Digital rectal exam: side view of the male reproductive and urinary anatomy, including the prostate, rectum, and bladder.
The digital rectal examination (DRE; Latin: palpatio per anum, PPA) is a relatively simple procedure. The patient undresses, then is placed in a position where the anus is accessible (lying on the side, squatting on the examination table, bent over the examination table, or lying down with feet in stirrups). During this procedure, areas which can be palpated are: the bulb of the penis, the urogenital diaphragm, the anorectal ring, and other nearby anatomical landmarks. However, structures like the ureter (the two tubes that run from each kidney to the urinary bladder), and the urethra (which, in a male. is divided into three parts, and is inside the penis) cannot be palpated.
If the patient is lying on his side, the physician will usually have him bring one or both legs up to his chest. If the patient bends over the examination table, the physician will have him place his elbows on the table and squat down slightly. If the patient uses the supine position, the physician will ask the patient to slide down to the end of the examination table until his buttocks are positioned just beyond the end. The patient then places his feet in the stirrups.
The physician spreads the buttocks apart and will usually examine the external area (anus and perineum) for any abnormalities such as hemorrhoids, lumps, or rashes. Then, as the patient relaxes, the physician slips a lubricated finger into the rectum through the anus and palpates the insides for approximately sixty seconds.
This examination may be used:
- for the diagnosis of rectal tumors and other forms of cancer;
- for the diagnosis of prostatic disorders, notably tumors and benign prostatic hyperplasia, but the DRE frequently misses more early-stage tumors than Prostate-specific antigen (PSA) among African American and Caucasian men. If PSA is positive (frequently false positive), then DRE can be done to reduce the false positive;
- for the diagnosis of appendicitis or other examples of an acute abdomen (i.e. acute abdominal symptoms indicating a serious underlying disease);
- for the estimation of the tonicity of the anal sphincter, which may be useful in case of fecal incontinence or neurologic diseases, including traumatic spinal cord injuries;
- in females, for gynecological palpations of internal organs;
- for examination of the hardness and color of the feces (i.e. in cases of constipation, and fecal impaction);
- prior to a colonoscopy or proctoscopy;
- to evaluate hemorrhoids;
- in newborns to exclude imperforate anus.
- through the insertion of medical devices including thermometers or specialized balloons; to identify digestion problems, parasites, organ damage, anal bruising, and foreign objects in the rectal cavity.
The DRE is inadequate as a screening tool for colorectal cancer because it examines less than 10% of the colorectal mucosa; sigmoidoscopy is preferred. However, it is an important part of a general examination, as many tumors or other diseases are made manifest in the distal part of the rectum.
Sometimes proctoscopy may also be part of a rectal examination.
In veterinary medicine rectal examination is useful in dogs for analysis of the prostate (as in men), pelvic urethra, sublumbar lymph nodes, and anal glands. In horses it is a vital component of the clinical examination for colic, to determine the presence or absence of bowel torsion, impaction, or displacement. When horses undergo a rectal examination there is a small risk of a rectal tear occurring, which can be a life-threatening event, rapidly leading to peritonitis and septic shock. It is also a common procedure in cattle, and is one method of diagnosing pregnancy in both the horse and the cow.
The procedure in dogs and cats is similar to humans. For the horse, the patient stands in a stock and may be sedated. The examiner puts on a long glove that extends to the shoulder. The examiner inserts the hand and arm into the rectum as far as necessary.
Due to the taboos surrounding the anus, and the potential for discomfort and embarrassment, the rectal exam is a common comedic device, including in episodes of Saturday Night Live, Futurama, Family Guy and South Park.
The practice of rectal exams without prior consent has been reported by many patients in various countries. According to a media report, a number of student physicians in Australia and the United Kingdom had not been taught to obtain prior consent from patients prior to examining their rectum. In 2008 a man in the United States alleged he had been forced to undergo a rectal examination while in hospital, despite lodging vigorous objections with hospital staff. 
- Chodak, GW.; Keller, P.; Schoenberg, HW. (May 1989). "Assessment of screening for prostate cancer using the digital rectal examination.". J Urol 141 (5): 1136–8. PMID 2709500.
- Schroder, F. H.; Kruger, A. B.; Rietbergen, J.; Kranse, R.; Maas, P. v. d.; Beemsterboer, P.; Hoedemaeker, R. (1998). "Evaluation of the Digital Rectal Examination as a Screening Test for Prostate Cancer". JNCI Journal of the National Cancer Institute 90 (23): 1817–1823. doi:10.1093/jnci/90.23.1817. ISSN 0027-8874.
- "Effects of False-Positive Prostate Cancer Screening Results on Subsequent Prostate Cancer Screening Behavior". Retrieved August 11, 2013.
- New York Magazine - Vol. 28, No. 11. "Saturday Night Live at twenty"
- "Alien anal probe saw Saints Row IV refused classification in Australia". IGN Entertainment Inc. June 25, 2013. Retrieved July 19, 2014.