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Great Ormond Street Hospital for Children London WC1N 3JH, United Kingdom
It is a curious phenomenon whereby ideas or observations in the medical literature get transformed, despite insufficient evidence, into irrefutable "fact." This process could be identified in an otherwise excellent article on intussusception in children by Koumanidou et al. [1]. In their introduction, the authors state that the absence of blood flow in the intussusceptum on sonography has been related to irreducibility. That is correct, and the authors cite three references to support the statement [2,3,4]. In those three articles, however, a combined total of only eight intussusceptions with absent blood flow was reported, and no perforation occurred during attempted reduction. Yet, in their concluding paragraph, Koumanidou et al. state, "The only criterion prohibiting a hydrostatic reduction attempt is the absence of blood flow in the intussusceptum."
I am aware of two or three intussusceptions that appeared avascular on Doppler sonography but were subsequently successfully reduced. Assessment of the blood flow within an intussusception is likely to be as dependent on the equipment used as on the lesion itself. In a wriggling, uncooperative child at two in the morning (why are intussusceptions virtually always seen in the middle of the night?), it can be difficult to reliably exclude absent blood flow in the intussusception mass. It is possible that, with the state-of-the-art scanners currently available, the statement that absent blood flow equals irreducibility may ultimately prove correct, but not all children are scanned by the best available equipment; and sonography is, of course, operator-dependent. I believe that until series with greater numbers are available, absent blood flow should remain a relative contraindication or a pointer to proceeding with caution in these children. Perhaps attempting a pneumatic reduction of the intussusception at 80 mm Hg only in this setting would be better advice for the moment.
References
"Agia Sophia" Children's Hospital Goudi 11527, Athens, Greece
We appreciate Dr. McHugh's interest in our recent article [1], raising an interesting point about the relationship between the absence of blood flow on color Doppler sonography and intussusception irreducibility.
Our work was on the sonographic detection of lymph nodes in the intussusception of infants and young children and on the relationship of lymph nodes with gastroenteritis and intussusception irreducibility. We had no observations on color Doppler sonography; therefore, we were not able to transform them to "irrefutable facts." However, we stated in our introduction that the absence of blood flow in the intussusceptum—among other factors—has been related to irreducibility; we cited three references to support this idea and to introduce such factors. McHugh is certainly right to criticize the overconclusive statement in our conclusion, "The only criterion prohibiting a hydrostatic reduction attempt is the absence of blood flow in the intussusception," which was originally preceded by the phrase, "In our opinion."
A review of the literature shows that the absence of signal in Doppler sonography is usually correlated with bowel necrosis and is a sign of irreducibility [2,3,4,5]. Lim et al. [2] presented three patients with absent blood flow who required bowel resection, out of 65 patients with intussusceptions. The authors underlined the relevance of the site of Doppler sonographic examination (i.e., that the distal segment is more vulnerable to perforation). In smaller series, Lagalla et al. [3], and Lam and Firman [4] reported two in 11 patients with intussusception and three in 15 patients with intussusception, respectively, who had absent signal and underwent surgery. Kong et al. [6], in a larger series of 125 patients with 134 intussusceptions, found 13 cases in which no blood flow was detected; however, bowel necrosis was not significantly correlated with the absence of Doppler signal. In accordance with McHugh, Kong et al. concluded that the lack of detection of blood flow on color Doppler sonography is not a contraindication for air reduction. A report of two patients by Hanquinet et al. [7] showed no blood flow in one of them.
Concerning our own experience, during the past 4 years, we had six patients with absence of blood flow who required segmental bowel resection because of intestinal necrosis. Our scanners are new and technologically up-to-date, and all children with a plausible intussusception are scanned by this equipment. The same two experienced radiologists in our department, even "at two in the morning," do their best to reliably exclude absent blood flow. Furthermore, color Doppler sonographic images are obtained in at least three sites of the intussusception (proximal, middle, and distal).
Taking all this into consideration, no definitive answer can be made to the point raised by McHugh. Further research has to be carried out in a large series of patients. Until then, we agree with McHugh that absence of blood flow on color Doppler sonography should at least point toward more cautious and gentle reduction attempts. We also agree that ideas in the literature should not be taken for granted without clear proof, and we want to express our gratitude for McHugh's comment.
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