Metformin Guidelines

Previous recommendation/black box warnings indicated that metformin should not be given to men with a serum creatinine greater than 1.5 mg/dL or women with a serum creatinine greater than 1.4 mg/Dl. The main concern here was the increased risk of developing lactic acidosis in patients with high serum levels of metformin due to decreased metformin excretion with decreased renal function. Current guidelines, based on the creatinine clearance (CC) rather than serum creatinine alone, are more liberal, reflecting greater clinical experience with the use of metformin in treating type 2 DM. They include normal use of metformin in patients with CC > 60 ml/min, and cautious use between CC of 45-60. At a creatine clearance of 30-45, patients doing well on metformin can continue taking it, but the dose should generally be reduced by one half. At this CC, patients should not be newly started on metformin. Metformin should not be used in patients with a creatinine clearance < 30 ml/min.

Anal Fistula and Perianal Abscess

Perianal or perirectal Abscess

Perianal abscesses are typically polymicrobial with both aerobic and anaerobic bacteria.

-They spread through the external sphincter below the level of the puborectalis and become ischiorectal abscesses.

-Anorectal abscesses are more common in early middle-aged males.

Symptoms & Signs: Severe pain in the anal or rectal area, fever, malaise, purulent rectal discharge ischiorectal abscess:  Swelling in the ischiorectal fossa on digital rectal examination


-Diagnosis can usually be made with physical exam alone;  CT or MRI help to delineate the anatomy of the abscess

Erythema, fluctuance, and swelling in the perianal region on external examination

-Digital rectal exam will reveal a painful swelling laterally in the ischiorectal fossa. Treatment: Perianal abscesses are treated with local incision and drainage, while ischiorectal abscesses require drainage in the operating room.

Prognosis: After drainage of an abscess, most patients are found to have a fistula in ano.

-Delayed treatment can result in tissue necrosis and sepsis.

-Surgical referral after drainage recommended because of the risk of fistula formation.


Anal Fistula

An anorectal fistula is the chronic manifestation of the acute perirectal process that forms an anal abscess

-The majority of anorectal fistulas originate from an infected anal crypt gland

-Drainage of an anorectal abscess results in cure for about 50% of patients while the remaining 50% develop an anal fistula.

-Causes of fistulas that connect to the rectum include: Crohn disease, Lymphogranuloma venereum, rectal tuberculosis, cancer

Symptoms & Signs: purulent discharge, itching, tenderness, and pain

Diagnosis: Drainage from the internal and/or external openings.

-An indurated tract is often palpable.

-Goodsall’s rule can be used as a guide in determining the location of the internal opening

Imaging studies: Endosonography (EUS), fistulography, CT or MRI show air or contrast material within the fistula.

Treatment: Fistula in ano is treated by surgical excision under anesthesia