianal abscess (a collection of pus next to the anus) or a thrombosed haemorrhoid (a swollen vein cushion at the anus, also called a pile, blocked by a clot).

Look for signs that hint at the underlying reason for the examination. Pallor may suggest anaemia, which is relevant if the patient is being investigated for gastrointestinal blood loss. A cachectic appearance (significant weight loss and muscle wasting) raises concern about an underlying cancer (malignancy), such as colorectal (large bowel) or prostate cancer.

Scan the bedside for relevant objects such as stoma bags (which collect stool from an opening in the abdominal wall), incontinence pads, catheters or a commode (a portable toilet chair), which can give clues about bowel or urinary symptoms. Ensure the equipment you need is to hand: gloves, water-based lubricating jelly, gauze or tissue, and a clinical waste bin.

Inspection of the Perianal Region

With the patient in the left lateral position, gently lift the upper buttock to expose the anus and perianal skin. Inspect carefully in good light before touching the patient. Many important diagnoses are made on inspection alone.

Look for the following:

  • Skin tags: small flaps of skin around the anus. They are often harmless but may be associated with previous haemorrhoids or, when multiple and large (florid), with Crohn’s disease (long-term inflammation of the gut that can affect any part from mouth to anus).
  • External haemorrhoids: swollen vascular cushions (clusters of blood vessels) arising below the dentate line (the point in the anal canal where the lining changes type). The lining there carries pain-sensing (somatic) nerves, so they tend to be felt and seen as a lump at the anal margin. A thrombosed haemorrhoid appears as a tense, dark, exquisitely tender lump, caused by clot within the haemorrhoidal vessel.
  • Anal fissure: a tear in the lining of the anal canal, most often in the posterior midline. Fissures usually arise from the passage of hard stool. They are intensely painful due to spasm of the internal anal sphincter. This pain may make digital examination impossible, in which case do not force the examination.
  • Fistula or abscess: an external fistula opening discharging pus, or a hot, red, fluctuant (fluid-filled, so it moves under pressure) swelling indicating a perianal abscess. Anal fistulae are abnormal tracts (tunnels) between the anal canal and the skin. Most follow a perianal abscess, but Crohn’s disease is a less common cause.
  • Rectal prolapse: a protruding mass of rectal mucosa, classically with concentric rings, that may appear or worsen when the patient bears down.
  • Anal warts (condylomata acuminata): fleshy, often clustered lesions around the anal margin, caused by human papillomavirus (HPV, a common virus) and usually, but not always, spread by sexual contact.
  • Excoriation (scratch marks or broken skin), rashes or discharge: suggesting pruritus ani (itching around the anus), dermatological (skin) conditions or infection.
  • Blood, mucus or faecal soiling: soiling may indicate poor sphincter control or overflow incontinence (liquid stool leaking around hard stool stuck in the rectum) secondary to constipation.

Now ask the patient to bear down or cough and watch the anus, as some abnormalities only declare themselves under raised intra-abdominal pressure:

  • Rectal prolapse may protrude or become more obvious on straining, confirming the diagnosis if it was not already apparent at rest.
  • Internal haemorrhoids: these originate above the dentate line and are covered by insensate (unable to feel pain) rectal mucosa, so they are usually painless and are not seen at rest. On straining they may bulge into view as soft, bluish, mucosa-covered swellings, and they are a common cause of painless, bright-red bleeding on defecation.

If inflammatory bowel disease (long-term inflammation of the gut, mainly Crohn’s disease and ulcerative colitis) is the reason for examination, the perianal findings can help distinguish the subtypes. Crohn’s disease can affect anywhere from mouth to anus and characteristically produces perianal disease: multiple skin tags, fistulae and abscesses. Ulcerative colitis (inflammation limited to the lining of the colon and rectum) is confined to the colon and rectum and more typically presents with bloody, mucoid stool rather than perianal complications.

It can be helpful to describe the position of any abnormality using a clock face. Here, 12 o’clock is anterior (towards the genitals) and 6 o’clock is posterior (towards the coccyx). This keeps findings documented unambiguously.

Digital Examination: Insertion and Anal Tone

Once external inspection is complete, warn the patient that you are about to begin the internal examination and that they will feel some pressure. Apply a generous amount of water-based lubricant to your gloved index finger.

Place the pulp of your index finger flat against the anal margin and apply gentle, steady pressure, allowing the sphincter to relax before slowly advancing the finger into the rectum. Pushing directly inwards against a closed sphincter is uncomfortable and counterproductive. Encouraging the patient to breathe steadily and relax can ease passage of the finger.

Digital Rectal Examination SimpleMed

Image: A digital rectal (PR) examination. The gloved, lubricated finger is inserted into the rectum to palpate the rectal walls and, in men, the prostate gland on the anterior wall.

Creative commons source by National Cancer Institute [Public domain]

As you insert your finger, assess the resting anal tone: the baseline squeeze of the internal anal sphincter around your finger.

  • Reduced tone may indicate neurological pathology. In the context of back pain, leg weakness or urinary symptoms, a lax anus is a red-flag sign (a warning sign of serious disease) of cauda equina syndrome (compression of the nerve roots at the lower end of the spinal cord), which requires urgent imaging and surgical referral. Suspicion of cauda equina syndrome is based mainly on red-flag symptoms in the history, so a rectal examination is not essential and must never delay emergency referral. Reduced tone may also follow obstetric injury (damage during childbirth), previous anorectal (anus and rectum) surgery or chronic neurological disease.
  • Increased tone or spasm may accompany a painful anal fissure or anxiety.

Next, ask the patient to squeeze down on your finger as if holding in wind, to assess the voluntary contraction of the external anal sphincter. A weak voluntary squeeze adds further evidence of neurological or sphincter dysfunction.

If cauda equina syndrome is suspected, also test perianal (saddle) sensation by lightly touching the skin around the anus on both sides. Reduced perianal sensation, together with reduced anal tone, is a key red flag pointing to compression of the sacral nerve roots and mandates urgent MRI and surgical referral.

Palpation of the Rectal Walls

With your finger fully inserted, systematically rotate it through a full 360° to palpate the entire circumference of the rectal wall. Move slowly and methodically so that no area is missed.

Feel for:

  • Masses: a hard, irregular, or ulcerated mass may represent a rectal carcinoma. Note its position (using the clock face), size, and whether it is fixed or mobile, as fixed masses suggest more advanced local invasion.
  • Polyps: growths from the lining of the rectum, which may be on a stalk (pedunculated) or flat against the wall (sessile). They may be benign but can harbour malignancy (cancer).
  • Tenderness: localised tenderness may indicate inflammation, an abscess or, anteriorly in women, gynaecological pathology.
  • Faecal loading: a rectum full of hard stool supports a diagnosis of constipation and faecal impaction (stool so hard and bulky that it cannot be passed), an important and easily missed cause of overflow diarrhoea (liquid stool leaking around the blockage) and confusion in elderly patients.

An empty, ballooned rectum (widened and containing no stool) in a patient who cannot pass stool or wind can be a sign of large bowel obstruction. Interpret it alongside the history and abdominal examination.

Palpation of the Prostate (in Males)

In male patients, rotate your finger to face anteriorly (towards the front of the body, at the 12 o’clock position) to palpate the prostate gland, which lies just beyond the anterior rectal wall. Assess its size, shape, consistency, symmetry, the presence of the central groove, and any tenderness or nodules (small lumps).

A normal prostate is approximately the size of a walnut, smooth, symmetrical, with a firm consistency similar to the tip of the nose, and a palpable central (median) sulcus dividing the two lateral lobes.

Abnormal findings and what they suggest:

  • Benign prostatic hyperplasia (BPH): a smoothly enlarged, symmetrical, rubbery and non-tender prostate. As the gland enlarges, the central sulcus may become less palpable. BPH commonly causes lower urinary tract symptoms such as hesitancy (difficulty starting to pass urine) and poor stream.
  • Prostate cancer: a hard, irregular or nodular prostate, often asymmetrical with loss of the central sulcus. The malignant gland may feel craggy (hard with an uneven, rocky surface) and, in advanced disease, fixed to surrounding tissues. Any such finding warrants urgent referral and further investigation, including PSA (prostate-specific antigen, a blood test) and prostate MRI.
  • Prostatitis: an acutely tender, boggy (soft and spongy), warm and swollen prostate. In suspected acute bacterial prostatitis, vigorous prostatic massage should be avoided as it may precipitate bacteraemia (bacteria in the bloodstream).

It is important to remember that the DRE is not a sensitive test for early prostate cancer, meaning that it can miss early cases. A normal-feeling prostate does not exclude malignancy. The DRE remains valuable for assessing gland size, consistency and obvious abnormality, and for guiding further investigation.

Withdrawal and Inspection of the Glove

Slowly withdraw your finger and, before removing your glove, inspect the gloved fingertip carefully. The appearance of any material on the glove provides valuable diagnostic information:

  • Fresh red blood: suggests a lower gastrointestinal source such as haemorrhoids, an anal fissure, or a rectal or colorectal tumour.
  • Melaena: black, tarry, offensive-smelling stool indicating digested blood from an upper gastrointestinal bleed (for example a peptic ulcer), as the blood has been altered by passage through the gut.
  • Mucus: may be seen in inflammatory bowel disease, infection, or with certain colorectal tumours.
  • Pale, bulky, greasy stool (steatorrhoea): suggests fat malabsorption, for example in pancreatic insufficiency (the pancreas not releasing enough digestive enzymes) or coeliac disease (gut damage triggered by gluten).
  • Hard stool: supports a diagnosis of constipation.

Wipe away any residual lubricant from the perianal skin with the gauze or tissue to leave the patient clean and comfortable.

Completing the Examination

Help the patient to clean themselves if needed, restore their dignity, and offer them privacy to get dressed.

Dispose of your gloves, apron and used equipment into the clinical waste bin, and wash your hands.

Thank the patient.

Document the examination clearly in the notes, including the indication, the findings, and the name of the chaperone present (or that the patient declined one).

Summarise your findings.

To complete the examination, suggest performing a full abdominal examination and taking a focused history. Where appropriate, also suggest further investigations. These include blood tests: a full blood count, haematinics (tests for iron, vitamin B12 and folate, to look for a cause of anaemia) and renal function. In men with urinary symptoms, erectile dysfunction or visible blood in the urine, consider adding a PSA (prostate-specific antigen, a blood test). Stool tests include faecal immunochemical testing (FIT, which detects hidden blood in stool). FIT is not needed first if a rectal mass is felt, because referral on the suspected cancer pathway can be considered straight away. Endoscopic (camera) or radiological (scan) assessment may include flexible sigmoidoscopy (a camera test of the lower colon), colonoscopy (a camera test of the whole colon) or CT of the abdomen and pelvis. In men with an abnormal prostate, a prostate MRI and urology referral would be indicated.

Quiz

Preview the Rectal (PR) OSCE Examination quiz

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