In general, intestinal foreign bodies are straightforward to treat and have a good prognosis as long as they are diagnosed early. Linear foreign bodies, however, present particular problems for surgeons. String, cords, fabric and tape are capable of passing through the gastrointestinal tract uneventfully, but create problems when one end becomes lodged and the remainder of the foreign body is propelled along the intestine by peristalsis. Because the tethered string cannot be expelled, the intestine telescopes orally and becomes plicated. The string may then cut through the intestinal wall as it becomes tight (usually at the mesenteric edge). Due to the plication of the intestines, it is not possible to simply extract the string by pulling on one end, as that tightens it further and exacerbates the risk of intestinal perforation. The combined difficulties of removing the string, and extensive intestinal damage, mean that multiple enterotomies and/or intestinal resection are often indicated. Patients with chronic linear foreign bodies may be suffering from malnutrition, dehydration or even peritonitis, and this combined with extended surgical times can lead to a high mortality rate.

Diagnosis

Patients usually present with classic signs of intestinal foreign body including vomiting, diarrhea, dehydration and abdominal pain. Septic peritonitis and shock occur when the intestine is perforated. Cats seem more tolerant of linear foreign bodies and may have signs for a few days before the diagnosis is made. Dogs seem to develop intestinal perforation more readily.¹ Plicated bunches of intestine may be palpable, and abdominal radiographs may show small, eccentrically placed air bubbles that correspond to each plicated loop. Radiographic contrast studies outline plicated intestine but are contraindicated if intestinal perforation is suspected, or if anesthesia and surgical exploration are imminent. Abdominal sonography is a sensitive method for detecting intestinal plication and the linear foreign body will often be seen as a discrete line within the lumen of the intestine.

The oral cavity should be examined carefully to rule out the possibility of a string foreign body tethered beneath the tongue, especially in cats. The string may cut through the frenulum of the tongue and bury itself in soft tissues, so the tongue should be lifted and the underside inspected carefully. It is also possible for linear foreign bodies to lodge in the esophagus, and a thoracic radiograph should be taken if this is suspected. However, most linear foreign bodies bunch up and lodge at the level of the pylorus.

Figure 1. Small intestinal plication in a dog.

Surgical Approach

Once any extra-abdominal site for tethering of the foreign body has been ruled out, a celiotomy is performed in order to fully evaluate the abdominal contents and gastrointestinal tract. The GI tract should be handled gently to avoid further damage from the tight string-like foreign body. If the linear foreign body is tethered in the stomach, a gastrotomy is performed and the main mass of foreign body removed. Do not try to pull the foreign body back out of the intestine if there is any evidence of plication. A length of foreign body that is long enough to be secured to a red rubber feeding tube should be teased out from the pyloric antrum. Undue traction should not be placed on the foreign body as it exits the pylorus, as this can cause it to cut through the plicated intestine. Once the linear foreign body is attached to the tip of the red rubber catheter, the catheter can be advanced into the gastrotomy incision, through the pylorus and down the small intestine, thereby unfolding the string in the direction of peristalsis and allowing the plicated intestine to stretch out behind it.²

Figure 2. Anderson technique for relieving plication.

Figure 3. A red rubber tube (arrow) has been attached to the linear foreign body and is being advanced down the intestine towards the ileum and colon (right). Thus the plicated intestine stretches out once the catheter and linear foreign body have passed through it (left).

This technique is only indicated in cases where perforation has not yet occurred. Even so, the intestine should be evaluated very carefully for perforation, often indicated by bruising along the mesenteric edge. Bulky foreign bodies may not be removable using this technique, in which case multiple enterotomies will be required. The total mass of foreign body increases as it is drawn towards the ileum, and in many cases this bunches up enough to necessitate removal via a single enterotomy in the terminal jejunum or ileum, but in some cases the catheter can be advanced all the way through the colon and out the anus, pulling the string behind it. Once the entire foreign body has been removed, and there are no residual areas of devitalized or perforated intestine, the abdomen is lavaged and closed routinely.

References

1.  Evans KL, Smeak DD, Biller DS. Gastrointestinal linear foreign bodies in 32 dogs - a retrospective evaluation and feline comparison. J Am Animal Hosp Assoc 1994;30:445–450.

2.  Anderson S, Lippincott CL, Gill PG. Single enterotomy removal of gastrointestinal linear foreign bodies. J Am Anim Hosp Assoc 1992;28:487–490.