The anus is the final 3 to 4 centimeters of the gastrointestinal tract, and it extends from the rectum to the anal margin.
The top and bottom of the anal canal are surrounded by the internal and the external anal sphincters, which are two muscular rings that control defecation.
The internal sphincter is under involuntary control, while the external sphincter is under voluntary control.
Within the anal canal, there are mucosal membrane infoldings that form the anal columns.
And at the base of these columns, there is the dentate or pectinate line, which divides the upper two thirds and lower third of the anal canal.
Above the dentate line, there’s the mucosa is lined by simple columnar epithelium, and below the dentate line, there’s the anoderm, which has no hair and sebaceous and sweat glands, and is lined by squamous epithelium.
Now, hemorrhoids are normal vascular structures in the anal canal that act as cushions for the stool as it passes through.
Hemorrhoidal disease is when hemorrhoids get swollen or inflamed; but the term "hemorrhoid" is often used to refer to the disease.
Hemorrhoids are often caused by chronically or recurrently increased abdominal pressure, from a variety of causes.
For example, straining during bowel movements, chronic diarrhea or constipation, obesity, pregnancy, and old age.
Complications of hemorrhoids can include anemia due to chronic blood loss; strangulation if the blood supply to an internal hemorrhoid is cut off, leading to ischemia; and thrombosed hemorrhoids, which is when blood pools inside a hemorrhoid and forms clots.
Internal hemorrhoids are ones above the dentate line, and external hemorrhoids are ones below the dentate line.
Internal hemorrhoids are subclassified into four grades based on the degree of prolapse from the anal canal.
Grade I hemorrhoids don’t protrude outside the anal canal.
Grade II hemorrhoids protrude outside the anus during bowel movement, but they retract spontaneously.
Grade III are prolapsed hemorrhoids that don’t retract spontaneously, but they can be pushed back in manually.
Finally, grade IV hemorrhoids are prolapsed hemorrhoids that cannot be manually pushed back in.
Internal hemorrhoids usually don’t cause symptoms, but sometimes they get inflamed, causing itching, burning, vague discomfort, and painless passage of bright red blood with a bowel movement.
On the other hand, external hemorrhoids are innervated somatically, and they’re typically painful, especially when associated with thrombosed hemorrhoids, which have no blood flow due to a blood clot in the vein, and swelling in the affected area.
A diagnosis is usually made based on a visual and digital exam of the anus.
However, the internal hemorrhoids grade I and II lie inside the rectum, so they can’t be seen or felt, and confirmation requires anoscopy, which involves the insertion of a hollow tube-shaped device with a light attached at one end.
Internal hemorrhoids look like bulging purplish-blue veins, and prolapsed internal hemorrhoids appear dark pink, glistening, and are sometimes tender masses at the anal margin.
Thrombosed external hemorrhoids are tender and have a purplish hue.
Further testing with flexible sigmoidoscopy or colonoscopy is recommended if signs and symptoms suggest another digestive system disease and in individuals older than 40 years with symptoms of colorectal cancer, like anemia, weight loss, and change in bowel habit - meaning a change in frequency, consistency, or in caliber of the stools.
The initial conservative management for symptomatic hemorrhoids is usually home-based by increasing fiber intake and drinking more water.
If this is not enough, stool softeners may be helpful.
Individuals may also take medications like oral or local NSAIDs like acetaminophen, ibuprofen, or naproxen to treat pain, as well as topical agents containing anesthetics like lidocaine for pain, or a hydrocortisone cream to reduce local swelling.
In addition, individuals may also take sitz baths, which are warm shallow baths that cleanse the perineum, to help relieve irritation, pruritus, and anal sphincter spasms.
Individuals with thrombosed hemorrhoids may also apply ointments containing antispasmodic agents like nitroglycerin - a nitric oxide donor - to reduce painful sphincter spasms.
Finally, individuals that have bleeding associated with their hemorrhoids may get venoactive agents or phlebotonics to increase venous tone of hemorrhoidal tissues and reduce bleeding.
Individuals with symptomatic internal hemorrhoids that don’t improve with conservative treatment may need a simple office-based procedure like rubber band ligation, sclerotherapy, or infrared cauterization for coagulation.
Rubber band ligation is commonly used for individuals with grade II or III internal hemorrhoids.
Elastic bands are applied onto an internal hemorrhoid at least 5 millimeters above the dentate line to cut off its blood supply while avoiding any somatically innervated tissue.
Within a week, the hemorrhoid tissue becomes necrotic and simply falls off.
The most common complication of rubber band ligation is pain.
Other uncommon complications include delayed hemorrhage if the rubber band dislodges, hemorrhoidal thrombosis, localized infection or abscess at the site of band ligation, sepsis, or urinary retention.
Sclerotherapy may be done in case of grade I or II hemorrhoids, and it involves the injection of a sclerosant agent, like phenol, into the hemorrhoid.
The sclerosant agent causes an intense inflammatory reaction, destroying the vein walls and making the hemorrhoid collapse and shrivel up.
Complications of sclerotherapy are uncommon, and include minor discomfort or bleeding with the injection, rectourethral fistulas, rectal perforations, and necrotising fasciitis, which can occur with misplaced injections into non hemorrhoidal tissues or into the vasculature.
Finally, there’s infrared cauterization which is commonly used for grade I or II internal hemorrhoids, and it’s usually only used for when other methods fail.
It involves applying infrared light waves onto hemorrhoidal tissues, making a tiny burn to remove tissue and painlessly seal the end of the hemorrhoid.
Within a week, the hemorrhoids generally dry up, shrink, and fall off.
Infrared cauterization is associated with more recurrences but fewer complications and causes less discomfort immediately after the procedure.
Now for hemorrhoids that don’t improve with home-based and office-based procedures, and for internal grade IV hemorrhoids, strangulated internal hemorrhoids, or severely symptomatic external hemorrhoids, surgery may be needed.
An external hemorrhoidectomy is done by making an elliptical incision in the skin overlying the hemorrhoid.
The incision goes around the hemorrhoid and its carefully separated from the anal sphincter, to avoid injury.
An internal hemorrhoidectomy can be done in a few different ways.
In a conventional hemorrhoidectomy, the hemorrhoid is carefully excised from the superficial internal and external sphincter muscles.
Stapled hemorrhoidopexy is an alternative to conventional internal hemorrhoidectomy.
It involves the removal of much of the abnormally enlarged hemorrhoidal tissue, followed by a repositioning of the remaining hemorrhoidal tissue back to its normal anatomical position.
The device also interrupts part of the hemorrhoidal blood supply, thereby decreasing vascularity.
A final alternative is Doppler-guided transanal hemorrhoidal artery ligation, which uses a specially designed proctoscope housing a Doppler transducer to identify each hemorrhoidal arterial blood supply, which is subsequently ligated, followed by plication of the redundant hemorrhoidal tissue.
Complications following hemorrhoidectomy are uncommon.
The main complications include urinary retention mainly associated to spinal anesthesia; urinary tract infection possibly secondary to urinary retention; fecal incontinence due to pain, anal spasm, and changes in sensation; anal stricture if too much anoderm is resected; and delayed hemorrhage due to sloughing of the primary clot, which usually occurs 7 to 16 days after the procedure.
Following surgery, pain can be controlled with NSAIDs and warm sitz baths.
In addition, increased dietary fiber with fruits, vegetables, and grains, as well as staying hydrated by drinking about 2 liters of fluids per day can help reduce postoperative constipation and pain with defecation.
Moving on, an anal fissure is a tear to the anoderm, which contains many sensory receptors.
So anal fissures cause anal pain and bleeding that often accompany bowel movements.
The pain can be so severe that it can lead to avoidance of toileting, which leads to fecal impaction and constipation.
As the stool remains in the gastrointestinal tract, more fluid gets reabsorbed, leaving the stool hard.
Passage of the hard stool can cause anal trauma and make the fissure worse.
An anal fissure can also cause exposure of the internal sphincter muscle, leading to muscle spasms which can worsen the pain, restrict blood flow to the fissure, and prevents healing of the fissure.
So some fissures are acute, lasting less than 4 to 6 weeks, whereas others become chronic, lasting for more than 6 weeks.
Chronic fissures typically show an exposed white edge of the internal anal sphincter muscle at the base of the fissure.
Often times chronic fissures are accompanied by external skin tags.
At distal end of the fissure, the tag is called a sentinel pile, and at the proximal end of the fissure, the tag is called a hypertrophied anal papillae.
A primary fissure is one that results from anal trauma, for example from constipation.
Other causes include the use of rectal thermometers, enemas, an endoscope, an ultrasound probe, from a vaginal delivery, and anal intercourse.
Most of the time, anal fissures are located in the posterior midline of the anal canal, and less often they can be in the anterior midline.
Sometimes, there are fissures in both the anterior and posterior midline, and these are called "kissing fissures".
Anal fissures in a lateral location are atypical and are more commonly due to a secondary cause, like Crohn’s disease, sarcoidosis, an infection such as HIV or syphilis, and anal cancer.
The diagnosis of an anal fissure is confirmed with inspection and gentle digital palpation of the anal verge causing anal pain.
Individuals with rectal bleeding or an atypical location of the fissure should get further evaluation, including anoscopy, colonoscopy, or sigmoidoscopy to exclude secondary causes of an anal fissure or an alternative diagnosis like hemorrhoids.
Treatment for anal fissures involves a combination of a stool softener like oral docusate sodium, sitz baths, and topical analgesic like lidocaine, and a topical vasodilator ointment like nifedipine or nitroglycerin for one month.
Individuals with persistent symptoms are given another month of the same treatment.
After that, individuals who still have persistent symptoms are sent for an endoscopy to evaluate for a secondary cause.
If there’s no evidence of another cause, the individual may need surgical treatment like a botulinum toxin type A injection or a lateral internal sphincterotomy, in which the internal sphincter is divided to lower its resting pressure, which helps improve blood supply to the fissure and allows faster healing.
The main complication of surgical treatment for anal fissures is fecal incontinence.
Now, individuals who aren’t surgical candidates are treated with the alternate topical vasodilator - so nitroglycerin ointment if they were initially treated with nifedipine ointment, and vice versa - or one of the second-line agents like topical diltiazem, topical bethanechol, oral nifedipine, or oral diltiazem.
Pilonidal disease is a common anal condition characterized by skin infection in the gluteal cleft.
This is usually related to mechanical forces on the skin damaging and opening pores that collect loose hairs and debris, leading to hair follicle infection.
Pilonidal disease most often affects individuals in their late teens and early twenties with a male predominance.
