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Figure 1.19. Small-bowel obstruction secondary to VP shunt. Supine film of the abdomen (A) reveals the presence of a VP shunt on the left. Dilated loops of small bowel indicate a small-

bowel obstruction. Small-bowel series on the same patient (B) shows an abrupt change in small-bowel caliber, with the VP shunt wrapped around the transition point.

around a loop of small bowel, resulting in a strangulated obstruction [64]. The authors recommended attempting to remove the knot by straightening the shunt catheter over a guide wire. In another patient, the catheter provided the axis about which a small-bowel volvulus occurred [65]. In a similar fashion, the small bowel may be acutely wrapped about a VP shunt with resultant obstruction (Fig. 1.19).

Ingested Mercury

Metallic mercury may enter the GI tract secondary to accidental or purposeful ingestion or rupture of a mercury-filled balloon of a small intestinal tube (Miller-Abbott or Cantor) (Fig. 1.20). Accidental ingestion is usually secondary to breakage of a thermometer in the mouth. Encountered much less often is swallowing of an oral thermometer (Fig. 1.21) with subsequent breakage and mercury spillage. Obviously in medical facilities the use of electronic instruments has greatly

Figure 1.20. Mercury spill from a Cantor tube.

Supine film of the abdomen reveals a Cantor tube in the small bowel. Although most of the mercury is still in the bag, multiple small globules have escaped and lie within the intestines.

Figure 1.20. Mercury spill from a Cantor tube.

Supine film of the abdomen reveals a Cantor tube in the small bowel. Although most of the mercury is still in the bag, multiple small globules have escaped and lie within the intestines.

Figure 1.21. Swallowed thermometer. Lateral film of the chest shows an accidentally ingested oral thermometer inside the stomach.

decreased the risk of such accidents, but they may still occur in the home setting.

Elemental mercury (valence = 0) is poorly absorbed from the gastrointestinal tract [66]. Therefore, large doses are necessary to cause toxicity. When inorganic mercury (valence = +1, +2) is placed in the GI tract, 7 to 15% of the dose is absorbed. This is the principal danger following the swallowing of a mercury "button" or disc battery by children. Organic mercury poisoning is usually associated with fungicides or other industrial contamination.

The risk to patients who have elemental mercury in the GI tract is related to its oxidation to inorganic mercury. This does not usually occur within the GI tract, partially because the mercury is fairly rapidly eliminated in the stool. However, if and when mercury extravasates, especially into the retroperitoneum, conditions are favorable for its oxidation. Retention within a diverticulum or the appendix may lead to local inflammation and systemic effects [67].

Another, and much more rare complication of mercury-filled balloons of Miller-Abbott tubes is that of aspiration. In one case, the balloon ruptured during removal and the patient aspirated approximately 5mL of mercury [68]. Acute mercurialism resulted in the patient's death 5 days later.

Retained Surgical Implements

The problem of the retained surgical implement is an old one that is not infrequently encountered. Estimates range from 1 in 1000 to 1 in 1500 laparotomies [69-72]. The true incidence of the problem may be more difficult to ascertain because "a foreign body problem is rarely discussed as there is an understandable tendency not to advertise one's errors" [73].

Surgeons have been using, and losing, sponges, and presumably other implements as well, since 1884 [74] (Figs. 1.22 and 1.23). By 1929, abdominal roentgenograms were recommended and used to detect inadvertently retained sponges [75] (Fig. 1.24). Markers of barium-impregnated threads were introduced after 1933 [76] (Fig. 1.25). Yet the problem continues to this day.

There are many interconnected factors leading to the ongoing problem. During laparotomy, changes in the operative field and in the positions of intestines that are displaced and packs (laparotomy or lap pads) that are moved for better visualization can lead to the obscuring of the sponge or "lap" pad. The pelvis, because of its many recesses, is the area most frequently involved in cases of "lost" sponges [70]. However, in our personal experience, widespread oncological resection is by far the most common procedure in which this happens. Long and difficult procedures in which it is easy to lose count of placed sponges and pads may also contribute to losing track of implantables, as does the patient's overall condition [77]. Changeovers in nursing and other ancillary personnel may also contribute to miscounts of the sponges and pads. Lastly, lack of familiarity with the x-ray, CT, and ultrasound appearance of retained sponges may lead to a failure to recognize their presence promptly on postoperative examinations [70,78].

The natural history the retained surgical sponge ranges from simple extrusion along surgical planes to erosion into an adjacent hollow viscus. Superimposed infection may lead to abscess formation and the need for drainage and/or reexploration. Four stages of the body's reaction to a retained surgical spine, namely, foreign body reaction, secondary infection, mass formation, and remodeling, were documented in an experimental study [79].

Detection during the first postoperative month is usually related to inflammation [70]. Aseptic reaction is usually without any significant symptoms. An exudative reaction leads to early but nonspecific symptoms [80]. Afterward, discovery is related to mass effect, bowel obstruction, erosion, and/or fistula formation [69,70,78,81]. Symptoms may include abdominal pain, postoperative ileus, bladder disturbances, or rectal tenesmus [78].

Figure 1.22. Retained surgical clamp. Antero-posterior (A) and lateral (B) films from an upper GI series show a large metallic clamp, retained in the abdomen. The patient was asymptomatic and had not had surgery in at least 20 years; this was an incidental finding.

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