Gallstones, fecaliths, and swallowed foreign bodies (including toothpicks and chicken and fish bones) may lodge at the anorectal junction. Urinary calculi, vaginal pessaries, or surgical sponges or instruments may erode into the rectum. Foreign bodies, sometimes bizarre and/or related to sexual play, or drug packets inserted in an attempt to conceal them from law enforcement officials, may be introduced intentionally but become lodged unintentionally; occasionally perforation may occur during insertion. Some objects are caught in the rectal wall, and others are trapped just above the anal sphincter.
Sudden, excruciating pain during defecation should arouse suspicion of a penetrating foreign body, usually lodged at or just above the anorectal junction. The presence of frank blood indicates that a laceration or perforation may have occurred. Other manifestations depend on the size and shape of the foreign body, its duration in situ, and the presence of infection or perforation.
Foreign bodies usually become lodged in the mid rectum, where they cannot negotiate the anterior angulation of the rectum. They may be felt on digital examination.
A plain x-ray of the abdomen is often helpful in identifying an object. An upright x-ray should also be done to evaluate for free air in the peritoneum due to perforation. CT may help identify radiolucent objects not seen on routine x-ray.
Removal of a rectal foreign body may be of high risk and should be done by a surgeon or gastroenterologist skilled in foreign body removal. An anoscope, proctoscope, and/or speculum can facilitate direct visualization and removal of rectal foreign bodies.
If the foreign body can be palpated, inject a local anesthetic, dilate the anus with a rectal retractor, and attempt to grasp and remove the foreign body. Regional or general anesthesia is infrequently necessary.
If the object cannot be palpated or visualized, blind attempts to grasp and remove the foreign body should not be made. Peristalsis frequently moves the foreign body down to the mid rectum, and removal attempts can then be made.
Removal via a sigmoidoscope or proctoscope can be attempted but is not always successful. Sometimes sigmoidoscopy forces the foreign body proximally, further delaying its extraction. If attempts to remove the foreign body are unsuccessful, laparotomy with milking of the foreign body toward the anus or colotomy with extraction of the foreign body is rarely necessary. After extraction, sigmoidoscopy should be done to rule out significant rectal injury.